JP5547285B2 - Optical logic circuit, control method thereof and integrated circuit - Google Patents

Description

  The present invention relates to an optical logic circuit configured using, for example, quantum dot elements, a control method thereof, and a technical field of an integrated circuit formed by integrating such an optical logic circuit.

  This type of optical logic circuit includes a quantum dot layer portion in which a plurality of quantum dot layers are stacked. Quantum dots are arranged in each quantum dot layer. The presence or absence of output light (strictly speaking, the intensity of the output light) changes depending on the presence or absence of input light due to the coupling of near-field light between these quantum dots or the propagation of light emission. . Therefore, by turning on / off the signal light of the input light according to the value of the digital information and detecting the output light, it is possible to perform a logical operation specific to each quantum dot layer unit (for example, Patent Document 1-8).

JP 2004-528705 A JP-A-2005-93553 JP 2006-269886 A JP 2007-53322 A JP 2007-157975 A JP 2005-534164 A JP 2009-10425 A JP 2009-231601 A

  However, in the technique disclosed in the patent document, the input light used in each quantum dot layer portion has a wavelength predetermined in design (that is, a specific or largest PL emission peak wavelength). Limited to light. Therefore, each individual quantum dot layer unit constructs a logic circuit that performs only one predetermined logic operation. Therefore, if the required logical operations are different, it is necessary to construct different quantum dot layer portions, or as many different quantum dot layer portions as the required logical operations are required. As a result, as the required logical operation increases, the number of quantum dot layer portions increases in proportion thereto, resulting in an increase in circuit scale.

  There is a technical problem that this is an essential impediment in the progress of circuit miniaturization, high-speed operation, low power consumption, etc., which are the greatest advantages of optical logic circuits.

  The present invention has been made in view of the above-described problems, for example, an optical logic circuit capable of suppressing the enlargement of the circuit scale or capable of efficient logic operation, its control method, and such An object is to provide an integrated circuit in which optical logic circuits are integrated.

In order to solve the above problems, the optical logic circuit of the present invention provides
A quantum dot layer portion including a base light layer and a signal light layer laminated on the base light layer; base light source means for emitting base light toward the base light layer; and A signal light source unit that emits light toward the signal light layer, and the quantum dot layer unit is configured as the signal light layer in order from the base light layer side to the mth layer (where m is (Natural number of 2 or more) layers are laminated, and the i-th layer (where i is a natural number from 1 to m-1) as the signal light layer has two or more PL emission peak wavelengths, The m-th layer as the signal light layer has a PL emission characteristic that is at least partially different from the i-th layer and has one or more PL emission peak wavelengths. The base light layer has two or more PL emission peak wavelengths, and the signal light source means uses the jth (where j is a natural number from 1 to m) signal light as the signal light, Controlling the signal light source means to emit to the j-th layer as a signal light layer, and to change the j- th signal light according to the value of information provided to a logical operation to be performed, The base light source means and the signal light source means so as to switch each of the wavelength of the base light and the wavelength of the j-th signal light to one of the two or more PL emission peak wavelengths according to the type of the logical operation. further control means for controlling includes at least one layer of the first layer to the m layer as the base-light layer and layer for the signal light, (i) the base light and the wavelength of light corresponding to the at least one layer of the j signal light, when the a first wavelength of the two or more PL emission peak wavelength, the first type of logical operation is performed, (ii The second type different from the first type when the wavelength of the light corresponding to the at least one layer is a second wavelength different from the first wavelength among the two or more PL emission peak wavelengths. The logic operation is performed.

In order to solve the above-described problem, a method for controlling an optical logic circuit according to the present invention includes a base light layer , a quantum dot layer portion including a signal light layer laminated on the base light layer, and a base light. A base light source unit that emits light toward the base light layer; and a signal light source unit that emits signal light toward the signal light layer. The quantum dot layer unit includes the base light as the signal light layer. The first to m-th layers (where m is a natural number of 2 or more) are stacked in order from the first layer, and the i-th (where i is 1 to m−1) layer as the signal light layer. The (natural number) layer has two or more PL emission peak wavelengths, and the m-th layer as the signal light layer has a PL emission at least partially different from the i-th layer. And the base light layer has two or more PL emission peak wavelengths, and the signal light source means has the jth ( Here, j is a natural number from 1 to m) and is a control method for controlling an optical logic circuit that emits signal light toward the j-th layer as the signal light layer, and the j- th signal light is executed. A change step for controlling the signal light source means to change according to a value of information to be subjected to a power logical operation, and each of the wavelength of the base light and the wavelength of the j-th signal light as the type of the logical operation in response, the to switch to one of two or more PL emission peak wavelength, wherein the base light source means and the signal source and a switching step of controlling means, Les for the base-light layer and the signal light At least one layer of the first layer to the m layers as yer is, (i) a wavelength of light corresponding to the at least one layer of said base light and the j-th signal light, said two or more When the first wavelength of the PL emission peak wavelengths is the first wavelength , the first type of logical operation is performed, and (ii) the wavelength of the light corresponding to the at least one layer is the two or more PL emission peak wavelengths. The second type of logical operation different from the first type is performed when the second wavelength is different from the first wavelength .

  In order to solve the above problems, the integrated circuit of the present invention is formed by integrating a plurality of the above-described optical logic circuits of the present invention.

  In order to solve the above-described problems, an optical logic element of the present invention has the above-described quantum dot layer portion used in the above-described optical logic circuit according to the present invention.

  In order to solve the above-described problems, another optical logic device of the present invention has the above-described quantum dot layer portion used in the above-described integrated circuit according to the present invention.

  In order to solve the above-described problems, another optical logic element of the present invention is the above-described quantum dot layer portion according to the present invention, wherein the signal light layer has two or more PL emission peak wavelengths.

  Such an operation and gain of the present invention will be clarified from the embodiments described below.

1 is a schematic perspective view showing a basic configuration of a first embodiment of an optical logic circuit of the present invention. It is typical sectional drawing of the quantum dot layer part in 1st Example. FIG. 6 is a characteristic diagram schematically showing wavelength spectra of signal light and base light when a first type of logical operation is performed in the first embodiment. It is a characteristic view which shows the wavelength spectrum of the 1st signal light in 1st Example. It is a truth table which shows the relationship between signal light and output light in the case of performing the first type of logical operation in the first embodiment. FIG. 6 is a characteristic diagram schematically showing wavelength spectra of signal light and base light when a second type of logical operation is performed in the first embodiment. It is a truth table showing the relationship between signal light and output light when performing the second type of logical operation in the first embodiment. 3 is a flowchart showing a logic operation in the embodiment of the control method of the optical logic circuit of the present invention. It is a schematic diagram explaining the layer structure and operation principle of the quantum dot layer part in 2nd Example of the optical logic circuit of this invention. 1 is a schematic perspective view showing a basic configuration of a first embodiment of an integrated circuit of the present invention. It is a typical perspective view which shows the basic composition of 2nd Example of the integrated circuit of this invention. It is process drawing which shows a part of process of the manufacturing method of the quantum dot layer part based on the Example of this invention. FIG. 13 is a process diagram illustrating a buffer layer forming process subsequent to the process of FIG. 12. It is process drawing which shows the quantum dot formation process following the process of FIG. It is process drawing which shows the cap layer formation process following the process of FIG.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments relating to an optical logic circuit, a control method therefor, and an integrated circuit will be described below in order as the best mode for carrying out the invention.
(Embodiment of optical logic circuit)
<1>
In order to solve the above problems, the optical logic circuit of the present embodiment includes a quantum dot layer portion in which a base light layer and a signal light layer are stacked, and a base light source that emits base light toward the base light layer Means, signal light source means for emitting signal light toward the signal light layer, and changing the signal light according to a value of information to be subjected to a logical operation to be performed, and the base light and the Control means for appropriately switching the wavelength of at least one of the signal lights according to the type of the logical operation, and at least one of the base light layer and the signal light layer is (i) When the wavelength of the at least one light is switched to the first wavelength by the control means, a first type of logical operation is performed, and (ii) the at least When the wavelength of one light is switched to a second wavelength different from the first wavelength by the control means, a second type of logical operation different from the first type is performed. .

  According to the optical logic circuit of the present embodiment, at the time of operation, for example, one or two or more PL (Photo-Luminescence) emission peak wavelengths, that is, PL emission from the base light source means which is a semiconductor laser, for example. Base light having a wavelength that gives a peak in the wavelength spectrum is input to the base light layer in the quantum dot layer portion. In parallel with this, signal light having the same or different base light, for example, one or two or more PL emission peak wavelengths from signal light source means such as a semiconductor laser is used for signal light in the quantum dot layer portion. Input to the layer.

  Here, “base light” refers to a constant light intensity regardless of the value of digital information or analog information so that optical coupling or light propagation corresponding to a predetermined type of logical operation is performed in the optical logic circuit. This means light input to the optical input terminal. “Signal light” is used for signal light input while being turned on / off according to the value of digital information or light intensity is changed according to the value of analog information. It means light input to the terminal.

  In the quantum dot layer portion, the base light layer is typically a single layer or two or more layers, for example, laminated on a GaN substrate. Further, the signal light layer is typically laminated on the base light layer in a single layer or typically two or more layers. In particular, when there are two or more signal light layers, signal lights having the same or different PL emission characteristics are input to each. In the quantum dot layer portion, a buffer layer, a cap layer, a passivation layer, a protective layer, a base layer, or the like including, for example, GaAs, InAs, InGaAs, or the like may be stacked between or above these layers.

  A plurality of quantum dots (QD: Quantum Dots) are arranged in each of the base light layer and the signal light layer. A plurality of quantum dots are arranged between two adjacent ones of two-dimensionally arranged quantum dots in one layer and between ones facing each other among three-dimensionally arranged quantum dots. On the condition that the base light is input, the coupling is caused by the interaction of the near-field light, or the light emission is propagated.

  Here, in particular, the wavelength of at least one of the base light and the signal light is set to a first wavelength (for example, one or one of two or more PL emission peak wavelengths by a control unit such as a laser control device). The wavelength that gives the second largest peak). Alternatively, it is assumed that default setting or initial setting is made. In this state, the signal light is changed by the control means in accordance with the value of information provided for the logical operation to be executed.

  Here, in the case of “first wavelength” and “second wavelength”, the “wavelength” of light has a certain width including a single wavelength in the center that causes near-field light in the quantum dot layer portion. It means wavelength range or band. Typically, it includes at least one of one or more wavelengths giving a peak in PL emission, and has a width sufficient to cover a high power portion on the wavelength spectrum related to the one wavelength. It means wavelength range or band.

  Wavelength "switching" is performed by switching a frequency signal, a power supply signal, an oscillation condition, etc. applied to a base light source means or a signal light source means composed of a semiconductor laser or the like, for example. The wavelength of light at the time of emission from the means may be switched. For example, the oscillation frequency itself may be switched. Alternatively, the wavelength may be switched by applying a switchable band shutter or band filter to the light emitted from the base light source means or the signal light source means. That is, in this case, the base light source means and the signal light source means such as a semiconductor laser are brought into the same oscillation state before and after the wavelength switching.

  Then, the intensity of the output light from the quantum dot layer part is assumed in advance to correspond to the first wavelength, for example, a first type of logical operation unique to the quantum dot layer part (for example, an AND gate) , OR gate, NAND gate, NOT gate, etc.). The specifics of the first type of logical operation are left to the design matters of the quantum dot layer portion.

  Thereafter, the control means appropriately sets the wavelength of at least one of the base light and the signal light to a second wavelength (for example, two wavelengths) according to a command or the like given from the outside or generated internally. The other PL emission peak wavelength or the wavelength giving the second largest peak, etc.). Alternatively, it is assumed that the wavelength of at least one of the base light and the signal light is switched to the second wavelength or is set by default or initially by the control means.

  In this state, the signal light is changed by the control means in accordance with the value of information provided for the logical operation to be executed. Then, the light intensity level of the output light from the quantum dot layer part is, for example, a second type of logical operation inherent in the quantum dot layer part that is assumed in advance as corresponding to the second wavelength (for example, Of the AND gate, the OR gate, the NAND gate, the NOT gate, and the like, the operation result of the other one (fixed different from the first type of logical operation) is represented. The specifics of the second type of logic operation are left to the design matters of the quantum dot layer portion.

  Note that the control means typically changes the signal light in accordance with the value of information provided to the logical operation to be executed (for example, to change the binary value of ON / OFF or multi-value change). Controls the signal light source means. Further, typically, at least one of the base light source means and the signal light source means is controlled so that the wavelength of at least one of the base light and the signal light is appropriately switched according to the type of logical operation required. To do.

  As a result, a plurality of types of logical operations can be performed by using light of different wavelengths using a single quantum dot layer portion. Therefore, as many different quantum dot layer portions as the number of required logic operations are not required. As a result, even if the required logical operation is increased, the number of quantum dot layer portions does not increase in proportion to this, and the circuit scale does not have to become relatively large. This can greatly contribute to the greatest advantage of the optical logic circuit, such as circuit miniaturization, high-speed operation, and low power consumption.

In this way, in the optical logic circuit, the enlargement of the circuit scale can be suppressed, and extremely efficient logic operation is possible.
<2>
In one aspect of the optical logic circuit of the present embodiment, the at least one layer has two or more PL emission peak wavelengths, and the wavelength of the at least one light is the two or more PL emission peak wavelengths. It is a wavelength corresponding to at least one of the wavelengths.

According to this aspect, for at least one layer, (i) when the wavelength of at least one light is switched to the first wavelength, the first type of logical operation is performed, and (ii) at least one layer When the wavelength of light is switched to the second wavelength, a configuration in which the second type of logical operation is performed can be realized relatively easily. In particular, by actively using each of the two or more PL emission peak wavelengths (for example, the first largest peak wavelength and the second largest peak wavelength), stable or reliable logic operation can be achieved. It becomes executable.
<3>
In another aspect of the optical logic circuit of the present embodiment, the quantum dot layer portion is formed by laminating the first layer to the m-th layer (where m is a natural number of 2 or more) as the signal light layer, The signal light source means emits the i-th signal light (where i is a natural number from 1 to m) of the signal light toward the i-th layer of the signal light layer.

  According to this aspect, the i-th signal light is input to the i-th layer from the signal light source means (where i = 1,..., M). For example, in a simple case, the quantum dot layer part is formed by laminating a first layer and a second layer as a signal light layer, and the first signal light is input to the first layer from the signal light source means, The second signal light is input to the second layer.

  Then, for example, when the wavelengths of the i-th signal light are collectively switched to the first wavelength, the intensity of the output light from the quantum dot layer portion represents the calculation result of the first type of logical operation. It will be. On the other hand, for example, when the wavelengths of the i-th signal light are collectively switched to the second wavelength, the light intensity of the output light from the quantum dot layer portion determines the calculation result of the second type of logical operation. Will represent.

The wavelengths of the i-th signal light do not necessarily have to be switched to the same wavelength collectively, and at least one or all of them may be switched to be different. Regarding the base light and the base light layer, there may be only one or a plurality of layers.
<4>
In this aspect, the i-th layer of the signal light layer has two or more PL emission peak wavelengths, and the j-th of the signal light layer (where j is a natural number from 1 to m different from i). The layer has a PL emission characteristic that is at least partially different from that of the i-th layer and has one or more PL emission peak wavelengths, and the wavelength of the at least one light is the two or more PL emission peak wavelengths. And a wavelength corresponding to at least one of the one or more PL emission peak wavelengths.

With this configuration, for at least one layer, (i) when the wavelength of at least one light is switched to the first wavelength, the first type of logical operation is performed, and (ii) at least one layer A configuration in which the second type of logical operation is performed when the wavelength of one light is switched to the second wavelength can be realized relatively easily. In particular, by actively using each peak wavelength of two or more PL emission peak wavelengths, a plurality of signal light layers having at least partially different PL emission characteristics can be adopted, and stable or reliable Multiple types of logical operations can be performed.
<5>
In the aspect in which the first layer to the m-th layer are used as the signal light layers, two layers of the base light layer and the first layer to the m-th layer have a pair of PL emission corresponding to each other. It has at least one peak wavelength, and is arranged in the quantum dot layer portion at a position where coupling by near-field light interaction is possible, so that at least one of the two layers forming the pair exists. You may comprise.

  If comprised in this way, if it says about two layers which make a pair, when the wavelength of a signal light and a base light is switched to the PL light emission peak wavelength corresponding to the mutual, it will depend on the interaction of near field light. Bonding occurs. Here, “having at least one PL emission peak wavelength corresponding to each other” does not require that the entire PL emission spectrum is mutually identical, and the PL emission peak wavelengths in each PL emission spectrum are mutually different. This means that it is roughly or exactly the same. On the other hand, when the wavelength of the signal light and the base light is switched to a wavelength that is not the same PL emission peak wavelength, the near field is at least about the same PL emission peak wavelength. No coupling occurs due to the interaction of light. Therefore, regarding the two layers forming a pair, the intensity of light according to the coupling due to the interaction of near-field light depends on whether the same PL emission peak wavelength is used or not. It appears clearly in their output light. Therefore, these output lights can be used as output lights indicating the results of a plurality of types of logic operations.

  The arrangement capable of coupling by interaction of near-field light is typically directly stacked without interposing another signal light layer, and at least partially facing the quantum dots. It is such an arrangement.

  Further, if there are a plurality of pairs of two layers as described above, it is possible to execute a more complicated logical operation by using a single quantum dot layer portion.

  For example, the first one of the plurality of PL emission wavelengths is configured to have all the signal light layers and the base light layer, and the second one of the plurality of PL emission wavelengths. Is configured to have all signal light layers and base light layers except the signal light layer that is the first farthest from the base light layer, and the third of the plurality of PL emission wavelengths Is configured to have all the signal light layers and the base light layers except the signal light layer that is the first and second farthest from the base light layer, and is the fourth of the PL emission wavelengths. For all signal light layers and base light layers except the signal light layer that is the first to third furthest from the base light layer. Similarly, for the Nth of the plurality of PL emission wavelengths, all except the signal light layer that is the first to (N−1) th farthest from the base light layer. The signal light layer and the base light layer are configured to have. Further, it is assumed that the layers stacked adjacently without interposing another signal light layer therebetween can be coupled by the interaction of near-field light.

If each signal light layer and base layer are configured so as to have PL light emission characteristics in this way, the base light can be obtained even when the wavelength of the signal light and the base light is switched to any of the plurality of PL light emission wavelengths. The position of the signal light layer to which the coupling due to the interaction of the near-field light reaches, or the total number to which the coupling reaches is uniquely determined from the layer for the near field. For this reason, the intensity of the light intensity caused by the near-field light in the output light changes depending on which wavelength is used. Therefore, it is possible to construct a single quantum dot layer portion that is extremely convenient for performing various logical operations by using all the signal light layers.
<6>
In another aspect of the optical logic circuit of the present embodiment, the control means controls the signal light source means so as to change the signal light, and the base light source means so as to switch the wavelength of the at least one light. And at least one of the signal light source means.

According to this aspect, during operation, the signal light source means, for example, a semiconductor laser is controlled so that the signal light is changed by, for example, a binary change of on / off, etc., by the control means, for example, a laser control device. . Furthermore, at least one of a base light source means and a signal light source means, each of which is a semiconductor laser, for example, is switched so that the wavelength of at least one light is switched between, for example, the first and second wavelengths by a control means, for example, a laser control device. One is controlled. Therefore, a plurality of types of logic operations can be executed stably and reliably.
<7>
In another aspect of the optical logic circuit of the present embodiment, the control unit switches the base light source unit and the signal light source unit so as to switch all wavelengths of the base light and the signal light to the same wavelength. Control.

According to this aspect, under the control of the control means, the base light source means and the signal light source means switch all the wavelengths of the base light and the signal light to the same wavelength all at once. For this reason, for example, by using the PL emission peak wavelength in the same manner in all layers, it is possible to execute the logic operation stably and reliably.
<8>
In this aspect, the at least one layer performs a logical operation of an AND gate as the first type when all the wavelengths are switched to the first wavelength as the same wavelength, and When the wavelength is switched to the second wavelength as the same wavelength, a NOT gate logical operation may be performed as the second type.

With this configuration, when the wavelength of at least one light is switched to the first wavelength, the logical operation of the AND gate is performed. On the other hand, the logical operation of the NOT gate is performed when the wavelength of at least one light is switched to the second wavelength. That is, by using light of different wavelengths using a single quantum dot layer portion, it is possible to selectively execute the logical operation of the AND gate and the logical operation of the NOT gate appropriately. This can greatly contribute to the greatest advantage of the optical logic circuit, such as circuit miniaturization, high-speed operation, and low power consumption.
<9>
In another aspect of the optical logic circuit of the present embodiment, a vertical light receiving element that receives the base light from the quantum dot layer part and output light resulting from the signal light in the stacking direction of the quantum dot layer part, and It further comprises at least one light receiving element among horizontal light receiving elements that receive light in the horizontal direction of the quantum dot layer portion.

  According to this aspect, corresponding to the result of the first type or second type logical operation being performed, the output light to which the intensity of light is given is emitted from the quantum dot layer unit. As one of the output lights, for example, “horizontal output light” is emitted in the horizontal direction along each layer from the side surface of the quantum dot layer portion and received by the horizontal light receiving element. Alternatively, “vertical output light” as another output light is emitted, for example, from the upper surface of the quantum dot layer portion in a direction perpendicular to the upper surface, and is received by the vertical light receiving element. Therefore, the operation result of the logic operation can be extracted as the light reception output of the light receiving element.

  As described above, a configuration in which the output light is input directly or through a light guide to the optical logic circuit in the next stage may be employed without adopting a configuration in which the output light is received by the light receiving element. In this way, continuous logical operation is possible. Alternatively, a configuration may be adopted in which a part of the output light is received by the light receiving element and the other part of the output light is input to the optical logic circuit in the next stage.

When a plurality of signal light layers are stacked, the horizontal output light output from the side surface of each signal light layer may be used as output light that indicates the calculation result in some form. Then, the horizontal output light output from the side surface of the base light layer may be used as output light indicating the calculation result in some form. Furthermore, the vertical output light emitted from the signal light layer positioned at one end of the quantum dot layer portion may be used as output light indicating the calculation result in some form, or positioned at the other end of the quantum dot layer portion. The vertical output light emitted from the base light layer may be used as output light that indicates the calculation result in some form.
<10>
In this aspect, the control means receives light by the at least one light receiving element in addition to or instead of controlling the base light source means and the signal light source means to switch the wavelength of the at least one light. Then, the at least one light receiving element may be controlled so as to switch a wavelength of the at least one light used for the logical operation.

  If comprised in this way, in addition to the wavelength of at least one light being switched by the base light source means and the signal light source means under the control of the control means, it is used for logical operation at the stage of receiving light by the light receiving element. The wavelength of at least one light is switched. Alternatively, under the control of the control means, the wavelength of light is not switched by the base light source means and the signal light source means, but at the stage of receiving light by the light receiving element, the wavelength of at least one light used for the logical operation is switched.

  Here, “the stage of receiving light by the light receiving element” means not only when the light receiving element receives light but also when the output light is emitted from the quantum dot layer part, the output light is received by the light receiving element and used as a light receiving signal. It means an arbitrary stage after being emitted from the quantum dot layer part. That is, the wavelength may be switched by applying a switchable band shutter or band filter to the emitted output light. The wavelength may be switched by switching a light receiving element having band characteristics or selectively using a light receiving element having band characteristics for receiving light after spectroscopy. The wavelength may be switched by applying a band filter to the received light signal or using a signal component that has passed through the band filter.

In any case, the switched wavelength can be stably and surely received by the light receiving element, so that a plurality of kinds of stable or reliable logic operations can be executed.
<11>
In another aspect of the optical logic circuit of this embodiment, the control means changes the signal light according to at least one value of digital information and analog information as the information.

According to this aspect, the signal light is binary-changed on and off by the control means in a form corresponding to “1” and “0” of the digital information. Alternatively, the signal light is analog-changed in multiple values including a halftone by the control means. That is, the light intensity of the signal light is changed in multiple values continuously or intermittently according to the value of the analog information. As a result, by using light of different wavelengths using a single quantum dot layer portion, it is also possible to perform a plurality of types of logical operations such as digital or analog.
(Embodiment of control method of optical logic circuit)
<12>
In order to solve the above problems, the optical logic circuit control method of the present embodiment has a quantum dot layer portion in which a base light layer and a signal light layer are laminated, and directs the base light toward the base light layer. A control method for controlling an optical logic circuit comprising a base light source means for emitting and a signal light source means for emitting signal light toward the signal light layer, wherein the signal light is subjected to a logical operation to be executed. A change step that changes according to the value of the information to be performed, and a switching step that appropriately switches the wavelength of at least one of the base light and the signal light according to the type of the logical operation, and the base light At least one of the signal layer and the signal light layer is: (i) when the wavelength of the at least one light is switched to the first wavelength by the switching step; In addition, when the first type of logical operation is performed and (ii) the wavelength of the at least one light is switched to the second wavelength different from the first wavelength by the switching step, the first type A second type of logical operation different from the above is performed.

  According to the control method of the optical logic circuit of the present embodiment, the wavelength of at least one of the base light and the signal light is changed by the switching step according to a command given from the outside or internally generated arithmetic processing, for example. , And appropriately switched to the first or second wavelength. At the same time, base light is input from the base light source means to the base light layer, and signal light is input from the signal light source means to the signal light layer. At this time, the signal light is changed according to the value of the information provided for the logical operation to be executed by the changing step. Then, the intensity or intensity of the output light from the quantum dot layer portion is first or inherent to the quantum dot layer portion assumed in advance as corresponding to the first or second wavelength that is currently switched. It represents the operation result of the second type of logical operation (for example, AND gate or NO gate).

Thus, as in the case of the optical logic circuit of the present invention described above, a plurality of types of logical operations can be performed by using light of different wavelengths using a single quantum dot layer portion. It becomes.
(Embodiment of integrated circuit)
<13>
In order to solve the above problems, the integrated circuit of the present embodiment is formed by integrating a plurality of optical logic circuits, and each of the plurality of optical logic circuits is an optical logic circuit according to the above-described embodiment (however, various types thereof) Embodiment).

  According to the integrated circuit of the present embodiment, a plurality of the optical logic circuits of the present embodiment described above are integrated, which is suitable for reducing the size of the circuit, increasing the operation speed, and reducing the power consumption.

  In particular, at least one of the quantum dot layer unit, the base light source unit, the signal light source unit, and the control unit may be shared at least partially between the plurality of optical logic circuits. Further, for at least a part of the input light and the output light in at least some of the optical logic circuits, the output light from one optical logic circuit may be used as it is as the input light of the next stage optical logic circuit. Alternatively, for at least a part of the input light and the output light in at least some of the optical logic circuits, the output light from one optical logic circuit is received by the light receiving element, and the corresponding input light is newly signal light source means May be input to the optical logic circuit in the next stage.

In any case, enlargement of the entire integrated circuit can be suppressed, and extremely efficient logic operation is possible.
(Embodiment of optical logic element)
<14>
In order to solve the above problems, the first optical logic element of the present invention has the above-described quantum dot layer portion used in the above-described optical logic circuit according to the present invention.

According to the first optical logic element of the present invention, as in the case of the optical logic circuit according to the present invention described above, enlargement of the circuit scale can be suppressed, and extremely efficient logic operation is possible. In particular, at least one of the base light source means and the signal light source means is disposed apart from the optical logic circuit, and the light such as the base light and the signal light is transmitted to the optical logic circuit via, for example, an optical fiber or a waveguide circuit. It is also possible to respond to cases such as The control by the control means may be at least partially controlled by remote operation.
<15>
In order to solve the above problems, the second optical logic element of the present invention has the above-described quantum dot layer portion used in the above-described integrated circuit according to the present invention.

According to the second optical logic element of the present invention, as in the case of the integrated circuit according to the present invention described above, it is suitable for downsizing of the circuit, high-speed operation, low power consumption, and the like. In particular, at least one of the base light source means and the signal light source means is disposed apart from the optical logic circuit, and the light such as the base light and the signal light is transmitted to the optical logic circuit via, for example, an optical fiber or a waveguide circuit. It is also possible to respond to cases such as The control by the control means may be at least partially controlled by remote operation.
<16>
In order to solve the above-described problem, a third optical logic element of the present invention has the above-described quantum dot layer portion used in the above-described optical logic circuit according to the present invention, and the signal light layer includes two or more layers. PL emission peak wavelength.

According to the third optical logic element of the present invention, as in the case of the optical logic circuit according to the present invention described above, enlargement of the circuit scale can be suppressed, and extremely efficient logic operation is possible. In particular, more efficient logic operation can be performed by appropriately using two or more PL emission peak wavelengths of the signal light layer.
<17>
In one aspect of the third optical logic element of the present invention, the quantum dot layer portion is formed by laminating a first layer to an m-th layer (where m is a natural number of 2 or more) as the signal light layer. The signal light source means emits the i-th signal light (where i is a natural number from 1 to m) of the signal light toward the i-th layer of the signal light layer, The i layer has the two or more PL emission peak wavelengths, and the jth layer (where j is a natural number from 1 to m different from i) of the signal light layer is at least a portion of the i layer. And having at least one PL emission peak wavelength, the at least one light wavelength being the two or more PL emission peak wavelengths and the one or more PL emission peak wavelengths. No It is a wavelength corresponding to at least one wavelength of.

  With this configuration, for at least one layer, (i) when the wavelength of at least one light is switched to the first wavelength, the first type of logical operation is performed, and (ii) at least one layer A configuration in which the second type of logical operation is performed when the wavelength of one light is switched to the second wavelength can be realized relatively easily. In particular, by actively using each peak wavelength of two or more PL emission peak wavelengths, a plurality of signal light layers having at least partially different PL emission characteristics can be adopted, and stable or reliable Multiple types of logical operations can be performed.

  Such an operation and other advantages of the present embodiment will be clarified from examples described below.

  As described above, according to the optical logic circuit according to the present embodiment, since the quantum dot layer unit, the base light source unit, the signal light source unit, and the control unit are provided, the enlargement of the circuit scale can be suppressed and extremely efficient. Logical operation is possible. According to the control method of the optical logic circuit according to the present embodiment, since the change process and the switching process are provided, it is possible to perform a plurality of types of logic operations using a single quantum dot layer unit. According to the integrated circuit according to the present embodiment, since the optical logic circuit of the present embodiment described above is provided, enlargement of the entire integrated circuit can be suppressed, and extremely efficient logical operation is possible. According to the optical logic device according to the present embodiment, since the quantum dot layer portion is provided, the enlargement of the circuit scale can be suppressed, and extremely efficient logic operation is possible.

Hereinafter, various embodiments of the present invention will be described with reference to the drawings. In the following, an example in which the optical logic circuit according to the present invention can be used as an AND gate and a NOT gate by switching the wavelength of signal light will be described.
<First Embodiment of Optical Logic Circuit>
First, a first embodiment of the optical logic circuit according to the present invention will be described with reference to FIGS. The present embodiment relates to a logic circuit capable of appropriately executing two types of logic operations of an AND gate and a NOT gate on a single quantum dot layer portion.

  In FIG. 1, the optical logic circuit includes a quantum dot layer unit 10, a laser control device 20, signal light lasers 21 and 22, a base light laser 25, a horizontal light receiving element 31, and a vertical light receiving element 32.

  The quantum dot layer unit 10 is formed by laminating signal light layers 11 and 12 and a base light layer 15 on a substrate 14.

As shown in FIG. 2, a plurality of quantum dots 51 are arranged in the signal light layer 11 . The signal light Li1 is input to the signal light layer 11 from the side surface (left side in the figure) during operation. For example, the signal light layer 11 is laminated on a substrate 14 containing GaN, and InAs quantum dots are formed on a GaAs buffer layer. The room temperature PL characteristic or the low temperature PL characteristic is determined by the material, position, size, density, and the like of the quantum dot 51.

As shown schematically in Figure 3, in this embodiment, the layer for signal light signal light Li1 is incident 1 1 (second stage in FIG. 3) is, quantum dots with two PL emission peaks P1 and P2 Formed as. In Figure 3, the first (i.e., maximum) wavelength giving an emission peak P1 is .lambda.2, wavelength giving a second peak emission P2 is λ1 (λ1 <λ2).

As shown in FIG. 2, a plurality of quantum dots 52 are arranged in the signal light layer 12 . The signal light Li2 is input to the signal light layer 12 from the side surface (left side in the figure) during operation. For example, the signal light layer 12 is laminated on a substrate 14 containing GaN, and InAs quantum dots are formed on a GaAs buffer layer. The room temperature PL characteristic or the low temperature PL characteristic is determined by the material, position, size, density, and the like of the quantum dot 52.

As schematically shown in FIG. 3, in this embodiment, the signal light layer 12 (the uppermost stage in FIG. 3) on which the signal light Li2 is incident is formed as a quantum dot having one PL emission peak P1. Is done. In FIG. 3, the wavelength giving the first emission peak P1 is λ2.

As shown in FIG. 2, a plurality of quantum dots 55 are arranged in the base light layer 15 . The for the layer 1 5 base light, during operation, the base light LiB is inputted from the side (left side in the figure). Base light for Layer 1 5 example, are stacked on the substrate 14 including GaN, the quantum dots of InAs is formed on the GaAs buffer layer. The room temperature PL characteristic or the low temperature PL characteristic is determined by the material, position, size, density, and the like of the quantum dot 55.

As shown schematically in Figure 3, in this embodiment, the base light for Layer 1 5 the signal light LiB is incident (the bottom in FIG. 3) is, quantum dots with two PL emission peaks P1 and P2 Formed as. In Figure 3, the first (i.e., maximum) wavelength giving an emission peak P1 is .lambda.2, wavelength giving a second peak emission is λ1 (λ1 <λ2).

As shown in FIG. 4, and more particularly, s signal light layer 1 1 and the base light for Layer 1 5 husband, not only two peaks P1 and P2, so as to perform PL emission having a third peak P3 In addition, quantum dots 51 and 55 are formed. In FIG. 4, the vertical axis represents emission intensity [intensity au], and the horizontal axis represents wavelength [nm]. Specifically, the signal light layer 11 has a first peak P1 near the wavelength 1100 nm, a second peak P2 near the wavelength 880n, and a third peak P3 near the wavelength 1360 nm. , Quantum dots 51 are formed. Similarly, quantum dots 55 are formed in the base light layer 15 . However, in the present embodiment, the first peak P1 and the second peak P2 are used, and the third peak P3 is not used.

Here, in particular, the same layer (i.e., signal light layer 11, the layer 1 5 for the signal light layer 12 or the base light) Between mutually adjacent quantum dots in binding due to the interaction of the near-field light, or emission of propagation However, the material, position, size, thickness, density, etc. of each quantum dot are defined so as to occur in response to the input of the signal light on condition that the base light LiB is incident on the base light layer 15. Yes. Further, even between the quantum dots facing each other in different layers (that is, between the quantum dots facing each other in the signal light layer 12 and the base light layer 15 , and in the signal light layer 11 and the signal light layer 12) (Even between the facing quantum dots), coupling due to the interaction of near-field light, or propagation of light emission occurs depending on the input of the signal light on condition that the base light LiB is incident on the base light layer 15 . The material, position, size, thickness, density, etc. of the quantum dot are specified.

  In addition, the manufacturing method including the film forming process of each layer and the composition of each layer will be described in detail later (see FIGS. 12 to 15).

  In FIG. 1 again, the base light laser 25 constitutes an example of the “base light source means” according to the present invention, and is set to the wavelength λ2 or λ1 for each arithmetic operation during operation without depending on the value of the input signal. The emitted base light LiB is steadily emitted. The base light laser 25 is composed of, for example, a semiconductor laser.

The signal light laser 21 constitutes an example of the “signal light source means” according to the present invention, and is controlled according to the value of the input signal under the control of the laser controller 20, that is, “ Depending on the value of “1” or “0”, the signal light Li1 is turned on and off to emit light. In addition, the wavelength of the signal light Li1 emitted or oscillated is set to the wavelength λ2 or λ1 for each calculation operation. The signal light laser 21 is composed of, for example, a semiconductor laser.

The signal light laser 22 constitutes another example of the “signal light source means” according to the present invention, and is controlled according to the value of the input signal under the control of the laser controller 20, that is, digital information relating to the input signal. Depending on the value of “1” or “0”, the signal light Li2 emits light while being turned on and off. In addition, the wavelength of the signal light Li1 emitted or oscillated is set to the wavelength λ2 or λ1 for each calculation operation. The signal light laser 21 is composed of, for example, a semiconductor laser.

  Which of these signal light lasers 21 and 22 is turned on and in which case is turned off depends on the type of logic operation to be executed by a predetermined optical logic circuit.

  In FIG. 1, the laser controller 20 is configured to switch the wavelengths of the base light LiB and the signal lights Li1 and Li2 as appropriate according to the type of logical operation to be executed. The quantum dot layer unit 10 (i) has a wavelength λ2 (FIG. 3 and FIG. 4) in which these wavelengths are wavelengths corresponding to the first PL emission peak P1, which is an example of the “first wavelength” according to the present invention. And (ii) these wavelengths are the second PL emission peak as an example of the “second wavelength” according to the present invention. When the wavelength is switched to the wavelength λ1, which is a wavelength corresponding to P2, in a unified manner, the logical operation of the NOT gate (in other words, the switching element) is performed.

Since the optical logic circuit of this embodiment is operated as described above, the base light LiB is input from the base light laser 25, and in parallel with this, the signal light lasers 21 and 22 transmit the signal light Li1. and Li2 are respectively input to the signal light layer 1 1 and 1 2.

  Here, in particular, the output wavelengths of the signal light lasers 21 and 22 and the base light laser 25 are switched to the wavelength λ2 (see FIGS. 3 and 4) by the laser controller 20, or the default setting or the initial setting is made. Suppose that it is set.

  This “switching” of the wavelength, for example, switches the frequency signal, the power supply signal, the oscillation condition, etc. supplied from the laser controller 20 to drive the signal light lasers 21 and 22 and the base light laser 25. Done in

  As shown in the truth table of FIG. 5, in this state, the signal light Li <b> 1 is binary-changed on and off according to the value of the digital information corresponding to the input signal.

Then, the output light Lo1 (see FIG. 1) from the signal light layer 11 which is the output light from the quantum dot layer unit 10 is as shown in the bottom of the truth table of FIG. That is, as apparent from the truth table of FIG. 5, in this situation, the optical logic circuit of this embodiment functions as an “AND gate”.

  When the output light Lo1 is received by the horizontal light receiving element 31, the calculation result is obtained as the intensity of the light. Under such circumstances, it is left to the design matters of the quantum dot layer unit 10 that the first type of logic operation becomes an “AND gate”. During operation, the signal lights Li1 and Li2 and the base light LiB Is set to the wavelength λ2 (that is, the wavelength corresponding to the first PL emission peak P1), thereby functioning as an AND gate.

  On the other hand, the output wavelengths of the signal light lasers 21 and 22 and the base light laser 25 are switched to the wavelength λ1 (see FIGS. 3 and 4) by the laser control device 20, or the default setting or the initial setting. Suppose that

However, in this case, as shown in FIG. 6, even if light of wavelength λ1 is incident on the signal light layer 12 (the uppermost stage in FIG. 6), PL light emission does not occur, which is meaningless. . For this reason, the signal light laser 22 is controlled by the laser control device 20 so as not to perform a light emitting operation so as not to waste the laser light.

As shown in FIG. 6, on the other hand, the signal light laser 21, the laser controller 20 is controlled to perform a light emitting operation at a wavelength .lambda.1, among the signal light Li1 signal light for Layer 1 1 (FIG. 6, It is input in the second row from the top). Then, the signal light layer 11 can emit PL at the wavelength λ1. Similarly, the base light laser 25 is controlled to perform a light emission operation at the wavelength λ1 by the laser controller 20, and the base light LiB is input to the base light layer 15 (the lowermost stage in FIG. 6). Then, the base light layer 15 can emit PL at the wavelength λ1.

  As shown in the truth table of FIG. 5, in this state, the signal light Li <b> 1 is binary-changed on and off according to the value of the digital information corresponding to the input signal.

Then, the output light Lo1 and the output light LvO (see FIG. 1) from the signal light layer 11 which are the output lights from the quantum dot layer unit 10 are as shown in the bottom of the truth table of FIG. Become. In the truth table, “horizontal” in the lowermost stage means that the horizontal light receiving element 31 receives light (more strictly, reception of relatively high-intensity output light Lo1). The term “perpendicular” means that the vertical light receiving element 32 receives light (more strictly, reception of relatively high intensity output light LoV). That is, as apparent from the truth table of FIG. 7, in this situation, the optical logic circuit of this embodiment functions as a “NOT gate”.

  When the output light Lo1 is received by the horizontal light receiving element 31 and the vertical light receiving element 32, the calculation result can be obtained as the intensity or intensity of the light intensity and as the direction of emission of the output light. In such a situation, it is left to the design matter of the quantum dot layer unit 10 that the second type of logical operation becomes a “NOT gate”. During operation, the wavelengths of the signal light Li1 and the base light LiB Is set to the wavelength λ1 (that is, the wavelength corresponding to the second PL emission peak P2), thereby functioning as a NOT gate.

  As described above, according to the present embodiment, it is possible to perform two types of logical operations by using light of wavelengths λ2 and λ1 using a single quantum dot layer unit 10.

In this embodiment, all the lasers are switched to the same wavelength, but it is also possible to switch to different wavelengths to perform a logical operation. Alternatively, in the present embodiment, the horizontal light receiving element 31 obtains the output light Lo1 or the output light LoV as the output light indicating the calculation result. However, as the output light indicating the calculation result, another layer (for example, signal light) is obtained. use layer 1 2, it may be used the output light from a base optical layer 1 5). With this configuration, it is possible to cause the same quantum dot layer unit 10 to perform further different logical operations.

Further, instead of arranging at least one of the horizontal light receiving element 31 and the vertical light receiving element 32, at least one of the output light Lo1 and the output light LoV is input directly or through a light guide path to the optical logic circuit in the next stage. You may employ | adopt the structure to make. Furthermore, and output light Lo2 from signal light Layer 1 2, may be adopted to input either directly or through the light guide path an output light LoB from a Layer 1 5 based light next stage of the optical logic circuits.

In addition, in addition to or instead of switching the wavelengths of the signal light lasers 21 and 22 and the base light laser 25 between the wavelengths λ2 and λ1 by the laser control device 20, or at the stage of receiving light by the light receiving element or quantum The horizontal light receiving element 31 and the vertical light receiving element 32 may be configured so that the wavelength of the received light Lo1 or LoV is switched between the wavelengths λ2 and λ1 at a stage after exiting the dot layer portion 10.
<Example of Control Method of Optical Logic Circuit>
Hereinafter, the control method of the optical logic circuit described with reference to FIGS. 1 to 7 will be described with reference to FIG. FIG. 8 shows a flowchart of the control method of the present embodiment.

  In FIG. 8, first, the type of logical operation requested this time is set as a flag in the laser controller 20 according to a command given from outside or internally generated arithmetic processing (step S1).

  Subsequently, it is determined whether or not the set type is an AND gate (step S12). If it is determined that the set type is an AND gate (step S12: YES), the signal light lasers 21 and 22 and the base light laser 25 are determined. Is set to the wavelength λ2 that gives the first PL issuance peak P1, which is the “first wavelength” (step S13).

  On the other hand, if it is determined in step S12 that it is not an AND gate (step S12: NO), the wavelength that gives the second PL emission peak P2 in which the wavelengths of the signal light laser 21 and the base light laser 25 are “second wavelengths”. λ1 is set (step S14).

  Subsequently, in any case, the signal light laser 21 or the signal light lasers 21 and 22 are turned on / off according to the input signal under the control of the laser control device 20. As a result, the signal light Li1 and the signal light Li2 having the wavelength λ2 or the wavelength λ1 or the signal light Li1 are input to the quantum dot layer unit 10. Furthermore, during the input of such signal light, the base light LiB having the wavelength λ2 or the wavelength λ1 is continuously input from the base light laser 25 (step S15).

  Almost at the same time, the horizontal light receiving element 31 or the horizontal light receiving element 31 and the vertical light receiving element 32 receive the output light Lo1 or the output light Lo1 and the output light LoV from the quantum dot layer unit 10 (step S16). Further, a calculation result corresponding to the received light signal indicating the intensity of the received output light is output (step S17). Here, the relative intensity in the light intensity of the output light Lo1 or LoV is applied to an appropriate threshold, so that the result of the logical operation of the AND gate or the NOT gate for the input signal is converted to a digital value of “1” or “0”. Output as a result indicated by a value.

  Subsequently, it is determined whether or not the requested calculation is the last (step S18). If not the last (step S18: NO), the process returns to step S11 and the subsequent processing is repeated. On the other hand, if it is the last, a series of arithmetic processing is completed.

As described above, two types of logical operations can be performed by using light of wavelengths λ2 and λ1 by using a single quantum dot layer unit 10.
<Second Embodiment of Optical Logic Circuit>
A second embodiment of the optical logic circuit will be described with reference to FIG. FIG. 9 is a schematic diagram for explaining the layer configuration and operation principle of the quantum dot layer portion in the second embodiment of the optical logic circuit. In particular, in FIG. 9, the left side shows a state in which the base light and the first to fourth signal lights are input to the layer configuration of the quantum dot layer unit 10, and the right side shows the wavelength spectrum corresponding to each layer. A state in which base light and first to fourth signal output lights are output together with 200 (particularly, PL emission peaks P1 to P4) is illustrated.

  As illustrated in FIG. 9, the quantum dot layer unit 10 according to this embodiment includes, in order from the bottom in the figure, a base light layer having quantum dots 55, a first signal light layer having quantum dots 51, and quantum dots 52. A five-layer structure of a second signal light layer having quantum dots 53, a third signal light layer having quantum dots 53, and a fourth signal light layer having quantum dots 54.

  Further, the base light LiB is input to the base light layer having the quantum dots 55, and the first signal light Li1 is appropriately turned on and off to the first signal light layer having the quantum dots 51. For the second signal light layer having the quantum dots 52, the second signal light Li1 is input while being appropriately turned on and off, and for the third signal light layer having the quantum dots 53, The third signal light Li3 is input while being appropriately turned on and off, and the fourth signal light Li4 is input to the fourth signal light layer having the quantum dots 54 while being appropriately turned on and off.

  In FIG. 9, the base light layer having the quantum dots 55 is configured to have four PL emission peaks P1, P2, P3, and P4 on the wavelength spectrum 200, as indicated by the wavelength spectrum 200. Specifically, the quantum dots 55 are formed to have four PL emission peaks depending on the material, position, size, density, and the like. From this layer, output light LoB is output and used for a light reception signal.

  The first signal light layer having the quantum dots 51 is configured to have three PL emission peaks P 1, P 2, P 3 and P 4 on the wavelength spectrum 200. Specifically, as in the case of the quantum dot 55, the quantum dot 51 is formed to have four PL emission peaks depending on its material, position, size, density, and the like. From this layer, output light Lo1 is output and used for a light reception signal.

  The second signal light layer having the quantum dots 52 is configured to have three PL emission peaks P1, P2, and P3 on the wavelength spectrum 200. Specifically, the quantum dots 52 are formed to have three PL emission peaks depending on the material, position, size, density, and the like. More specifically, for example, it is formed to have three peaks as shown in FIG. However, unlike the case of FIG. 4, the emission peak P3 has a relatively higher intensity than the case shown in FIG. A peak having a similar light intensity) is preferred. From this layer, output light Lo2 is output and used for a light reception signal.

  The third signal light layer having the quantum dots 53 is configured to have two PL emission peaks P 1 and P 2 on the wavelength spectrum 200. Specifically, the quantum dots 53 are formed to have two PL emission peaks depending on the material, position, size, density, and the like. From this layer, output light Lo3 is output and used for a light reception signal.

  The fourth signal light layer having the quantum dots 54 is configured to have only one PL emission peak P1 on the wavelength spectrum 200. Specifically, the quantum dots 54 are formed so as to have one PL emission peak depending on the material, position, size, density, and the like. From this layer, output light Lo4 is output and used for a light reception signal.

  As in the case of the first embodiment, the output light LoV emitted in the vertical direction from the top surface of the quantum dot layer unit 10 may be output and used as a light reception signal.

  Here, in particular, as shown by the wavelength spectrum 200 in FIG. 9, the emission peaks P1 to P4 in these layers have the same wavelength between the layers.

  According to the present embodiment, at the time of the operation, the signal light and the base light are set to a wavelength that gives any one of the emission peaks P1 to P4. That is, the wavelengths of the signal light and the base light are switched uniformly according to the logical operation under the control of the laser control device as in the first embodiment.

  For example, in the present embodiment, on the other hand, it is assumed that the signal light and the base light are all switched to a wavelength that gives the emission peak P3. In this case, as indicated by the arrow AR1, the three layers of the base light layer, the first signal light layer, and the second signal light layer, which are in the three stages from the bottom in FIG. 9, are close to each other in the stacking direction. Coupling occurs due to the interaction of field light. At this time, the two layers of the third signal light layer and the fourth signal light layer, which are two steps from the top in FIG. 9, are coupled by the interaction of near-field light from the lower three layers in the stacking direction. Does not occur. Therefore, in the output light Lo1 to Lo4, the intensity of the light intensity is generated according to the presence or absence of the coupling due to the interaction of the near-field light. In this case, in particular, the output light Lo3 is inferior to the output light Lo2 in light intensity due to the absence of near-field light coupling.

  As a result, as the logical operation, if the intensity of the output light Lo1 to Lo4 with respect to the input signal light Li1 to Li4 is associated with the logical operation, the first type of logical operation assumed in advance is assumed. Can be executed.

  In this embodiment, on the other hand, it is assumed that the signal light and the base light are all switched uniformly to a wavelength that gives the emission peak P1. In this case, as indicated by the arrow AR2, coupling due to the interaction of near-field light occurs in the stacking direction in all five layers of the base light layers and the first to fourth signal light layers. Therefore, all of the output lights Lo1 to Lo4 have their light intensities depending on the presence or absence of coupling due to the interaction of near-field light. In this case, in particular, all of the output lights Lo1 to Lo4 are superior in light intensity as compared to the case where no near-field light is coupled.

  As a result, as the logical operation, if the intensity of the output light Lo1 to Lo4 with respect to the input signal light Li1 to Li4 is associated with the logical operation, it is assumed in advance (emission as described above). A second type of logical operation (which is clearly different from the first type of logical operation in the case of the wavelength giving peak P3) can be performed.

  As described above, according to the second embodiment, a single quantum dot including a number of signal light layers having different PL emission characteristics (specifically, different wavelengths giving different PL emission peaks). By using various wavelengths corresponding to various PL emission peaks using the layer unit, various logical operations can be performed.

In addition, in this embodiment, for example, if light having a wavelength that gives the emission peak P1 and light having a wavelength that gives the emission peak P3 are incident simultaneously as the base light LiB and the input signal lights Li2 to Li4, the output light Lo2 And output light Lo4 are respectively output. At this time, if the intensity ratio between the emission peak P1 and the emission peak P3 is set to 5 to 1, for example, the output ratio between the output light Lo2 and the output light Lo4 becomes 1 to 5 according to this ratio. By using this, when the sensitivity, number, connection distance, etc. of the device connected to the output destination are changed, it is possible to change the signal intensity required for this device and assign it.
<Example of integrated circuit>
Various embodiments of the integrated circuit will be described with reference to FIGS.

  One embodiment of the integrated circuit shown in FIG. 10 is formed by integrating a plurality of quantum dot layer portions 10 (see FIGS. 1 and 2) so as to be directly adjacent to each other. The laser controller 20, the signal light lasers 21 and 22, the base light laser 25, and the horizontal light receiving element 31 and the vertical light receiving element 32 are attached to the quantum dot layer unit 10 in the first stage and the last stage. ing.

As the output light, the quantum dot layer 10 of the final stage, the output light Lo1 from signal light layer 1 1, the output from the output light Lo2, Layer 1 5 for the base light from signal light Layer 1 2 Of the light LoB and the output light LoV from the upper surface, any one or a plurality of output lights can be used according to the logical operation to be realized.

Furthermore at least one quantum dot layer portion layer signal light 1 1 10 and 1 2 and the base light for Layer 1 5 positioned the laser (not shown) to the first stage except stage, or further as a further signal light It is also possible to input as the base light.

  At this time, the input signal light and base light can be made to perform different logic operations using lasers having different wavelengths.

Or a light receiving element (not shown) from at least one quantum dot layer portion layer signal light 1 1 10 and 1 2 and the base light for Layer 1 5 positioned stages other than the final stage, a further horizontal output light or vertical It is also possible to output as output light.

  As described above, according to the integrated circuit of this embodiment, it is possible to execute a more complicated logic operation or a logic operation combining a plurality of logic operations while adopting a compact overall configuration.

  In another embodiment of the integrated circuit shown in FIG. 11, a plurality of quantum dot layer portions 10 (see FIGS. 1 and 2) are integrated with the light receiving elements 31 and 32 and the laser control device 20 interposed therebetween. .

Note that the final as the output light and intermediate output light that is passed on the way, in each of the quantum dot layer 10, the output light Lo1 from signal light layer 1 1, the output from the signal light Layer 1 2 light Lo2, the output light LoB from a layer 1 5 based light, and out of the output light LoV from the upper surface, it is possible to use any one or more of the output light in accordance with the logic operation to be realized .

  As described above, according to the integrated circuit of this embodiment, it is possible to execute a more complex logic operation or a logic operation combining a plurality of logic operations.

It is also possible to construct one integrated circuit by combining the embodiment of FIG. 10 and the embodiment of FIG.
<Example of Manufacturing Method of Quantum Dot Layer>
Among the optical logic circuits according to the present embodiment, a method for manufacturing the quantum dot layer unit 10 (see FIGS. 1 and 2) will be described with reference to FIGS.

  First, as shown in FIG. 12, a GaAs substrate 110 is installed on a substrate rotation heating mechanism 211 in a growth chamber 201 of an MBE (Molecular Beam Epitaxy) growth apparatus 200. FIG. 12 is a process diagram showing a part of the process of the forming method according to the present embodiment. In FIG. 12, detailed members of the MBE growth apparatus 200 are omitted as appropriate, and only directly related members are shown.

In FIG. 12, next, the inside of the growth chamber 201 is set to 1 × 10 ⁻⁹ Torr or less, for example. Subsequently, As is irradiated from the evaporation source 214 to the GaAs substrate 110 at an irradiation amount of, for example, about 1 × 10 ⁻⁵ Torr. Under As irradiation, the substrate temperature of the GaAs substrate 110 is heated to, for example, about 600 degrees Celsius by the substrate rotation heating mechanism 211, and the surface of the GaAs substrate 110 is cleaned.

  Next, the substrate temperature is set to, for example, 560 degrees Celsius. Subsequently, As and Ga are irradiated to the GaAs substrate 110 from the evaporation sources 214 and 212, respectively, for about 10 minutes, for example. As a result, a GaAs buffer layer 120 is formed on the (001) plane of the GaAs substrate 110 as shown in FIG. FIG. 13 is a process diagram showing a buffer layer forming process subsequent to the process of FIG. In FIG. 13, members related to the MBE growth apparatus 200 are not shown (the same applies hereinafter).

  In FIG. 13, the doses of As and Ga are set as doses that allow the GaAs buffer layer 120 to grow at a growth rate of about 1 ML / s, for example. The thickness of the formed GaAs layer is, for example, about 150 nm.

  Next, the substrate temperature is set to a temperature of 490 ° C. or higher and 530 ° C. or lower as an example of the “first growth temperature” according to the present invention. Subsequently, As and In are irradiated from the evaporation sources 214 and 213 onto the GaAs buffer layer 120, respectively. Here, as the InAs layer 130 grows, a plurality of quantum dots 131 containing InAs (corresponding to the quantum dots 51, 52, or 55 shown in FIG. 2) are self-organized on the upper surface 130a of the InAs layer 130. Formed by growth. As a result, an InAs layer 130 is formed on the GaAs buffer layer 120 as shown in FIG. FIG. 14 is a process diagram showing a quantum dot forming process following the process of FIG.

  In FIG. 14, the doses of As and In are set as doses that allow the InAs layer 130 to grow at a growth rate of 0.02 ML / s to 0.4 ML / s. The growth amount of the InAs layer 130 is, for example, 1.8 ML. Moreover, the diameter of the quantum dot 131 is 30 nm or more and 60 nm or less, and the height of the quantum dot 131 is 15 nm or less.

  FIG. 15 is a process diagram showing a cap layer forming process subsequent to the process of FIG.

  In FIG. 15, the doses of As and Ga are set as doses that allow the GaAs cap layer 140 to grow at a growth rate of 0.1 ML / s to 0.5 ML / s. The formed cap layer 140 has a thickness of 24 nm, for example.

  As a result, an example of the quantum dot layer unit 24 is completed.

  By repeating the film forming process similar to the above on the GaAs substrate 110, a desired number of signal light layers can be formed on the GaAs substrate 110. Alternatively, it is also possible to construct a single quantum dot layer portion by preparing a plurality of such quantum dot layer portions 24 and stacking them so that they can be optically coupled to each other or simply.

  Further, the present invention can be appropriately changed without departing from the gist or concept of the invention that can be read from the claims and the entire specification, and an optical logic circuit, a control method thereof, and an integrated circuit accompanied with such a change. Is also included in the technical idea of the present invention.

DESCRIPTION OF SYMBOLS 10 Quantum dot layer part 11 Signal light layer 12 Signal light layer 14 Substrate 15 Base light layer 20 Laser control device 21, 22 Signal light laser 25 Base light laser 31 Horizontal light receiving element 32 Vertical light receiving element

Claims (12)

A quantum dot layer portion comprising a signal layer optical laminated on the base-light layer and the base-light on a layer,
Base light source means for emitting base light toward the base light layer;
Signal light source means for emitting signal light toward the signal light layer;
With
The quantum dot layer portion is formed by laminating a first layer to an m-th layer (where m is a natural number of 2 or more) in order from the base light layer side, as the signal light layer.
The i-th layer (where i is a natural number from 1 to m−1) layer as the signal light layer has two or more PL emission peak wavelengths,
The m-th layer as the signal light layer has a PL emission characteristic at least partially different from the i-th layer and has one or more PL emission peak wavelengths,
The base light layer has two or more PL emission peak wavelengths,
The signal light source means emits j-th (where j is a natural number from 1 to m) signal light as the signal light toward the j-th layer as the signal light layer,
The signal light source means is controlled to change the j-th signal light according to the value of information to be subjected to a logical operation to be executed, and each of the wavelength of the base light and the wavelength of the j-th signal light Further comprising a control means for controlling the base light source means and the signal light source means so as to switch to any one of the two or more PL emission peak wavelengths according to the type of the logical operation ,
At least one of the first layer to the m-th layer as the base light layer and the signal light layer corresponds to (i) the at least one layer of the base light and the j-th signal light. When the light wavelength is the first wavelength of the two or more PL emission peak wavelengths , the first type of logical operation is performed, and (ii) the light wavelength corresponding to the at least one layer is The second type of logical operation different from the first type is performed when the second wavelength of the two or more PL emission peak wavelengths is a second wavelength different from the first wavelength . An optical logic circuit characterized by Of the base light layer and the first layer to the m-th layer, two layers forming a pair have at least one PL emission peak wavelength corresponding to each other, and in the quantum dot layer portion, It is arranged at a position where coupling by light interaction is possible,
The optical logic circuit according to claim 1 , wherein at least one of the two layers forming the pair exists. The control means controls the base light source means and the signal light source means so as to switch all wavelengths of the base light and the i-th signal light to the same wavelength. The optical logic circuit described. The at least one layer comprises:
When all the wavelengths are switched to the first wavelength as the same wavelength, an AND gate logical operation is performed as the first type, and all the wavelengths of the light are switched to the second wavelength as the same wavelength. 4. The optical logic circuit according to claim 3 , wherein the optical logic circuit is configured to perform a logical operation of a NOT gate as the second type.   A vertical light receiving element that receives the base light and the signal light from the quantum dot layer portion in the stacking direction of the quantum dot layer portion and a horizontal light receiving in the horizontal direction of the quantum dot layer portion The optical logic circuit according to claim 1, further comprising at least one light receiving element among the light receiving elements. The control means receives light by the at least one light receiving element in addition to or instead of controlling the base light source means and the signal light source means so as to switch a wavelength of light corresponding to the at least one layer. The optical logic circuit according to claim 5 , wherein the at least one light receiving element is controlled to switch a wavelength of light corresponding to the at least one layer used for the logical operation. 2. The optical logic circuit according to claim 1, wherein the control means changes the i-th signal light according to at least one of digital information and analog information as the information. A quantum dot layer portion including a base light layer and a signal light layer laminated on the base light layer; base light source means for emitting base light toward the base light layer; and A signal light source unit that emits light toward the signal light layer , wherein the quantum dot layer unit is the signal light layer in order from the base light layer side to the mth layer (where m is 2). The above (natural number) layer is laminated, and the i-th layer (where i is a natural number from 1 to m−1) layer as the signal light layer has two or more PL emission peak wavelengths, The m-th layer as the signal light layer has a PL emission characteristic that is at least partially different from the i-th layer and has one or more PL emission peak wavelengths. The base light layer has two or more PL emission peak wavelengths, and the signal light source means uses the jth (where j is a natural number from 1 to m) signal light as the signal light. A control method for controlling an optical logic circuit that emits toward a j-th layer as an optical layer ,
A changing step of controlling the signal light source means so as to change the j-th signal light according to a value of information to be subjected to a logical operation to be executed;
The base light source means and the signal light source are configured to switch each of the wavelength of the base light and the wavelength of the j-th signal light to one of the two or more PL emission peak wavelengths according to the type of the logical operation. A switching step for controlling the means ,
At least one of the first layer to the m-th layer as the base light layer and the signal light layer corresponds to (i) the at least one layer of the base light and the j-th signal light. When the light wavelength is the first wavelength of the two or more PL emission peak wavelengths , the first type of logical operation is performed, and (ii) the light wavelength corresponding to the at least one layer is The second type of logical operation different from the first type is performed when the second wavelength of the two or more PL emission peak wavelengths is a second wavelength different from the first wavelength . A method for controlling an optical logic circuit. A plurality of optical logic circuits are integrated,
Each of the plurality of optical logic circuits is
A quantum dot layer portion comprising a signal layer optical stacked on the layer for the base-light layer and the base light,
Base light source means for emitting base light toward the base light layer;
Signal light source means for emitting signal light toward the signal light layer;
With
The quantum dot layer portion is formed by laminating a first layer to an m-th layer (where m is a natural number of 2 or more) in order from the base light layer side, as the signal light layer.
The i-th layer (where i is a natural number from 1 to m−1) as the signal light layer has two or more PL emission peak wavelengths,
The m-th layer as the signal light layer has a PL emission characteristic at least partially different from the i-th layer and has one or more PL emission peak wavelengths,
The base light layer has two or more PL emission peak wavelengths,
The signal light source means emits j-th (where j is a natural number from 1 to m) signal light as the signal light toward the j-th layer as the signal light layer,
The signal light source means is controlled to change the j-th signal light according to the value of information to be subjected to a logical operation to be executed, and each of the wavelength of the base light and the wavelength of the j-th signal light Further comprising a control means for controlling the base light source means and the signal light source means so as to switch to any one of the two or more PL emission peak wavelengths according to the type of the logical operation ,
At least one of the first layer to the m-th layer as the base light layer and the signal light layer corresponds to (i) the at least one layer of the base light and the j-th signal light. When the light wavelength is the first wavelength of the two or more PL emission peak wavelengths , the first type of logical operation is performed, and (ii) the light wavelength corresponding to the at least one layer is The second type of logical operation different from the first type is performed when the second wavelength of the two or more PL emission peak wavelengths is a second wavelength different from the first wavelength . An integrated circuit characterized by. Base light source means for emitting base light, signal light source means for emitting signal light, and controlling the signal light source means to change the signal light according to the value of information to be subjected to a logical operation to be executed with the wavelength of the wavelength and the signal light of the base light, quantum for optical logic circuits and a control means for controlling the base light source means and said signal source means to switch according to the type of the logic operation An optical logic element having a dot layer portion,
The quantum dot layer part is
And layer for the base beam to be directed to the base light emitted from the front SL based light source means,
A signal light layer that is laminated on the base light layer and to which the signal light emitted from the signal light source means is directed ;
Have
The quantum dot layer portion is formed by laminating a first layer to an m-th layer (where m is a natural number of 2 or more) in order from the base light layer side, as the signal light layer.
The i-th layer (where i is a natural number from 1 to m−1) as the signal light layer has two or more PL emission peak wavelengths,
The m-th layer as the signal light layer has a PL emission characteristic at least partially different from the i-th layer and has one or more PL emission peak wavelengths,
The base light layer has two or more PL emission peak wavelengths,
At least one of the first layer to the m-th layer as the base light layer and the signal light layer corresponds to (i) the at least one layer of the base light and the j-th signal light. When the light wavelength is the first wavelength of the two or more PL emission peak wavelengths , the first type of logical operation is performed, and (ii) the light wavelength corresponding to the at least one layer is The second type of logical operation different from the first type is performed when the second wavelength of the two or more PL emission peak wavelengths is a second wavelength different from the first wavelength . An optical logic device characterized by. Base light source means for emitting base light, signal light source means for emitting signal light, and controlling the signal light source means to change the signal light according to the value of information to be subjected to a logical operation to be executed together with the wavelength of the wavelength and the signal light based light, the logical said to switch according to the type of computing-based light source means and the signal a plurality of optical logic circuits and control means comprise respective controlling the light source means An optical logic device having a quantum dot layer portion for an integrated circuit in which are integrated,
The quantum dot layer part is
And layer for the base beam to be directed to the base light emitted from the front SL based light source means,
A signal light layer that is laminated on the base light layer and to which the signal light emitted from the signal light source means is directed ;
Have
The quantum dot layer portion is formed by laminating a first layer to an m-th layer (where m is a natural number of 2 or more) in order from the base light layer side, as the signal light layer.
The i-th layer (where i is a natural number from 1 to m−1) layer as the signal light layer has two or more PL emission peak wavelengths,
The m-th layer as the signal light layer has a PL emission characteristic at least partially different from the i-th layer and has one or more PL emission peak wavelengths,
The base light layer has two or more PL emission peak wavelengths,
At least one of the first layer to the m-th layer as the base light layer and the signal light layer corresponds to (i) the at least one layer of the base light and the j-th signal light. When the light wavelength is the first wavelength of the two or more PL emission peak wavelengths , the first type of logical operation is performed, and (ii) the light wavelength corresponding to the at least one layer is The second type of logical operation different from the first type is performed when the second wavelength of the two or more PL emission peak wavelengths is a second wavelength different from the first wavelength . An optical logic device characterized by. A base light layer into which base light is incident, a first signal light layer into which first signal light is incident, and a second signal light layer into which second signal light is incident are laminated in this order. An optical logic circuit comprising: a quantum dot layer unit; and a control unit that controls a light source that emits each of the base light, the first signal light, and the second signal light ,
The first signal light layer includes a first quantum dot having a first PL emission peak and a second PL emission peak,
The second signal light layer includes a second quantum dot having the first PL emission peak,
The base light layer includes a third quantum dot having the first PL emission peak and the second PL emission peak,
A first wavelength of light that provides the first PL emission peak is greater than a second wavelength of light that provides the second emission peak;
The control means controls the light source so as to change each of the first signal light and the second signal light according to a value of information to be subjected to a logical operation to be performed, and the base light, The light source is controlled so that the wavelength of each of the first signal light and the second signal light is switched to one of the first wavelength and the second wavelength according to the type of the logical operation. An optical logic circuit.

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