JP5065320B2 - Optical delay device using quantum dots - Google Patents

Description

  The present invention relates to an optical delay device, and more particularly to an optical delay device suitable for application to a nanoscale optical communication network, optical measurement, and various devices.

  In order to realize a high-speed optical network using light, an optical router indispensable for the latest optical technology such as a quantum computer, and a highly efficient nonlinear device, an optical delay circuit with information is required.

  Since the conventional optical delay device is configured by winding an optical fiber for several tens of kilometers, even when a nanometer-sized device is manufactured, the optical delay device is large, so that the optical device can be miniaturized. could not.

  In addition, the application of an optical memory as an optical delay device has been tried in the past, and its development has been promoted by an optical switch using a nonlinear optical effect. However, since this conventional optical memory uses the nonlinearity of the medium to the last, enormous power is required to control this, and femtosecond pulsed laser light is required for its excitation. However, since such a femtosecond pulse laser is huge, it is difficult to mount it on a portable information terminal or the like, which has been a barrier in practical use.

  In addition, the optical transmission line connecting the elements needs to be miniaturized. However, in the transmission line using the optical fiber, there is a problem that it is impossible in principle to downsize to the wavelength dimension or less. .

  In order to meet such demands, conventionally, for the purpose of accumulating light without being controlled by the diffraction limit of light, we have found a unique photophysical phenomenon between quantum dots arranged in the nanometer region. An optical accumulator using dots has been proposed (see, for example, Patent Document 1). In the technique disclosed in Patent Document 1, an even number of quantum dots having energy levels that resonate with each other are formed on a substrate made of a dielectric material, and the sizes and intervals of the quantum dots are supplied to the adjacent proximity. It is adjusted to be equal to or less than the wavelength of the field light. These energy levels are configured to resonate with each other based on antiparallel dipole interactions.

JP 2005-64200 A

  However, the technique disclosed in Patent Document 1 described above has a problem in that the light loss accumulated in the quantum dots is large and a stable light storage function and light delay mechanism cannot be expected over a long period of time.

  Therefore, the present invention has been devised in view of the above-described problems, and the object of the present invention is to use quantum dots that can be configured on a nanoscale and that can delay optical transmission. It is to provide an optical delay device.

  An optical delay device using quantum dots according to claim 1 is configured with an input quantum dot and a larger volume than the input quantum dot, and the first excitation from the input quantum dot. A quantum dot in which a plurality of delay quantum dots having a resonance level into which a child is injected and a lower level capable of relaxing the first exciton from the resonance level are arranged in a plurality of substantially the same size The input quantum dots, when an optical signal corresponding to the data to be stored is supplied, the first excitons excited according to the wavelength of the input quantum dots are used as the delay quantum dots. The quantum dot array stores the first excitons injected from the input quantum dots by transmitting each other between the resonance levels in the plurality of delay quantum dots. And the optical signal The second excitons transmitted between the resonance levels are further excited by exciting the second excitons to the lower levels based on the supply of relaxation-preventing optical signals having different wavelengths. It is characterized by delaying relaxation through the position.

  An optical delay device using quantum dots according to claim 2 is the invention according to claim 1, wherein the quantum dot array is arranged so that the delay quantum dots constituting the quantum dot array form a ring. It is characterized by that.

  The transmission path using the quantum dots according to claim 3 is configured with an input quantum dot and a larger volume than the input quantum dot, and the first exciton from the input quantum dot. Dot array in which a plurality of transmission quantum dots having substantially the same size are arranged having a resonance level into which the first excitons can be relaxed from the resonance level. When the optical quantum signal according to the data to be transmitted is supplied to the input quantum dot, the first exciton excited according to the wavelength is transferred to the transmission quantum dot. The quantum dot array transmits the first excitons injected from the input quantum dots to each other between the resonance levels in the plurality of transmission quantum dots. Mitigation prevention optical signals consisting of different wavelengths Delaying the relaxation of the first excitons transmitted between the resonance levels via the lower level by further exciting the second excitons to the lower level based on the supply. Features.

  5. The data delay method using quantum dots according to claim 4, wherein the input quantum dots are configured to have a larger volume than the input quantum dots, and the first excitation is performed from the input quantum dots. A quantum dot in which a plurality of delay quantum dots having a resonance level into which a child is injected and a lower level capable of relaxing the first exciton from the resonance level are arranged in a plurality of substantially the same size By supplying an optical signal corresponding to data to be stored to the input quantum dot, the first excitons excited in accordance with the wavelength are supplied to the delay quantum dot. The first excitons injected from the input quantum dots to the delay quantum dots are transmitted to each other between resonance levels and stored, and are different from the optical signal. wavelength By supplying the relaxation-preventing optical signal and further exciting the second excitons to the lower level, the first excitons transmitted between the resonance levels are passed through the lower level. It is characterized by delaying the relaxation.

  6. The signal transmission method using quantum dots according to claim 5, wherein the input quantum dots and the input quantum dots have a larger volume than the input quantum dots, and the first excitation from the input quantum dots. A quantum dot in which a plurality of transmission quantum dots having a resonance level into which a child is injected and a lower level capable of relaxing the first exciton from the resonance level are arranged in a plurality of substantially the same size By supplying an optical signal corresponding to the data to be transmitted to the input quantum dot, the first excitons excited in accordance with the wavelength are supplied to the transmission quantum dot. The first excitons injected from the input quantum dot to the transmission quantum dot are transmitted to each other between resonance levels, and for relaxation prevention having a wavelength different from that of the optical signal. Provide optical signal Then, by further exciting the second excitons to the lower level, the relaxation of the first excitons transmitted between the resonance levels via the lower level is delayed. To do.

  The optical delay device using the quantum well according to claim 6, wherein the input quantum well, the resonance level in which the first excitons are injected from the input quantum well, and the first resonance frequency from the resonance level A plurality of delay wells having a lower level capable of relaxing the excitons of the plurality of quantum wells, and the input quantum well has an optical signal corresponding to data to be stored. When supplied, the first exciton excited according to the wavelength is injected into the delay quantum well, and the quantum well array is injected from the input quantum well. The excitons of the above are stored by transmitting each other between the resonance levels in the plurality of delay quantum wells, and based on the supply of the relaxation preventing optical signal having a wavelength different from that of the optical signal. Further exciting the second exciton to a lower level More, wherein the delaying the relaxation through the lower level of the first excitons are allowed to transmit between the resonance level.

  The optical transmission line using the quantum well according to claim 7 includes an input quantum well, a resonance level in which a first exciton is injected from the input quantum well, and the first to the first resonance level. A plurality of transmission quantum wells each having a lower level capable of relaxing the excitons of the plurality of quantum wells. The input quantum well has an optical signal corresponding to data to be transmitted. When supplied, the first excitons excited according to the wavelength are injected into the transmission quantum well, and the quantum well array is injected from the input quantum well. Of the excitons are transmitted to each other between the resonance levels in the plurality of transmission quantum wells, and further to the lower level based on the supply of the relaxation preventing optical signal having a wavelength different from that of the optical signal. By exciting two excitons between the resonance levels. There wherein the delaying relaxed through the lower level of the first excitons are allowed to transmit.

  The data delay method using a quantum well according to claim 8, wherein the input quantum well, the resonance level in which the first excitons are injected from the input quantum well, and the first resonance frequency from the resonance level. An optical signal corresponding to data to be stored is input to a device comprising a quantum well array in which a plurality of delay quantum wells having lower levels capable of relaxing the excitons of By supplying to the well, the first exciton excited according to the wavelength is injected into the delay quantum well, and the first quantum well injected from the input quantum well into the delay quantum well. One exciton is transmitted between the resonance levels to be stored, and an relaxation-preventing optical signal having a wavelength different from that of the optical signal is supplied to further supply the second exciton to the lower level. By exciting the resonance And wherein the delaying the relaxation through the lower level of the first excitons are allowed to transmit among position.

  The signal transmission method using the quantum well according to claim 9, wherein the input quantum well, the resonance level in which the first excitons are injected from the input quantum well, and the first resonance frequency from the resonance level. An optical signal corresponding to data to be transmitted to a device comprising a plurality of quantum dot arrays in which a plurality of delay quantum dots having substantially the same size and a lower level capable of relaxing the excitons of To the input quantum well, the first exciton excited according to the wavelength is injected into the transmission quantum dot, and the transmission quantum well is transferred from the input quantum well. The first excitons injected into the channel are transmitted between the resonance levels, and a relaxation preventing optical signal having a wavelength different from that of the optical signal is supplied to the second level. By exciting the above resonance level. And wherein the delaying the relaxation through the lower level of the first excitons are allowed to transmit at.

  According to the present invention having the above-described configuration, a relaxation preventing optical signal having a frequency corresponding to the quantum level, which is a lower level in the delay quantum dot, is supplied to the quantum level. By exciting the second exciton, it is possible to control the resonance level so as to be optically forbidden with respect to the resonance level, and the lower level of the first exciton transmitted between the resonance levels can be determined. It is possible to delay relaxation via In particular, according to the present invention, it is possible to delay to the order of nanoseconds, and the optical delay amount can be greatly improved as compared with a delay circuit of about femtoseconds that has been possible in the past.

It is a figure for demonstrating the structure of the optical delay device using the quantum dot to which this invention is applied. It is a figure for demonstrating an energy state. It is a figure for demonstrating the other structure of the optical delay device using the quantum dot to which this invention is applied. It is a figure for demonstrating the structure of a comparative example. It is a figure for demonstrating the result of simulation.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

First, the configuration of an optical delay device using quantum dots to which the present invention is applied will be described. For example, as shown in FIG. 1, the optical delay device 1 includes an input quantum dot 12 arranged on a dielectric substrate made of a material such as NaCl, KCl, Al 2 O 3, glass, or CaF _2, and an input. And a quantum dot array 13 including a plurality of quantum dots 14 having a larger volume than the quantum dots 12 for use.

  The quantum dot array 13 is arranged from the quantum dot 14a located at the start end to the quantum dot 14b located at the end, and is held between the quantum dots 14 through the exchange of excitons. It functions as an optical delay device. An input quantum dot 12 is located in the vicinity of the quantum dot 14a. The quantum dot 12 causes a near-field light interaction with the quantum dot 14, and one quantum dot 14 has at least a near-field light interaction with another adjacent quantum dot 14. Will be caused.

  Each quantum dot 12, 14 controls a single electron (photoexcited carrier) based on discrete energy levels formed by confining the photoexcited carrier in three dimensions. In the quantum dots 12 and 14, the energy level of the carriers in the quantum dot becomes discrete by the exciton confinement system, and the state density can be sharpened in a delta function. The excitons handled in the quantum dots 12 and 14 can be replaced with any photoexcited carriers such as excitons, electrons, and holes.

  The quantum dots 12 and 14 are made of a material system such as CuCl, GaN, or ZnO. When the material system that constitutes each quantum dot 12 or 14 is CuCl, these are configured as a cubic quantum box. When the material system constituting the quantum dots 12 and 14 is GaN or ZnO, these are configured as quantum boxes, hexagonal columns, spheres, or disks. Each of the quantum dots 12 and 14 can have a side length and a diameter of about 4 nm to 10 nm, and can be formed on the substrate with a smaller size than the diffraction limit of light.

  Here, in the case where the quantum dots 12 and 14 are each configured as a cube, when the side length L of the quantum dots 12 and 14 is L, the side length of the quantum dots 12 and 14 is adjusted to be √2L. May be.

  Each of these quantum dots 12 and 14 may be fabricated on a substrate based on the Bridgman method or molecular epitaxy (MBE) growth method, and the formation position of the quantum dots is accurately controlled using near-field light CVD. May be.

The quantum level E ( _nx , _ny , _nz ) in each quantum dot 12, 14 is expressed by the following equation (1) when the mass of the particle is m and the side length of the quantum dot is L. Defined.
E (n _x , n _y , n _z ) = h ² / 8π ² m (π / L) ² (n _x ² + _ny ² + n _z ² ) (1)

In the present invention, depending on the shape and material of the quantum dot, in addition to the quantum level E ( _nx , _ny , _nz ) defined by the formula (1), other general quantum In some cases, level formulas may apply.

Based on this equation (1), E (n _x , n _y , n _z ) of each quantum dot 12, 14 is calculated. Here, when the side length ratio between the quantum dot 12 and the quantum dot 14 is 1: √2, the quantum level in the quantum dot 12 is (1,1,1) as shown in FIG. E (111) is equal to E (211) when the quantum level in the quantum dot 14 is (2,1,1). That is, the quantum level (1, 1, 1) of the quantum dot 12 and the quantum level (2, 1, 1) in the quantum dot 14 are in a relationship in which the excitation energy levels of the excitons resonate with each other.

  In other words, the quantum dots 12 and the quantum dots 14 need to be configured with a larger volume than the input quantum dots 12. In addition, the quantum dot 14 needs to have a resonance level in which excitons can be injected from the input quantum dot 12. This resonance level corresponds to the quantum level (1, 1, 1) of the quantum dot 12 and the quantum level (2, 1, 1) of the quantum dot 14 in the above-described example.

  In addition, the quantum dot 14 is required to have a lower level that can relax excitons in the resonance level. This lower level is the quantum level (1, 1, 1) in the quantum dot 14 in the above-described example.

  In the optical delay device 1 to which the present invention is applied, the exciton is transmitted from the quantum dot 14 a located at the transmission direction start end to the quantum dot 14 b located at the end in the quantum dot array 13, thereby storing it. If no quantum dot that can serve as an output end is formed with respect to the quantum dot 14b positioned at the end, excitons transmitted to the quantum dot 14b return to the quantum dot 14a again. It will be transmitted. And it will continue to reciprocate between these quantum dots 14a-14b. That is, microscopically this is nothing other than transmitting excitons in the quantum dot array 13, but when viewed from the outside, the excitons are stored in the quantum dot array 13. .

  Next, a processing method by the optical delay device 1 will be described.

  First, an optical signal A having a frequency ω1 corresponding to the quantum level (1, 1, 1) is supplied to the input quantum dot 12 to excite excitons to the quantum level. When this exciton is excited, resonance occurs between (1, 1, 1) in the quantum dot 12 and the quantum level (2, 1, 1) in the quantum dot 14. As a result, excitons existing at the quantum level (1, 1, 1) in the quantum dot 12 move to the quantum level (2, 1, 1) of the quantum dot 14. As a result, the exciton apparently moves from the quantum dot 12 to the quantum dot 14.

  In the present invention, an optical signal B having a frequency ω2 different from that of the optical signal A is further supplied. The frequency ω2 in the optical signal B corresponds to the quantum level (1, 1, 1) in the quantum dot 14, and the quantum level (1, 1, 1) of the quantum dot 14 is irradiated by irradiating this to the quantum dot 14. 1,1) can excite excitons. Hereinafter, the exciton transmitted from the quantum dot 12 to the quantum level (2, 1, 1) of the quantum dot 14 is referred to as a first exciton, and the quantum of the quantum dot 14 is determined based on the supply of the optical signal B. An exciton excited to the level (1,1,1) is called a second exciton.

  In the quantum dot 14, the first excitons existing at the quantum level (2,1,1) try to relax to the quantum level (1,1,1) at the lower level. However, the second exciton already excited by the optical signal B exists in the quantum level (1, 1, 1) which is the lower level. As a result, even if this first exciton tries to relax to the lower level quantum level (1, 1, 1), the second exciton exists in the quantum level. It cannot be relaxed and remains as it is in the quantum level (2,1,1). The quantum dots 14 store the first excitons as they are transmitted between the quantum levels (2, 1, 1).

  As described above, according to the optical delay device 1 to which the present invention is applied, the quantum level (1, 1, 1), which is the lower level in the quantum dot 14, is used for relaxation prevention having the frequency ω2 corresponding thereto. By supplying the optical signal B, it is possible to control the quantum level (2, 1, 1) so as to be optically forbidden by exciting the second exciton. It is possible to prevent relaxation through the lower level of the first exciton transmitted between the resonance levels. As a result, it is possible to suppress light loss during storage as much as possible.

  In the above-described embodiment, the quantum level as illustrated in FIG. 2 is described as an example. However, the present invention is not limited to this and satisfies the requirements for the quantum dots 12 and 14 described above. Of course, any other quantum level may be used.

  In the above-described example, the description has been made between the quantum dots 12 and 14 and the quantum levels constituting the quantum dots 12 and 14, but the present invention is not limited to this. May be used. In such a case, each quantum level described above corresponds to an energy band in a quantum well, but other configurations and operations are all the same as those of the quantum dots 12 and 14, and the desired effect is achieved. become.

  In the present invention, for example, as shown in FIG. 3, the quantum dot array 13 may be arranged so that the quantum dots 14 constituting the quantum dot array 13 form a ring.

  As a result, the first excitons injected from the input quantum dots 12 to the quantum dot array 13 side are stored in this by transmitting between the resonance levels of the annular quantum dots 14. Will be.

  Further, the present invention is not limited to the application to the optical delay device described above, but may be applied as a transmission line. When this is actually applied to the transmission path, the quantum dots having a larger volume are arranged on the output side of the quantum dots 14b in the quantum dot array 13 to be transmitted to the quantum dots 14b. The first exciton that has been emitted is emitted through the first exciton to emit light.

  Even in such transmission, the relaxation prevention optical signal B having the frequency ω2 corresponding to the quantum level (1, 1, 1) which is the lower level in the quantum dot 14 is supplied. By doing so, it is possible to control the quantum level (2, 1, 1) to be optically forbidden by exciting the second exciton. As a result, it is possible to prevent relaxation via the lower level of the first exciton transmitted between the resonance levels, and it is possible to improve transmission efficiency.

  Embodiments of the optical delay device 1 to which the present invention is applied will be described below. In Example 1 below, in addition to the optical delay device 1 configured as described above, a comparative example configured as shown in FIG. 4 was prepared.

  In the comparative example shown in FIG. 4, a plurality of quantum dots 12 are arranged from the quantum dot 12a to the quantum dot 12b, and in the vicinity of the quantum dot 12b located at the end, the quantum dot 14 having a larger volume than this. Are arranged over one piece. The relationship between the resonance levels of the quantum dots 12 and 14 is the same as that of the above-described embodiment.

  In the comparative example having such a configuration, the first excitons excited in the quantum dots 12a are transmitted to the quantum dots 12b through the resonance levels, and further to the quantum dots 14 through the resonance levels. Can be transmitted. However, many excitons that transmit between the resonance levels of the quantum dots 12 are emitted. This is because the quantum dot 12 does not supply an optical signal for preventing relaxation for preventing relaxation. In addition to this, the exciton that transmits between the resonance levels in the quantum dot 12 may generate so-called return light that returns to the quantum dot 12 of the transmission source, and the optical loss increases in principle. It has a configuration.

  FIG. 5 shows the result of calculating the optical output by simulation when optical transmission is actually performed between the example of the present invention and the comparative example. The horizontal axis indicates the number of quantum dots 14 in the present invention example, the number of quantum dots 12 in the comparative example, and the vertical axis indicates the output ratio. Both Inventive Example 1) and Comparative Example 1) assume that there is no return light to the source quantum dot, and Inventive Example 2) Comparative Example 2) both return to the source quantum dot. Assume that there is light.

  From the simulation results, the output of Example 1) of the present invention is higher than that of Comparative Example 1) under the same conditions, and Example 2) of the present invention is compared with Comparative Example 2) of the same conditions. You can see that the output is high.

  That is, it is shown that the optical transmission efficiency is higher in the example of the present invention than in the comparative example. Therefore, if the present invention configured as described above is applied to an optical delay device, data can be stably stored for a longer time, and if it is applied as an optical transmission line, it is more efficient. Data transmission can be realized.

DESCRIPTION OF SYMBOLS 1 Optical delay device 12, 14 Quantum dot 13 Quantum dot row

Claims (9)

Quantum dots for input,
Resonance levels in which the first excitons are injected from the input quantum dots and the first excitons are relaxed from the resonance levels. A quantum dot array in which a plurality of delay quantum dots having possible lower levels are arranged in a plurality of substantially the same size,
When the input quantum dot is supplied with an optical signal corresponding to the data to be stored, the first exciton excited according to the wavelength is injected into the delay quantum dot,
The quantum dot array stores the first excitons injected from the input quantum dots by transmitting each of the first excitons between resonance levels in the plurality of delay quantum dots, and The first excitons that are transmitted between the resonance levels by further exciting the second excitons to the lower level based on the supply of the relaxation preventing optical signal having a wavelength different from that of the optical signal. An optical delay device using quantum dots, characterized by delaying relaxation through the lower level of. 2. The optical delay device using quantum dots according to claim 1, wherein the quantum dot array is arranged such that delay quantum dots constituting the quantum dot array form a ring. Quantum dots for input,
Resonance levels in which the first excitons are injected from the input quantum dots and the first excitons are relaxed from the resonance levels. A quantum dot array in which a plurality of quantum dots for transmission having a possible lower level are arranged with a plurality of substantially the same size,
When the input quantum dot is supplied with an optical signal corresponding to the data to be transmitted, the first exciton excited according to the wavelength is injected into the transmission quantum dot,
The quantum dot array transmits the first excitons injected from the input quantum dots between resonance levels in the plurality of transmission quantum dots, and has a wavelength different from that of the optical signal. The second exciton is further excited to the lower level based on the supply of the relaxation preventing optical signal, thereby passing through the lower level of the first exciton transmitted between the resonance levels. A transmission line using quantum dots characterized by delaying the relaxation. The input quantum dot is configured to have a larger volume than the input quantum dot, and the first exciton is injected from the input quantum dot and the resonance level from the resonance level. For a device comprising a quantum dot array in which a plurality of delay quantum dots having a lower level capable of relaxing the first excitons are arranged in a plurality of substantially the same size,
By supplying an optical signal corresponding to data to be stored to the input quantum dot, the first excitons excited according to the wavelength are injected into the delay quantum dot,
The first excitons injected from the input quantum dots into the delay quantum dots are transmitted between each other between resonance levels, and are stored, and relaxation is made of a wavelength different from that of the optical signal. By supplying an optical signal for prevention to further excite the second exciton to the lower level, the first exciton transmitted between the resonance levels is relaxed through the lower level. A data delay method using quantum dots characterized by delaying. The input quantum dot is configured to have a larger volume than the input quantum dot, and the first exciton is injected from the input quantum dot and the resonance level from the resonance level. For a device comprising a quantum dot array in which a plurality of quantum dots for transmission having a lower level capable of relaxing the first excitons are arranged in a plurality of substantially the same size,
By supplying an optical signal corresponding to the data to be transmitted to the input quantum dot, the first excitons excited according to the wavelength are injected into the transmission quantum dot,
The first excitons injected from the input quantum dot to the transmission quantum dot are transmitted between resonance levels, and a relaxation preventing optical signal having a wavelength different from that of the optical signal is supplied. Then, by further exciting the second exciton to the lower level, the relaxation of the first excitons transmitted between the resonance levels via the lower level is delayed. A signal transmission method using quantum dots. A quantum well for input;
A plurality of delay quantum wells having a resonance level in which the first exciton is injected from the input quantum well and a lower level capable of relaxing the first exciton from the resonance level. An arranged quantum well array,
When the input quantum well is supplied with an optical signal corresponding to the data to be stored, the first exciton excited according to the wavelength is injected into the delay quantum well,
The quantum well array stores the first excitons injected from the input quantum well by transmitting the first excitons between the resonance levels in the plurality of delay quantum wells, and The first excitons that are transmitted between the resonance levels by further exciting the second excitons to the lower level based on the supply of the relaxation preventing optical signal having a wavelength different from that of the optical signal. An optical delay device using a quantum well, characterized by delaying relaxation through the lower level. A quantum well for input;
A plurality of transmission quantum wells having a resonance level where the first exciton is injected from the input quantum well and a lower level capable of relaxing the first exciton from the resonance level. An arranged quantum well array,
When the input quantum well is supplied with an optical signal corresponding to the data to be transmitted, the first exciton excited according to the wavelength is injected into the transmission quantum well,
The quantum well array transmits the first excitons injected from the input quantum well to each other between resonance levels in the plurality of transmission quantum wells and has a wavelength different from that of the optical signal. The second exciton transmitted between the resonance levels is further excited by exciting the second exciton to the lower level based on the supply of the relaxation preventing optical signal. An optical transmission line using a quantum well characterized by delaying relaxation via the quantum well. For delay having an input quantum well, a resonance level in which a first exciton is injected from the input quantum well, and a lower level capable of relaxing the first exciton from the resonance level For a device consisting of a quantum well array in which multiple quantum wells are arranged,
By supplying an optical signal corresponding to data to be stored to the input quantum well, the first excitons excited according to the wavelength are injected into the delay quantum well,
The first excitons injected from the input quantum well into the delay quantum well are transmitted between the resonance levels to store them, and the relaxation is made of a wavelength different from that of the optical signal. By supplying an optical signal for prevention to further excite the second exciton to the lower level, the first exciton transmitted between the resonance levels is relaxed through the lower level. A data delay method using a quantum well characterized by delaying. For delay having an input quantum well, a resonance level in which a first exciton is injected from the input quantum well, and a lower level capable of relaxing the first exciton from the resonance level For a device comprising a quantum dot array in which a plurality of quantum dots are arranged with a plurality of substantially the same size,
By supplying an optical signal corresponding to the data to be transmitted to the input quantum well, the first excitons excited according to the wavelength are injected into the transmission quantum dot,
The first excitons injected from the input quantum well to the transmission quantum well are transmitted between resonance levels, and a relaxation preventing optical signal having a wavelength different from that of the optical signal is supplied. Then, by further exciting the second exciton to the lower level, the relaxation of the first excitons transmitted between the resonance levels via the lower level is delayed. A signal transmission method using a quantum well.

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