JPH0766133B2 - Optical D flip-flop circuit driving method - Google Patents

Description

The present invention relates to a method for driving an optical D flip-flop circuit,
In particular, the present invention relates to an optical D flip-flop circuit driving method suitable for optical communication, optical information processing, optical switching systems, and optical computers.

[Prior art and its problems]

With the recent development of optical technologies such as optical fiber technology and optical semiconductor technology, a long-distance optical communication system for the purpose of backbone transmission, an optical LAN system for connecting distributed processing devices with high efficiency, and the like have been put into practical use. In these systems, the optical technology is mainly used as a connecting means between the functional devices, and the functional devices themselves are composed mainly of electronic circuits centering on LSI.

In the near future, diversification and large capacity of processing information will progress, ultra-high processing speed and complicated processing will be required. To meet this demand, optical technology is not only used as a connecting means. It becomes necessary to use it as a logical processing means.
In other words, the optical digital signal that has been transmitted can be digitally processed as it is, and the result can be output as light and transmitted to other devices. Optical processing devices (optical information processing systems, optical switching systems, etc.) that utilize the above are essential.

To realize such an optical processing device, an inverter circuit / OR
An optical logic functional block such as an optical gate, an optical flip-flop circuit, an optical shift register circuit, an optical counter, etc., having respective functions such as a circuit, an AND circuit, an exclusive OR circuit, etc. must be constructed.

However, in the past, there have not been sufficient optical logic functional blocks that are sufficient for practical use.

[Object of the Invention]

An object of the present invention is to provide an optical D flip-flop circuit driving method for realizing an optical D flip-flop circuit having a high practicality by using an optical bistable semiconductor laser.

[Structure of Invention]

In order to achieve the above object, the present invention is to inject a constant current value I _C1 into a first electrode of an optical bistable semiconductor laser, thereby injecting a current I ₂ into the second electrode and the optical bistable semiconductor laser. of are allowed to appear in the first optical bistability characteristics in relationship between the optical output P _out, the first optical bistable characteristics, between the current I ₂ is high threshold I _th2 than the threshold value I _th1 and the threshold value I _th1 It shows optical bistable and the current value is applied to the first electrode of the optical bistable semiconductor laser.
By injecting a constant current value I _C2 lower than I _{C1, a} second optical bistable characteristic appears in the relationship between the current I ₂ injected into the second electrode and the optical output P _out of the optical bistable semiconductor laser. , The second optical bistable characteristic is that the current I ₂ is _equal to the threshold I _th3 and the threshold I _th3.
Shows optical bistability with a higher threshold I _th4 ,
_The current value I _C1 and the current value I _C2 are set so that _th3 becomes higher than the threshold value I _th2 , and the amplitude of the logical value “1” of the first clock signal is made to correspond to the current value I _C1. , The amplitude of the logical value “0” of the first clock signal is set to the current value I _C2
And the amplitude of the logical value “1” of the second clock signal having the phase in the inverted state with respect to the first clock signal corresponds to the intermediate current value I _b2 between the threshold I _th3 and the threshold I _th4. Then, the amplitude of the logical value “0” of the second clock signal is made to correspond to the current value I _b1 lower than the threshold value I _th1 , and the first clock signal is applied to the first electrode of the optical bistable semiconductor laser. , The second clock signal is applied to the second electrode, and when the logical value of the first clock signal is "1" and the logical value of the second clock signal is "0", the optical input of the optical bistable semiconductor laser P _in the allowed to appear third optical bistable characteristics of the relationship between the optical output P _out, the third optical bistable characteristics, the light input P _in the threshold is higher than the threshold value P _th2 and the threshold P _th2 P _th1 Optical bistability between the first clock signal and the logical value "0" and the second clock signal is logical. When the theoretical value is "1", a fourth optical bistable characteristic appears in the relationship between the optical input P _in and the optical output P _out, and the fourth optical bistable characteristic is the optical input P in
_in exhibits optical bistability between zero and the threshold P _th3 , and the threshold P _th3
Is set higher than the threshold P _th1 , and the amplitude A _D of the logical value “1” of the input optical logic signal to the optical bistable semiconductor laser is set to an intermediate value between the threshold P _th1 and the threshold P _th3. Thus, the output optical logic signal is output by synchronizing the input optical logic signal with the first clock signal.

〔Example〕

 Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an optical bistable semiconductor laser which realizes an optical D flip-flop circuit to which the driving method according to the present invention is applied.
2 and 3 are characteristic diagrams showing various optical bistable relationships such as input and output of an optical bistable semiconductor laser, and FIG. 4 is a waveform diagram for explaining operation characteristics as an optical D flip-flop circuit. A characteristic diagram of the relationship is shown.

In FIG. 1, an optical bistable semiconductor laser 1 has a slit 4 provided in parallel with Fabry-Perot resonator surfaces 2 and 3.
P-side electrodes 5 and 6 electrically insulated from each other. electrode
When the currents given to 5 and 6 are I ₁ and I ₂ , if the current I ₁ is set to a predetermined value, an optical bistable characteristic can be provided between the current I ₂ and the optical output Pout.

FIG. 2 shows the optical bistable characteristics between the current I ₂ and the optical output Pout, and two types of optical bistable characteristics in the case of I ₁ = I _C1 , I _C2 (I _C1 > I _C2 ) 7 , 8 is shown. In the figure, the horizontal axis is the current I ₂ ,
The vertical axis represents the optical output Pout. The optical bistable characteristic 7 occurs when the current I ₁ is set to a constant value I _C1 , and when the current I ₂ increases and reaches the threshold value I _th2 , the optical output Pout suddenly increases and reaches the point P ₁ . . After that, even if the current I ₂ is increased, the optical output Pout only gradually increases and takes a substantially constant value. Conversely,
In such a high value state, the current I ₂ decreases and the threshold value I _th1
At point P ₂ , the optical output Pout suddenly decreases. In this way, the optical output Pout is calculated based on the two values I _th1 and I _th2 of the current I _2.
Has two stable states.

The optical bistable characteristic 8 occurs when the current I ₁ is set to a constant value I _C2 , and it has two thresholds I _th3 and I _th4 in the current I ₂ .
The optical output Pout has two stable states based on In this case, I _C2 <I _C1 and the thresholds I _th3 and I _th4 take values larger than the thresholds I _th1 and I _th2 .

Next, based on FIG. 3, the optical input Pi of the optical bistable semiconductor laser 1
The optical bistable characteristic between n and the optical output Pout will be described.
In this case, the currents I ₁ and I ₂ both have fixed values. First, the optical bistable characteristic 9 is a characteristic obtained when the current I ₁ is set to I _C1 and the current I ₂ is set to a value I _b1 smaller than the threshold I _th1 . With this optical bistable characteristic 9, the optical input Pin
If There reaches the threshold P _th1 increases from the point Q _1, the optical output Pout is suddenly increased takes a high value P _H. Optical output Pout even then the light input Pin is increased is kept substantially constant value P _H. Conversely,
When the optical input Pin is reduced in such a high state, the optical output Pout suddenly becomes a low value P _L at a threshold P _th2 smaller than the threshold P _th1.
Take

The optical bistable characteristic 10 is a characteristic obtained when the current I ₁ is set to I _C2 and the current I ₂ is set to an intermediate value I _b2 between the thresholds I _th3 and I _th4 . With the optical bistable characteristic 10, the optical input Pin
There increased light output Pout reaches the threshold P _th3 by suddenly high value P _H, and the then substantially maintains a constant value P _H. Conversely, decreasing the light input Pin in the state to take such a high value P _H, the light output Pout be light input Pin becomes zero if is located at point Q _2, held to a high value P _H It remains as it was.

In the above, the respective current values I _C1 , I _C2 , I _b1 , I _b2 are set so that the threshold P _th1 of the optical bistable characteristic 9 is smaller than the threshold P _th3 of the optical bistable characteristic 10. It

Next, using the various optical bistable characteristics 7, 8, 9, 10 generated in the optical bistable semiconductor laser 1 as described above, the input optical digital signal is output in synchronization with the rise of the current clock signal, A driving method for causing the optical bistable semiconductor laser 1 to function as an optical D flip-flop circuit will be described.

In Figure 4, an optical digital signal having an amplitude value A _D L _D
Is input as the optical input Pin of the optical bistable semiconductor laser 1. The amplitude value A _D is set to an intermediate value between the threshold P _th1 of the optical bistable characteristic 9 and the threshold P _th3 of the optical bistable characteristic 10. The current I ₁ given to the electrode 5 is used as the positive current clock signal I _K (first clock signal), and the logical value “0” has the current value I _K.
C2 is set, and the current value I _C1 is set to the logical value "1". On the other hand, the current I ₂ given to the electrode 6 is used as a negative current clock signal _K (second clock signal), and the current value I _b1 is set to the logical value “0” and the current value I _b2 is set to the logical value “1”. To set. The phase of this negative current clock signal _k is the positive current clock signal.
It has an inversion relation with the phase of I _k . In the above signal relation,
The optical digital signal L _D is synchronized with the current clock signal I _K , and the signal L ₀ is obtained as the optical output Pout.

FIG. 4 will be described with respect to the time t in the order of t ₁ to t ₃ .
First, before time t = t ₁ , the amplitude value of the optical digital signal L _D is 0 (logical value “0”), the current clock signal I _K is I _C2 ,
The current clock signal _K is I _b2 . Therefore, the optical input Pin
The relationship between the optical output Pout and the optical output Pout is governed by the optical bistable characteristic 10, and therefore the optical output Pout is held at a low value P _L. Therefore, the optical output signal L ₀ takes the logical value “0”.

At time t = t ₁ , the optical digital signal L _D has an amplitude value A _D (logical value “1”). At this time, since the positive current clock signal I _K and the negative current clock signal _K are maintained as they are I _C2 and I _b2 , the optical bistable semiconductor laser 1 is excited at the point Q ₃ in the optical bistable characteristic 10. However, the light output Pout is still held at a low value P _L. That is, even if the optical digital signal L _D has the logical value “1”, the optical output signal L ₀ remains the logical value “0”.

When the positive current clock signal I _K changes to I _C1 and the negative current clock signal _K changes to I _b1 at time t = t ₂ , the optical bistable semiconductor laser 1 is dominated by the optical bistable characteristic 9. Therefore, since the amplitude value of the optical digital signal L _D is A _D , the operating point is the point Q ₄ , and the optical output Pout changes to a high value P _H. Therefore, the optical output signal L ₀ becomes the logical value “1” at this point. This means that the rising edge of the optical output signal L ₀ is synchronized with the rising edge c ₁ of the positive current clock signal I _K.

At time t = t ₃ , the positive current clock signal I _K changes to I _C2 and the negative current clock signal _k changes to I _b2 . As a result,
The optical bistable semiconductor laser 1 is dominated by the optical bistable characteristic 10, and the optical digital signal L _D still holds the high value A _D , so its operating point changes from the point Q ₄ to the point Q ₅ . varies, the optical output Pout is held to a high value P _H.

Therefore, the optical output signal L ₀ is held at the logical value “1”.

At time t = t ₄ , each current clock signal I _K , _K is kept at the same value as above, and only the optical digital signal L _D changes its amplitude value to zero. However, since the optical bistable semiconductor laser 1 is governed by the optical bistable characteristic 10, the operating point is
Moved from Q ₅ to the point Q _2, the light output Pout is held to a high value P _H. This means that the optical output signal L ₀ is held at the logical value “1” even if the optical digital signal L _D changes to the logical value “0”.

At time t = t ₅ , the positive current clock signal I _K changes to I _C1 and the negative current clock signal _K changes to I _b1 while the amplitude value of the optical digital signal L _D remains 0. The optical bistable semiconductor laser 1 is thereby governed by the optical bistable characteristic 9, and the operating point changes from the point Q ₂ to the point Q ₁ . Therefore, at this time, the optical output signal L ₀ changes from the logical value “1” to the logical value “0”. This is a positive current clock signal
It means that the optical output signal L _D becomes a logical value “0” in synchronization with the rising edge c _{2 of} I _K.

Time t = t ₆ after t _7, t _8, t ₉ in the above-described operation is repeated Kaee.

According to the above operation, the signal L ₀ that is the optical output Pout is
It occurs when the optical digital signal L _D, which is a pin, is delayed for a certain time in synchronization with the rising edges c ₁ , c ₂ , c ₃ , c ₄ , c _5, ... Of the current clock signal I _K. Therefore, the optical bistable semiconductor laser 1
It is controlled by the currents I ₁ (I _K ) and I ₂ ( _K ) given to the electrodes 5 and 6 by setting the predetermined current values to the logical values “1” and “0”,
Further, by receiving the optical digital signal L _D having the predetermined amplitude value A _D as the optical input, it is possible to operate as an optical D flip-flop circuit, that is, an optical circuit having a function of a D flip-flop.

〔The invention's effect〕

As is apparent from the above description, according to the present invention, in an optical bistable semiconductor laser, a positive current clock signal is applied to the first electrode, a negative current clock signal is applied to the second electrode, and a logical value By setting a predetermined value for "1" and "0", two kinds of bistable characteristics are provided between the optical input and the optical output, and the optical output signal is synchronized with the positive current clock signal, thereby making it practical. It is possible to realize an optical D flip-flop circuit that is rich in properties.

[Brief description of drawings]

FIG. 1 is a perspective view of an optical bistable semiconductor laser which realizes an optical D flip-flop circuit by applying the driving method according to the present invention, and FIG. 2 is an optical bistable semiconductor laser generated between a current applied to an electrode and an optical output. FIG. 3 is a diagram showing a stability characteristic, FIG. 3 is a diagram showing an optical bistable characteristic generated between an optical input and an optical output, and FIG. 4 is a waveform diagram for explaining an operating characteristic as an optical D flip-flop circuit and this. FIG. 3 is an optical bistable characteristic diagram related to. 1 …… Optical bistable semiconductor laser 5,6 …… Electrodes 7,8,9,10 …… Optical bistable characteristics I ₁ , I ₂ …… Current Pin …… Optical input Pout …… Optical output I _K …… Positive Current clock signal (1st clock) _K ... Negative current clock signal (2nd clock) L _D ...... Optical digital signal as optical input signal L ₀ ...... Optical output signal

Claims (1)

[Claims] 1. A current I injected into a second electrode by injecting a constant current value I _C1 into the first electrode of an optical bistable semiconductor laser.
₂ and the optical output P _out of the optical bistable semiconductor laser, a first optical bistable characteristic appears, and the first optical bistable characteristic is that the current I ₂ is greater than the threshold I _th1 and the threshold I _th1 . High threshold
It exhibits optical bistable between I _th2 and a constant current value I _C2 lower than the current value I _C1 at the first electrode of the optical bistable semiconductor laser.
Is injected into the second electrode to cause a second optical bistable characteristic to appear in the relationship between the current I ₂ injected into the second electrode and the optical output P _out of the optical bistable semiconductor laser. Current I ₂
There indicates optical bistable between the threshold I _th3 and the threshold value I _th3 higher threshold I _th4, the threshold I _th3 and the current value I _C1 so as to be higher than the threshold value I _th2 and the current value I _C2 Is set, the amplitude of the logical value “1” of the first clock signal is made to correspond to the current value I _C1, and the logical value “0” of the first clock signal is set.
Of the made to correspond to the current value I _C2 amplitude, the amplitude of the logic value of the second clock signal "1" having the phase of the inverted state with respect to the first clock signal and the threshold value I _th3 and said threshold I _th4 Corresponding to an intermediate current value I _b2 , making the amplitude of the logical value “0” of the second clock signal correspond to a current value I _b1 lower than the threshold value I _th1 , and making the first clock signal the optical bistable semiconductor laser. When the logical value of the first clock signal is “1” and the logical value of the second clock signal is “0”, the second clock signal is applied to the first electrode, the second clock signal is applied to the second electrode,
The optical input P _in of the optical bistable semiconductor laser and the optical output P in
The third optical bistable characteristic appears in the relation with _out ,
The optical bistable characteristic is that the optical input P _in is _equal to the threshold P _th2 and the threshold P
_th2 shows the optical bistable between higher threshold P _th1, when the first clock signal has a logic value of "0" and the second clock signal has a logic value of "1", the light input P _in and the light Output P _out
Allowed to appear fourth optical bistable characteristics of the relationship between the fourth optical bistable characteristics indicates optical bistable between said optical input P _in is zero and the threshold P _th3, the threshold P _th3 is the threshold P _th1 higher is set from, by setting the amplitude a _D having the logic value "1" of the input optical logic signal to said optical bistable semiconductor laser to an intermediate value between the threshold value P _th3 and the threshold value P _th1, the An optical D flip-flop circuit driving method, wherein an output optical logic signal is output by synchronizing an input optical logic signal with the first clock signal.