JPS61259234A - Method of driving optical d flip-flop circuit - Google Patents

Abstract

PURPOSE:To realize an optical DFF circuit of high practical utility by giving positive current clock signal to the first electrode and giving negative current clock signal to the second electrode of an optical bistable semiconductor laser and setting prescribed values for logical values '1', '0'. CONSTITUTION:In an optical bistable semiconductor 1, current given to electrically insulated P side electrodes 5, 6 is made I1, I2, and a positive current clock signal IK is given to the current I1, and a negative current clock signal, the inverse of IK is given to current I2. A optical digital signal LD is inputted as the optical input Pin of the laser 1. Under this condition, when the signal IK is '0', and the signal, the inverse of IK is '1', logical value of the optical output signal LO becomes logical value '1'. When signals IK, the inverse of IK are kept at the same values as before, and the signal LO is changed to '0', the signal LO remains at logical value '1'. When the signal LD remains '0' and the signal IK becomes '1' and signal, the inverse of becomes '0', the signal LO changes to '0'.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an optical D flip-flop circuit driving method,
In particular, the present invention relates to an optical D flip-flop circuit driving method suitable for optical communications, optical information processing, optical switching systems, and optical combination systems.

[Prior art and its problems]

In recent years, with the development of optical technologies such as optical fiber technology and optical semiconductor technology, long-distance optical communication systems for the purpose of backbone transmission, optical LAN systems that connect distributed processing bag lids with high efficiency, etc. have been put into practical use.

In these systems, optical technology was mainly used as a means of connection between functional devices, and the functional devices themselves were comprised exclusively of electronic circuits, mainly LSI.

In the near future, processing information will become more diverse and large in volume, and ultra-high processing speeds and processing complexity will be required.In order to meet these demands, optical technology will not only be used as a means of connection. It becomes necessary to use it as a logical processing means.

In other words, it is possible to digitally process the transmitted optical digital signal as it is, output the result as light, and transmit it to other devices, which is a feature of light such as its high speed, broadband property, and non-inductive nature. Optical processing equipment (optical information processing systems, optical switching systems, etc.) that takes advantage of this will become essential.

In order to realize such an optical processing device, an inverter circuit and an O
Optical logic functional blocks such as optical gates, optical flip-flop circuits, optical shift register circuits, and optical counters having various functions such as R circuits, AND circuits, and exclusive OR circuits must be constructed.

However, in the past, there were no optical logic functional blocks sufficient for practical use.

[Purpose of the invention]

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

[Structure of the invention]

The optical D flip-flop circuit driving method according to the present invention provides a first clock signal to a first electrode of an optical bistable semiconductor laser, and a second clock signal having a phase inverted with respect to the first clock signal to a second electrode. A signal is applied to the optical bistable semiconductor laser so that the optical output of the optical bistable semiconductor laser is synchronized with the first clock signal and changed in response to the optical input.

〔Example〕

The present invention will be described in detail below using the drawings.

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

Referring to FIG. 1, an optical bistable semiconductor laser 1 includes P-side electrodes 5 and 6 electrically insulated by a slit 4 provided parallel to the Fabelli-Perot cavity surface 2.3.

When the current given to the electrode 5.6 is II, 12,
When current 11 is set to a predetermined value, current I2 and optical output P
Optical bistability can be provided between outO.

Figure 2 shows the optical bistable characteristics between the current ■2 and the optical output PoutO, where I+=ICI, IC2(IC
Two types of optical bistability characteristics 7 and 8 in the case of I>IC2) are shown. In the figure, the horizontal axis is the current I2, and the vertical axis is the optical output Pout.
It is assumed that it represents Optical bistable property 7 is based on the current I,
is set to a constant value rC1, and when the current 2 increases and reaches the threshold value Ith2, the optical output Pout suddenly increases and reaches the point P. Even if the current I2 is subsequently increased, the optical output pout only gradually increases and remains at a substantially constant value. On the contrary, when the current (2) decreases and reaches the threshold value Ithl in such a high value state, the optical output Pout suddenly decreases at a point P2. In this way, the current ■2 I t)ll+
The optical output Pout takes two stable states based on the two values of I th2.

The optical bistable characteristic 8 is such that the current 11 is kept at a constant value I. This occurs when the current is set to 2, and the two thresholds I at the current
The optical output pout takes two stable states based on ths and I th4. In this case, there is a relationship of IC2<ICI, and the threshold value 1 th3. r ths is the threshold It
hllI Takes a larger value than th2.

Next, based on FIG. 3, the optical input P of the optical bistable semiconductor laser 1 is
The optical bistability characteristic between in and optical output poutO will be explained. In this case, both currents II and I2 take fixed values. First, the optical bistable characteristic 9 is a characteristic obtained when the current 1 is set to the ICI and the current I2 is set to a value Ibl smaller than the threshold 1 thl. In this optical bistable characteristic 9, when the optical input Pin increases from the point Q+ and reaches the threshold value Pthl, the optical output Pout suddenly increases and takes a high value PH. After that, even if the optical power Pin increases, the optical output Pout remains at a substantially constant value P.

is maintained. On the contrary, when the optical input Pin is decreased in such a high state, the optical output Pout suddenly takes a low value P at a threshold value p th2 smaller than the threshold value P thl.

The optical bistable characteristic 10 is a characteristic obtained when the current I is set to the IC2 and the current I2 is set to the intermediate value rbz between the threshold 1 tb+ and ILh4. In the optical bistable characteristic 10, when the optical input Pin increases and reaches the threshold value P th3, the optical output Pout suddenly becomes a high value PII,
After that, it maintains a substantially constant value Pa. On the contrary, if the optical input Pin is decreased in a state where the high value PK is taken, in this case, even if the optical input Pin becomes zero, the optical output Pout will be located at the point Q2, and will remain at the high value PH. becomes.

In the above, each current value IC1+ Iel Ib++ is set so that the threshold value Pthl of the optical bistable characteristic 9 is smaller than the threshold value P tb+ of the optical bistable characteristic 10.
Ibz is set.

Next, by utilizing the various optical bistable characteristics 7, 8, 9, and 10 occurring in the optical bistable semiconductor laser 1 as described above, the input optical digital signal is output in synchronization with the rising edge of the current clock signal. As a result, the optical bistable semiconductor laser 1
A driving method for making the circuit function as an optical D flip-flop circuit will be explained.

In FIG. 4, an optical digital signal having an amplitude value An is input manually as an optical input pin of the optical bistable semiconductor laser 1. The amplitude value An is the threshold value Pth of the optical bistable characteristic 9.
It is set to an intermediate value between l and the threshold value P thz of the optical bistable characteristic 10. The current value given to the electrode 5 is used as the current value Ic2 for the logic value "0" and the current value ■ for the logic value "1". Set 1.

On the other hand, the current I2 applied to the electrode 6 is used as a negative current clock signal TK (second clock signal), and has a logical value of "
0” is the current value Ibl, and logical value “1” is the current value Ib.
Set 2. The phase of this negative current clock signal Tk is in an inverse relationship with the phase of the positive current clock signal Ik. In the above signal relationship, the optical digital signal LD is the current clock signal 1. and signaled as the optical output Pout. is obtained.

Regarding time t 1. -1. FIG. 4 will be explained in the following order. First, time 1=1. Earlier, the amplitude value of the optical digital signal Ln was 0 (logical value "0").

The current clock signal Ig is IC2, and the current clock signal Tyo is Ib2. Therefore, optical input Pin and optical output Pou
The relationship between t is governed by the optical bistability characteristic 10, and therefore the optical output Pout is maintained at a low value Pt. Hence the optical output signal. takes the logical value "0".

Time 1=1. Then, the optical digital signal Lo has an amplitude value of A
. (logical value “1”). At this time, the positive current clock signal I and the negative current clock signal Ill remain as they are.
Since C2 and IB2 are maintained as they are, the optical bistable semiconductor laser 1 is excited to point Q3 in the optical bistable characteristic 10, but the optical output Pout is still maintained at a low value PL. That is, even if the optical digital signal LD has a logical value of "1", the optical output signal is not output. remains at the logical value "0".

Time 1=1. When the positive current clock signal I changes to IC3 and the negative current clock signal T changes to Ibl, the optical bistable semiconductor laser 1 is dominated by the optical bistable characteristic 9.

Therefore, the amplitude value of the optical digital signal LD is A. Therefore, the operating point is point Q, and the optical output Pout is a high value P.
■Changes to. Therefore, the optical output signal Lo has a logical value of "1"' at this point. This means that the optical output signal is generated at the rising edge C1 of the positive current clock signal IN. This means that the rises of are synchronized.

At time t=t3, the positive current clock signal I, IC2
Then, the negative current clock signal Tk changes to Ib2. As a result, the optical bistable semiconductor laser 1 is dominated by the optical bistable characteristic 10, and the optical digital signal is generated. remains at a high value An, its operating point changes from point Q4 to point Q5, but the optical output pout remains at a high value PII.
is maintained.

Therefore, the optical output signal. is held at the logical value "1".

Time 1=1. In this case, each current clock signal I*, Tg is kept at the same value as above, and the optical digital signal is changed.

only changes its amplitude value to 0. However, since the optical bistable semiconductor laser 1 is governed by the optical bistable characteristic 10, the operating point moves from point Q5 to point Q2, and the optical output P
out is held at a high value Pa. This means that even if the optical digital signal Ln changes to the logical value "0", the optical output signal remains unchanged. means that it is held at the logical value "1".

Time 1=1. Then, the amplitude value of the optical digital signal Ln is 0.
As it is, the positive current clock signal Ill changes to ICI, and the negative current clock signal Ill changes to Ibl.

The optical bistable semiconductor laser 1 is thereby governed by the optical bistable characteristic 9, and the operating point changes from point Q2 to point Q,
Changes to Therefore, at this point, there is no optical output signal. changes from logical value “1” to logical value “0”. This means that
This means that in response to the rising edge C2 of the positive current clock signal I, the optical output signal wrinkle becomes a logical value "0" in synchronization with this rising edge C2.

Time 1=1. From now on 1. , 1. , 1. Then the above operation is repeated.

According to the above operation, a signal which is the optical output Pout is generated.

The optical digital signal Ln, which is the optical input Pin, is the rising edge of the current clock signal It CI+ 02r 03+ C4
This occurs due to a certain period of delay in synchronization with +C%...

Therefore, the optical bistable semiconductor laser 1 is controlled by the currents II (Ill) and I2 (Tll) applied to the electrodes 5 and 6 with predetermined current values set to logical values "1" and "0", and An optical digital signal having a predetermined amplitude value An. By using as an optical input, it is possible to operate as an optical D flip-flop circuit, that is, an optical circuit having the function of a D flip-flop.

〔Effect of the invention〕

As is clear 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 predetermined values for "1" and "0", two types of bistable characteristics are provided between the optical input and the optical output, and by synchronizing the optical output signal with the positive current clock signal. , it is possible to realize a highly practical optical D flip-flop circuit.

[Brief explanation of drawings]

FIG. 1 is a perspective view of an optical bistable semiconductor radar that implements an optical D flip-flop circuit by applying the driving method according to the present invention, and FIG. Figure 3 is a diagram showing the optical bistability characteristic that occurs between optical input and optical output. Figure 4 is a waveform diagram for explaining the operating characteristics as an optical D flip-flop circuit. FIG. 2 is an optical bistability characteristic diagram related to . 1... Optical bistable semiconductor laser 5.6... Electrode? , 8.9.10... Optical bistable characteristics II, I2... Current Pin... Optical input Pout... Optical output ■,... Positive current clock signal (first clock number) T ... Negative current clock signal (second clock number) La... Optical digital signal L0 as an optical input signal
...Light output signal agent Patent attorney Yoshiyuki Iwasa 1 person, 7 stable guides, 1 flute, 1 craftsman, 1 person

Claims (2)

[Claims] (1) Applying a first clock signal to the first electrode of the optical bistable semiconductor laser and applying a second clock signal having an inverted phase with respect to the first clock signal to the second electrode, A method for driving an optical D flip-flop circuit, characterized in that the optical output is synchronized with the first clock signal and changed in accordance with the optical input. (2) The amplitude value of the optical input of the optical bistable semiconductor laser is
When the first clock signal has a logical value of "0" and the second clock signal has a logical value of "1", the optical output has a logical value of "0", and the first clock signal has a logical value of "1" and the second clock signal has a logical value of "1". 2. The method of driving an optical D flip-flop circuit according to claim 1, wherein the optical output is set to have a logical value of "1" when the logical value is "0".