JPS61153900A - Optical information memory circuit - Google Patents

Abstract

PURPOSE:To make an optical inverter unnecessary and to execute a room temperature action by changing an injected electric current from an electric current supplying circuit to a bistable semiconductor laser in accordance with the output electric signal of the photoelectric converter. CONSTITUTION:A binary seven setting incident light 11 are photodetected by the photoelectric converter 13, and an electric current supplying circuit 14 is controlled by the binary signal from the converter 13. When the incident light 11 is zero, the light quantity of an emitting light 16 is drastically increased at a bistable semiconductor 15, the electric current (i) of the middle value of the injected electric current values I1 and I2 to show a hysteresis characteristic which drastically decreases following the decrease of injected electric current value is supplied to a laser 15, and the laser 15 outputs the emitting light 16 in accordance with the incident light 12. On the other hand, when the incident light 11 goes to be 1 of a binary, an output electric current (i) from the circuit 14 becomes smaller than the electric current value I2, the laser 15 is reset, and the emitting light 16 is hardly emitted. By these, the light inverter, which processes the resetting incident light and is operated at the low temperature, becomes unnecessary, and the room temperature action can be executed for the set and reset an optical information memory circuit.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an optical information storage circuit that can be set and reset by an optical input signal.

(Problems with the prior art) Current mode logic, which uses a current switch as a basic block, has been known as a device that performs logical operations on electrical signals at high speed, and in recent years, GaAs F
Research is progressing on ultrahigh-speed arithmetic circuits using ETs, Josephson coupling elements, and the like.

However, in order to perform high-speed digital information processing of large amounts of two-dimensional data such as image information using electrical signals, the calculation speed is
There are limits in terms of power consumption, etc. For this reason, it is desired to realize an optical logic arithmetic circuit that can process optical signals as they are in the form of light, which is compatible with high-speed, two-dimensional parallel information processing. Optical information storage circuits that can read and write optical information are essential.

A patent application for such an optical information storage circuit was filed in 1984 ='04.
There is one described in the specification of No. 2573, which uses an optical inverter and a bistable semiconductor laser as shown in FIG.

Optical inverters utilize the phenomenon that when light is incident on an oscillating semiconductor laser in a direction that cuts through the resonance axis, the oscillation stops due to a quenching effect. When no incident light is input, the output light is output, and when the incident light is input, the output light is stopped, thus fulfilling the logical function of an inverter.

A bistable semiconductor laser has a saturable absorption region in a part of the resonator of the semiconductor laser, and exhibits a hysteresis loop in the characteristics of the amount of incident light versus the amount of output light by appropriately selecting the injection current. By applying bias light with an intermediate light intensity between the rising incident light intensity and the falling incident light intensity of the hysteresis loop, it is possible to store one of two states: a set state in which oscillation occurs and a reset state in which oscillation does not occur. It can be set by applying a larger amount of incident light than the rising incident light amount of the hysteresis loop, and can be reset by reducing the bias light amount to be smaller than the falling light amount of the hysteresis loop.

In FIG. 4, the bistable semiconductor laser 45 is connected to the current supply circuit 46.
A constant current i is input as main input from i, and set or reset is made by inputting set incident light 41 and reset incident light 42 with bias light 44 whose logic is inverted by an optical inverter 43, and outputs output light 47 in the set state. .

If neither the set incident light 41 nor the reset incident light 42 is incident, the optical inverter 43 applies a predetermined amount of bias light 44, and the bistable single conductor laser 45 memorizes the previous state. If the bistable semiconductor laser 45 is in the reset state, it can be set by inputting the set incident light 41. On the other hand, if the bistable semiconductor laser 45 is in the set state, when the reset incident light 42 is input, the optical inverter 43 stops oscillating, the amount of the bias light 44 decreases, and the bistable semiconductor laser 45 can be reset. In this way, the optical information storage circuit shown in FIG.
It only operates at low temperatures and cannot be used at elevated temperatures. Therefore, conventional optical information storage circuits must be cooled to extremely low temperatures before they can be used.

(Object of the Invention) An object of the present invention is to provide an optical information storage circuit that does not require the use of an optical input and operates at room temperature.

Structure of the Invention) According to the present invention, when the injection current is increased from zero in the characteristics of the injection current versus the output light amount under the condition that the incident light amount is zero, the output light amount increases sharply at 11 (injection type). ■When decreasing from 1, the amount of output light decreases rapidly at I2.
I has the IJ cis characteristic, and the intermediate value of I3 between ■2? In the incident light intensity vs. output light intensity characteristic at the main input current value, when the incident light intensity is increased from zero, the output light intensity rapidly increases at P1, which has a hysteresis characteristic, and the light signal has a binary value of light intensity greater than Pl or zero. a bistable semiconductor laser into which a binary reset optical signal is input; a photoelectric converter into which a binary reset optical signal is input; There is obtained an optical information storage circuit comprising a current supply circuit that supplies an injection current of 1 to the bistable semiconductor laser.

(Detailed explanation of the lecture) The present invention solves the problems of the prior art by adopting the above-described configuration. By changing the current injected from the current supply circuit to the bistable semiconductor laser according to the output electrical signal of a photoelectric converter that operates sufficiently stably at room temperature, it is possible to set and reset using optical signals without using an optical inverter. The structure of the optical information storage circuit that can be used is different.

(Example) Hereinafter, the present invention will be explained in detail with reference to the drawings.

FIG. 1 is a diagram showing an embodiment of the present invention.

According to FIG. 1, the embodiment of the present invention includes a bistable semiconductor laser 15 that receives a set incident light 12 and emits an output light 16, a photoelectric converter 13 that receives a reset incident light 11,
A current supply circuit 14 that changes the value i of the current injected into the bistable semiconductor laser 15 according to the output electric signal of the photoelectric converter 13 is included. For more information about the bistable semiconductor laser 15, please see Electronics.
ter) Volume 17, page 741, and Lectures at the 1985 National Conference of the Optical and Radio Division of the Institute of Electronics and Communication Engineers (Part 2) #272.

FIG. 2 is a diagram for explaining the characteristics of the bistable semiconductor laser 15 of the embodiment shown in FIG. FIG. 2(a) shows the injection current i and the light amount P of the output light 16 when the light amount Pinl of the set incident light 12 is 0. It shows the relationship with ut. When i is increased from 0, the current suddenly becomes P at 1. When ut increases from 0 and then i decreases, it exhibits a hysteresis characteristic in which it rapidly decreases to 0 at 12. At this time, if i is set to iB, which is a value between 11 and 12, P is obtained. Two states can be taken: operating point A where ut is 0 and operating point B where Ph is. Figure 2(b) shows the set incident light 1 when 1=ib.
2 light quantity Pinl and P. ut, and operating points A and B are in the same state as operating points A and B in FIG. 2(a), respectively. If the operating point is A at first, then P
When inl is increased from O, Pinl=PL and P. ut
Even if P is rapidly increased from 0 to Ph and then P is decreased. ut is almost constant with ph and Pinl=0
Even if it is reduced to P. Maintain operating point B of ut=Ph.

FIG. 3 is a diagram for explaining the operation of the embodiment shown in FIG. 1. In the memorized state, the light intensity of the set incident light 12 is
The light intensity Pin2 of the reset incident light 11 is both O, and the main input current i1. It is tiB. Therefore, the bistable semiconductor laser 15 maintains either the operating point A or the operating point B in FIG. ut is 0 or Ph, respectively.

P from the reset state where Pout=0. The setting operation to change ut=Ph is to change Pinl from 0 to Fig. 2(b).
This is done by increasing Ps to the value shown in . Pin2
and i remain at 0 and iB, respectively. Figure 2 (
As shown in b), Ps is set larger than Pl.
Due to the change in inl from 0 to Ps, the operating point moves from A to C and becomes Pout"Ph. After that, even if Pinl decreases to 0, the operating point moves from C to B and sets P.ut=Ph. State is preserved.

P from the set state. The reset operation to change ut"0 is performed by increasing Pin2 from 0 to Pr. The change in Pin2 causes a change in the output electrical signal of the photoelectric converter 13, and the current supply circuit 14 changes the injection current i from iB to i
change to r. As shown in Figure 2(a), ir is 12
It is set smaller and the operating point moves from B to D and P.

ut” becomes 0. After that, Pin2 decreases to 0, and i becomes i
, even if it returns to iB, the operating point moves from D to A and P. u
The reset state of t''O is maintained.

(Effects of the Invention) As described above, according to the present invention, it is possible to construct an optical information storage circuit that can be set and reset using an optical signal without using an optical inverter (that is, can be moved at room temperature).

[Brief explanation of drawings]

1 is a diagram showing an embodiment of the present invention, FIG. 2 is a diagram for explaining the characteristics of the bistable semiconductor laser 15 in FIG. 1, and FIG. 3 is a diagram for explaining the operation of the embodiment of FIG. 1. diagram for,
FIG. 4 is a diagram showing the configuration of a conventional optical information storage circuit. In the figure, 13 represents a photoelectric converter, 4.16 represents a current supply circuit, 15.45 represents a bistable semiconductor laser, and 43 represents an optical inverter. Figure 2 Pou and 3rd Mouth Lo

Claims (1)

[Claims] In the injection current vs. output light amount characteristics under the condition where the amount of incident light is zero, when the injection current is increased from zero, the output light amount increases rapidly at I_1, and when the injection current is decreased from I_1, I
It has a hysteresis characteristic in which the amount of emitted light rapidly decreases at _2, and when the amount of incident light is increased from zero in the incident light amount vs. output light amount characteristic at the injection current value I_3, which is the intermediate value between I_1 and I_2, the amount of output light increases rapidly at P_1. a bistable semiconductor laser, which has a hysteresis characteristic of
a photoelectric converter into which a value reset optical signal is input; and a current supply circuit that supplies the bistable semiconductor laser with a binary injection current of a current value smaller than I_2 or I_3 according to the output electric signal of the photoelectric converter. An optical information storage circuit comprising: