JPS6133015A - Optical flip-flop - Google Patents

Abstract

PURPOSE:To attain both setting and resetting actions with an optical input signal by providing two optical input switches and two semiconductor light emitting elements so as to form mutual positive feedback loops. CONSTITUTION:A part of the optical output of a semiconductor laser 3 is supplied to phototransistor PT2; while a part of the output light of a semiconductor laser 4 is supplied to a phototransistor PT1 respectively. When an optical input is given to the PT1 from a set terminal S, the laser 4 has oscillations since the PT2 is kept off. Then an optical output is obtained from an output terminal Q. While the laser 4 stops oscillations when an optical input is given to a reset terminal R. Then an optical output is obtained at an output terminal Q' concurrently with the start of oscillations of the laser 3. Thus it is possible to perform both setting and resetting actions with an optical input signal.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) Among optical flip-flops used for applications such as optical information processing and optical pulse signal memory, the present invention particularly relates to set-reset type optical flip-flops.

(Prior art and its problems) Optical fiber communication and optical switching are used for high-speed signal transmission and high-speed information processing using optical pulses.

Development of optical computers, etc. is progressing. Optical flip-flops are essential for these applications as basic logic function circuits.

Conventionally, as having the function of an optical flip-flop,
Optical bistable circuits have been known that are constructed by combining photodiodes and semiconductor lasers or light emitting diodes and utilizing the nonlinearity of these elements and positive feedback loops (for example, IEICE technical research report, 0QE81). -89
．． (described on pages 49-56). However, since conventional optical bistable circuits only have a single positive feedback loop, once partially set by an optical input signal, the circuit can be reset by cutting off the power supplied to the circuit. The drawback was that while setting could be done using an optical signal, resetting could only be done using an electrical signal.

(Objective of the Invention) An object of the present invention is to eliminate the above-mentioned drawbacks and to provide an optical flip-flop that can be set and reset using an optical input signal.

(Structure of the Invention) According to the present invention, the first semiconductor light emitting device is connected in parallel with the first optical input electronic switch, and the second semiconductor light emitting device is connected in parallel with the second optical input electronic switch. including;
At least a portion of the output light of the first semiconductor light emitting device becomes an input signal of the second optical input electronic switch, and at least a portion of the output light of the second semiconductor light emitting device becomes the input signal of the second optical input electronic switch. An optical free-lag flop is obtained, which is characterized in that it is arranged to serve as an input signal to an electronic switch.

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

FIG. 1 is a circuit diagram representing one embodiment based on the present invention. In this example, two phototransistors 1.2 and 2 are used.
The two semiconductor lasers 3.4 are arranged so that they mutually form positive feedback loops.

The phototransistor 1 and the semiconductor laser 3 are connected in parallel and connected via a resistor 5 to a power source of a positive voltage Vce. When no light is input to the phototransistor 1, the phototransistor 1 is turned off, current flows through the resistor 5 to the semiconductor laser 3, and the semiconductor laser 3 performs an oscillation operation. When light input to the phototransistor 1 exceeds a certain value, the phototransistor 1 is turned on, no voltage is applied to the semiconductor laser 3, and the oscillation operation is stopped. On the other hand, another pair of phototransistor 2 and semiconductor laser 4 are connected in the same way, and part of the output light of semiconductor laser 3 is input to phototransistor 2, and further, part of the output light of semiconductor laser 4 is input to phototransistor. 1.

Now, in this embodiment, when the power is turned on with a strong optical input signal from the outside, it is uncertain which of the semiconductor lasers 3 and 4 output light will be obtained, but for example, from the set terminal S to the phototransistor. 1, the semiconductor laser 3 will be in a state where there is no output light. At that time, if there is no light input from the reset terminal R, the phototransistor 2 will be in the OFF state, and current will flow to the semiconductor laser 4 through the resistor 6. is supplied, and an optical output is obtained from the output terminal Q along with the oscillation operation. Once the semiconductor laser 4 oscillates and produces optical output, a portion of it is input to the phototransistor 1, so even if the optical input to the set terminal S is removed, the state does not change. On the other hand, when optical input is made to reset terminal R,
The semiconductor laser 4 stops oscillating by a similar mechanism, and optical output is obtained at the output terminal Q at the same time as the semiconductor laser 3 starts oscillating.

At this time, the optical output from the output terminal Q is zero.

As described in detail above, this embodiment provides a set/reset flip-flop that uses light as an input/output signal.

In the above embodiment, a photo-input electronic switch, which is excellent in terms of the simplicity of the circuit configuration, was used, but a combination of a photodiode and a transistor may also be used, or a multi-stage transistor may be used to improve the input sensitivity. An amplifier may also be used. Further, as the semiconductor light emitting element, a light emitting diode may be used instead of a semiconductor laser.

(Effects of the Invention) To summarize the effects obtained by the present invention, it is possible to obtain an optical flip-flop that operates entirely by optical signals.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of an embodiment according to the present invention. In the figure, 1.2 is a phototransistor, 3.4 is a semiconductor laser, and 5 and 6 are resistors. Chrysanthemum 1 Figure L 2--7 Strands 3.4-44 Straw L, 2 Toray °wa °.

Claims (1)

[Claims] a first semiconductor light emitting device connected in parallel with the first optical input electronic switch; and a second semiconductor light emitting device connected in parallel with the second optical input electronic switch; Arranged so that at least a portion of the output light becomes an input signal of the second optical input electronic switch, and further, at least a portion of the output light of the second semiconductor light emitting element becomes an input signal of the first optical input electronic switch. An optical flip-flop characterized by: