JPH0740665B2 - Optical logic gate - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical logic gate that is a constituent element of a logic circuit (parallel optical logic circuit) that processes optical signals in parallel.

2. Description of the Related Art Conventionally, various proposals have been made regarding optical logic gates considering application to optical computers. Many of these use optical materials, but as an example in which an optical logic gate is composed of an opto-electronic element using a semiconductor material, for example, the semiconductor disclosed in Japanese Patent Application No. 57-30124 is disclosed. There is a device. An equivalent circuit of this semiconductor device is shown in FIG. In the figure, the phototransistor 1 is connected to a power supply terminal 3 via a resistor 2, and a light emitting diode 4 is connected in parallel with the phototransistor 1.
Further, the input optical signal 5 and the output optical signal 6 are input through the optical waveguide. According to this configuration, when the input optical signal 5 is off, the output optical signal 6 is on, and when the input optical signal 5 is on, the output optical signal 6 is off. Therefore, this device can function as an optical inverter circuit. become.

Problems to be Solved by the Invention The conventional example shown in FIG. 7 functions as an optical inverter, and it is easy to realize an optical NAND gate, an optical NOR gate and the like with a similar configuration. However, this configuration method merely replaces the input / output electric signal in the ordinary electronic logic circuit with an optical signal, and is not a configuration method suitable for parallel signal processing, which is an advantage of the optical logic circuit. The parallel signal processing mentioned here means that a two-dimensional optical signal is input from one side of an optical logic gate that is two-dimensionally arranged and a logically processed optical signal is output from the other side. is there. As such a two-dimensional signal processing, considering the simple processing of outputting the negation of the input signal, the optical inverter shown in FIG. 7 can be used. However, considering that a complicated logical operation is performed on a plurality of input signals, it can be inferred from FIG.
The use of NAND gates or NOR gates causes a problem in how to input a plurality of two-dimensional optical signals. The present invention has been made in view of such a point, and an object of the present invention is to provide an optical logic gate capable of easily performing parallel signal processing.

Means for Solving the Problems In order to solve the above problems, the present invention electrically connects in series a light emitting device having a double hetero structure, a first transistor and a phototransistor, and the light emitting device and the first light emitting device. The optical logic gate is configured to include a circuit in which the second transistor is connected in parallel to the serial connection part of the transistor and the third transistor is connected in parallel to the direct connection part of the first transistor and the phototransistor. Is to do.

Function First, the function of the optical logic gate of the present invention will be described. The equivalent circuit of the optical logic gate of the present invention is as shown in FIG. That is, the light emitting element (for example, light emitting diode) 7 and the phototransistor 8 are connected in series via the first transistor 9. In addition, the second transistor 10 is connected in parallel to the light emitting element 7 and the first transistor 9,
A third transistor 11 is connected in parallel with the first transistor 9 and the phototransistor 8. Here, the first to third transistors function as switching transistors, and if all the first to third transistors are off, the light emitting element 7 does not depend on whether the input signal 12 to the phototransistor is on or off. The output optical signal 13 from is off. Where the second and third transistors 10,1
If only 1 is turned on, the equivalent circuit at this time is as shown in Fig. 3, and if it is connected to the power supply through the external resistor 14,
The optical inverter is the same as the conventional example shown in the figure. Also,
If only the first transistor 9 is turned on, the equivalent circuit becomes as shown in FIG. 4, and the output optical signal 13 turns on and off according to the turning on and off of the input optical signal 12. That is, the present optical logic gate "turns off" the output optical signal with respect to the input optical signal by turning on and off the first to third transistors (off mode),
The three states of "invert and output" (inverter mode) and "output as it is" (transfer mode) are acquired.

Next, a method of forming a parallel optical logic circuit using the present optical logic gate will be described. A block diagram of this parallel optical logic circuit is shown in FIG. In the figure, an optical logic gate array
Reference numeral 15 is a two-dimensional array of optical logic gates 16, and optical storage element array 17 is a two-dimensional array of optical storage elements 18 whose equivalent circuit is shown in FIG. The optical storage element array 17 is the same as the image storage device shown in Japanese Patent Application No. 60-184047. The optical storage element comprising the light emitting element 21 and the phototransistor 22 connected in series shown in FIG. 6 is turned on by supplying the input optical signal 23 and outputs the output optical signal 24. In this state, the input optical signal 23 Even if is turned off, the positive feedback light 25 exists and is maintained until the bias voltage is turned off. This optical storage element 18 and optical logic gate 16
By combining, it becomes possible to perform a logical operation on a plurality of input optical signals. However, a plurality of input optical signals in this case are sequentially input to the optical logic gate, not simultaneously. For example, consider performing a logical operation of A ++ C on the three input optical signals A, B, and C. When inputting the input optical signals A and C, the optical logic gate 16 is set to the transfer mode,
When the input optical signal B is input, the inverter mode is set so that the output of the optical logic gate 16 is input to the optical storage element 18. If any of the input optical signals is on, the optical storage element 18 is turned on and maintains that state, so that A, B,
Inputting the 3 signals of C will output A ++ C. The parallel optical logic circuit shown in FIG. 5 is a two-dimensional array in which the combination of the optical logic gate 16 and the optical storage element 18 is arranged two-dimensionally by performing the above logical operation on the two-dimensional input optical signal 19. The output optical signal 20 can be output.

As is clear from the above description, the parallel optical logic circuit shown in FIG. 5 enables logical operation on a plurality of input optical signals, and connecting these in multiple stages enables more complicated logical operation.

Practical Example FIG. 1 is a sectional view showing an embodiment of an optical logic gate of the present invention. In this embodiment, p-Al _0.3 Ga _0.7 As clad 26,
The n-GaAs active layer 27 and the n-Al _0.3 Ga _0.7 As clad 28 constitute a light emitting device, and the n-Al _0.3 Ga _0.7 As emitter 30 and the p-Ga
Phototransistor with As base 31 and n-GaAs collector 32
33 are configured. Further, n-Al _0.3 Ga _0.7 As emitter 34, p-
A first transistor 37 composed of a GaAs base 35 and an n-GaAs collector 36 is provided. Further, the emitter 34 'and the base 3 using the same layer as the first transistor 37 are used.
The second transistor 38 is composed of 5'and the collector 36 ', and the emitter uses the same layer as the phototransistor 33.
30 ', base 31', collector 32 'with third transistor
39 are configured. Second p-clad 26 of light emitting device 29 and second
The collector 36 'of the transistor 38 of is the wiring on the insulator 40.
41, and the collector 36 of the first transistor 37 and the collector 32 'of the third transistor 39 are also connected by the wiring 41' on the insulator 40 '. The above configuration can be represented by an equivalent circuit as shown in FIG. Electrodes 42 and 4 are provided on the p-clad 26 of the light emitting element 29 and on the emitter 30 of the phototransistor 33 as external circuits and connection terminals.
2'is provided and is not explicitly shown in FIG. 1, the bases 35,3 of the first to third transistors 37,38,39 are provided.
Electrodes are also provided on the 5'and 31 '.

The input optical signal 43 of the optical logic gate of FIG. 1 is input from the emitter 30 side of the phototransistor 33, and the output optical signal 44 is output from the p-clad 26 side of the light emitting element 29. Light emitting element 29
The output light to the n-clad 28 side is absorbed by the collector layer of each transistor, so that the transistor does not malfunction.

The equivalent circuit of the optical logic gate shown in FIG. 1 is as shown in FIG. 2 as described above. It is effective for the optical logic gate whose equivalent circuit is shown in FIG. 2 to obtain the three states of the off mode, the inverter mode, and the transfer mode by turning on and off the first to third transistors. As described in section. Furthermore, in the same paragraph, an optical logic circuit can be constructed by combining it with an optical storage element whose equivalent circuit is shown in FIG. 6, and a parallel optical logic circuit can be realized by the configuration of FIG. As explained.

Although the light emitting element is a light emitting diode in the description of this embodiment, it may be a semiconductor laser. The material forming the optical logic gate is not limited to the AlGaAa / GaAs system, and other semiconductor material systems may be used.

EFFECTS OF THE INVENTION As described above, according to the present invention, the output optical signal can be selected from three modes of “not output”, “inverted output”, and “output as is” with respect to the input optical signal It is possible to realize a simple optical logic gate, and by combining it with an optical storage element, it is possible to configure an optical logic circuit that can easily perform parallel signal processing.

[Brief description of drawings]

FIG. 1 is a sectional view of an optical logic gate according to an embodiment of the present invention, FIG. 2 is an equivalent circuit diagram thereof, and FIGS. 3 and 4 are equivalent circuit diagrams for explaining the operation principle thereof. Is a configuration diagram showing an application of the present invention, FIG. 6 is an equivalent circuit diagram of elements other than the optical logic gate of the present invention used in FIG. 5, and FIG. 7 is an equivalent circuit diagram of a conventional example. 29 ... Light emitting element, 33 ... Phototransistor, 37 ... First transistor, 38 ... Second transistor, 39 ... Third transistor.

Claims (1)

[Claims] 1. A light emitting device having a double hetero structure, a first transistor and a phototransistor are electrically connected in series, and a second transistor is connected in parallel to a series connection portion of the light emitting device and the first transistor. An optical logic gate including a circuit connected to the first transistor and the phototransistor in series with a third transistor connected in parallel.