JP2694139B2 - Optical logic circuit - Google Patents

Description

TECHNICAL FIELD The present invention relates to a digital logic circuit in which an input / output signal is an optical signal. (2) Conventional technology and its problems Currently, the digital logic circuit that is practically used is an electric circuit, but if digital logic processing of an optical signal can be performed, it is effective from the viewpoint of improving the operation speed. Is. Among the basic logic circuits, circuits such as CR and AND circuits that do not include signal inversion can be configured as an optical signal processing circuit by utilizing the characteristics of the laser diode as shown in FIG. 1, for example. In FIG. 1, 1 is an input side optical fiber, 2 is an optical coupler, 3 is a semiconductor laser, 4 is an output side optical fiber, 5
Is a driving power source, and 6 is an intermediate optical fiber. By appropriately adjusting the current from the drive power source 5, for example, the first
From either input 1 or input 2 as shown in Figure (A),
Alternatively, if the current is adjusted so that the semiconductor laser 3 oscillates when light is input from both, the optical OR circuit, and as shown in FIG. 1 (B), light is input from both input 1 and input 2 at the same time. An optical AND circuit can be constructed by adjusting the current so that the semiconductor laser 3 oscillates when input. However, in order to configure a flip-flop circuit or the like, a basic logic circuit including inversion of signals such as an inverter and a NOR circuit is required, and since there has been no optical signal processing circuit of this type in the past, it is more complicated. There was a problem in constructing the optical signal processing circuit. (3) Object of the Invention It is an object of the present invention to provide an optical logic circuit such as an inverter and a NOR circuit in which an input / output signal operates with an optical signal. (4) Configuration of the Invention (4-1) Differences between Features of the Invention and Conventional Techniques The present invention uses a phase-locked semiconductor laser array to change the phase-locked semiconductor laser array by injection of input light. It is characterized in that a part of the far field pattern is used as output light. It differs from the conventional technology in that an inverter, a NOR circuit, etc., in which an input / output signal is an optical signal can be configured. (4-2) Embodiment FIG. 2 is a diagram for explaining an optical signal inverter which is a first embodiment of the present invention. Here, 7 is a phase-locked type semiconductor laser array, which is obtained by forming a plurality of stripes in parallel on the same substrate so that the lights in the stripes interfere with each other to oscillate. The meaning of other numbers is the same as in other figures. The input optical signal is guided by the input side optical fiber 1 to one end face of the phase locked semiconductor laser array 7 which is oscillating in the phase locked state. The output optical signal is obtained by extracting a part of the far field pattern of the oscillation light emitted from the other end surface of the phase-locked semiconductor laser array 7 by the output side optical fiber 4. By appropriately selecting the injection current of the phase-locked semiconductor laser array 7, the far-field pattern of the output light can be made bimodal when there is no input light, and can be monomodal when there is input light. (ELECTRONICS LETT
ERS, PP858-859, 31 July 1986, Vol.22, No.16). The present invention realizes an optical logic circuit by effectively utilizing this phenomenon. FIG. 3 shows a structure of FIG. 2 using a phase-locked type semiconductor laser array with an oscillation wavelength of about 0.8 μm and 10 stripes. It is a result of measuring the far field pattern when light is input (B) and when light is not input (A). It can be seen that when there is no input light, it is bimodal as in (A), and when there is input light, it is monomodal as in (B). If the output side optical fiber 4 for taking out the output light is attached to the position A shown by the solid line in FIG. 3, the relationship shown in Table 1 is established. This operates as an optical inverter. FIG. 4 is a diagram for explaining another embodiment of the present embodiment, and the meaning of the numbers is the same as the other drawings. There are two input side optical fibers, which are coupled by the optical coupler 2 and then connected to the end face of the phase-locked semiconductor laser array 7 by one intermediate optical fiber 6. The output side optical fiber is attached at the position shown by the solid line in FIG. 3 as in FIG. Because of this, like the embodiment of FIG.
The relationships in Table 2 hold. This is the operation of the optical NOR circuit. As shown in FIG. 5, an optical NOR circuit can be used to easily configure an optical flip-flop circuit. In FIG. 5, reference numeral 8 denotes an optical beam splitter, and the input / output relationship of the optical NOR circuit surrounded by the dotted line in the figure is the same as that of the embodiment of FIG. (5) Effects of the Invention As described above, by using the present invention, an optical inverter and an optical NOR circuit can be easily configured, so that a more complicated optical signal processing circuit can be configured.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1A and 1B are block diagrams showing a configuration example of a conventional optical OR circuit and an optical AND circuit, and FIG. 2 is an optical signal according to a first embodiment of the present invention. FIG. 3 is a block diagram showing an inverter, FIG. 3 (A) and (B) are measurement example diagrams of measurement results of far-filled patterns, and FIG. 4 is a block diagram showing a configuration example of an optical NOR circuit according to a second embodiment of the present invention. Figures and 5 show the optical NOR of the present invention.
It is a block diagram showing an example of composition of an optical flip-flop circuit using a circuit. 1 ... Input-side optical fiber, 2 ... Optical coupler, 3 ... Semiconductor laser, 4 ... Output-side optical fiber, 5 ... Driving power supply, 6 ... Intermediate optical fiber, 7 ... Phase-locked semiconductor laser array , 8 ... Optical beam splitter.

   ────────────────────────────────────────────────── ─── Continuation of front page    (72) Inventor Koichi Aoyama               1-1-6 Uchisaiwaicho, Chiyoda-ku, Tokyo               Nippon Telegraph and Telephone Corporation (72) Inventor Seiji Nakagawa               1-1-6 Uchisaiwaicho, Chiyoda-ku, Tokyo               Nippon Telegraph and Telephone Corporation                (56) References JP-A-59-164532 (JP, A)                 JP 64-42878 (JP, A)                 Japanese Patent Publication 5-80653 (JP, B2)

Claims (1)

(57) [Claims] A phase-locked semiconductor laser array in which a plurality of the stripes are formed close to each other in parallel on the same substrate so that the lights in the stripes interfere with each other and oscillate, and on one end face of the phase-locked semiconductor laser array. An optical circuit for guiding the input signal light, and an optical circuit for detecting a change in the far field pattern of the oscillation light of the phase-locked semiconductor laser array depending on the presence or absence of the input signal light from the other end face of the phase-locked semiconductor laser array. Optical logic circuit characterized by.