JPS628132A - Optical and circuit device - Google Patents

Abstract

PURPOSE:To obtain an optical AND circuit of extremely simple constitution by branching one optical fiber in the middle and using the branch side as an input terminal and the opposite confluence side as an output terminal, and providing an optical control means which transmit light when receiving composite light from both branch fibers in the middle of the confluence fiber. CONSTITUTION:When signal light is inputted to only either of the 1st and the 2nd branch fibers 4 and 5, this signal light is transmitted through a polarizing plate 11 and rotated by a specific angle in a Faraday element 13 to reach polarizing plate 12, where the light is cut off. When the signal light is inputted to both of the 1st and the 2nd branch fibers 4 and 5, on the other hand, both light energy signals are mixed and the light having high energy is transmitted through the polarizing plate 11 to convert the Faraday element 13 into a paramagnetic body. Thus, the signal light is outputted only when the signal light is inputted to both 1st and 2nd branch fibers 4 and 5, so the AND circuit is constituted.

Description

[Detailed Description of the Invention] 11, Standing Unit ±1 The present invention provides an optical AN capable of directly inputting and outputting optical signals.
This relates to a D circuit device.

In recent years, optical application technology has made remarkable progress, and communication technology using optical fibers has come into practical use. However, conventional electronic circuit technology is used to process signals transmitted via light, and although integration and miniaturization are progressing through integration technology, there are various limitations. Currently, optical functional elements that directly process optical signals are required. Among them, logic circuits represented by OR operation and AND operation are
They are used in almost all devices that handle digital signals and are in high demand, and the practical application of optical logic circuits that directly process optical signals is desired.

Several optical logic circuits have been proposed recently, but
These are types that drive a light-receiving area and a light-emitting area formed on the same substrate, and although they are suitable for integration, they have a complex structure and are expensive, making them difficult to put into practical use. Currently, there are only a few.

The present invention has been devised from this viewpoint, and an object of the present invention is to provide an optical AND circuit device that is particularly simple in structure and low in cost among optical logic circuits.

In order to solve the problems of the prior art described above, the present invention merges a plurality of branched optical fibers to form a merging fiber, and eliminates the light input to all the branched fibers. An optical AND circuit device is provided in which a light control means is disposed within the merging fiber and transmits light only when receiving combined light.

According to a preferred embodiment of the present invention, an optical fiber is branched into a first branch fiber and a second branch fiber via a spacer from an output end side to an input end side, and the input ends of these branch fibers are connected to a signal. Used for light incidence. In the middle of the merging fiber where the first branch fiber and the second branch fiber join, there is a light beam that is emitted only when the combined light of the signal light input to the first branch fiber and the signal light input to the second branch fiber is received. A light control means having a property of transmitting the light is provided. The light control means is constructed by applying a magnetic field to a Faraday element inserted between a pair of polarizing plates having polarization properties in the same direction.

According to the present invention, when signal light is input to only one of the branched fibers, the light control means functions to prevent transmission of the light, and the signal light is not output. Furthermore, when signal light is input to both branch fibers, the light control means functions to allow the light to pass through, and the signal light is output. Naturally, when no signal light is input to either of the branch fibers, no signal light is output.

In this way, since the signal light is output only when the signal light is input to both branch fibers, it functions as an AND circuit even though it has a simple configuration.

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the present invention will be described below with reference to the drawings.

As shown in FIG. 1, an optical fiber 1 is configured to be branched into two from an output end (right side in the figure) to an input end (left side) via a spacer 2.

The optical fiber 1 is made of, for example, a quartz glass-based material,
Its structure is formed by covering a transparent core (core material) with a cladding (sheath material) having a lower refractive index than the transparent core. The optical fiber 1 used here is preferably a polarization constant fiber whose polarization plane is preserved.

The first branch fiber 4 branched from the merging fiber 3 consists of a core 6 and a clad 7, and the other second branch fiber 5 consists of a core 8 and a clad 9. The cores 6 and 8 join in the middle and are connected to the core 10 of the joining fiber 3. Between the first branch fiber 4 and the second branch fiber 5, a spacer 2 made of, for example, vinyl chloride coated on the surfaces of the claddings 7 and 9 is provided for the purpose of preventing signal light leakage and supporting the branch fiber. Intervening. Note that the connection between the branch fiber and the converging fiber is achieved, for example, by a general fusion means.

On the other hand, a Faraday element 13 is inserted in the middle of the merging fiber 3 with polarizing plates 11 and 12 interposed therebetween. Polarizing plate 1
1 functions as a polarizer that polarizes the passing light into linearly polarized light, and the polarizing plate 12 functions as an analyzer for the polarized light.
and 12 are arranged in parallel so that their polarization directions are the same.

This polarizing plate does not necessarily have to be formed as a plate; for example, it can also be formed by applying a substance having the above-mentioned function to the end face of the converging fiber 3 or the Faraday element 13.

The Faraday element 13 is a magneto-optical element having magnetic optical rotation in a magnetic field, and when this element is used, polarized light input from the polarizing plate 11 is rotated by a magnetic field M applied by a permanent magnet or the like (not shown).

This magnetic field M causes the polarized light that has passed through the polarizing plate 11 to travel through the Faraday element 13 while rotating by a predetermined angle.
．． E□5. □12. F: It is set to be approximately perpendicular to the direction, and no light is output in this state. The material and shape of the Faraday element 13 are such that the temperature rises when light of a predetermined intensity or higher (in this example, the combined light of the signal light from the first branch fiber and the second branch fiber) is input. The material is set to transition from ferromagnetic to paramagnetic by, for example, Ga(
YIG (yttrium/iron/garnet) doped with gallium (gallium) or the like can be used.

Now, the first branch fiber 4 or the second branch fiber 5
When the signal light is input to only one of the two, the signal light passes through the polarizing plate 11, rotates by a predetermined angle in the Faraday element 13, reaches the polarizing plate 12, and is cut there. On the other hand, in a state where signal light is input to both the first branch fiber 4 and the second branch fiber 5, the light energy of both is combined, and after passing through the polarizing plate 11, the Faraday light has high energy. The element 13 is transformed into a paramagnetic material. In this case, the Faraday element 13 no longer has magnetic optical rotation, and the polarizing plate 1
The polarized light according to No. 1 passes through the polarizing plate 12 without being rotated and is output.

In this way, since the signal light is output only when the signal light is input to both the first branch fiber 4 and the second branch fiber 5, an AND circuit is formed. This AN
It is convenient to provide a light receiving element (not shown) for converting an optical signal into an electrical signal downstream of the Faraday element 13 of the D circuit, since the output signal can also be used as an electrical signal.

In this embodiment, the case where there are two branched fibers has been described, but the present invention is not limited to this. It is also possible to create a multi-input AND circuit by selecting a Faraday element according to the number of branched fibers and the energy of the signal light.

Further, although the present invention particularly aims to provide an AND circuit among optical logic circuits, if the optical control means is removed from the AND circuit device of the present invention, it is possible to make it function as an OR circuit. That is, in the optical fiber 1' in which the branch fiber 4.5 and the converging fiber 3 are connected as shown in FIG. 2, when the signal light is input to either one or both of the branch fibers, Light is output and an optical OR circuit is formed. In this case as well, by providing multiple branch fibers instead of two, multi-input OR
Of course, a circuit can be constructed.

As described in detail above, according to the present invention, one optical fiber is branched midway, and this branched side is used as an input end, and the merging side on the opposite side is used as an output end, and the merging fiber is Since a light control means that transmits the light when receiving the combined light from both branch fibers is provided in the optical fiber, it is possible to provide an optical AND circuit with a very simple configuration.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram of an optical AND circuit device showing a preferred embodiment of the present invention, and FIG. 2 is a schematic configuration diagram showing an example of an OR circuit device. 1.1'...Optical fiber, 2...Spacer, 3
... Merging fiber, 4... First branch fiber, 5... Second branch fiber, 6.8.10... Core, 7,9... Clad 1
1.12... Deflection plate, 13... Faraday element.

Claims (2)

[Claims] (1) A plurality of branched optical fibers are merged to form a merged fiber, and a light control means is installed in the merged fiber to transmit light only when the composite light of the light input to all the branched fibers is received. An optical AND circuit device characterized in that: (2) The light control means includes a pair of polarizing plates having polarization properties in the same direction, a Faraday element having magnetic optical rotation disposed between the pair of polarizing plates, and means for applying a magnetic field to the Faraday element. Claim 1 characterized in that
The optical AND circuit device described in .