JPS628131A - Optical inverter circuit - Google Patents

Abstract

PURPOSE:To invert an input signal from a branch fiber and easily lead it out from an output terminal with simple constitution by branching one optical fiber and using the branch side as an input terminal and the opposite confluence side as an output terminal, and providing an optical control element which cuts off light when receiving composite light from the branch fiber in the middle of the confluence fiber. CONSTITUTION:When there is no light pulse on the 1st branch fiber 4, a photochromic cell 11 is transparent, so bias light from the 2nd branch fiber 5 is transmitted through the photochromic cell 11 and photodetected by a photodetecting element as it is. When a light pulse is inputted to the 1st branch fiber 4, the light pulse signal and bias light from the 2nd branch fiber 5 are both mixed and light with high light energy is inputted to the photochromic cell 11, which colors as a result to cut of the composite light, so no light is received by the photodetecting element.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical inverter circuit for inverting an optical signal in an optical fiber.

ii Koei 1 In recent years, optical application technology has made remarkable progress, and as a result, various optical circuit elements have begun to be required.

Among optical circuit elements, optical inverter circuits can be used in a wide range of fields such as communications, information processing, and control, and the need for them has become quite large. Optical inverter circuits are necessary when switching signals from positive logic to negative logic, and are one of the important optical elements that are indispensable in the structure of complex optical circuits.

However, all conventional inverter circuits are composed of electronic circuits, and an optical inverter circuit has never been proposed.

The present invention was devised from this viewpoint, and an object of the present invention is to provide an optical inverter circuit with a simple structure and low cost.

In order to achieve the above object of the present invention, the optical inverter circuit of the present invention merges a plurality of branched optical fibers to form a merging fiber, and injects a signal light into one of the branched fibers. input, bias light is input to the other side of the branching fiber, and a light control element is arranged in the merging fiber to block the light when the combined light consisting of the signal light and the bias light is received from the branching fiber to the merging fiber. do.

According to a preferred embodiment of the present invention, the optical fiber is branched into two from the output end side to the input end side, preferably via a spacer, and one of the branched optical fibers (hereinafter referred to as the first
The input end of one optical fiber (hereinafter referred to as a branch fiber) is used for inputting signal light, and the input end of the other optical fiber (hereinafter referred to as a second branch fiber) is used for inputting bias light. These signal light input optical fibers and bias light input optical fibers are merged, and in the middle of this merged fiber there is a photochromic cell or a micropolarizing plate that blocks the light when it receives the combined light of the signal light and bias light. A light control element such as a Faraday element is provided on both sides.

According to the present invention, when no signal light is input from the first branch fiber, the light control element functions to allow the transmission of light, and the bias light input from the second branch fiber is transmitted to the merging fiber. transmitted to the output end.

Conversely, when signal light is input from the first branch fiber, the light control element functions to block transmission of the light, and the bias light input from the second branch fiber is blocked by the preemptive ALL element. Ru.

Like a bow, when there is no signal light, bias light is emitted from the output side, and when there is signal light, the bias light to the output side is blocked, so it functions as an inverter despite its simple configuration. can do.

Embodiments of the present invention will be described below based on the drawings.

11 As shown in Figure 1, optical fiber 1 is connected to the output end (right side).
It is configured such that it is branched into two parts with a spacer 2 interposed therebetween toward the input end side (left side). This spacer is for crosstalk prevention and fiber fixing, and is not necessarily required to achieve the functions of the present invention. The material of the optical fiber 1 is, for example, quartz glass, multi-component glass, plastic, etc., and its structure includes a transparent core (core material).
A cladding (sheath material) with a lower refractive index than that surrounding the
It is formed by covering □. The optical fiber 1 that can be used here can be either a discontinuous refractive index distribution type in which the refractive index changes stepwise or a continuous refractive index distribution type in which the refractive index within the core changes radially. can do.

A branch fiber (first branch fiber) 4 branched from the merging edge bar 3 consists of a core 6 and a cladding 7, and the other branch fiber (second branch fiber) 5 consists of a core 8 and a cladding 9. These cores 6 and 8 join in the middle and are connected to the core 10 of the merging fiber 3. A spacer 2 made of, for example, vinyl chloride and coated on the surfaces of the claddings 7 and 9 is interposed between the first branched fiber 4 and the second branched fiber 5.

A photochromic cell 11 is provided in the middle of the merging fiber 3, which is colored when it receives light with a certain level of high energy. On the output side of the photochromic cell 11, although not shown, a light receiving element for receiving bias light from the branched fiber 5 is provided. in this case,
The core of the first branch fiber 4 serves as a signal line, and the core 8 of the second branch fiber 5 serves as a bias line.

Now, when there is no optical pulse in the first branch fiber 4, the photochromic cell 11 is transparent, so the bias light from the second branch fiber 5 passes through the photochromic cell 11 and is received by the light receiving element as it is. It turns out.

When a light pulse is input to the first branch fiber 4, the light energy of both the light pulse signal and the bias light from the second branch fiber 5 is combined, and light with high light energy is transmitted to the photochromic cell 11. As a result, the photochromic cell 11 is colored and blocks this combined light, so that the light receiving element does not receive the light.

That is, the electrical output of the light receiving element is transmitted to the first branch fiber 4.
If the light pulse from the first branched fiber 4 is off, it will be in the on state, and if the light pulse from the first branch fiber 4 is on, that is, if it is incident on the photochromic cell 11, it will be in the off state.

In this way, the signal light from the first branch fiber 4 is inverted and the bias light from the second branch fiber 5 is transmitted to the light receiving element via the photochromic cell 11. Note that by changing the energy of the bias light input to the second branch fiber 5 and transmitting it to the light receiving element via the photochromic cell 11, a plurality of bias signal lights can be transmitted through a single optical fiber with an inverter function. It can be transmitted to a light receiving element.

115-1 In this embodiment, as shown in FIG.
The structure is similar to the embodiment shown in the figure, and a Faraday element 15 is attached in place of the photochromic cell 11 shown in FIG. In FIG. 2, components that are substantially the same as those in FIG. 1 are given the same reference numerals. In this embodiment, since a Faraday element is used, it is necessary to use a constant polarization fiber, so it is desirable to use a silica-based optical fiber.

As the Faraday element 15, for example, YIG (yttrium-iron-garnet) doped with Qa can be used. When this Faraday element 15 is used, the plane of polarization of the light input from the polarizer 16 is rotated by the applied magnetic field, that is, it undergoes Faraday rotation, and the light rotated by a predetermined rotation angle is extracted from the analyzer 17, and the light is The light transmitted by the photon 17 is detected by the light receiving element on the right side in the figure (not shown).

When there is no optical pulse in the first branch fiber 4,
Due to the Faraday rotation by the Faraday element 15, the second
The bias light from the branched fiber 5 is outputted to the light receiving element through the polarizer 16, the Faraday element 15, and the analyzer 17.

Conversely, in a state where a light pulse is input to the first branch fiber 4, when this light pulse is input to the Faraday element 15, the temperature of the Faraday element 15 rises and becomes a paramagnetic substance, and Faraday rotation disappears. , the bias light input to the second branch fiber 5 and the first branch fiber 4
Both of the optical pulses inputted from the light receiving element are cut by the Faraday element 15, and the output from there to the light receiving element is cut off.

Therefore, the electrical output of the light receiving element is in the on state when the optical pulse of the first branch fiber 4 is off;
When the optical pulse of the branch fiber 4 is turned on, it is turned off, thereby functioning as an inverter.

Note that by changing the optical energy of the bias light input to the second branch fiber 5, a plurality of signals can be simultaneously detected by the light receiving element using one optical fiber having an inversion function.

As explained above, according to the present invention, one optical fiber is branched in the middle, this branching side is used as an input end, the merging side on the opposite side is used as an output end, and both sides are connected in the middle of this merging fiber. Since a light control element is provided that blocks the light when it receives the combined light from the branch fibers, the input signal from the branch fibers can be inverted and easily taken out from the output end, even though the configuration is simple.

Furthermore, by changing the energy of the light incident on the input end of the branched fiber and using this as an input signal, it is possible to simultaneously and selectively invert and extract a plurality of signals.

[Brief explanation of the drawing]

FIG. 1 is a schematic block diagram showing one embodiment of the present invention, and FIG. 2 is a schematic block diagram showing another embodiment of the present invention. 1... Optical fiber, 2... Spacer, 3...
- Merging fiber, 4... First branch fiber, 5...
...Second branch fiber, 11...Photochromic cell, 15...Faraday element.

Claims (1)

[Claims] A plurality of branched optical fibers are merged to form a converging fiber, a signal light is inputted into one of the branched fibers, a bias light is inputted into the other branched fiber, and the above-mentioned signal light and the above-mentioned signal light are inputted from the branched fiber to the confluence fiber. 1. An optical inverter circuit characterized in that a light control element is disposed within a converging fiber to block the light when it receives combined light consisting of bias light.