JPH0666004B2 - Optical branching device - Google Patents

Description

The present invention relates to an optical signal branching device in an optical waveguide.

[Conventional technology]

FIGS. 5 and 6 show a conventional optical branch communication device shown in, for example, JP-A-62-73225 "Optical Switch".

5 and 6, FIG. 5 (a) shows a branching device of the optical switch, and the transmission prism 51 has an upper optical input end 52.
From the lower light output end 53, which is, for example, the sixth
After passing through the B station 61 in the figure and the lower optical input end 54, the prism 51
And the optical switch 63 of the next station C station 62 for optical transmission. In this way A
The optical signal from the station 64 is transmitted through the optical fiber 65 to B, C, D
Transmitted to station 66. Then, under normal conditions, the stations B, C and D amplify the optical signal to compensate for the attenuation in the optical path.

If a failure occurs in these stations, the prism 51 is removed from the optical path above the optical switch 63 as shown in FIG. 5 (b), and the light is transmitted to the next station without branching and amplification. It is configured to do.

[Problems to be solved by the invention]

Since this conventional optical switch (optical branching device) is configured as described above, it is necessary to use an optical transmissive prism that is expensive and difficult to mass-produce because of the optical branching, and the optical amplification section of each communication station. In case of failure, a driving mechanism for mechanically removing the transmission prism 51 from the main optical path is required as shown in FIG.

[Means for solving problems]

In order to solve the above-mentioned problems, in the present invention, a half mirror is used, and the half mirror and the photodetector that receives the reflected light are integrated with a transparent resin body, and a groove is provided in the transparent resin body. A light emitting element driven by a signal obtained by amplifying the output of the photodetector is arranged on the side opposite to the photodetector across the half mirror, and a convex portion is provided on the transparent resin body.

[Action]

With this configuration, the input optical signal is reflected and branched by the half mirror, detected by the photodetector, and easily fixed to the transparent resin body of the optical fiber. Further, it is amplified to drive the light emitting element, and the optical signal from the light emitting element is reflected by the half mirror and output, and at the same time, the light from the optical fiber is easily guided to the photodetector.

Then, even if an optical signal is not output from the light emitting element for some reason, the input optical signal is transmitted through the half mirror and output.

〔Example〕

Hereinafter, the present invention will be described with reference to an embodiment. In FIG. 1, the light receiving ICs 11 are molded in a transparent resin body 12 such as epoxy. In this molded body,
The light receiving surface of the IC, 11 is, for example, a metal powder such as aluminum, indium or tin, which is vapor-deposited on a 45 ° surface.
The half mirror 13 is configured. Of course, a polyester translucent reflective film obtained by vapor deposition of these metal powders may be attached to the surface, or a glass half mirror may be provided. This is referred to as an optical branching device 14.

This optical branching device 14 is arranged in the middle of the optical paths of the optical fiber 15 which is an upward waveguide and the optical fiber 16 which is a downward waveguide so that the light receiving IC, 11 receives the reflected light from the half mirror 13 and the passing light. Is placed so that it passes through the optical fiber from upstream to downstream.

Further, the light-receiving IC, 11 has, for example, a photodiode P
D. (Photodetector) 11a, an electronic amplifier circuit 11b, a constant voltage power supply, an output drive transistor 11c is a photodetection / amplifier, which converts reflected light of an optical signal from an upstream optical fiber into an electric signal, Amplify and transistor 11
It is configured to output a digital pulse by c.

Its output is connected to the cathode of the light emitting element, LED, LD, 17 through the current limiting resistor, and its anode is the power supply of the light receiving IC.
Connected to 11. Here, the light emitting element 17 is a half mirror 13.
It is placed on the opposite side of the light receiving IC, 11 with the interposition of, and has a role of injecting light into the downstream optical fiber 16 by utilizing the reflection of the half mirror 45 °.

Here, there is concern about a phase shift due to a response delay inside the light receiving IC, 11 with respect to the transmitted light of the half mirror of the optical fiber from the upstream, but according to the experiment, for example, a response delay of 1 μS
Even in such a case, it turns out that there is no problem in low-speed signal transmission such as 9600 bPS.

Further, the present embodiment is based on only a combination of a light receiving IC of only 3 mm square, 11, a light splitting device 14 of about 10 mm solid having a half mirror function that molds it, and a light emitting element 17 of about 10 mm solid. Therefore, it is possible to provide an ultra-small integrated optical branching device 18 having an optical fiber connection structure. This can also be used as an optical branch connector.

Here, the operation and usage of this embodiment will be described with reference to FIG.

The optical signal transmitted from the A station passes through the optical fiber 15 and reaches the optical branching device 18 of the B station. As described above, the reflected light from the half mirror is received, the optical signal is self-amplified in the optical branching device, passed through the downstream optical fiber 16, and the optical branching device 18 of the C station is used.
A strong optical signal is emitted and transmitted in a strong direction. Therefore, it is possible to transmit directly to the D station through the C station. In the B station, the output 21 of the light receiving IC is passed through a buffer and is input to RD by the microcomputer 22, for example, and the signal is decoded. Furthermore, if your station needs to transmit to other stations, pulse drive the driver (drive circuit by external signal) 23 from the TD output and send by aiming for signal idle time of main optical paths 15 and 16 The element 17 emits pulsed light and transmission communication can be performed.

Here, if the electrical function of the B station and the optical branching device 18 of the B station fails, for example, a connection failure of the power source Vcc, a light receiving IC, 1
1. Even if the light emitting element 17 fails, the transmission signal from station A is B
After passing through the optical branching device of the station and reaching the station C, if the station C is alive, it can be transmitted in the direction after the next station D one after another.

3 (a) (b) and FIGS. 4 (a) (b) are other embodiments, and those shown in FIG. 3 are upstream optical fibers of the optical branching device 14 described above. 15 In order to improve the optical coupling with the end and to secure the mechanical coupling, a groove 31 is provided on the end face in the direction of the optical path of the fiber, and the one shown in FIG. 4 is the same for improving the optical coupling. A convex portion 41 is provided on the end surface.

〔The invention's effect〕

As described above, according to the present invention, there is no mechanical driving mechanism, and the half mirror and the photodetector, which are the constituent elements of the device, are not integrally combined with the transparent resin body and are not required to be combined. Only by providing a groove for fixing the end of the optical fiber on the body, high optical axis accuracy can be obtained for both transmitted light and reflected light incident on the photodetector. Further, since the transparent resin body is provided with the convex portion, even if the position of the end of the optical fiber is slightly displaced, the light beam is narrowed by the convex portion, so that the light easily reaches the photodetector.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an embodiment of the present invention, FIG. 2 is an explanatory diagram of the operation and usage of the same embodiment, and FIG. 3 is a configuration diagram of a second embodiment of the present invention, and FIG. The drawing is a block diagram of the third embodiment of the present invention. In FIGS. 3 and 4, (a) shows a vertical section and (b) shows a horizontal section. FIG. 5 is a block diagram of a conventional device, (a) is normal, (b)
Indicates a failure, and FIG. 6 is an explanatory view of the operation and usage of the conventional device. In the figure, 11 is a light receiving IC, 12 is a transparent resin body, 13 is a half mirror, and 17 is a light emitting element, and the same reference numerals indicate the same or corresponding portions.

 ─────────────────────────────────────────────────── --Continued from the front page (56) References JP-A-54-85045 (JP, A) JP-A-54-88136 (JP, A) JP-A-60-119513 (JP, A) JP-A-61- 213809 (JP, A)

Claims (3)

[Claims] 1. An optical branching device in which a half mirror on a surface inclined with respect to a surface orthogonal to an optical path of a waveguide such as an optical fiber and a photodetector for receiving the reflected light are integrated by a transparent resin body. For the half mirror, a metal such as indium, tin, or aluminum is directly vapor-deposited on the surface of the transparent resin body, or a half-mirror film obtained by vapor-depositing the metal on a polyester film or the like is attached to the surface of the transparent resin body. Or a half mirror made of a glass material is provided on a transparent resin body, and a groove for fixing an optical fiber end is provided on a surface of the transparent resin body opposite to the half mirror surface in the optical path direction. An optical branching device characterized in that 2. A member in which a half mirror on a surface inclined with respect to a surface orthogonal to an optical path of a waveguide such as an optical fiber and a photodetector for receiving the reflected light are integrally structured by a transparent resin body, An optical branching device comprising a light emitting element which is arranged on the opposite side of the photodetector across a half mirror and which is driven by a signal obtained by amplifying the output of the photodetector,
For the half mirror, a metal such as indium, tin, or aluminum is directly vapor-deposited on the surface of the transparent resin body, or a half mirror film obtained by vapor-depositing the metal on a polyester film or the like is attached to the surface of the transparent resin body, or glass. A half mirror of the material is provided on the transparent resin body, and a convex portion for facilitating the light is provided on the surface opposite to the surface where the half mirror is in the optical path direction of the transparent resin body. Optical branching device. 3. The optical branching device according to claim 2, wherein a drive circuit for an external signal is connected to the light emitting element.