JPH10160958A - Light attenuating and receiving device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light attenuating and receiving device which makes the light emission level of a light emitting element not exceed the maximum light reception level of a light receiving element without using individual optical attenuators. SOLUTION: Of a light receiving device which converges the emitted light of an optical fiber 10 by a lens 2 and receives it by the light receiving element 3, an end surface part 10A of the optical fiber 10 is roughened. Namely, the end surface 10A is adjusted with a polishing grindstone or abrasive sheet so that the emitted light from the optical fiber 10 does not exceed the maximum light reception level of the light receiving element 3, and the emitted light from the optical fiber 10 is scattered.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light receiving device used for digital transmission and the like, and more particularly, to an attenuated light receiving device for receiving light by attenuating a light receiving level incident from an optical fiber.

[0002]

2. Description of the Related Art With the development of optical fiber communication, the light emission level of a light emitting device used is steadily increasing. On the other hand, the light receiving element has a limit in the light receiving level, and the light emitting level of the light emitting element has already exceeded the limit of the light receiving level of the light receiving element. Therefore, conventionally, a light receiving device that receives light with a semiconductor light receiving element has a built-in light attenuating element and attenuates the light emission level of the light emitting element to receive light.

Next, FIG. 3 shows a configuration diagram of a conventional technology of an optical attenuation light receiving device. 3 is an optical fiber, 2 is a lens, 3
Denotes a photodiode, and 4 denotes an optical attenuation element. In FIG.
The light emitted from the optical fiber 1 is attenuated by a certain amount by the light attenuating element 4, further condensed by the lens 2 and received by the photodiode 3. Here, the light attenuation amount of the light attenuation element 4 is selected and set so as not to exceed the maximum light receiving level of the photodiode 3.

FIG. 4 shows another configuration diagram of the prior art of the optical attenuation light receiving device. 4 are the same as those in FIG. 3 except that the optical attenuating element 5 has a very small size and is generally built in a ferrule in an optical plug. Are shown as being equivalent to those built in.

In FIG. 4, light propagating in the optical fiber 1 is emitted after being attenuated by a predetermined amount by a light attenuating element 5 built in the optical fiber 1, condensed by a lens 2, and discharged by a photodiode 3. Received. Here, the light attenuation amount of the light attenuating element 5 is selected and set so as not to exceed the maximum light receiving level of the photodiode 3 as in FIG.

[0006]

In the conventional light attenuated light receiving device, as shown in FIGS. 3 and 4, a separate optical attenuator is required, and the work time for installing the optical attenuator is reduced. There was such a problem. SUMMARY OF THE INVENTION It is an object of the present invention to provide a light attenuating light receiving device that does not use a separate light attenuator and prevents the light emitting level of a light emitting element from exceeding a maximum light receiving level of a light receiving element.

[0007]

In order to achieve this object, according to the present invention, the light emitted from the optical fiber 10 is transmitted through the lens 2.
In the light receiving device that collects light at the light receiving element 3 and receives light at the light receiving element 3,
The end face portion 10A of the optical fiber 10 is set in a rough surface state. That is, the emitted light from the optical fiber 10 is scattered by adjusting the end face 10A with a polishing grindstone or a polishing sheet so that the light emitted from the optical fiber 10 does not exceed the maximum light receiving level of the light receiving element 3.

[0008]

FIG. 1 shows the configuration of an embodiment according to the present invention. 1 is an optical fiber, 2 is a lens, and 3 is a photodiode. 2 and 3 in FIG.
Is the same as In FIG. 1, light propagating in the optical fiber 10 is emitted from an end face 10A of the optical fiber 10,
Further, the light is condensed by the lens 2 and received by the photodiode 3.

Next, the end face 10 of the optical fiber 10 shown in FIG.
An enlarged view of A is shown in FIG. FIG. 2 shows a state in which the surface of the end face portion 10A of the optical fiber 10 is intentionally kept to rough polishing (rough surface state).

Normally, the surface of the end face 10A of the optical fiber 10 is mirror-polished in order to improve light transmission. This is because it is assumed that a light attenuating element is used to attenuate the light emitting element so that the light emitting level does not exceed the maximum light receiving level of the light receiving element.

The polishing procedure of the end face portion 10A of the optical fiber 10 is generally performed by first using a polishing sheet or a polishing grindstone whose polishing roughness is determined stepwise, firstly by rough polishing, secondly by medium polishing, and finally by finishing. Polishing is performed in this order, and mirror polishing is performed.

However, the light emitted from the end face 10A of the optical fiber 10 is scattered and emitted by intentionally keeping the surface of the end face 10A of the optical fiber 10 at a stage before finish polishing. Thereby, the photodiode 3
When light is received by the photodiode 3, a part of the light leaks out of the light receiving area, and as a result, the light receiving level of the photodiode 3 is attenuated.

The adjustment of the light receiving level incident on the photodiode 3 is realized by adjusting the amount of light leaking out of the light receiving area of the photodiode 3 according to the polished state of the end face portion 10A of the optical fiber 10.

For example, in optical digital transmission, fine fluctuation in the transmission level is not a problem. Therefore, even if the optical attenuated light receiving device according to the present invention is applied, the optical attenuated light receiving device having the configuration shown in FIGS. There is nothing different from when it was applied. In the configuration of FIGS. 3 and 4, the reflection / return light from the end face of the optical fiber generated when the end face of the optical fiber is mirror-polished is not mirror-polished in the optical attenuation light receiving device according to the present invention. To be reduced.

[0015]

According to the present invention, the light emitted from the optical fiber is scattered by setting the polished state of the end face of the optical fiber to the state of rough polishing instead of mirror polishing, so that the light receiving element of the light receiving element is scattered. It is possible to realize a light attenuated light receiving device that does not exceed the maximum light receiving level of the light receiving element without providing an individual light attenuating element in the preceding stage.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an optical attenuation light receiving device according to the present invention.

FIG. 2 is an enlarged view of an end face portion 10A of the optical fiber 10 of FIG.

FIG. 3 is a configuration diagram of an embodiment of a light attenuated light receiving device according to the prior art.

FIG. 4 is a configuration diagram of another embodiment of the light attenuating light receiving device according to the prior art.

[Explanation of symbols]

 Reference Signs List 1 optical fiber 2 lens 3 photodiode 4 optical attenuator 10 optical fiber 10A end face

Claims (2)

[Claims] In an optical receiving device for collecting light emitted from an optical fiber (10) by a lens (2) and receiving it by a light receiving element (3), the end face (10A) of the optical fiber (10) is roughened. A light-attenuating light-receiving device, wherein the device is in a planar state. 2. A light receiving device for collecting light emitted from an optical fiber (10) by a lens (2) and receiving the light by a photodiode (3), wherein the emitted light from the optical fiber (10) is 3. The optical attenuation according to claim 1, wherein the end face (10A) is adjusted with a polishing grindstone or a polishing sheet so as not to exceed the maximum light receiving level of (3) to scatter the light emitted from the optical fiber (10). Light receiving device.