JPS60175007A - Variable optical attenuator for optical fiber - Google Patents

Abstract

PURPOSE:To adjust the rate of attenuation with high accuracy by contg. optical fibers into a turning member in such a way that the optical axes thereof are made eccentric with the turning central axial line of said member and turning the turning member with respect to a stationary member so that the optical axes of the fibers shift from each other. CONSTITUTION:Optical fibers 1, 1' are housed into a turning member 13 in such a way that the optical axes thereof are made eccentric with the turning central axial line O-O' of said member. The member 13 is fitted turnably with respect to a stationary member 12. The member 13 is turned by an optional angle between 0-180 deg. with respect to the member 12. The optical axes of the fibers 1, 1' are then shifted from each other and the leakage of light arises between the cores 1A and 1A'. The light is thus attenuated optionally as desired between the fibers 1 and 1' and the rate of attenuation is made adjustable with high accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a variable optical attenuator for an optical fiber, which is necessary for adjusting the amount of light in optical communication using an optical fiber.

[Prior art]

In a conventional variable optical attenuator, optical attenuation is performed by making the amount of optical attenuation variable by passing the optical signal through an attenuation filter such as a metal evaporated film. FIG. 1 shows a typical example. In the light wave device shown in Fig. 1, the optical fiber 1 or 1
The light emitted from ' is converted into parallel light by a microlens 3 or 3' coupled by a connector 2 or 2',
The parallel light is passed through a filter 4 coated with metal vapor deposition,
The light is again focused by the microlens 3' or 3, and the other light 7 eye! ' or 1, and the amount of light attenuation is changed by changing the angle formed with the optical axis of the metal vapor deposited filter 4.

This method requires the use of expensive components such as microlenses 3,3' and optical attenuation filters 4.

Therefore, the price is high and the structure is complicated, so there is a limit to miniaturization below a certain size. Furthermore, if we look at the characteristics.

Since the transmitted light passes through the microphone lens 3, 3' and the light attenuation filter 4, it undergoes light attenuation therebetween.

Although it depends on the type of optical attenuation filter 4, the attenuation amount ranges from 10 to 30 dB.

It was difficult to create a device with a minimum attenuation close to 0 (IB).

In the case of a normal optical data link, the difference in transmission and reception levels is about 10 to 30 dB, and it is necessary to be able to perform optical attenuation between 0 and zOdB.

However, conventional optical attenuators such as those described above cannot meet these demands.

〔the purpose〕

Therefore, an object of the present invention is to solve the above-mentioned problems.

An object of the present invention is to provide a variable optical attenuator for an optical fiber that can adjust the attenuation amount in the range of 0 to ω dB as desired with high precision and reproducibility, is small, lightweight, and low in price. .

[Structure of the invention]

In order to achieve such an object, the present invention performs light development by utilizing the phenomenon that the deviation of the optical axis of the optical 7-eyeper attenuates transmitted light.

That is, in the first embodiment of the present invention, a fixed member to which a first optical fiber is attached, and a rotatable member to which a second optical fiber is attached such that its end surface substantially abuts the end surface of the first optical fiber. the fixed member and the rotating member house the first and second optical fibers in such a manner that their optical axes are eccentric with respect to the central axis of rotation of the rotating member; The optical axis of the first and second optical fibers is shifted from each other by rotating the rotating member with respect to the fixed member.

In a second embodiment of the present invention, a fixing member is provided in which the first and second optical fibers are arranged opposite to each other; a rotating member rotatably attached, the rotating member houses an intermediate transmission medium eccentrically with respect to the rotation center axis, and both end surfaces of the intermediate transmission medium The rotating member is rotated relative to the fixed member so that the rotating member is substantially in contact with each end face of the second optical fiber, so that the optical axis of the intermediate transmission medium and the first and second light beams are It is characterized in that the optical axes of the fibers are offset from each other by 5K.

〔Example〕

The present invention will be described in detail below with reference to one drawing.

The first embodiment of the present invention is shown in FIGS. 2, 3A, 3B,
It is shown in FIGS. 4, 5A and 5B.

Here, the optical fibers 1 and 1' each have a core I
A and l and cladding IB and IB'. These optical fibers 1 and 1' are inserted into tube members 11A and 11A', respectively. These pipe members 11A
and l I A', together with hollow cylindrical screw members 11B and 11B' formed surrounding them, form dedicated connectors 11 and 11', respectively.

The screw members 11B and 11B' are threaded protrusions 1 provided at each end of the fixed member 12 and the rotating member 13, respectively.
4 and 15. The screw protrusion 14 and the fixing member 12 are provided through through holes 1'4A and 12A coaxial with each other.
The screw protrusion 15 and the rotating member 13 have mutually coaxial through holes 15A and 13A. Here, the through holes 12A and 14A are eccentrically arranged with respect to the central axis 0 of the fixing member 12, as shown in FIGS. 3A and 5A. And as shown in FIG. 5B, the rotating member 13 is eccentric to the central axis O'.
and O' are consistent. However, the end surfaces of the optical cores (1 and 1') fixed to the fixing member 12 and the rotating member 13, respectively, by the connectors 11 and 11' are assumed to substantially abut each other.

The rotating member 13 is rotatably fitted to the fixed member 12, and by rotating the rotating member 13 by an arbitrary angle between 0 and 180 degrees with respect to the fixed member 12, as shown in FIG. Alternatively, as shown in FIG. 4, light leakage is caused between cores IA and IA' of optical fibers 1 and 1', thereby achieving any desired optical attenuation between optical fibers 1 and 1'. It can be performed.

In the case of FIGS. 2, 3A, and 3B, the amount of deviation of the optical axes of the optical fibers 1 and 1' from the center axis 0°0' of the fixed member 12 and the rotating member 13 is % of the radius of each core IA and IA'. The range of optical attenuation in this case is 0.5 (iB~
It was 10dB.

In the case of FIGS. 4, 5A, and 5B, the above-mentioned deviation amount is
is the same as the radius of A', and the range of optical attenuation in this case is Q
, 5dB to ωdB.

As described above, in this embodiment, by appropriately determining the amount of deviation of the optical axis of the optical fiber, the range of the amount of optical attenuation can be set as desired.

In the first embodiment described above, dedicated connectors 11 and 11' were required, but a second embodiment in which this point has been improved and ordinary connectors can be used is shown in FIGS. 6 and 7.
This is shown in Figures A and 7B.

In this example, optical fibers 1 and 1', respectively.

It is inserted into the pipe members 21A and 21K of ordinary connectors 21 and 21'. These tube members 21A and 21A'
The hollow cylindrical screw members 21B and 21B' of the connectors 21 and 21' surrounding the fixing member 2
It is screwed into hollow cylindrical screw members 22A and 22A' formed at both ends of 20.

The axis 0- of this fixing member 22 is located inside the fixing member 22.
A rotating member 23 having the same axis as θ' is rotatably disposed. For example, as shown in FIG. 7B.

The fixed member 221C has a window 22B open so that the rotating member 23 can be rotated through this window.

A through hole 23A is formed in the rotating member 23 eccentrically with respect to the central axis 0-θ', and an intermediate transmission medium 24 is inserted into the hole 23A.
For example, an optical fiber or a Rondo lens consisting of a core 24A and a cladding 24B is inserted. It is assumed that both end surfaces of this intermediate transmission medium 24 substantially abut respective end surfaces of optical fibers 1 and 1' fixed to fixing member 22 by connectors 21 and 21'.

The optical axis of the intermediate transmission medium 24 is aligned with the central axis 0- of the rotating member 22.
0', and the rotating member 23 is connected to the fixed member 22.
The optical axis of the intermediate transmission medium 24 is rotated by an arbitrary angle between 0 and 180 degrees relative to the optical fiber 1.
The amount of deviation of the optical fibers 1 and 1' from the optical axis can be appropriately selected, and thereby the amount of optical attenuation between the optical fibers 1 and 1' can be varied to any desired value.

In the examples shown in FIGS. 7A and 7B1, a plastic optical fiber is used as the intermediate transmission medium 24, and the amount of deviation of the optical axis is
The case where the radius is the same as that of is shown. In this case, the range of optical attenuation was 1 (iiB-0:) dB.

In this example, the optical axes of the optical fibers 1 and 1' are aligned as shown in FIG. Of course, the respective optical axes may be shifted and opposed to each other.

〔effect〕

As explained above, since the present invention attenuates light by shifting the optical axis, the principle of optical attenuation is simple, and therefore the structure can be simplified, and a variable optical attenuator that is small, lightweight, and low in price can be created. Furthermore, in terms of characteristics, the minimum optical attenuation can be made small. Furthermore, since the amount of light attenuation is adjusted by rotating the rotating member, there is an advantage that fine adjustment can be made and the reproducibility of the amount of light attenuation can be improved. Therefore, the present invention is suitable as a variable optical attenuator for large diameter plastic optical fibers.

[Brief explanation of the drawing]

FIG. 1 is a line diagram showing an example of a conventional optical attenuator, FIG. 2 is a vertical sectional view showing the configuration of the first embodiment of the present invention, and FIGS. 3A and 3B are line A-A' and FIG. B
4 is a vertical sectional view showing a modified example of the embodiment shown in FIG. A vertical cross-sectional view showing the configuration of the embodiment, and FIGS. 7A and 7B are lines A-A' and B.
-B'' is a sectional view. 1.1'...Optical fiber, IA, IA'...Optical fiber core, 1B
, I B'...Optical fiber cladding, 2.2' river connector, 3.3'... Microlens, 4... Metal evaporated filter, s t, lt! ...Connector, 11A, 1. IA'...tube member, 11B, 11B'...hollow cylindrical screw member,
12... Fixed member, 12A... Through hole, 13... Rotating member, 13A... Through hole, 14.15... Screw protrusion. 14A, 15A... through hole, 21, 21'... connector. 21A, 21A'・0・Tube member, 21B, 21B'...Hollow cylindrical screw member. 22...Fixing member, 22A, 22A'...Hollow cylindrical screw member, Patent applicant Nippon Telegraph and Telephone Public Corporation Fig. 4 Fig. 5A Fig. 58 Fig. 6 Fig. 7A Fig. 70

Claims (1)

[Claims] 1) Rotation of a fixing member to which a first optical fiber is attached and a second optical fiber attached so that its end surface substantially abuts the end surface of the first optical fiber. the fixed member and the rotating member accommodate the first and second optical fibers such that their optical axes are eccentric with respect to the central axis of rotation of the rotating member; A variable optical attenuator for an optical fiber, characterized in that the optical axis forces of the first and second optical fibers are made to deviate widely by rotating a rotating member with respect to the fixed member. 2) A fixing member in which first and second optical fibers are arranged facing each other, and in the fixing member, the first and second optical fibers are rotatably attached in the space in which they face each other. Rotating part 浫J-Sei 1. - An intermediate transmission medium is accommodated eccentrically with respect to the connection. Both end surfaces of the intermediate transmission medium are approximately equal to each end surface of the first and second optical fibers. The optical axis of the intermediate transmission medium and the optical axes of the first and second optical fibers are shifted by K from each other by rotating the rotating member with respect to the fixed member so that they come into contact with each other. A variable optical attenuator for optical fibers, which is characterized by the following.(Left below)