JP2002072009A - Optical branching filter/coupler - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical branching filter/coupler in which an optical axis and a filter or the like are easily adjusted and miniaturization is attained. SOLUTION: The optical multiplexer/demultiplexer is provided with a ferrule 21, a first optical fiber 22 and a second optical fiber 23 which are fixed to the ferrule 21 in parallel, a lens barrel 24 which is fixedly provided in the ferrule 21 coaxially with the ferrule 21, a collimator lens 25 which is positioned in the lens barrel 24 and is arranged in front of end surfaces of the first and second optical fibers 22 and 23, a mounter 30 which is provided with a light passing hole 31 and is fixed to the lens barrel 24 directly or via an indirect member 27, and a filter or a half mirror 32 which covers the light passing hole 31, is positioned in front of the collimator lens 25 and is attached to the mounter 30.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical multiplexer / demultiplexer used for optical communication.

[0002]

2. Description of the Related Art In optical communication, there is a multiplex communication system for transmitting signals of a plurality of different wavelengths. In this multiplex communication system, signals of a plurality of different wavelengths are multiplexed into one optical fiber or one multiplex communication system. Therefore, an optical multiplexer / demultiplexer that separates a signal of a specific wavelength from the optical fiber is required. FIG. 4 is an explanatory diagram of a conventional general optical multiplexer / demultiplexer. 10
Denotes a first collimator, and 11 denotes a second collimator, which is attached to the box 12 at a required angle.

[0003] A first optical fiber 13 is attached to the first collimator 10 via a ferrule 14.
Further, a collimator lens (not shown) is built in, and converts the light from the first optical fiber 13 into parallel light. The second optical fiber 15 is also attached to the second collimator 11 via a ferrule 16 and has a built-in collimator lens (not shown). Reference numeral 17 denotes a filter (dielectric multilayer film) or a half mirror arranged at a position where the first collimator 10 and the second collimator 11 intersect at a required angle.

[0004] For example, light of wavelengths λ1, λ2, and λ3 enters from the first collimator 10, and is transmitted through the filter 17 to λ.
The first light is transmitted, and the light of λ1 enters the third collimator 18. The lights of λ 2 and λ 3 are reflected by the filter 17, condensed by the collimator 11, and conveyed through the second optical fiber 15. That is, light of a required wavelength is split and extracted. In the opposite case, ie, the third
When the light of λ1 is input from the collimator 18 and the light of λ2 and λ3 is input from the second optical fiber 15, the light of λ1, λ2 and λ3 is collected on the first collimator 10.
That is, they are multiplexed.

When 17 is a half mirror, it has a coupler function. For example, in the case of a half mirror having a reflectance of 30%, the light (λ1, λ
70% of (2, λ3) is extracted to the third collimator 18 (or the third optical fiber), and 30% of the light is extracted to the second collimator 11 side. In the opposite case, the signal is multiplexed.

[0006]

The conventional optical multiplexer / demultiplexer has the following problems. That is,
High precision is required for adjusting the optical axes of the two collimators 10 and 11 and for adjusting the angle of the filter or the half mirror 17, but these adjustments are not always easy with the above-mentioned conventional spatial system. It took a long time to adjust.
In addition, since the two collimators 10 and 11 have a required size in space, a certain degree of open angle θ is required between the two due to spatial obstacles, and the size of the module is reduced. Had limitations.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide an optical multiplexer / demultiplexer which can easily adjust an optical axis and a filter and can be downsized.

[0008]

An optical multiplexer / demultiplexer according to the present invention comprises a ferrule, a first optical fiber and a second optical fiber fixed parallel to the ferrule, and a ferrule coaxial with the ferrule. A lens barrel fixedly provided, a collimator lens located in the lens barrel and disposed in front of the end faces of the first and second optical fibers, and a light passage hole; And a mounter fixed directly or via an indirect member to the mounter, and a filter or a half mirror mounted on the mounter so as to cover the light passage hole and to be located in front of the collimator lens. It is characterized by:

As described above, the first optical fiber and the second optical fiber
Are arranged in parallel in one ferrule, so that the optical axis and position of the collimator lens can be easily adjusted, and the angles of the filter and the half mirror can be easily and accurately adjusted. . Also, ferrule,
Since the collimator lens is shared and the mounter is provided with a light passage hole, the size of the apparatus can be reduced.

[0010] The invention is characterized in that the indirect member is a cylinder fixed to the lens barrel, and the mounter is fixed to the cylinder. A gold plating film is formed on the cylinder and the mounter, and the mounter is fixed to the cylinder by soldering. By soldering, heat resistance is improved and reliability is excellent.

[0011] The mounter is formed with a fitting cylindrical portion which enters the cylindrical body with a gap from the inner peripheral surface of the cylindrical body, and a flange portion opposed to an end surface of the cylindrical body. However, solder is filled between the inner peripheral surface of the cylindrical body and the outer peripheral surface of the fitting cylindrical portion, and between the end surface of the cylindrical body and the flange portion, and is fixed to the cylindrical body. It is characterized by. Since there is a gap between the fitting cylinder and the cylinder, while tilting the mounter by a small angle with respect to the optical axis,
The position of the filter and the half mirror can be easily adjusted, and the mounter can be accurately fixed by solder at the adjusted position.

[0012]

Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 shows a partial cross-sectional view of an optical multiplexer / demultiplexer 20 according to the present embodiment. 21 is a ferrule. Inside the ferrule 21, the first optical fiber 22 and the second optical fiber 23 are fixed in parallel at the ends. The ferrule main body 21a has a cylindrical shape made of ceramic such as zirconia, and both optical fibers are fixed in the ferrule main body 21a so as to be parallel with a resin adhesive. The end faces of both fiber core wires are exposed at the end face of the ferrule 21 (not shown).

Reference numeral 24 denotes a lens barrel, which is fixed to an end of the ferrule 21 coaxially with the ferrule 21. In the lens barrel 24, a collimator lens 25 is disposed in front of the end faces of the first and second optical fibers 22 and 23. Reference numeral 27 denotes a cylinder, which is fixed on the end of the lens barrel 24 and has a required length. Collimator lens 25
And the distance between the open end of the cylinder 27 and n. As shown in FIG. 2, the relationship between the first and second optical fibers 22 and 23 and the collimator lens 25 is such that the mirror 28 is positioned at a distance n from the collimator lens 25 at a required angle ( If the light is emitted from the end face of the first optical fiber 22, the light emitted from the end face of the first optical fiber 22 is collimated by the collimator lens 25, and the light reflected by the mirror 28 is reflected by the collimator lens 25. Are adjusted so as to have a positional relationship of being condensed on the end face of the second optical fiber 23. This adjustment is performed by the first and second optical fibers 2.
This is performed by adjusting the position, angle, and the like of the collimator lens 25 for each optical multiplexer / demultiplexer 20 in advance in relation to the positions of the end faces 2 and 23. This adjustment can be performed relatively easily because the first and second optical fibers 22 and 23 are arranged close to and parallel to each other.

Reference numeral 30 denotes a mounter. Mounter 30
Has a light passage hole 31 formed in the center thereof. A filter 32 or a half mirror 32 is mounted on the inner surface of the mounter 30 so as to cover the light passage hole 31. Further, a fitting cylindrical portion 30 a is formed on the mounter 30 so as to surround the filter 32. The outer diameter of the fitting cylinder 30a is smaller than the inner diameter of the cylinder 27. At the end of the mounter 30, an outwardly protruding flange portion 30b is formed.

The mounter 30 converts the light emitted from the end face of the first optical fiber 22 into parallel light by the collimator lens 25, and converts the light reflected by the filter 32 or the half mirror 32 into a collimator lens. The optical fiber 25 is adjusted to have a positional relationship of being condensed on the end face of the second optical fiber 23 at 25, and is fixed to the end of the cylindrical body 27.

That is, the mounter 30 is arranged so that the fitting cylindrical portion 30a enters the end of the cylindrical body 27. At this time, since the outer diameter of the fitting cylindrical portion 30a is smaller than the inner diameter of the cylindrical body 27, the mounter 30 can be inclined in an arbitrary direction with respect to the optical axis. Thus, the inclination angle of the mounter 30 is adjusted, and the second optical fiber 2
While monitoring the light from 3, the position of the mounter 30 is finely adjusted to be in the above-mentioned relational position, and the mounter 30 is soldered and fixed to the end of the cylindrical body 27 at the optimum position. . As described above, this adjustment can be easily performed even in the stage of adjusting the position of the collimator lens 25 in advance because similar adjustment has been performed. The soldering of the mounter 30 is performed by removing the gap between the inner peripheral surface of the cylindrical body 27 and the outer peripheral surface of the fitting cylindrical portion 30a,
Soldering is performed between the end face and the flange portion 30b. In order to improve the soldering, it is preferable to form a gold plating film on the cylindrical body 27 and the mounter 30. The fixing of the mounter 30 may be performed by using a resin instead of soldering.
Since solder is superior in heat resistance, a more reliable multiplexer / demultiplexer can be provided.

In the above description, the mounter 30 is fixed to the lens barrel 24 via the cylindrical body (indirect member) 27. However, the lens barrel 24 is provided in a required length, and the mounter 30 is directly mounted on the lens barrel 24. It may be fixed. Also, the fitting cylinder 30a and the flange 30b of the mounter 30 need not necessarily be provided.

With the above configuration, a part of the light (for example, the wavelength of λ1, λ2, and λ3) from the first optical fiber 22 (for example, the wavelength of λ1) passes through the filter 32, The light passes through the light passage hole 31 and is detected by a photodiode (not shown) or the like (that is, it is split). The remaining light (λ2, λ3) is reflected by the filter 32, condensed on the end face of the second optical fiber 23 by the collimator lens 25, and conveyed through the second optical fiber 23. In the above description, an example of demultiplexing is shown, but it is a matter of course that the light can be multiplexed by the reverse optical path. As described above, the function of the coupler may be provided by disposing the half mirror 32 instead of the filter 32.

FIG. 3 shows three optical multiplexers / demultiplexers 20a and 20a.
An example in which b and 20c are connected in series is shown. With such a connection, the first optical multiplexer / demultiplexer 20a outputs the wavelength λ.
The light of wavelength 1 can be split by the second optical multiplexer / demultiplexer 20b, and the light of wavelength λ3 can be split by the third optical multiplexer / demultiplexer 20c. Alternatively, the wavelengths λ1, λ
By transmitting the light beams of λ1, λ3, respectively, it is possible to take out the multiplexed light beams of λ1, λ2, λ3 from the first optical fiber 22a and to carry them.

[0020]

According to the optical multiplexer / demultiplexer according to the present invention, as described above, the first optical fiber and the second optical fiber are arranged in parallel in one ferrule. There is an advantage that the adjustment of the optical axis, the position, and the like can be easily performed, and the angle of the filter and the half mirror can be easily and accurately adjusted. In addition, since the ferrule and the collimator lens are shared and the mounter is provided with the light passage hole, the size of the apparatus can be reduced.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view of an optical multiplexer / demultiplexer.

FIG. 2 is an explanatory diagram of adjustment of a collimator lens of the optical multiplexer / demultiplexer.

FIG. 3 is an explanatory diagram of a state where a plurality of optical multiplexer / demultiplexers are connected in series.

FIG. 4 is an explanatory diagram of a conventional optical multiplexer / demultiplexer.

[Explanation of symbols]

 Reference Signs List 20 optical multiplexer / demultiplexer 21 ferrule 22 first optical fiber 23 second optical fiber 24 lens barrel 25 collimator lens 27 cylinder 30 mounter 30a fitting cylinder 30b flange 31 light passage hole 32 filter or half mirror

Claims (4)

[Claims] 1. A ferrule, a first optical fiber and a second optical fiber fixed parallel to the ferrule, a lens barrel fixed to the ferrule coaxially with the ferrule, and a position in the lens barrel. A collimator lens disposed in front of the end faces of the first and second optical fibers; and a mounter having a light passage hole and fixed to the lens barrel directly or via an indirect member; An optical multiplexer / demultiplexer, comprising: a filter or a half mirror mounted on the mounter so as to cover the light passage hole and in front of the collimator lens. 2. The optical multiplexer / demultiplexer according to claim 1, wherein the indirect member is a cylinder fixed to the lens barrel, and the mounter is fixed to the cylinder. 3. The optical multiplexer / demultiplexer according to claim 2, wherein a gold plating film is formed on the cylindrical body and the mounter, and the mounter is fixed to the cylindrical body by soldering. 4. The mounter is formed with a fitting cylindrical portion having a gap with an inner peripheral surface of the cylindrical body and entering the cylindrical body, and a flange portion facing an end surface of the cylindrical body. However, solder is filled between the inner peripheral surface of the cylindrical body and the outer peripheral surface of the fitting cylindrical portion, and between the end surface of the cylindrical body and the flange portion, and is fixed to the cylindrical body. 4. The optical multiplexer / demultiplexer according to claim 2, wherein: