JPH06102432A - Optical module - Google Patents

Abstract

(57) [Summary] [Purpose] To provide an optical module that is excellent in insertion loss temperature characteristics, small in size, and low in cost. In an optical module including a holder for butt-joining at least two optical components, the optical components 11, 13, 17 are housed in metal holders 10, 14, 16 having the same substantially circular cross-sectional outer shape. It is characterized by being.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical module having a holder for butt-joining at least two optical components.

[0002]

2. Description of the Related Art FIG. 4 is an external perspective view of a conventional optical module.

In FIG. 1, a single-core optical fiber 1 and a 4-core tape-shaped optical fiber (hereinafter referred to as 4-core tape fiber) 2 are bonded and fixed on the precision V-grooves 3 and 4, respectively. These precision V-grooves 3 and 4 are metal holders 5 having a concave cross section,
Each of them is fixedly adhered in the inside of 6.

On the other hand, a quartz type 1 × 4 (1 input 4 output) star type coupler element 7 is a metal holder 8 having a concave cross section.
It is glued and fixed on top. After the end faces of each of the optical components 1 to 4 and 7 together with the metal holders 5, 6 and 8 are mirror-polished and aligned so that the optical axes of the optical fibers 1 and 4 and the optical axis of the coupler element 7 are aligned with each other. The joints of the metal holders 5, 6 and 8 are welded and fixed by a YAG laser to form an optical module.

4 core tape fiber 2 of this optical module
When the laser light is incident on each of the optical fibers, the combined laser light is emitted from the single-core optical fiber 1, and conversely, when the laser light is incident on the single-core optical fiber 1, the branched laser light is a 4-core tape. The light is emitted from each optical fiber of the fiber 2.

[0006]

However, in the above-mentioned conventional optical module, when the temperature changes, the fluctuation of the insertion loss becomes large and the temperature characteristic of the insertion loss deteriorates. This is because the shape of the cross section of each metal holder 5, 6, 8 is
Since the optical components 1 to 4 and 7 on the metal holders 5, 6 and 8 are not point-symmetric with respect to the center (center of gravity) or the optical axis, the optical axis shifts at the joint surface due to expansion and contraction when the temperature changes. This is because it occurs.

Further, in the conventional optical module, a part of the optical components 1 to 4 and 7 on the metal holders 5, 6 and 8 are exposed, and it is necessary to separately house them in a package in order to protect them. As a result, the optical module becomes large and the cost becomes high.

Therefore, an object of the present invention is to solve the above problems and to provide an optical module which is excellent in temperature characteristics of insertion loss, small in size, and low in cost.

[0009]

In order to achieve the above object, the present invention provides an optical module having a holder for abutting and joining at least two optical components, wherein the optical components have the same substantially circular cross-sectional outer shape. It is housed in a metal holder.

[0010]

According to the above construction, since the optical parts are housed in the metal holder having the same substantially circular cross-sectional outer shape, even if the metal holder expands or contracts due to temperature change, the center part of the cross-section expands or contracts. The amount of displacement accompanying it becomes substantially zero, and by arranging the optical component at the center of this cross section, the optical component does not receive a force in a certain direction. That is, the temperature characteristic of insertion loss is improved. In addition, since the optical component is housed in the metal holder, the package is not required, and the size can be reduced and the cost can be suppressed.

[0011]

An embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is a partial cross-sectional perspective view of an embodiment of the optical module of the present invention.

In the figure, an insertion hole 10a is formed along the central axis at the center of the cylindrical holder 10. In this insertion hole 10a, for example, each optical fiber (not shown) of the four-core tape fiber 11 is adhered and fixed, and the precision V groove 13 to which the pressing lid 12 is attached is also adhered and fixed. One surface (right side of the drawing) of the holder 10 is flush with the end surface of each optical fiber, the pressing lid 12 and the precision V groove 13, and the end surface of each optical fiber is of the pressing lid 12 and the precision V groove 13. The end faces are mirror-polished.

An insertion hole 14a is formed along the central axis of a cylindrical holder 14 having the same substantially circular cross-sectional outer shape as the holder 10. A silica-based 1 × 4 star type coupler element 15 and the like are adhesively fixed in the insertion hole 14a. The length of the holder 14 in the axial direction is equal to the length of the coupler element 15 in the longitudinal direction.
Both end faces of 4 are the same face, and both end faces of the coupler element 15 are mirror-polished together with the holder 14.

An insertion hole (not shown) is formed along the central axis of the holder 16 having the same substantially circular cross section as the holder 14. A pipe (not shown) for holding the single-core optical fiber 17 is inserted into the insertion hole,
Adhesive fixed. The end surface of the single-core optical fiber 17 is exposed so as to be flush with one end surface (left side in the drawing) of the holder 16, and the end surface of the holder 16 is mirror-polished.

The cross-sectional shape of each holder 10, 14, 16 is substantially the same as described above, and each optical component 11,
The optical axis is designed to pass through the center of the cross section when 12, 13, 15, 17 are mounted.

The end faces of these holders 10, 14 and 16 are butted against each other so that the laser light is incident from the single-core optical fiber 17 and the amount of laser light emitted from each optical fiber of the tape fiber 11 is maximized. After the optical axes are aligned with each other, the side surfaces of the joints of the holders 10, 14, and 16 are spot-welded or continuously welded by, for example, a YAG laser, to form an optical module.

4 core tape fiber 1 of this optical module
When the laser light is incident on each of the optical fibers 1, the combined laser light is emitted from the single-core optical fiber 17, and conversely, when the laser light is incident on the single-core optical fiber 17, the branched laser light is divided into four cores. Each tape fiber 11 emits light.

Next, the operation of the embodiment will be described.

4-fiber tape fiber 11, coupler element 15
Since the optical components such as the single-core optical fiber 17 and the single-core optical fiber 17 are housed in the holders 10, 14, 16 made of stainless steel having the same cross-sectional outer shape, the holders 10, 14, 16 are affected by the temperature change.
Even if 14 and 16 expand and contract, the displacement amount due to expansion and contraction at the center of the cross section becomes substantially zero, and the optical components 11, 12, and 1
By arranging 3, 15, 17 in the center of this cross section, the optical components 11, 12, 13, 15, 17 are not subjected to a force in a fixed direction. That is, the temperature characteristic of the insertion loss is improved (see FIGS. 2A and 2B). Also, each optical component 1
1, 12, 13, 15, 17 are stainless holders 1
0, 14, 16 are housed in the optical components 11, 12,
Since 13, 15, 17 are not exposed and the mechanical strength is sufficient, the package is not required, the size can be reduced, and the cost can be suppressed.

Here, FIG. 2A is a diagram showing the relationship between the insertion loss change amount and temperature when the optical module is subjected to a temperature cycle test, and FIG. 2B is a diagram showing the temperature cycle. The horizontal axes of (a) and (b) of FIG. 10 both indicate the time axis, the vertical axis of (a) thereof indicates the amount of change in insertion loss, and the vertical axis of (b) thereof indicates temperature.

In FIG. 4A, the solid line indicates the insertion loss change amount of the optical module shown in FIG. 1, and the broken line indicates the insertion loss change amount of the conventional optical module shown in FIG.

The temperature cycle has a temperature change of 2 cycles from 0 to + 70 ° C. When the laser light of the wavelength band of 1.3 μm is made incident, the conventional optical module showed a loss increase exceeding 0.3 dB. In the optical module of the present application, it was possible to obtain a very good temperature characteristic of less than 0.1 dB.

FIG. 3 is a partial sectional perspective view of another embodiment.

The difference from the optical module shown in FIG. 1 is that
This is that the shape of each holder 20, 21, 22 is not a columnar shape, but parallel planes (reference planes) 20a, 21a, 22a are pseudo-columnar formed on both side surfaces (upper and lower surfaces in the figure).

Each of the holders 20, 21 and 22 is a metal holder having the same pseudo-circular cross-sectional outer shape, and an insertion hole along the central axis is formed in the central portion. Similar to the optical module shown in FIG. 1, the tape fiber 11, the precision V groove 12, the coupler element 15, the single-core optical fiber 17 and the like are inserted and fixed in the insertion hole by adhesion. Each holder 2 to which these optical components 11, 12, 15, 17 are adhesively fixed
The optical axes of 0, 21, and 22 are aligned and then YAG-welded to form an optical module.

Each holder 20, 21, of this optical module,
22 has a slightly sacrificed insertion loss because the cross-sectional outer shape is not a circle, but at the time of manufacturing the optical module, particularly during alignment of the optical axis, the outer peripheral portions of the holders 20, 21, and 22 are
Since each of the holders 20, 21, and 22 is provided with a reference plane that is line-symmetric with respect to the central axis of the cross section of the holders 20, 21, and 22 and is parallel to the arrangement direction of the optical axes of the optical components 11, 12, 15, and 17, the holders 20, 21, and 22 are stable. It is easy to fix the rotation angle θ at the time of optical axis alignment between the precision V-groove 13 and the coupler element 15, and workability is significantly improved.

As described above, in the present embodiment, since the optical components are housed in the metal holder having the same substantially circular cross-sectional outer shape, an optical module having excellent temperature characteristics of insertion loss, small size and low cost is realized. be able to.

Although the present embodiment has been described by using the 4-fiber tape fiber, the single-fiber optical fiber and the coupler element of 1 × 4 star type as the optical component, the present invention is not limited to these, and the optical fiber having two or more fibers is used. It goes without saying that it may be applied to other optical components such as a tape fiber, a light emitting element and a light receiving element. Further, although the number of holders is three in the figure, the number of holders may be increased or decreased according to the number of optical components. Further, the material of the holder is not limited to stainless steel, and other metals may be used.

[0030]

In summary, according to the present invention, the following excellent effects are exhibited.

(1) The temperature characteristic of insertion loss of the optical module is improved.

(2) A compact and low-cost optical module can be obtained.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional perspective view of an embodiment of an optical module of the present invention.

FIG. 2A is a diagram showing a relationship between an insertion loss change amount and a temperature when an optical module is subjected to a temperature cycle test,
(B) is a figure which shows a temperature cycle.

FIG. 3 is a partial cross-sectional perspective view of another embodiment.

FIG. 4 is an external perspective view of a conventional optical module.

[Explanation of symbols]

 10, 14 and 16 Holders 10a and 14a Insertion hole 11 Four-core tape fiber (optical part) 12 Holding lid 13 Precision V groove (optical part) 15 Coupler element (optical part) 17 Single-core optical fiber (optical part)

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroyuki Kakuyama 5-1-1 Hidaka-cho, Hitachi-shi, Ibaraki Hitachi Cable Co., Ltd. Hidaka factory

Claims (3)

[Claims] 1. An optical module including a holder for butt-joining at least two optical components, wherein the optical components are housed in a metal holder having the same substantially circular cross-sectional outer shape. module. 2. The optical module according to claim 1, wherein an optical axis of the optical component passes through a center of a cross section of the metal holder. 3. A reference plane, which is line-symmetric with respect to the central axis of the cross section of the metal holder and is parallel to the arrangement direction of the optical axes of the optical components, is provided on the outer peripheral portion of the metal holder. The optical module according to claim 1, characterized in that