JP2004138910A - Optical module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical module which can realize a cost reduction and an improvement in productivity and can at the same time improve hermeticity. <P>SOLUTION: In the optical module 100 in which optical fibers 104 and 106 coated with resins are taken out of optical fiber take-out holes of a holding case 120 housing an optical fiber device, the portions of the optical fibers 104 and 106 near the optical fiber take-out holes are coated with metal and the metal coated areas 104D and 106D of the optical fibers and the optical fiber take-out holes are joined by a metallic joining material 130. The portions near the optical fiber take-out holes of the holding case 120 are thus hermetically sealed. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an optical module such as an optical fiber coupler, and more particularly to an optical module capable of improving airtightness while realizing cost reduction and improvement in productivity.
[0002]
[Prior art]
Conventionally, in an optical module such as an optical fiber coupler, an optical fiber filter, and an optical fiber attenuator, it is necessary to remove the resin coating layer in a part of the optical fiber device. (Coupling area: light branching / coupling area) is protected by the holding case.
[0003]
FIG. 7 shows a cross-sectional structure of a general resin-coated optical fiber (hereinafter, referred to as a resin-coated optical fiber) 40. FIG. 7 schematically shows the cross-sectional structure, and the ratio of the thickness of each layer is different from the actual ratio. The resin-coated optical fiber 40 includes a core 42 through which light propagates, a cladding 44 concentrically covering the periphery of the core 42 and confining light in the core 42, and a resin covering and protecting the core 42 and the cladding 44. 46.
[0004]
Next, FIG. 8 shows a structural example of a conventional optical tap coupler (optical module) 1.
[0005]
The optical fiber device 2 in the optical tap coupler 1 is composed of two optical fibers (element wires) 4 and 6. In the optical fibers 4 and 6, the resin coating layer is removed in the coupling region 5, and the bare optical fibers 4B and 6B are exposed. The bare optical fibers 4B and 6B are integrated under predetermined conditions by a melt drawing method. In this example, light incident from the optical fiber 4A is branched in the coupling region 5, for example, at a ratio of approximately 99: 1, The light is output from the main optical fiber 4C and the monitor optical fiber 6C.
[0006]
The bare optical fibers 4B and 6B in the coupling region 5 are protected by the holding case 8 because they are extremely weak against external impact.
[0007]
The holding case 8 includes a substrate 10 for supporting the coupling area 5 and a tubular member (reinforcing member) 12 for housing the entire optical fiber device 2 including the substrate 10. The substrate 10 is generally formed of quartz glass, and the optical fiber device 2 is fixed on the substrate 10 by a resin 14. At this time, the coupling region 5 slightly floats from the substrate 10 and is held in a predetermined tension state.
[0008]
Here, the reason why glass is used as the material of the substrate 10 is to make the coefficient of thermal expansion approximately equal to the coefficient of thermal expansion of the bare optical fibers 4B and 6B. In this way, when the temperature environment at the time of use differs from that at the time of manufacturing the optical module, it is possible to prevent a transient tension fluctuation from acting on the coupling region 5 of the optical fiber device 2.
[0009]
The tubular member 12 is generally formed of stainless steel having sufficient rigidity, and protects the optical fiber device 2 and the substrate 10 fixed therein from external impact.
[0010]
Further, both ends 12A and 12B in the axial direction of the cylindrical member 12 are sealed with an ultraviolet curing resin, a thermosetting resin, or the like (not shown) to prevent moisture, dust, dust and the like from entering the inside. .
[0011]
However, such an optical module such as the optical tap coupler 1 may be used in a severe environment outdoors or in the sea, and in such an environment, the two ends 12A and 12B of the cylindrical member 12 may be used. There is a problem that moisture, dust, dust, and the like enter the interior of the optical fiber 12, and as a result, the characteristics of the optical fiber fluctuate or deteriorate. Various techniques have been developed to improve such problems. One of the techniques is to join metal-coated optical fibers at both ends of a metal outer case as described in Patent Document 1, for example. There has been proposed an airtight optical fiber coupler which is joined by an agent and hermetically sealed.
[0012]
[Patent Document 1]
JP 2001-91786 A
[Problems to be solved by the invention]
However, the optical fiber coupler described in Patent Document 1 is a metal-coated optical fiber in which the surface of a bare optical fiber (42, 44) is directly metal-coated with gold, nickel, or the like, separately from the general resin-coated optical fiber 40. Then, the metal-coated optical fiber and the metal holding case need to be joined to ensure airtightness in the holding case.
[0014]
Therefore, it is necessary to prepare a special metal-coated optical fiber different from the general low-cost resin-coated optical fiber 40, and there is a problem that the cost is increased.
[0015]
When it is necessary to form a bare optical fiber as in the formation of the coupling region 5 described above, the metal coating is cut off little by little with a cutting edge such as a cutter or dissolved with a solvent such as an acid or an alkali. It is difficult to remove the coating, the productivity is low, and when bonding with a metal bonding agent, heat is easily transmitted to the bare optical fiber via the metal coating, As a result of the application of thermal stress, there is a problem that the characteristics of the optical fiber tend to deteriorate.
[0016]
The present invention has been made to solve such a problem, and an object of the present invention is to provide an optical module capable of improving airtightness while realizing cost reduction and improvement in productivity. I have.
[0017]
[Means for Solving the Problems]
The present invention is directed to an optical module in which a resin-coated optical fiber is taken out from an optical fiber taking-out hole of a holding case containing an optical fiber device, wherein the vicinity of the optical fiber taking-out hole of the optical fiber is coated with metal. In addition, the above problem has been solved by joining the metal coating portion of the optical fiber and the optical fiber extraction hole with a metal bonding material and hermetically sealing the vicinity of the optical fiber extraction hole of the holding case. .
[0018]
According to the present invention, the vicinity of the optical fiber extraction hole of the resin-coated optical fiber is coated with metal, and the metal-coated portion and the optical fiber extraction hole are joined by a metal bonding material. The vicinity of the optical fiber take-out hole can be completely airtightly sealed. In addition, since resin-coated optical fibers are basically used, even if it is necessary to remove the coating to form a coupling area, the resin-coated portion can be removed using a general tool such as an optical fiber stripper. It is sufficient to remove the coating as usual, and the coating can be removed very easily. In particular, the processing is easier and the productivity can be improved as compared with a case where a bare optical fiber is directly coated with a metal-coated optical fiber.
[0019]
Moreover, not only can a commonly used, low-cost resin-coated optical fiber be used, but the portion requiring metal coating is limited to the vicinity of the optical fiber exit hole of the holding case, which can reduce costs. Become.
[0020]
Furthermore, when joining with a metal joining material, a resin having a lower thermal conductivity than metal is interposed between the metal coating portion and the bare optical fiber, so that thermal stress is applied to the bare optical fiber. It is difficult to be transmitted, and it is possible to prevent the characteristic fluctuation and deterioration of the optical fiber.
[0021]
The holding case may be an optical module including a substrate for holding the optical fiber device and a case body capable of housing the entire substrate.
[0022]
Furthermore, the holding case has an accommodation portion for accommodating the optical fiber device and the optical fiber connected thereto, and has a strength capable of maintaining the external strength of the entire holding case by itself, and as a material. An optical module including a case body made of a low thermal expansion material may be used.
[0023]
The main point of this configuration is that the substrate itself is made of a low thermal expansion material (for example, a low thermal expansion metal such as an Invar alloy), and the main body of the holding case is used as it is, that is, the external strength of the entire holding case is maintained by itself. It is intended to be used as a member having the required strength.
[0024]
Note that the term “has enough strength to maintain the external strength of the entire holding case by itself” is a concept used according to the conventional double structure, and one case body itself is And the function of a reinforcing cylindrical member (outer shell member) provided outside the substrate.
[0025]
When a protective case having such a case body is employed, the product size can be made more compact as compared with the conventional double structure, and the shape can be set more flexibly than a substrate made of quartz glass. be able to. Therefore, by utilizing this flexibility, the formation of the storage portion in the present invention can be realized simultaneously with the formation of the main body of the protective case, and the present invention can be easily applied to optical modules for various uses. .
[0026]
Further, if the holding case is mainly composed of the box-shaped case main body and a lid that covers the box-shaped case main body, and the space between the case main body and the lid is sealed with a cured resin, The airtightness of the holding case can be further improved.
[0027]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an example of an embodiment of the present invention will be described in detail with reference to the drawings.
[0028]
1 and 2 show an optical module 100 (optical fiber coupler) according to an embodiment of the present invention. The optical module 100 includes an optical fiber device 102 and a holding case 120 that holds the optical fiber device 102.
[0029]
The optical fiber device 102 has substantially the same configuration as the conventional optical fiber device 2 shown in FIG. Therefore, for the same or similar parts / members, the lower two digits of the reference numerals are made to coincide with each other to omit the description of the configuration / operation and the like, and only the differences will be described below.
[0030]
The resin-coated optical fibers (hereinafter, simply referred to as resin-coated optical fibers) 104 and 106 are coated with gold (metal) 148 in this example around the optical fiber outlet 120A of the holding case 120. Metal coating portions 104D and 106D are formed on portions of the optical fibers 104 and 106, respectively.
[0031]
FIG. 3 is a cross-sectional view taken along the line III-III in FIG. 1, and shows a cross-sectional structure of the metal coating portions 104D and 106D. FIG. 3 schematically shows a cross-sectional structure, and the thicknesses of the resin 146 and the gold 148 in the figure are different from actual dimensions.
[0032]
As shown in the figure, the metal coating portions 104D and 106D of the resin-coated optical fiber 104 (106) are plated with gold 148 by an electroless plating method in this example. Here, the electroless plating method is generally a method for plating a plastic surface with copper, nickel, or the like, and has a feature that high shielding performance can be obtained with a thin coating layer.
[0033]
Returning to FIGS. 1 and 2, the holding case 120 includes a case body 124 having a longitudinal accommodation portion 122, and a lid that is fitted into the lid seat portion 124 </ b> A of the case body 124 so as to cover the accommodation portion 122. 126 mainly.
[0034]
The housing portion 122 of the case body 124 is formed with a fan-shaped groove portion 123 that expands toward one side (left side in the figure) of the optical fiber outlet hole 120A of the holding case 120. A projection 123T is disposed substantially at the center of the fan-shaped groove 123, and the fan-shaped groove 123 is separated into an accommodation groove 123A and a branch accommodation groove 123B by the projection 123T.
[0035]
The accommodation section 123A has a size capable of accommodating the optical fiber device 102 and all the optical fibers 104 and 106 connected thereto. On the other hand, the branch accommodating groove 123B is capable of branching and accommodating only the optical fiber 106C to be taken out at a different angle, and constitutes a “guide portion” that defines the taking-out direction of the optical fiber 106C.
[0036]
Here, both the case main body 124 and the lid 126 are made of a low thermal expansion metal (for example, an Invar alloy), and are further plated with gold. However, the lid 126 may be made of, for example, quartz glass.
[0037]
Next, an assembly process of the optical module 100 will be described.
[0038]
When assembling the optical module 100, first, the optical fiber device 102 and all the optical fibers 104 and 106 connected thereto are inserted and positioned in the receiving groove 123A of the receiving portion 122. Thereafter, the optical fiber 106C to be housed in the branch housing groove 123B is branched and housed in the branch housing groove 123B.
[0039]
As a result, the optical fiber 106C is taken out (exposed) from the one end 120A of the holding case 120 at a "different angle" with respect to the optical fiber 104C by the branch accommodation groove 123B as a guide.
[0040]
After the optical fiber 106C is branched, the cover 126 is fitted into the cover seat 124A of the case body 124, and the space between the case body 124 and the cover 126 is entirely sealed with a cured resin (not shown). ).
[0041]
In the optical module 100 assembled in this manner, as shown in FIGS. 4 and 5, the metal coating portions 104D and 106D of the optical fibers 104 and 106 are respectively connected to the optical fiber extraction holes 120A and the solder (metal bonding material). 130, and the vicinity of the optical fiber extraction hole 120A is hermetically sealed. 4 is a perspective view showing a state after assembling the optical module 100 (after hermetically sealing the vicinity of the optical fiber take-out hole 120A), and FIG. 5 is a sectional view taken along line VV in FIG. It is a schematic diagram which shows a part.
[0042]
Next, the operation of the optical module 100 according to the example of the embodiment of the present invention will be described.
[0043]
According to the optical module 100 according to the example of the embodiment of the present invention, the resin-coated optical fibers 104 and 106 are coated with gold (metal) 148, and the metal-coated portions 104D and 106D and the optical fiber extraction hole 120A are formed of metal. Since the bonding is performed by the bonding material 130, the vicinity of the optical fiber extraction hole 120A of the holding case 120 can be completely hermetically sealed.
[0044]
Furthermore, since the space between the case body 124 and the lid 126 is entirely sealed with the cured resin, the airtightness of the holding case 120 can be further improved.
[0045]
In addition, since the resin-coated optical fibers 104 and 106 are used, even when the coating needs to be removed for forming the coupling region 105, the resin coating 146 can be removed with a general tool such as an optical fiber stripper. It is only necessary to remove the coating, and it is extremely easy to remove the coating. In particular, the productivity can be improved as compared with a case where a bare optical fiber is directly used with a metal-coated optical fiber.
[0046]
In addition, not only the generally used and low-cost resin-coated optical fibers 104 and 106 can be used, but also the portion requiring metal coating is located near the optical fiber extraction hole 124A of the holding case 120, that is, the metal coating portion. Since it is limited to 104D and 106D, cost reduction is possible.
[0047]
Furthermore, also at the time of joining with the metallic joining material 130, the resin coating 146 having a lower thermal conductivity than metal is interposed between the metal coating portions 104D and 106D and the bare optical fibers (142 and 144). Therefore, it is difficult for thermal stress to be transmitted to the bare optical fibers (142, 144), and it is possible to prevent characteristic fluctuations and deterioration of the optical fibers 104, 106 from occurring.
[0048]
In the optical module 100, the case body 124 itself holding the optical fiber device 102 has a strength capable of maintaining the external strength of the entire holding case, and constitutes an outer shell member. Therefore, the entire optical module 100 can be made more compact as compared with the conventional double structure including the substrate 10 and the cylindrical member 12.
[0049]
In the above embodiment, the resin-coated optical fibers 104 and 106 are covered with gold. However, the present invention is not limited to this, and may be covered with another metal such as nickel. Further, the shapes and sizes of the metal coating portions 104D and 106D are not limited to those shown in the drawing, and the metal coating portions 104D and 106D only need to cover the vicinity of the optical fiber extraction hole 120A.
[0050]
Further, the holding case 120 is provided with two optical fiber extraction holes 120A, but the present invention is not limited to this.
[0051]
On the other hand, when the present invention is applied to the holding case 120 including the case main body 124 described above, many advantages can be obtained. However, the present invention itself is applicable even without the case main body 124.
[0052]
FIG. 6 shows an example.
[0053]
In this embodiment, a substrate 210 that supports the optical fiber device 202 and a case body 212 (212A, 212B) that can accommodate the entire substrate 210 are provided. The case main body 212 is constituted by two cylindrical member pieces 212A and 212B by dividing a member corresponding to the cylindrical member 12 in the conventional example described with reference to FIG. 8 along the axial direction. The present invention is also applicable to the optical module 200 including such a substrate 210.
[0054]
【The invention's effect】
According to the present invention, it is possible to provide an optical module capable of improving airtightness while realizing cost reduction and productivity improvement.
[Brief description of the drawings]
FIG. 1 is an exploded perspective view showing an optical module according to an embodiment of the present invention. FIG. 2 is an end view seen from an arrow II in FIG. 1. FIG. 3 is a cross-sectional view taken along a line III-III in FIG. 4 is a perspective view showing an assembled state of an optical module according to an embodiment of the present invention; FIG. 5 is a cross-sectional view taken along the line VV in FIG. 4; FIG. 7 is an exploded perspective view showing an optical module according to the present invention. FIG. 7 is a view showing a sectional structure of a resin-coated optical fiber. FIG. 8 is a sectional view showing a structure of a conventional optical module.
100, 200 optical modules 2, 102, 202 optical fiber devices 8, 120, 220 holding case 40 resin-coated optical fibers 42, 142 core 44, 144 clad 46 resin 104D, 106D metal coating 120A ... Optical fiber take-out hole 122. Housing portion 124. Case main body 126. Lid body 130. Metal bonding material 148.

Claims (4)

In the optical module from which the resin-coated optical fiber is taken out from the optical fiber taking-out hole of the holding case containing the optical fiber device,
Around the optical fiber extraction hole of the optical fiber, and coated with metal,
An optical module, wherein a metal covering portion of the optical fiber and the optical fiber outlet are joined by a metal bonding material, and the vicinity of the optical fiber outlet of the holding case is hermetically sealed. In claim 1,
The holding case,
An optical module comprising: a substrate that holds the optical fiber device; and a case body that can accommodate the entire substrate. In claim 1,
The holding case,
A case body having a housing portion for housing the optical fiber device and an optical fiber connected thereto, having a strength capable of maintaining the external strength of the entire holding case by itself, and made of a low thermal expansion material as a material An optical module comprising: In claim 3,
The holding case is mainly composed of the box-shaped case main body and a lid that covers the box-shaped case main body, and the space between the case main body and the lid is sealed with a cured resin. Optical module.

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