JP3764509B2 - Optical waveguide module - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a highly reliable optical waveguide module including an optical waveguide chip and an optical fiber whose optical axes coincide with each other and are connected and fixed.
[0002]
[Prior art]
A conventional optical waveguide module is composed of an optical waveguide chip and a connecting optical component as main components. For example, a V-groove is formed on a quartz substrate and an optical fiber is bonded to a desired position. A material fixed with an agent or the like is used. In addition, the optical waveguide chip has a function of branching and switching, in which a portion having a high refractive index and confining light is formed in the optical waveguide substrate.
[0003]
FIG. 9A is a diagram showing an example of connection between the 1 × 4 branching type optical waveguide chip 3 and the optical fiber block 1, and the connection end faces of the optical waveguide chip 3 and the connecting optical component 1 are on the optical axis. On the other hand, end faces are polished at a desired angle in order to prevent reflected return light, and each core interval of the four-core optical fiber block 1 which is the connecting optical component 1 is the interval between the optical waveguides 4 of the optical waveguide chip 3. Are made to match. The optical waveguide chip 3 and the optical fiber block 1 are generally connected and fixed with an adhesive (for example, an ultraviolet curable adhesive) or the like after the optical axes are aligned.
[0004]
Therefore, an adhesive layer 7 is interposed in the connection portion between the optical waveguide chip 3 and the optical fiber block 1, and the adhesive layer 7 absorbs moisture in the presence of moisture. It will cause deterioration. As a result, an increase in optical loss at the connection portion has occurred.
[0005]
As a countermeasure, a measure is taken such that the thermosetting resin 11 is applied and sealed on the side surface including the connection portion that is connected and fixed as shown in FIG. 9B.
[0006]
[Problems to be solved by the invention]
However, in the above-described sealing method, a thermosetting resin is applied as a sealing material. Therefore, if the application is not performed with a uniform thickness, a difference in stress occurs due to a difference in the thickness of the thermosetting resin. As a result, the reliability of the optical waveguide module is impaired.
[0007]
In addition, since a thermosetting resin is used as the sealing material, it takes a long time to cure, and in order to maintain the thermosetting resin with a uniform thickness after curing, a light guide is used to prevent the influence of the thermosetting resin due to its own weight. There has been a problem that work must be performed for each side of the waveguide module, and work efficiency is poor.
[0008]
The present invention has been made in view of the above points, and an object of the present invention is to provide an optical waveguide module that has excellent long-term reliability and good working efficiency without destabilizing optical characteristics. .
[0009]
[Means for Solving the Problems]
The present invention has been made in order to solve these problems. At least one light that is connected and fixed to the optical waveguide chip and both end faces of the optical waveguide chip so that the optical axes coincide with each other. In an optical waveguide module equipped with an optical fiber block to which the fiber is fixed, the optical waveguide chip and the optical axis of the optical fiber are aligned, the connection is fixed, and a heat shrink tube is used to seal the connection. It is characterized by.
[0010]
[Action]
In the optical waveguide module as described above, it is possible to easily make the thickness of the heat-shrinkable tube, which is a sealing material, uniform. Therefore, the difference in stress due to the difference in the thickness of the thermosetting resin that has been a problem in the past. All the side surfaces including the connection part of the optical waveguide module can be prevented, and after the optical waveguide chip and the optical axis of the optical fiber are aligned, the connected and fixed one is inserted into the heat shrinkable tube and contracted by heat Can be sealed at a time, and work efficiency can be improved.
[0011]
【Example】
Hereinafter, reference examples of the present invention will be described in detail with reference to the drawings. FIG. 1 shows a configuration diagram and a sealing method showing a reference example of an optical waveguide module 10 according to the present invention. In FIG. 1A, the optical waveguide chip is a 1 × 8 branch type optical waveguide chip 3, and a silica-based optical waveguide is formed on a silicon substrate. The optical fiber block 1 connected to the eight optical waveguides has eight optical fibers of the tape fiber 5 in the eight V-grooves on the V-groove substrate formed with the same precision as the interval of the optical waveguides by cutting. In the optical fiber block 1 that is arranged and connected to one optical waveguide, one optical fiber 2 is arranged in one V-groove on a V-groove substrate manufactured by the same processing method. In this state, the connection cross section is produced at a desired angle with respect to the optical axis by polishing by pressing with a cover from above the optical fibers arranged in both V-grooves and then using an ultraviolet curable adhesive. . In addition, the optical waveguide chip 3 and the optical fiber block 1 are, for example, adjusted in optical axis on each connection side, and then applied with an ultraviolet curable adhesive and irradiated with ultraviolet rays to form an adhesive layer 7 between connection cross sections. And the connection is fixed. Next, as shown in FIG. 1B, the two connecting portions of the optical waveguide module 10 are inserted into one fluororesin heat-shrinkable tube 8 having a uniform thickness so as to be hidden. The fluororesin heat shrinkable tube 8 is shrunk at an appropriate temperature. Here, the fluororesin heat shrinkable tube 8 uses a tetrafluoroethylene-6 fluoropropylene copolymer resin FEP (Fluorinated-Ethylene-Propyrene, shrinkage temperature 140 ° C., shrinkage rate 40%), and its inner diameter is shrinkage. Later, the size was set such that no gap was formed between the side surface of the waveguide module 10 and the inner wall of the fluororesin heat-shrinkable tube 8. After contraction, it becomes as shown in FIG.
[0012]
FIG. 2 is a configuration diagram showing another reference example of the present invention, in which separate fluororesin heat-shrinkable tubes 8 are used for each of the two connecting portions.
[0013]
FIG. 3 is a configuration diagram showing another reference example of the present invention, in which the entire optical waveguide module 10 is covered with a fluororesin heat-shrinkable tube 8.
[0014]
4, 5 and 6 are configuration diagrams showing an embodiment of the present invention, in which the stepped portion is made smaller when the optical fiber block 1 and the optical waveguide chip 3 are different in height. In FIG. 4, for example, a taper portion is provided on the optical waveguide chip 3 so that the thickness of the UV curable adhesive used for connection is gradually reduced in the direction opposite to the connection portion. 5 and 6, the auxiliary substrate 9 is provided on the optical waveguide chip 3 so that the heights of the optical fiber block 1 and the optical waveguide chip 3 are matched.
[0015]
FIG. 7 is a block diagram showing another embodiment of the present invention. After the optical waveguide chip 3 and the optical fiber block 1 are fixed to the housing 6 having a circular cross section as shown in FIGS. 7 (a) and 7 (b), the optical axis is adjusted on each connection side as shown in FIG. 7 (c). After that, an ultraviolet curable adhesive is applied, and an ultraviolet ray is irradiated to form an adhesive layer 7 between the connection cross sections, and the connection is fixed. Then, as shown in FIG. The tube 8 is sealed.
[0016]
FIG. 8 is a cross-sectional view showing another embodiment of the present invention. A structure in which an elastic silicon resin 12 is applied to the outer periphery of the optical waveguide chip 3 and the optical fiber block 1 in a portion where the heat shrinkable tube is used to seal the connection portion, and the stress at the time of shrinkage of the heat shrinkable tube 8 is relaxed. It has become.
[0017]
Although the embodiments of the present invention have been described in detail above, the present invention is not limited thereto, and for example, the following modifications are possible.
[0018]
(1) In the above embodiment, the heat-shrinkable tube 8 is made of a fluororesin, but other components may be used as long as they have excellent moisture resistance and can be reinforced. As the fluororesin, vinylidene fluoride resin (PVDF: Polyvinylidene-fluoride, eg: shrinkage temperature 175 ° C., shrinkage rate 50%), tetrafluoroethylene resin (TFE: Tetrafluoroethylene), eg: shrinkage temperature 327 ° C., shrinkage rate 50% , 75%) Tetrafluoroethylene-perfluoroalkoxyethylene copolymer resin (PFA: Perfluoroalkoxy, eg, shrinkage temperature 140 ° C., shrinkage 25%), tetrafluoroethylene resin TFE and tetrafluoroethylene-6 fluoride There is a double structure TFE / FEP of propylene copolymer resin FEP (example: shrinkage temperature 327 ° C., shrinkage rate 67%).
[0019]
Moreover, a heat-shrinkable tube can be obtained even if the crosslinked polyolefin is formed into a tube shape. Cross-linked polyolefin is a three-dimensional network structure in which polymer molecules are cross-linked by radiation cross-linking in order to improve the heat resistance of polyolefin (Polyolefin: for example, various types such as polyethylene) which is a polymer of olefin (ethylene series hydrocarbon). It is a thing. A crosslinked polyolefin having a shrinkage temperature of 121 ° C. and a shrinkage rate of 50% was used. In addition, there are semi-rigid crosslinked polyolefins (eg, shrinkage temperature 135 ° C., shrinkage rate 50%).
[0020]
A heat-shrinkable tube can also be obtained using synthetic rubber. Synthetic rubbers include cross-linked fluororubber (eg, shrinkage temperature 175 ° C., shrinkage rate 50%), chloroprene rubber (eg, shrinkage temperature 135 ° C., shrinkage rate 50%) and the like.
[0021]
Further, when a heat shrinkable tube is formed of a double structure material in which a heat-meltable layer is provided inside these heat-shrinkable materials, the inner layer is melted by heating and the outer heat-shrinkable material is shrunk. This is effective for removing and sealing the gap between the entire circumference of the connection portion of the waveguide module and the inner wall of the heat shrinkable tube. For such a material, a heat-shrinkable tube can be realized by forming a tube with a cross-linked polyolefin and polyolefin having a two-layer structure, with the cross-linked polyolefin on the outside and the polyolefin on the inside (example: shrink temperature 121 ° C., Shrinkage rate 60%). In addition, there are a crosslinked polyolefin and a polyamide-based adhesive (eg, shrinkage temperature 121 ° C., shrinkage rate 67%).
(2) The cross-sectional shape of the heat-shrinkable tube 8 before shrinkage may be circular or rectangular as long as no gap is generated between the side surface of the optical waveguide module 10 and the inner wall of the heat-shrinkable tube 8 after shrinkage.
[0022]
(3) In the above embodiment, no reinforcing material is used for the connection fixing portion between the optical waveguide chip 3 and the optical fiber block 1, but sealing is performed after the reinforcing material is provided over both sides of the optical waveguide chip and the optical fiber block. You may do it.
[0023]
(4) In the above-described embodiment, the cross-sectional shape of the housing 6 is circular. However, the shape is not limited to this, and may be rectangular, for example.
[0024]
In addition, this invention can combine the Example shown in FIGS. 1-8 and the technical matter of said (1)-(3).
[0025]
【The invention's effect】
As described above in detail, in the optical waveguide module according to the present invention, since the heat shrinkable tube is used for sealing the connection portion, the difference in stress due to the difference in the thickness of the thermosetting resin that has been a problem in the past is used. All the side surfaces including the connection part of the optical waveguide module can be prevented, and after the optical waveguide chip and the optical axis of the optical fiber are aligned, the connected and fixed one is inserted into the heat shrinkable tube and contracted by heat Can be sealed at a time, and work efficiency can be improved.
[Brief description of the drawings]
FIGS. 1A, 1B, and 1C are side views showing an example of a method for sealing an optical waveguide module according to a reference example of the present invention.
FIG. 2 is a side view of an optical waveguide module showing another reference example of the present invention.
FIG. 3 is a side view of an optical waveguide module showing another reference example of the present invention.
FIG. 4 is a side view of an optical waveguide module showing an embodiment of the present invention.
FIG. 5 is a side view of an optical waveguide module showing another embodiment of the present invention.
FIG. 6 is a side view of an optical waveguide module showing another embodiment of the present invention.
FIGS. 7A and 7B show another embodiment of the optical waveguide module according to the present invention, in which FIG. 7A is a connection end view of an optical fiber block, FIG. 7B is a connection end view of an optical waveguide chip, and FIG. FIG. 4 is a perspective view of an optical waveguide module in which optical fiber blocks are connected and fixed to both end faces of the waveguide chip, and FIG. 4D is a perspective view showing a state in which the optical waveguide module is sealed.
FIG. 8 is a cross-sectional view of an optical waveguide module showing another embodiment of the present invention.
9A and 9B show a conventional example, in which FIG. 9A is a top view of an optical waveguide module in which a 1 × 4 branch type optical waveguide chip and an optical fiber block are connected, and FIG. 9B is a thermosetting type at a connection portion of the optical waveguide module. It is sectional drawing of the optical waveguide module which shows the example which apply | coated resin.
[Explanation of symbols]
1: optical fiber block, 2: optical fiber, 3: optical waveguide chip, 4: optical waveguide, 5: tape fiber, 6: housing, 7: adhesive layer, 8: fluororesin heat shrinkable tube, 9: auxiliary substrate, 10: Optical waveguide module, 11: Thermosetting resin, 12: Silicon resin

Claims (3)

In an optical waveguide module in which an optical waveguide chip in which an optical waveguide is formed and an optical fiber block to which an optical fiber is fixed are connected, the optical waveguide chip and the optical fiber block have different heights, and the optical waveguide chip and The position of the optical fiber block and the optical fiber to be connected to the optical waveguide are aligned and fixed by an adhesive, and the adhesive is tapered on the optical waveguide chip so that the thickness gradually decreases in the direction opposite to the connecting portion. An optical waveguide module characterized in that the entire periphery of the connection fixing portion is sealed by providing a portion and further heat-shrinking the heat-shrinkable tube. 2. The optical waveguide module according to claim 1, wherein the heat-shrinkable tube is formed by forming one material selected from fluororesin, crosslinked polyolefin, and synthetic rubber into a tube shape. Optical waveguide module according to claim 1 or 2 wherein the heat shrink tubing outer heat shrinkable material layer, the inner characterized in that it comprises a double structure composed of a heat-meltable material layer.

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