JPH07230020A - Optical module - Google Patents

Abstract

PURPOSE:To obtain an optical module which has excellent environmental resistance and reliability over a long period of time and is producible at a low cost by providing this optical module with an enclosing member composed of a heat shrink tube which covers a metallic casing and makes engagement of this metallic casing with optical fibers airtight by thermal shrinkage. CONSTITUTION:This optical module is enclosed by a metallic piece 12 consisting of super-Invar which is a low-linear expansion material and further, the outer periphery thereof is covered an packaged by the heat shrink tube 13. The module has an EVA(ethylene-vinyl acetate copolymer) 14 which is an elastic material in this metallic piece 12 to enclose the circumference of the optical fiber arrays 6A, 6B and a waveguide element 5 an to clamp both in a vertical direction. The metallic piece 12 and the heat shrink tube 13 expand or shrink when a temp. change arises in such constitution. At this time, the expansion and contraction of the waveguide element 5 are absorbed by the EVA 14 enclosing its circumference, by which its thermal stress is relieved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a waveguide type optical module, and more particularly to an optical module which can obtain good optical characteristics for a long period of time, and can be manufactured at low cost.

[0002]

2. Description of the Related Art In recent years, optical communication technology has advanced, and the demand for an optical waveguide circuit including an optical branching device, an optical multiplexer, etc. is increasing. Along with this, high reliability and economical efficiency of the optical waveguide circuit are required.

A waveguide type optical module is widely used in this type of optical waveguide circuit, but the waveguide type optical module is generally constructed by connecting an optical fiber for optical input / output to the end face of a waveguide element. The connection is an important part that affects the reliability of the optical waveguide circuit.

FIG. 9 shows a plan view of a conventional waveguide type optical module in which a single-core optical fiber 4 on the incident side is inserted into the metal blocks 1, 2 and 3 which are integrated by bonding. The optical fiber element wire 4a is fixed to the side surface of the waveguide element 5 which divides the incident light into 16 pieces with an adhesive in a state where the optical axis is aligned. An optical fiber array 6 is fixed to the other side surface of the waveguide element 5 with an adhesive, and four four-core tape fibers 7 are connected to the optical fiber array 6. An optical unit is composed of the single-core optical fiber 4, the waveguide element 5, the optical fiber array 6 and the four-core tape fiber 7 described above.

The manufacturing process will be described. First, a single-core optical fiber 4 is provided in the metal block 1, a waveguide element 5 is provided in the metal block 2, and an optical fiber array 6 is provided in the metal block 3.
And four four-core tape fibers 7 are inserted and fixed, respectively, and the end faces to be joined surfaces are optically polished. Next, a bending ratio matching agent is applied to this end face to adjust the optical axis, and then the metal blocks 1 and 3 are welded and fixed to both end faces of the metal block 2 by a YAG laser to be integrated. As a result, the single-core optical fiber 4 and the four-core tape fiber 7 are provided.
Are butted and joined to the waveguide element 5. Each block is usually aligned with an accuracy of 1-2 μm to maintain optical bonding.

In the process of joining and fixing the metal blocks 1 and 3 and the metal block 2 as described above, instead of welding, adhesive fixing using an adhesive such as an ultraviolet curable resin may be used.

In the case of an optical module in which the single-core optical fiber 4 and the four four-core tape fibers 7 and the waveguide element 5 are joined by using an adhesive such as an ultraviolet-curing resin, the adhesive absorbs moisture under high temperature and high humidity. 10 may be absorbed to reduce the bonding strength of the joint portion, so that the incident side optical fiber 10A and the waveguide are formed by the mounting package 9 made of plastic or metal and having the recess 8 therein, as shown in FIG. The optical fiber arrays 6A and 6B and the emission side optical fiber 10B which are adhered to the element 5 with the adhesive 11 are housed,
There is one that hermetically seals integrally from above and below.

Further, instead of the mounting package, an optical unit is housed in a housing made of a metal material, and a jelly resin is further filled and sealed.
There is an optical module disclosed in Japanese Patent Application Laid-Open No. 5-45531 in which the surface of an optical unit is coated with a rubber-like silicone resin having a small water absorption rate.

[0009]

However, according to the conventional optical module, the metal block or resin as a constituent element may expand or break due to temperature change, and moisture may occur at the joint portion joined by the adhesive. Since it is not possible to flexibly cope with the environment resistance such that the optical characteristics are likely to be deteriorated due to the intrusion of, there is a problem that it is difficult to simplify the configuration and the cost increases. Therefore, an object of the present invention is to provide an optical module which is excellent in long-term environmental resistance and reliability and can be manufactured at low cost.

[0010]

According to the present invention, an elastic member in contact with a side surface of an optical component and an optical fiber at an end portion are provided so as to have excellent environmental resistance and reliability for a long period of time and to be manufactured at low cost. An enclosure composed of a metal housing that optically engages and sandwiches an elastic member, and a heat-shrinkable tube that covers the metal housing and heat-shrinks to hermetically engage the end of the metal housing with the optical fiber. An optical module having a member is provided.

Alternatively, there is provided an optical module having an enclosing member formed by coating a glass filler-containing epoxy resin from an optical fiber to an optical component to a predetermined thickness.

Alternatively, a tube member, which is located from the optical fiber to the optical component and has an opening at both ends that surrounds the optical component, is hermetically engaged with the optical fiber, and is bonded to the inner wall of the tube member at the opening at both ends of the tube member. Provided is an optical module having an enclosing member composed of a flange member.

[0013]

According to the optical module of the present invention, the optical component is protected from the invasion of moisture and the like by the covering member or the resin having the elastic material, and the optical component is deformed and destroyed by the strain due to the temperature change. To prevent.

[0014]

Embodiment 1 An optical module of the present invention will be described in detail below with reference to the drawings. The parts having the same configurations and functions as those of the conventional art are denoted by the same reference numerals, and thus the duplicate description will be omitted.

FIG. 1 is a sectional view showing a first embodiment of an optical module according to the present invention. An optical fiber array 6A to which a single-core optical fiber 4 on the incident side is connected and an optical fiber array 6 are shown.
A waveguide element 5 in which A is joined to one end, an optical fiber array 6B joined to the other end of the waveguide element 5, and four four-core tape fibers 7 connected to the optical fiber array 6B
Is a vertically divided type, and is surrounded by a metal piece 12 made of super-invar, which is a low linear expansion material, and is further packaged by covering the outer periphery thereof with a heat shrinkable tube 13.

FIG. 2 is a cross-sectional view of the optical module taken along the line AA of FIG. 1, in which the metal piece 12 has EVA (ethylene-vinyl acetate copolymer) as an elastic material.
14 respectively, and the optical fiber arrays 6A, 6
B (both not shown) and the waveguide element 5 are surrounded and sandwiched in the vertical direction.

EVA used as an elastic substance includes
Although there are various types of EVA having different vinyl acetate contents and melt flow rates, it is preferable to use EVA having high tensile strength and softening point.

In the optical module having the above structure, when the temperature changes, the metal piece 12 and the heat shrinkable tube 13 expand or contract. At this time, the waveguide element 5 absorbs the expansion and contraction due to the temperature change by the EVA 14 surrounding the waveguide element 5, so that the strain stress is relaxed, and as a result,
Optical axis misalignment and angle bending are prevented.

Further, since the metal piece 12 is used for packaging, a highly accurate joining operation is not required, so that the manufacturing is easier than the conventional optical module.
Cost reduction is possible.

[0020]

[Embodiment 2] FIG. 3 is a perspective view showing a second embodiment of the optical module of the present invention, and parts having the same configurations and functions as those of the first embodiment are designated by the same reference numerals. Therefore, redundant description will be omitted. The optical fiber array 6A to which the single-side optical fiber 4 on the incident side is connected, the optical fiber array 6B to which four four-core tape fibers 7 on the emitting side are connected, and the optical fiber arrays 6A and 6B are UV-cured at both ends. It has a waveguide element 5 joined by an adhesive, and its periphery is coated with a glass filler-containing epoxy resin 14 used for hermetically sealing ICs, LSIs and the like.

The glass filler-containing epoxy resin 14 is
Since the heat resistance of the tape fiber 7 used in the optical module is 100 to 120 ° C., it is necessary to select an epoxy resin that can be molded within this heat resistant temperature range.

FIG. 4 is a sectional view of an optical module according to the second embodiment, in which a glass molding filler-containing epoxy resin 14 is provided around a waveguide element 5 integrally fixed by fixing blocks 5a and 5b by a transfer molding machine. If the coating thickness is 0.7 mm or more, it can be used as a substitute for a mounting package.

FIG. 5 shows −2 from 0 to 10000 seconds.
FIG. 5 is a temperature characteristic diagram showing the relationship between the loss fluctuation amount and time of the optical module coated with the glass filler-containing epoxy resin 14 in a temperature change range of 5 to 75 ° C., and FIG. Content is 50wt
%, (B) is 60 wt%, and (c) is 70 wt%.

As shown in each temperature characteristic diagram,
As the glass filler content increases, the loss fluctuation amount with respect to the temperature change decreases, and it is possible to reduce the loss fluctuation amount to 0.2 dB or less in the epoxy resin having a glass filler content of 60 wt% or more. Become.

From this, the content of glass filler is 6
By using 0 wt% or more of epoxy resin and matching the thermal expansion coefficient with the waveguide element and the optical fiber array, the hermetic sealing property can be improved. In addition, since it is possible to form an optical module with less loss variation while giving excellent mechanical strength to the joint with the optical fiber without using a mounting package, the configuration is simplified and the cost is reduced. Down is possible.

[0026]

[Third Embodiment] FIG. 6 is an exploded perspective view of an optical module according to a third embodiment of the present invention, in which parts having the same configurations and functions as those of the first and second embodiments are designated by the same reference numerals. Therefore, duplicate description will be omitted.

An optical fiber array 6A to which the single-side optical fiber 4 on the incident side is connected and an optical fiber array 6B to which four four-core tape fibers 7 on the emitting side are connected are joined at both ends by an ultraviolet curing adhesive. The waveguide element 5 is housed in a tube 15 composed of a super invar, and a flange 16 through which four four-core tape fibers 7 are passed is thermoset in an opening 15A at the end of the tube 15. The tube 15 is hermetically sealed by bonding with a mold epoxy adhesive.

The outer surface of the flange 16 has an adhesive portion 16A that is adhered to the inside of the tube 15. In this embodiment, the adhesive portion 16A is formed with a width of 5 mm in the X direction shown in the drawing.

The penetrating portion (not shown) of the four-core tape fiber 7 in the flange 16 has a width 8 in the X direction shown in the drawing.
The four-core tape fiber 7 is penetrated and supported by mm, and the gap is filled with an epoxy adhesive.

Further, a rubber boot 17 for protecting the four-core tape fiber 7 is provided outside the flange 16. The end on the side of the single-core optical fiber 4 is also configured in the same manner as above.

When the He leak test was conducted on the optical module thus constructed to measure the airtightness, it was confirmed that the He leak rate was less than 10 ⁻⁷ atm cc / sec.

On the other hand, with respect to the optical module in which the four-core tape fiber 7 has a penetrating portion (not shown) in the flange 16 and the adhesive width of the adhesive portion 16A is 2 mm, the He leak test is conducted to measure the airtightness. However, the He leak rate remained at 10 ^-1 to 10 ^-3 atm cc / sec.

Next, in order to measure the change in the transmission characteristics of the optical module under high temperature and high humidity, the optical module is left under high temperature and high humidity of 75% and 95% (RH), and an arbitrary port is inserted at regular intervals. The loss was measured.

FIG. 7 is a characteristic diagram showing the relationship between the leaving time of the optical module under high temperature and high humidity and the amount of change in insertion loss. FIG. 7A shows the bonded portion 16A of the flange 16 of 5 mm and the four-core tape fiber 7 of FIG. An optical module in which a through portion (not shown) is formed with 8 mm, (B) is an adhesive portion 16 of the flange 16
The measurement results of the optical module in which both A and the penetrating portion (not shown) of the four-core tape fiber 7 are formed to be 2 mm are shown.

According to FIG. 7, the optical module of FIG.
It was confirmed that the insertion loss did not change even after 000 hours, and the long-term reliability was improved. On the other hand, the optical module of (B) is about 18
The insertion loss increases after 00 hours. This is because moisture penetrates into the joints between the waveguide element 5 and the optical fiber arrays 6A and 6B to deteriorate the ultraviolet-curable adhesive and peel it off.

FIG. 8 is an exploded perspective view showing a modified example of the optical module of the third embodiment, which is a vertically divided case 18A composed of a super invar instead of the tube 15.
An optical fiber array 6A having an incident side single-core optical fiber 4 connected to the case 18B and an optical fiber array 6B connected to four emission side four-core tape fibers 7 are provided at both ends with ultraviolet rays. After housing the waveguide element 5 to be joined with a curing adhesive, the case 18A is covered and integrated.

Instead of forming the cases 18A and 18B with super invar, glass having sufficient mechanical strength can be used.

The single-core optical fiber 4 is an optical fiber array 6
It is fixed to the case 18A by an adhesive portion 18C having an adhesive length of 8 mm formed on the A side, and the four-core tape fiber 7 is also similarly attached to the case by an adhesive portion 18D having an adhesive length of 8 mm formed on the optical fiber array 6B side. It is fixed to 18A. Further, adhesive reinforcing plates 19 made of superinvar having a thickness of 0.2 mm are adhered to both side surfaces where the cases 18A and 18B are integrated to obtain an adhesion margin of 3 mm or more in total.

A He leak test was conducted on the above-mentioned optical module to measure the airtightness, which was 10 ⁻⁷ atm cc /
A He leak rate of sec can be obtained, and the step of filling the resin inside the cases 18A and 18B can be omitted. This simplifies the assembly process and reduces the weight of the optical module.

[0040]

As described above, according to the optical module of the present invention, the elastic member that is in contact with the side surface of the optical component and the metal housing that has the end portion optically engaged with the optical fiber and sandwiches the elastic member. And a surrounding member composed of a heat-shrinkable tube that covers the metal housing and hermetically engages the end of the metal housing with the optical fiber by heat-shrinking, so that long-term environmental resistance and reliability And can be manufactured at low cost.

Alternatively, the glass filler-containing epoxy resin is coated on the optical fiber to the optical component to a predetermined thickness so that the surrounding member has an environment resistance and reliability for a long period of time, and at a low cost. It can be manufactured.

Alternatively, a tube member located at both ends of the optical fiber and surrounding the optical part and surrounding the optical part is hermetically engaged with the optical fiber, and is bonded to the inner wall of the tube member at the both ends openings of the tube member. Since it has the surrounding member composed of the flange member, it is excellent in long-term environmental resistance and reliability, and can be manufactured at low cost.

[Brief description of drawings]

FIG. 1 is a sectional view of an optical module according to a first embodiment of the present invention.

FIG. 2 is a cutaway view taken along the line AA of FIG.

FIG. 3 is a perspective view of an optical module according to a second embodiment of the present invention.

FIG. 4 shows a cutaway view of FIG.

FIG. 5 is a temperature characteristic diagram showing the relationship between loss fluctuation amount and time of the optical module according to the second embodiment of the present invention.

FIG. 6 is an exploded perspective view of an optical module according to a third embodiment of the present invention.

FIG. 7 is a characteristic diagram showing a relationship between a leaving time and an insertion loss change amount of an optical module according to a third embodiment of the present invention.

FIG. 8 is an exploded perspective view of a modified example of the optical module according to the third embodiment of the present invention.

FIG. 9 is an explanatory diagram showing a conventional optical module.

FIG. 10 is an exploded perspective view showing another conventional optical module.

[Explanation of symbols]

 1, 2 and 3 metal block 4, single-core optical fiber 5 waveguide element 6, 6A, 6B optical fiber array 7 four-core tape fiber 8 recess 9 mounting package 10A incident side optical fiber 10B emission side optical fiber 11 adhesive 12 Metal piece 13 Heat shrinkable tube 14 EVA 15 Tube 15A Opening 16 Flange 17 Rubber boot 18A, 18B Case 18C, 18D Adhesive part 19 Adhesive reinforcement plate

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshinobu Kurosawa 5-1, 1-1 Hidaka-cho, Hitachi-shi, Ibaraki Hitachi Cable Co., Ltd. Optro System Research Laboratories (72) Inventor Ryuta Takahashi Hidaka-cho, Hitachi-shi, Ibaraki 5-1-1, Hitachi Cable Co., Ltd., Optro System Research Center

Claims (9)

[Claims] 1. An optical module configured by surrounding an optical component such as a waveguide element connected to an optical fiber with a surrounding member, wherein the surrounding member includes the elastic member in contact with a side surface of the optical component, A metal casing having an end portion optically engaged with the optical fiber and sandwiching the elastic member, and an end portion of the metal casing that engages the optical fiber by heat contraction to cover the metal casing. An optical module comprising an airtight heat-shrinkable tube. 2. The optical module according to claim 1, wherein the elastic member is an ethylene-vinyl acetate copolymer resin. 3. The optical module according to claim 1, wherein the metal housing is a super invar. 4. An optical module configured by enclosing an optical component such as a waveguide element connected to an optical fiber with an enclosing member, wherein the enclosing member includes a glass filler-containing epoxy resin from the optical fiber to the optical component. An optical module, which is characterized in that it is coated to a predetermined thickness. 5. The epoxy resin containing glass filler is 6
The optical module according to claim 4, which contains 0 wt% or more of a glass filler. 6. The surrounding member has a predetermined thickness of 0.
The optical module according to claim 4 or 5, wherein the optical module has a length of 7 mm or more. 7. An optical module configured by surrounding an optical component such as a waveguide element connected to an optical fiber with an enveloping member, wherein the enveloping member is located from the optical fiber to the optical component and A light comprising a tube member surrounding both ends of the component and a flange member that is hermetically engaged with the optical fiber and is bonded to the inner wall of the tube member at the both end apertures of the tube member. module. 8. The optical module according to claim 7, wherein the surrounding member is made of a plastic material having a thin metal film on the surface thereof. 9. The optical module according to claim 7, wherein the surrounding member has an airtightness of less than 10 ⁻⁴ atm cc / sec in terms of He leak rate.