JP3085344B2 - Optical module - Google Patents

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 provide good optical characteristics over a long period of time, is low-cost, and is easy to manufacture.

[0002]

2. Description of the Related Art In recent years, optical communication technology has advanced, and the demand for an optical waveguide circuit composed of an optical branching element, an optical multiplexer and the like has been increasing. Accordingly, high reliability and economic efficiency of the optical waveguide circuit are required.

A waveguide type optical module is widely used in this type of optical waveguide circuit, and the waveguide type optical module is generally configured by connecting an optical fiber for inputting and outputting light to an end face of a waveguide element. The connection is an important part that affects the reliability of the optical waveguide circuit.

FIG. 9 is a plan view of a conventional waveguide type optical module. A single-core optical fiber 4 on the incident side is inserted into metal blocks 1, 2, and 3 integrated by bonding. The optical fiber 4a is fixed by an adhesive with its optical axis aligned with the side surface of the waveguide element 5 which divides the incident light into 16 lines. 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 constituted by the single-core optical fiber 4, the waveguide element 5, the optical fiber array 6, and the four-core tape fiber 7.

[0005] The manufacturing process will be described. First, the single-core optical fiber 4 is placed on the metal block 1, the waveguide element 5 is placed on the metal block 2, and the optical fiber array 6 is placed on the metal block 3.
Then, the four four-core tape fibers 7 are inserted and fixed, respectively, and the end face to be the joining surface is optically polished. Next, after applying a bending-rate matching agent to the end faces to adjust the optical axis, 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 four-core tape fibers 7
Are butt-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 to the metal block 2, instead of welding, an adhesive such as an ultraviolet curing 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 are bonded to the waveguide element 5 using an adhesive such as an ultraviolet curable resin, the adhesive has a high moisture content under high temperature and high humidity. As shown in FIG. 10, the incident side optical fiber 10A and the waveguide are formed by a mounting package 9 made of plastic or metal and having a recess 8 therein, as shown in FIG. The optical fiber arrays 6A and 6B and the output side optical fiber 10B bonded to the element 5 by the adhesive 11 are housed,
Some of them are hermetically sealed integrally from the vertical direction.

In addition, an optical unit is housed in a housing made of a metal material instead of a mounting package, and is further filled with a jelly-like resin and sealed therein.
And 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 low water absorption.

[0009]

However, according to the conventional optical module, the metal block and the resin, which are the components, may expand and break due to a temperature change. Since it is difficult to flexibly cope with environmental resistance such that optical characteristics are likely to be deteriorated due to intrusion, it is difficult to simplify the configuration and the cost increases. Accordingly, 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]

DISCLOSURE OF THE INVENTION The present invention provides an elastic member in contact with the side surface of an optical component and an optical fiber at the end so as to be excellent in long-term environmental resistance and reliability and to be manufactured at low cost. An enclosure comprising an optically engaged metal housing that sandwiches an elastic member, and a heat-shrinkable tube that covers the metal housing and heat-shrinks the end of the metal housing to the optical fiber by heat shrinkage. An optical module having a member is provided.

Another object of the present invention is to provide 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 which is open at both ends surrounding the optical component, is airtightly engaged with the optical fiber, and is bonded to the inner wall of the tube member at both end openings of the tube member. Provided is an optical module having an enclosing member constituted by 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 substance, and the optical component is deformed and destroyed by the distortion due to the temperature change. To prevent.

[0014]

Embodiment 1 Hereinafter, an optical module according to the present invention will be described in detail with reference to the drawings. Portions having the same configuration and function as those of the related art are denoted by the same reference numerals, and duplicate description will be omitted.

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

FIG. 2 is a cross-sectional view of the optical module taken along the line AA in FIG. 1, and EVA (ethylene / vinyl acetate copolymer) which is an elastic substance is provided inside the metal piece 12.
14 and the optical fiber arrays 6A and 6A.
B (both not shown) and the periphery of the waveguide element 5 and are vertically sandwiched.

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 a high tensile strength and a high softening point.

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

In addition, by packaging using the metal piece 12, it is not necessary to perform a high-precision joining operation, so that the manufacturing becomes easier as compared with the conventional optical module.
Cost reduction becomes possible.

[0020]

Embodiment 2 FIG. 3 is a perspective view showing a second embodiment of the optical module according to the present invention, and portions having the same configuration and function as those of the first embodiment are denoted by the same reference numerals. Therefore, duplicate description will be omitted. The optical fiber array 6A to which the single-core optical fiber 4 on the incident side is connected, the optical fiber array 6B to which four four-core tape fibers 7 on the output side are connected, and the optical fiber arrays 6A and 6B are cured at both ends by ultraviolet rays. 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 hermetic sealing of IC, LSI and the like.

The epoxy resin 14 containing glass filler 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 a second embodiment, in which a glass molding filler epoxy resin 14 is provided around a waveguide element 5 integrally fixed by fixing blocks 5a and 5b by a transfer molding machine. When the coating thickness is 0.7 mm or more, it can be used as a substitute for a package for mounting.

FIG. 5 shows that -2 from 0 to 10000 seconds.
FIG. 4 is a temperature characteristic diagram showing a relationship between a loss variation amount and time of an optical module coated with a glass filler-containing epoxy resin 14 in a temperature change range of 5 to 75 ° C., and FIG. Content is 50wt
%, (B) shows 60 wt%, and (c) shows 70 wt% of the epoxy resin.

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

From this, the content of the glass filler was 6%.
By using 0 wt% or more 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 fluctuation while giving excellent mechanical strength to a joint with an optical fiber without using a mounting package, the configuration is simplified and cost is reduced. Down becomes possible.

[0026]

Embodiment 3 FIG. 6 is an exploded perspective view of an optical module according to a third embodiment of the present invention. Parts having the same structure and function as those of the first and second embodiments are denoted by the same reference numerals. Therefore, duplicate description will be omitted.

An optical fiber array 6A to which the single-core optical fiber 4 on the incident side is connected and an optical fiber array 6B to which four four-fiber tape fibers 7 on the output side are connected are bonded at both ends with an ultraviolet curing adhesive. The waveguide element 5 to be formed is housed in a tube 15 composed of a super invar. Further, a flange 16 having four four-core tape fibers 7 penetrated therethrough is thermoset at 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 a bonding portion 16A bonded to the inside of the tube 15. In this embodiment, the bonding portion 16A is formed with a width of 5 mm in the X direction shown in the drawing.

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

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

The optical module thus constructed was subjected to a He leak test to measure the airtightness, and it was confirmed that the He leak rate was less than 10 ^-7 atm cc / sec.

On the other hand, a He leak test was performed to measure the airtightness of the optical module in which the four-core tape fiber 7 penetrating portion (not shown) in the flange 16 and the bonding width of the bonding portion 16A were formed to 2 mm. 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 95% (RH) at 75 ° C., and an arbitrary port is inserted at regular intervals. The loss was measured.

FIG. 7 is a characteristic diagram showing the relationship between the standing time of the optical module and the amount of change in insertion loss under high temperature and high humidity. FIG. An optical module in which a penetrating portion (not shown) is formed by 8 mm, and FIG.
A measurement result is shown for an optical module in which both the A and the four-core tape fiber 7 have a penetrating portion (not shown) of 2 mm.

According to FIG. 7, the optical module of FIG.
Even after a lapse of 000 hours, there was no change in the insertion loss, and improvement in long-term reliability was confirmed. On the other hand, the optical module of FIG.
The insertion loss increases after the lapse of 00 hours. This is because moisture penetrated into the junction between the waveguide element 5 and the optical fiber arrays 6A and 6B, and the ultraviolet curing adhesive was deteriorated and peeled off.

FIG. 8 is an exploded perspective view showing a modified example of the optical module according to the third embodiment. In FIG.
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 having four outgoing four-core tape fibers 7 connected to the case 18B. After accommodating the waveguide element 5 joined by the curing adhesive, the case 18A is covered and integrated.

Instead of forming the cases 18A and 18B by super invar, it is possible to use glass having sufficient mechanical strength.

The single-core optical fiber 4 includes an optical fiber array 6
The four-core tape fiber 7 is also fixed to the case 18A by an adhesive part 18D having an adhesive length of 8 mm similarly formed on the optical fiber array 6B side by an adhesive part 18C having an adhesive length of 8 mm formed on the side A. 18A. Further, an adhesive reinforcing plate 19 formed of a super invar having a thickness of 0.2 mm is adhered to both side surfaces on which the cases 18A and 18B are integrated to obtain an adhesive margin of 3 mm or more.

The above optical module was subjected to a He leak test to measure the airtightness. As a result, 10 ^-7 atm cc /
A He leak rate of sec can be obtained, and the step of filling the inside of the cases 18A and 18B with resin 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 in contact with the side surface of the optical component and the metal housing whose end is 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 seals the engagement of the end of the metal housing with the optical fiber by heat shrinkage, thereby providing long-term environmental resistance and reliability. And can be manufactured at low cost.

Alternatively, since an enclosing member constituted by coating a predetermined thickness from the optical fiber to the optical component with the glass filler-filled epoxy resin is provided, it is excellent in long-term environmental resistance and reliability, and at low cost. Can be manufactured.

Alternatively, a tube member located at both ends from the optical fiber to the optical component and surrounding the optical component is airtightly engaged with the optical fiber, and is bonded to the inner wall of the tube member at both ends of the tube member. Since the surrounding member constituted by the flange member is provided, it is excellent in long-term environmental resistance and reliability, and can be manufactured at low cost.

[Brief description of the drawings]

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

FIG. 2 is a sectional view taken along a line AA in 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 a relationship between a loss fluctuation amount of an optical module and time according to a 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 an idle time of an optical module and an insertion loss change amount according to a third embodiment of the present invention.

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

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

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

[Explanation of symbols]

 1, 2, 3 Metal block 4, Single-core optical fiber 5 Waveguide element 6, 6A, 6B Optical fiber array 7 Four-core tape fiber 8 Depression 9 Mounting package 10A Incident optical fiber 10B Exit optical fiber 11 Adhesive 12 Metal piece 13 Heat shrink tube 14 EVA 15 Tube 15A Opening 16 Flange 17 Rubber boot 18A, 18B Case 18C, 18D Adhesive part 19 Adhesive reinforcing plate

──────────────────────────────────────────────────続 き Continuing on the front page (72) Takayuki Kadori, Inventor 5-1-1, Hidaka-cho, Hitachi City, Ibaraki Prefecture Nippon Electric Cable Co., Ltd. Opto-System Research Laboratory (72) Inventor Yoshinobu Kurosawa Hidaka, Hitachi City, Ibaraki Prefecture 5-1-1, Machimachi, Optio System Research Laboratory, Hitachi, Ltd. (72) Inventor Ryuta Takahashi 5-1-1, Hidakacho, Hitachi, Ibaraki Prefecture, Optosystem Research Laboratory, Hitachi, Ltd. (56) References JP-A-7-43566 (JP, A) JP-A 64-32505 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) G02B 6/24-6/42

Claims (9)

(57) [Claims] 1. An optical module configured by surrounding an optical component such as a waveguide element connected to an optical fiber with an enclosing member, wherein the enclosing member comprises: an elastic member in contact with a side surface of the optical component; An end is optically engaged with the optical fiber, and a metal housing that sandwiches the elastic member, and covers the metal housing and engages the end of the metal housing with the optical fiber by heat shrinkage. An optical module comprising a heat-shrinkable tube for airtightness. 2. The optical module according to claim 1, wherein said 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 surrounding an optical component such as a waveguide element connected to an optical fiber with an enclosing member, wherein the enclosing member converts glass-filled epoxy resin from the optical fiber to the optical component. An optical module characterized in that the optical module is coated to a predetermined thickness. 5. The epoxy resin containing a glass filler is 6
The optical module according to claim 4, wherein the optical module 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, wherein the optical module is 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 enclosing member, wherein the enclosing member is located from the optical fiber to the optical component and the optical component is formed. A light member comprising: a tube member having both ends opened to surround a component; and a flange member hermetically engaged with the optical fiber and bonded to an inner wall of the tube member at both ends 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 surface provided with a metal in a thin film shape. 9. The optical module according to claim 7, wherein the surrounding member has an air density of less than 10 ⁻⁴ atm cc / sec in He leak rate.