JP6811289B1 - Optical module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical module having a structure capable of miniaturization. An optical module 301 has a structure in which a part of a fiber block 13 is projected from a housing 11. Due to the gap between the opening 10 of the housing 11 and the fiber block 13, the position of the fiber block 13 due to the mounting position error of the optical waveguide chip 12 in the housing 11 and the position of the opening 10 due to the dimensional error of the housing 11 Displacement due to displacement or temperature change can be tolerated, and coupling loss due to optical axis deviation can be reduced. By providing the sealing resin 27, the optical module can prevent dust from entering the space in the housing 11 where the optical waveguide chip 12 is arranged. [Selection diagram] Fig. 2

Description

The present disclosure relates to optical modules used for optical communication.

In order to connect an optical component such as an optical waveguide chip to an optical fiber, an optical module is used in which the optical component is installed inside the housing and the optical fiber introduced from the outside of the housing is connected to the optical component inside the housing. (See, for example, Patent Documents 1 and 2).

Japanese Unexamined Patent Publication No. 08-286075 Japanese Unexamined Patent Publication No. 2004-309978 JP-A-2009-139861

Usually, when connecting an optical fiber and an optical component, an optical element (fiber block) as described in Patent Document 3 is used. The optical modules of Patent Documents 1 and 2 are housed in a housing including a fiber block in order to protect optical components from temperature changes and impacts. With such a configuration, there is a problem that it is difficult to reduce the size of the optical module due to the existence of the fiber block even if the optical component is miniaturized.

Therefore, in order to solve the above problems, it is an object of the present invention to provide an optical module having a structure capable of miniaturization.

In order to achieve the above object, the optical module according to the present invention has a structure in which a part of the fiber block protrudes from the housing.

Specifically, the optical module according to the present invention
A housing with an opening on a part of the side surface,
An optical waveguide chip installed inside the housing and
One end of the optical fiber outside the housing is held, and one end of the optical fiber is directly connected to the optical input / output end of the optical waveguide chip through the opening of the housing, and one on the optical fiber side. With a fiber block whose part is outside the housing,
A sealing resin that separates the space inside the housing into which the optical waveguide chip to which the fiber block is connected from the space in which the fiber block is inserted and another space.
To be equipped.

In this optical module, the size of the optical module can be reduced by exposing a part of the fiber block to the outside of the housing. Therefore, the invention can provide an optical module having a structure that can be miniaturized.

With such a structure, it is necessary to maintain reliability by preventing foreign matter such as dust from entering the housing through the opening. Therefore, in this optical module, a sealing resin is arranged inside the opening of the housing to prevent dust from entering the housing from entering the housing.

For example, the sealing resin is arranged so as to contact the upper plate and the bottom plate of the housing and surround the fiber block. When the sealing resin is arranged on the fiber block, the force from the housing due to vibration or heat is transmitted to the fiber block, which may cause the optical axis to shift. Therefore, the sealing resin is arranged so as not to touch the fiber block.

The sealing resin may be formed by contacting the upper plate side resin on the upper plate side of the housing and the bottom plate side resin on the bottom plate side of the housing. If the top plate side resin and the bottom plate side resin are different types of resins, for example, the bottom plate side resin in contact with the optical waveguide chip is used as an insulating resin for insulation, and the top plate side resin is used as a noise countermeasure. Therefore, it is made of conductive resin.

For example, the sealing resin is characterized by having a hardness (shore A) of 50 or less.

When the optical fiber connected to this module is bent, it is necessary to reduce the load (bending moment) applied to the fiber block to reduce the force applied to the connection portion between the optical component and the fiber block. Therefore, the present invention is characterized in that the optical fiber held by the fiber block is a small diameter fiber having a diameter smaller than 125 μm. By using a small diameter fiber, the optical fiber can be easily bent and the bending moment can be reduced. That is, by adopting the small diameter fiber, the force applied to the connection portion between the optical component and the fiber block can be reduced. Specifically, when a small-diameter fiber is used, when the optical fiber is bent with a radius of 10 mm, the force applied to the connection between the optical component and the fiber block is 50% of that when a normal optical fiber (diameter 125 μm) is used. The above can be reduced.

Further, since the fiber block of this module is outside the housing, moving the optical module or moving the optical fiber may cause a large force to be applied to the base portion of the fiber block of the optical fiber to damage the module. Therefore, in the present invention, a reinforcing material for limiting the movement of the optical fiber is further provided on the end surface of the fiber block on the side opposite to the connection surface with the optical input / output end of the optical component. For example, the reinforcing material is an elastic adhesive that covers the optical fiber and adheres to the end face of the fiber block (elongation at break is 100% or more and hardness (shore A) is 80 or less, preferably at break. Elongation is 200% or more and hardness (shore A) is 60 or less), boots that penetrate the optical fiber and adhered to the end face of the fiber block, or adhered to the end face of the fiber block with an elastic adhesive. This is a heat-shrinkable tube that penetrates the optical fiber. In this way, the reinforcing material limits the movement of the optical fiber at the base of the fiber block, so that the optical fiber can be prevented from being damaged. Further, when the reinforcing material is provided, the proof stress is improved by 500% or more as compared with the case where there is no reinforcing material in the side pull test (tensile test of the optical fiber).

The above inventions can be combined as much as possible.

The present invention can provide an optical module having a structure that can be miniaturized.

It is a figure explaining the structure of the conventional optical module (the figure which omitted the upper surface of the housing). (A) It is a top view (the figure which omitted the upper surface of the housing) explaining the structure of the optical module which concerns on this invention. (B) It is sectional drawing explaining the structure of the optical module which concerns on this invention. (A) It is a top view (the figure which omitted the upper surface of the housing) explaining the structure of the optical module which concerns on this invention. (B) It is sectional drawing explaining the structure of the optical module which concerns on this invention. It is a figure explaining the fiber block part of the optical module which concerns on this invention. It is a figure explaining the fiber block part of the optical module which concerns on this invention. It is a figure explaining the fiber block part of the optical module which concerns on this invention.

Embodiments of the present invention will be described with reference to the accompanying drawings. The embodiments described below are examples of the present invention, and the present invention is not limited to the following embodiments. In this specification and drawings, the components having the same reference numerals shall indicate the same components.

(Embodiment 1)
FIG. 2 is a diagram illustrating an optical module 301 of the present embodiment. FIG. 2A is a top view of the optical module 301 (the upper plate of the housing 11 is omitted), and FIG. 2B is a cross-sectional view taken along the line XX'of the optical module 301. ..
The optical module 301 of this embodiment is
A housing 11 having an opening 10 in a part of the side surface 11a,
The optical waveguide chip 12 installed inside the housing 11 and
One end of the optical fiber 50 outside the housing 11 is held, and one end of the optical fiber 50 is directly connected to the optical input / output end 15 of the optical waveguide chip 12 through the opening 10 of the housing 11, and the optical fiber 50 side. Fiber block 13 with a part of the outside of the housing 11
A sealing resin 27 that separates the space inside the housing 11 in which the optical waveguide chip 12 to which the fiber block 13 is connected is inserted into the space AR1 in which the fiber block 13 is inserted and the other space AR2.
To be equipped.

It has an end face having an optical input / output end 15 and a fiber array end of the optical waveguide chip 12 so that the centers of the optical input / output end 15 of the optical waveguide chip 12 and the fiber array end on the end surface of the fiber block 13 coincide with each other. It is directly connected and fixed to the end face of the fiber block 13 with an adhesive.
Although the case where three optical fibers 50 are arranged in parallel will be described in the present specification, the number of optical fibers 50 is not limited to three.

As shown in FIG. 2B, the sealing resin 27 is characterized in that it is in contact with the upper plate 11b and the bottom plate 11c of the housing 11 and is arranged so as to surround the fiber block 13.

FIG. 1 is a diagram illustrating an optical module 300 related to the invention. The optical module 300 has an optical waveguide chip 12 and a fiber block 13 inside the housing 11. Functional elements (14a, 14b) are formed in the functional circuit portion 12a of the optical waveguide chip 12 in accordance with the function of the optical waveguide chip 12. The functional elements (14a, 14b) are, for example, a VOA (Variable Optical Attenator) that adjusts the light intensity of signal light in an optical interference circuit used for a demultiplexer and an optical receiver, and a bias that separates the polarization of signal light. Wave beam splitter (PBS), Polarization Beam Splitter, Polarization Rotator that rotates the polarization of signal light or station emission, 90 degree hybrid that detects phase difference by interference between signal light and station emission It is a functional circuit such as. Although only a part of the functional elements are shown in FIG. 1, the functional elements may be formed on the entire surface of the functional circuit unit 12a. Only the input / output waveguide 14c connected to the optical fiber 50 is formed in the waveguide portion 12b on the input / output end 15 side of the optical waveguide chip 12. The structure of the optical waveguide chip 12 is the same in FIGS. 2 to 6.

In the optical module 300, the optical fiber 50 is fixed to the housing 11 as described in Patent Documents 1 and 2. Since the optical module 300 has a structure in which the fiber block 13 is completely housed in the housing 11, the housing 11 cannot be made smaller.

Therefore, in the optical module 301, the housing 11 is miniaturized by forming an opening 10 in the housing 11 and projecting a part of the fiber block 13 from the opening 10. The housing 11 can be miniaturized to the extent that it is in contact with the optical waveguide chip 12 at the maximum. For example, if the sizes of the optical waveguide chip 12 and the fiber block 13 are the same, the optical module 301 can be reduced in size by 20% or more in terms of volume ratio as compared with the optical module 300.

If dust enters the housing 11 through the gap between the opening 10 of the housing 11 and the fiber block 13, it becomes difficult to secure the reliability of the optical waveguide chip 12. In order to make the gap as small as possible, it is conceivable to make the size of the opening 10 slightly larger than the cross section of the fiber block (the outer dimension of the surface perpendicular to the longitudinal direction of the optical fiber 50). However, the position shift of the fiber block 13 due to the mounting position error of the optical waveguide chip 12 in the housing 11, the position shift of the opening 10 due to the dimensional error of the housing 11, or the displacement due to the temperature change (longitudinal direction of the optical fiber 50). Since there is a deviation or displacement in the direction perpendicular to the fiber block 13, the fiber block 13 may come into contact with the opening 10 if the gap is reduced. When the fiber block 13 and the opening 10 come into contact with each other, a force is applied to the connection portion between the fiber block 13 and the optical waveguide chip 12, and the optical input / output end 15 and the end portion of the optical fiber 50 are displaced, resulting in an optical axis deviation. Causes a coupling loss due to. Therefore, there is a limit to reducing the gap between the opening 10 and the fiber block 13.

Therefore, the optical module 301 blocks the dust with the sealing resin 27 so that the dust entering through the gap between the opening 10 and the fiber block 13 does not reach the optical waveguide chip 12. As shown in FIG. 2A, the sealing resin 27 is arranged so as to surround the fiber block 13 without gaps. Here, the sealing resin 27 is arranged in the waveguide portion 12b of the optical waveguide chip 12, and is not arranged on the functional circuit portion 12a. That is, since the sealing resin 27 is arranged so as to cover only the waveguide portion 12b of the optical waveguide chip 12 so as not to be affected by the stress on the functional circuit portion 12a, the characteristics of the optical waveguide chip 12 are not impaired. .. Further, in order to prevent the optical axis shift caused by the stress caused by the vibration, heat, and thermal expansion difference from the housing being transmitted to the fiber block 13, the sealing resin 27 is arranged so as not to touch the fiber block 13. ..

Further, as shown in FIG. 2B, the sealing resin 27 is filled around the optical waveguide chip 12 without a gap from the top plate 11b to the bottom plate 11c of the housing 11. In order to fill the sealing resin 27 into a desired shape without gaps, the sealing resin 27 may be filled in a plurality of times while adjusting the amount of the sealing resin. Further, even if the sealing resin 27 is water-repellent treated in the vicinity of the entrance / exit end side of the waveguide portion 12b or the boundary between the functional circuit portion 12a and the waveguide portion 12b so that the sealing resin 27 does not protrude from the waveguide portion 12b. good.

The sealing resin 27 is preferably a CIPG (Cured-In-Place Gasket) material having a hardness (shore A) of 50 or less, such as ThreeBond TB3081J. This is due to the following reasons. Since the sealing resin 27 surely fills the gap from the top plate 11b to the bottom plate 11c of the housing 11, the optical waveguide chip 12 is affected by the curing of the sealing resin 27 or the mechanical or thermal fluctuation of the housing 11. Is easily received via the sealing resin 27. Therefore, the lower the hardness of the sealing resin 27, the less the stress applied from the sealing resin 27 to the optical waveguide chip 12.

By arranging the sealing resin 27 in this way, the inside of the housing 11 can be separated into the space AR1 of the functional elements (14a, 14b) and the space AR2 on the opening 10 side. In the space AR1, functional elements (14a, 14b) formed in the functional circuit portion 12a of the optical waveguide chip 12 and optical elements (light receiving elements and light emitting elements) installed between the optical waveguide chip 12 and the housing 11 Includes drive circuits, control circuits, and optical elements and components (not shown) such as wiring. Since the space AR1 and the space AR2 are completely blocked by the sealing resin 27, the dust entering through the gap between the opening 10 and the fiber block 13 stays in the space AR2 and does not enter the space AR1. Therefore, the optical module 301 can ensure the reliability of the optical elements and parts inherent in the space AR2.

(Embodiment 2)
FIG. 3 is a diagram illustrating an optical module 302 of the present embodiment. FIG. 3A is a top view of the optical module 302 (the upper plate of the housing 11 is omitted), and FIG. 3B is a cross-sectional view taken along the line XX'of the optical module 302. .. The difference between the optical module 302 and the optical module 301 in FIG. 2 is that the sealing resin 27 of the optical module 302 is on the upper plate side resin 27b on the upper plate 11b side of the housing 11 and on the bottom plate 11c side of the housing 11. It is configured to be in contact with the bottom plate side resin 27c.

Since the top plate side resin 27b and the bottom plate side resin 27c are different types of resins, functions can be added. For example, since the bottom plate side resin 27c in contact with the optical waveguide chip 12 is required to be insulated, a resin having high insulating properties (for example, volume resistivity> 1 GΩ · m [Specific example: ThreeBond TB3081J, etc.]) is used. On the other hand, since noise countermeasures are required for the optical module, the upper plate side resin 27b is made of a highly conductive resin (for example, volume resistivity <1Ω · m [Specific example: Cemedine SX-ECA48, etc.]).

(Embodiment 3)
In the optical module of the present embodiment, unlike the optical modules of Patent Documents 1 and 2, the optical fiber is not fixed to the housing. Therefore, depending on the handling of the optical module and the wiring (bent state) of the optical fiber, a large force is applied to the connection portion between the fiber block and the optical waveguide chip, and a coupling loss due to the optical axis shift may occur. Therefore, the optical module of the present embodiment takes the following measures.

FIG. 4 is a diagram illustrating an optical module 304 of the present embodiment. The optical module 304 is characterized in that the optical fiber 50 held by the fiber block 13 is a small diameter fiber having a diameter smaller than 125 μm. For example, the optical fiber 50 is preferably a small diameter fiber having an optical fiber diameter of less than 180 μm including a coating having a fiber diameter of 80 μm.

A normal optical fiber has a fiber diameter of 125 μm and an optical fiber diameter including a coating of 250 μm. Small diameter fibers are easier to bend than ordinary optical fibers and have a smaller bending moment. That is, by using a small diameter fiber for the optical fiber 50 held by the fiber block 13, even if the optical fiber 50 is bent as specified, the force on the connection portion between the fiber block 13 and the optical waveguide chip 12 is usually applied. It can be made smaller than when using the optical fiber of. That is, it is possible to reduce the coupling loss due to the optical axis shift due to the bending of the optical fiber.

Therefore, the optical module 304 can reduce the coupling loss caused by handling and wiring of the optical fiber 50. The structure other than the above-mentioned portion is the same as that of the optical module described in the first and second embodiments.

(Embodiment 4)
In the optical module of the present embodiment, unlike the optical modules of Patent Documents 1 and 2, the optical fiber is not fixed to the housing. Therefore, a large force is applied to the root of the fiber block of the optical fiber depending on the handling of the optical module and the wiring (bent state) of the optical fiber, and the optical fiber may be damaged. Therefore, the optical module according to the present invention takes the following measures. The root of the fiber block of the optical fiber refers to the part of the optical fiber that the fiber block does not hold and is closest to the fiber block.

FIG. 5 is a diagram illustrating an optical module 305 of the present embodiment. The optical module 302 further includes a reinforcing member 29 that limits the movement of the optical fiber 50 at the end surface of the fiber block 13 opposite to the connection surface of the optical waveguide chip 12 with the optical input / output end 15. For example, the reinforcing material 29 is an elastic adhesive that covers the optical fiber 50 and adheres to the end face of the fiber block 13. In this elastic adhesive, not only softness (hardness) but also elongation (elongation at break) is important so as not to peel off when the optical fiber is bent, elongation at break is 100% or more, and hardness (shore A). ) Is 80 or less, preferably the elongation at break is 200% or more, and the hardness (shore A) is 60 or less. DOWN CORNING® SE 9186 can be exemplified as such an elastic adhesive. Further, the reinforcing material 29 is a boot through which the optical fiber 50 is adhered to the end surface of the fiber block 13. Further, as shown in FIG. 6, the reinforcing material 29 may be a heat-shrinkable tube penetrating the optical fiber 50, which is adhered to the end face of the fiber block 13 with an elastic adhesive. Examples of the material of the heat-shrinkable tube include polyimide and silicone.

The optical module 305 protects the optical fiber 50 at the base of the fiber block 13 with a reinforcing material 29, and even if the optical fiber 50 is bent as specified, the force applied to the optical fiber at the base of the fiber block 13 is applied to the reinforcing material. It can be made smaller than when there is no. That is, damage to the optical fiber due to bending of the optical fiber can be reduced. Therefore, the reinforcing material 29 can improve the ease of handling of the optical module 305. The structure other than the above-mentioned portion is the same as that of the optical module described in the first and second embodiments.

(Differences from conventional technology)
Patent Document 2 also aims to reduce the size of the optical module, but has a structure in which the optical fiber is held by rubber boots (a structure in which a bending moment is not applied to the fiber block). On the other hand, the optical module according to the present invention has a configuration in which the fiber block 13 is not held but is exposed from the housing 11. Further, in the optical module of Patent Document 2, the position error of the fiber block at the time of fabrication and the fluctuation of the housing due to the temperature fluctuation are allowed in the optical axis direction (fiber longitudinal direction), but in the optical axis direction. No consideration is given to the vertical direction. The optical module according to the present invention has a configuration in which dust from gaps is blocked by a sealing resin, so that a positional error of the fiber block 13 is allowed even in a direction perpendicular to the optical axis. The optical module according to the present invention is based on the premise that a bending moment is applied to the fiber block 13 by bending the optical fiber 50, and employs root reinforcement and the use of a small diameter fiber.

10: Opening 11: Housing 12: Optical waveguide chip 12a: Functional circuit unit 12b: Waveguide unit 13: Fiber block 14a, 14b: Optical functional element 14c: Input / output waveguide 15: Optical input / output end 27: Sealing Resin 29: Reinforcing material 31: Boots 32: Fiber fixture 50: Optical fiber 300 to 305: Optical module

Claims (5)

A housing with an opening on a part of the side surface,
An optical waveguide chip installed inside the housing and
One end of the optical fiber outside the housing is held, and one end of the optical fiber is directly connected to the optical input / output end of the optical waveguide chip through the opening of the housing, and one on the optical fiber side. part is Ri outside near the housing, a fiber block which is not in contact with said opening,
The space inside the housing in which the optical waveguide chip to which the fiber block is connected is installed is separated from the space in which the fiber block is inserted and another space so as not to come into contact with the fiber block. With the sealing resin
Optical module with. The sealing resin is
The optical module according to claim 1, wherein the optical module is arranged so as to be in contact with the upper plate and the bottom plate of the housing and to surround the fiber block. The sealing resin is
The optical module according to claim 1 or 2, wherein the upper plate side resin on the upper plate side of the housing and the bottom plate side resin on the bottom plate side of the housing are in contact with each other. The optical module according to claim 3, wherein the top plate side resin and the bottom plate side resin are different types of resins. The optical module according to any one of claims 1 to 4, wherein the sealing resin has a hardness (shore A) of 50 or less.

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