JPH0886933A - Optical waveguide module - Google Patents

Abstract

PURPOSE: To provide an optical waveguide module having excellent reliability and low loss. CONSTITUTION: This module consists of a waveguide block 9 and optical fiber arrays 10, 11 provided on the entrance side and the exit side of the block 9. The waveguide block 9 consists of an optical waveguide element 1 and a dummy plate 2 which covers the element 1. The optical fiber arrays 10, 11 consist of V-groove blocks 4, 7 and pressing plates 5, 8 which press the V-groove blocks. In this module, the optical waveguide element 1 and the dummy plate 2, and the V-groove blocks 4, 7 and the pressing plates 5, 8 are adhered and fixed with a high elasticity heat-resistant adhesive (having >=1 GPa (10<4> kgf/cm<2> ) elasticity modulus and >=130 deg.C heat resistance). On both ends in the entrance and exit sides of the waveguide block 9, optical fibers in the entrance side and exit side are fixed with an optical adhesive having matched refractive index (refractive index <=D=1.45 to 1.59) so as to align the optical axes with end faces of the optical waveguide element 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical waveguide module, and more particularly to a structure of an optical waveguide module in which an optical fiber is bonded and fixed to one end or both end faces of an optical waveguide element.

[0002]

2. Description of the Related Art With the progress of optical communication technology, conventional light sources,
In addition to optical fibers and receivers, optical splitters
Optical components such as optical switches, optical switches, and optical multiplexers / demultiplexers are required. Small size, mass productivity, and high reliability were essential for these optical components. Since it is very difficult for the conventional fiber type and bulk type to meet the above requirements, practical application of a waveguide type optical component has been desired.

At the present time, the biggest problem in putting a waveguide type optical component into practical use is the combination of the optical waveguide that constitutes the waveguide type optical component.
The point is how to make the connection with the output optical fiber efficient and stable. As a method of connecting the optical waveguide and the input / output optical fiber, a method using a UV curable adhesive, which is expected to reduce cost, so-called UV adhesive is generally used.

Here, the structure of the optical waveguide module will be described by taking a 1 × 4 splitter module as an example. As shown in FIG. 1, the waveguide block 9, the incident side optical fiber array 10 and the emitting side optical fiber are shown. Array 1
In the waveguide block 9, the optical waveguide is covered with a quartz dummy plate 2 of the same size as the upper surface of the waveguide element 1 in which the optical waveguide is formed on a quartz substrate, and both are fixed by adhesion with a UV adhesive. It has been configured. The dummy plate 2 is for preventing the optical waveguide (core) from being chipped or sagging (curved surface) when polishing both end surfaces of the optical waveguide.

On the other hand, the incident-side optical fiber array has a quartz single-core V-groove block 4 in which V-grooves are formed, and a pressing plate 5, and the V-grooves on the single-core V-groove block 4 are incident on the incident side. The single-core optical fiber 3 is arranged, and the pressing plate 5 is put on the optical fiber 3 and U
It is configured by adhering and fixing with a V adhesive. One output side optical fiber array has a four-core V-groove block 7 made of quartz in which four V-grooves are formed and a pressing plate 9, and has four V-groove blocks of the four-core V-groove block 7 on the output side. Each of the cores of the four-core tape fiber 6 is arranged, the pressing plate 8 is covered over the core, and the UV-adhesive is used to bond and fix the cores.

However, the both end surfaces of the waveguide block 9 and the end surfaces of the optical fiber arrays 10 and 11 are mirror-polished or mirror-ground, and scratches on the optical fiber end surface and the optical waveguide (core) portion which cause connection loss. It is finished until it disappears. The waveguide block 9 and the optical fiber arrays 10 and 11 that have been polished are subjected to power monitoring with light emitted from the incident side single-core optical fiber 3 and emitted from the emission side four-core tape fiber 6 on the precision fine movement table. While adjusting the optical axis,
After the optical axis adjustment, the end faces (mirror faces) of the waveguide block 9 and the optical fiber arrays 10 and 11 are bonded and fixed with a UV adhesive to complete the modularization. (JP-A-59-28416)

[0007]

Generally, since the UV adhesive has a small elastic modulus and is soft, the optical waveguide in the waveguide block is subjected to mirror polishing or mirror cutting of the end face of the waveguide block or the optical fiber array. The UV adhesive fixing portion between the element, the dummy plate, and the V groove block and the pressing plate in the optical fiber array is chipped or cracked, which not only significantly deteriorates the reliability but also easily causes the peeling of the UV adhesive. As a result, especially in the optical fiber array, V
The optical fiber floats above the groove, and the accuracy of the V groove is not reflected in the optical fiber, which is the largest factor for increasing the insertion loss of the module.

Therefore, an object of the present invention is to solve the above-mentioned problems of the prior art and to provide an optical waveguide module having excellent reliability and low loss.

[0009]

The optical waveguide module (first means) provided by the present invention is a waveguide block and an optical fiber array provided at the incident side end and the emitting side end of the block. And a waveguide block comprising an optical waveguide element and a dummy plate covering the element, and an optical fiber array comprising an V-groove block and a pressing plate covering the block, an optical waveguide in the waveguide block. The element and the dummy plate, and the V-groove block and the pressing plate are bonded and fixed with a high-elasticity and heat-resistant adhesive, so that as a hard and highly heat-resistant adhesive fixing part with a large elastic modulus. , Machining (polishing,
It is the one that eliminates chipping and cracking due to cutting, etc.).

The high elastic and heat resistant adhesive has an elastic modulus of 1
It is preferable to use an ultraviolet curable adhesive having a GPa (10 ⁴ kgf / cm ² ) or more and a heat resistance temperature of 130 ° C. or more.

Further, an optical waveguide module (second means) provided by the present invention has a waveguide block and optical fiber arrays provided at an incident side end portion and an output side end portion of the block. The waveguide block is composed of an optical waveguide element and a dummy plate covering this element, and the optical fiber array is V
In an optical waveguide module composed of a groove block and a pressing plate covering the block, the end faces of the optical waveguide element and the dummy plate are mirror-polished or ground-cut at both the entrance side and the exit side of the waveguide block. At the same time, the V groove block of the optical fiber array and the end faces of the pressing plate are polished or mirror-ground, and the incident side and the outgoing side optical fibers are matched in refractive index so that the optical axes coincide with both end faces of the optical waveguide device. It is fixed with the above-mentioned optical adhesive, and thus, the refractive index of the adhesive portion is optimized so that the loss can be reduced.

As the optical adhesive, the refractive index η _D = 1.
Controllable in the range of 45 to 1.59 (accuracy of 0.005)
It is preferable to use a UV-curable adhesive.

[0013]

Embodiment FIG. 1 shows an embodiment of the optical waveguide module of the present invention.
The 1 × 4 splitter module will be described. First, in the waveguide block 9, the optical waveguide device 1
Put a dummy plate 2 on top of them, and make them both highly elastic and heat resistant UV
Fix with adhesive. On the other hand, the incident-side single-core optical fiber 3 is arranged in the V-groove of the quartz V-groove block 4 in the incident-side single-core type optical fiber array 10, and is covered with the pressing plate 5 to provide high elasticity and heat resistance. It is adhesively fixed with a UV adhesive. Further, the outgoing side four-core tape fiber 6 is arranged in the V groove (four-core fiber pair four V grooves) of the quartz V groove block 7 in the outgoing side four-core optical fiber array 11, and is pressed from above. The plate 8 is covered and bonded and fixed with a high elasticity and heat resistant UV adhesive.

Then, both the entrance and exit end faces of the waveguide block 9 assembled as described above and the end faces of both the entrance and exit optical fiber arrays 10 and 11 are mirror-polished or ground-ground. , Finish until there are no scratches. The mirror-finished waveguide block 9 and optical fiber arrays 10 and 11 monitor the power of the light emitted from the incident side single-core optical fiber 3 on the precision fine movement table and emitted from the output side four-core tape fiber 6. While adjusting the optical axis. After the optical axis adjustment, the end faces of the waveguide block 9 and the optical fiber arrays 10 and 11 are made to have an epoxy-based UV of η _D = 1.45 to 1.46 which is almost equal to the refractive index of the core of the optical fiber.
The adhesive is fixed by an adhesive to form a 1 × 4 splitter module. When the optical waveguide element is made of silica, the refractive index of the core of the optical fiber η _D = 1.45
It is optimum to use an epoxy UV adhesive having the same refractive index as 1.46 (however, the refractive index at the time of curing).

Table 1 shows the UV used in this example.
3 shows an example of characteristics of an adhesive.

[0016]

[Table 1]

As is clear from Table 1, by using the adhesive according to this embodiment, connection excess loss is within 0.2 dB,
The temperature characteristic of −25 to + 70 ° C. is within ± 0.1 dB, and it is possible to realize the loss reduction of about 1/2 of the conventional one.

The material of the optical waveguide element is LiNbO3.
In the case of, the optical adhesive of η _D = 1.59 is used for the adhesive fixation of the waveguide and the end face of the optical fiber, considering the difference in the refractive index of the core of the optical fiber and the refractive index of the optical waveguide of LiNbO3. Good. Even if the material of the optical waveguide element is other than the above, it can be arbitrarily set within the range of η _D = 1.45 to 1.59.

[0019]

According to the optical waveguide module of the present invention as described above, the first means; the mutual adhesion portion between the optical waveguide element and the dummy plate in the waveguide block, and the incident and outgoing optical fiber array. Since the mutual adhesive portion between the V-groove block and the pressing plate is adhered and fixed with an adhesive having high elasticity and heat resistance, even if the end face of the optical fiber array or the waveguide block is mirror-polished or ground-polished, the optical waveguide It is possible to manufacture an optical waveguide module that is more reliable than the conventional module of this type without causing cracks or cracks in the UV bonding portions between the element and the dummy plate and between the V groove block and the pressing plate. (75 ° C, 95% wet heat test 4000h
No peeling at r. Conventionally, about 100 under the same test conditions
Delamination occurs in time. ) Second means: Refractive index η _D = 1.4 for bonding the optical fiber array and both end faces of the waveguide block.
By using an optical adhesive that can be arbitrarily set to 5 to 1.59, it is possible to provide an optical waveguide module having a lower loss by selecting an optimum refractive index regardless of the material of the optical waveguide element.

[Brief description of drawings]

FIG. 1 is an external perspective view of a 1 × 4 splitter module that is an optical waveguide module.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Optical waveguide element 2 Dummy plate 3 Incident optical fiber (single-core optical fiber) 4 V groove block 5 Holding plate (incident side) 6 Emitting optical fiber (4 core tape fiber) 7 V groove block 8 Holding plate (emission side) ) 9 Waveguide block 10 Optical fiber array (incident side) 11 Optical fiber array (exit side)

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Ryuta Takahashi 5-1, 1-1 Hidaka-cho, Hitachi-shi, Ibaraki Hitachi Cable Co., Ltd., Optro System Laboratory (72) Inventor Hiromasa Nemoto Hidaka-cho, Hitachi-shi, Ibaraki 5-1-1, Hitachi Cable Ltd., Optoro System Laboratories

Claims (4)

[Claims] 1. A waveguide block, and an optical fiber array provided at an entrance side end and an exit side end of the block, the waveguide block comprising an optical waveguide element and a dummy plate covering the element, The optical fiber array is an optical waveguide module including a V-groove block and a pressing plate covering the block, and the optical waveguide element and the dummy plate in the waveguide block and the V-groove block and the pressing plate have high elasticity. An optical waveguide module characterized by being bonded and fixed with a heat-resistant adhesive. 2. The elastic modulus of 1 as the high-elasticity / heat-resistant adhesive.
The optical waveguide module according to claim 1, wherein an ultraviolet curable adhesive having a GPa (10 ⁴ kgf / cm ² ) or more and a heat resistant temperature of 130 ° C. or more is used. 3. A waveguide block, and an optical fiber array provided at an incident side end portion and an output side end portion of the block, the waveguide block comprising an optical waveguide element and a dummy plate covering the element, The optical fiber array is an optical waveguide module including a V-groove block and a pressing plate covering the block. In the optical waveguide module, the end faces of the optical waveguide element and the dummy plate are polished or polished at both ends of the waveguide block on the incident side and the emitting side. In addition to the mirror-surface grinding and cutting, the V groove block of the optical fiber array and the end surface of the pressing plate are mirror-polished or mirror-ground, and the optical fibers on the incident side and the emitting side are aligned so that the optical axes coincide with both end surfaces of the optical waveguide device. An optical waveguide module, characterized in that is fixed by an optical adhesive having a matched refractive index. 4. The refractive index η _D = 1.
Controllable in the range of 45 to 1.59 (accuracy of 0.005)
4. The optical waveguide module according to claim 3, wherein the ultraviolet curable adhesive is used.