JPH05307129A - Optical fiber array - Google Patents

Abstract

PURPOSE:To provide the optical fiber array which remains uniform in quality to a temp. change and to eliminates the coupling loss depending on the temp. change by constituting the optical fiber array of the same material as the material of an optical waveguide. CONSTITUTION:This optical fiber array is constituted by using the same material as the material of an optical waveguide element substrate as the array material. The array is formed by forming a V-grooved substrate A for the array and a holding plate for pressure contact by using LiNbO3, then adhering the V-grooved substrate fixed with optical fibers to a metallic base B by the holding plate for pressure contact in the case of use of, for example, an LiNbO3 substrate as the optical waveguide element substrate. The waveguide surface of the optical waveguide substrate D is then covered with an end face block C made of the LiNbO3 and is similarly adhered to the metallic base. The optical fibers and the optical waveguide are then aligned in accordance with the conventional method and the metallic bases are fused and fixed to each other by using a YAG laser beam. Alloys which are so composed and formulated as to have the same coefft. of thermal expansion as the coefft. of thermal expansion of the LiNbO3 are used for the metallic bases at this time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a close contact two-core optical fiber array useful for an optical waveguide type device.

[0002]

2. Description of the Related Art In recent years, optical waveguide type single crystal elements such as optical modulators, optical switches and optical multiplexer / demultiplexers have been proposed and attracted attention as constituent devices of optical measuring devices in the fields of optical communication and optical measurement. .. When using such an element, a plurality of input / output terminals of the element are connected to an optical fiber which is a transmission line. Since this connection state directly affects the performance of the optical measuring device, the element and the optical fiber are usually connected via an optical fiber array to obtain a good connection state.

However, the conventional optical fiber array is not always sufficient for obtaining a good connection state. Among the conventional arrays, it is said that the best connection state can be obtained. A ceramic plate having a V-shaped groove on its surface is mounted with an optical fiber core wire on the groove part, , And then crimped and sandwiched, and at the time of connection, the array and the optical waveguide element substrate were adhered to metal bases made of the same material, respectively, and the optical axes were aligned, and then the two metal bases were separated by a YAG laser. It is a fused product. The reason why the metal base of the same material is used is to prevent stress from being applied to the fusion-bonded portion of the metal base due to a temperature change and the fusion-bonded portion being destroyed. Therefore, when the heat load changes, the difference in the coefficient of thermal expansion between the ceramic and the metal plate causes a gap in the connecting portion, which causes a coupling loss.

For example, LiNbO ₃ is used as an optical waveguide single crystal element substrate, an array is formed by using zirconia having a thermal expansion coefficient close to that of LiNbO ₃ as a ceramic, and LiNb is used as a metal stand.
It is assumed that a Fe-Cr-Ni alloy whose composition is adjusted to have the same coefficient of thermal expansion as that of bO ₃ is used. In this case, the coefficient of thermal expansion in the light propagation direction is 1.54 × 10 for LiNbO _3.
^-5 (K ^-1 ), and 1.00 × 10 ^-5 (K ^-1 ) for zirconia
Is. Therefore, when an array with a length of 6 mm in the light propagation direction is used, the difference in the amount of thermal expansion between the array and the metal base to which the array is attached is 1.62 microns at a temperature difference of 100 ° C.

Further, even in the plane orthogonal to the propagation direction, the optical fiber and the optical waveguide are displaced due to the difference in the amount of thermal expansion, thereby increasing the coupling loss.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an optical fiber array which is not affected by temperature change without the above problems.

[0007]

The optical fiber array of the present invention for solving the above problems is constructed by using the same material as the optical waveguide element substrate as the array material.

[0008]

If the same material as the optical waveguide element substrate is used as the array material as in the present invention, the thermal expansion coefficient of the metal base holding the array and the array can be made the same, and as a result, the temperature change It is possible to prevent the occurrence of a gap in the connection portion due to the above and the positional deviation between the optical fiber and the optical waveguide in the plane orthogonal to the propagation direction.

For example, as an optical waveguide device substrate, LiNbO _{3 is used.}
When a substrate is used, a V-grooved substrate for the array and a crimping sandwich plate are created using LiNbO ₃ , and a V-grooved substrate on which an optical fiber is fixed with the crimp sandwiching plate is adhered to a metal base to form an array. create. FIG. 1 is a cross-sectional view of this array. Next, the waveguide surface of the optical waveguide device substrate is covered with an end face block made of LiNbO ₃ and similarly bonded to the metal base. FIG. 2 is a sectional view of this product. Next, the optical fiber and the optical waveguide are aligned in accordance with a conventional method, and the metal bases are fused with each other using YAG laser light. Of course, this metal base is LiNbO ₃
An alloy whose composition is adjusted to have the same coefficient of thermal expansion as that of

[0010]

EXAMPLES described below for the embodiment of the present invention (Example 1) and the LiNbO ₃ optical waveguide element substrate 30 mm long by covering the end face block made of LiNbO ₃ and the waveguide surface,
Length 6 mm with V-shaped groove with center spacing aligned with optical waveguide
LiNbO ₃ Place the fiber in a V-groove in the substrate, LiNbO ₃ of
It has a thermal expansion coefficient of 1.54
It is adhered to a metal base made of Fe-Cr-Ni alloy of × 10 ^-5 (K ^-1 ) by using an ultraviolet curable resin, and is aligned according to a conventional method, and the metal base is fused by using a YAG laser. , Fixed. The laser diode light is made incident from the optical waveguide side of the connection product of the optical waveguide and the optical fiber created in this way, and the connection product is detected while the output is detected on the optical fiber side.
It was kept at 70 ° C for about 30 minutes, and then left to cool to room temperature.
The output change with respect to the temperature change obtained in (a) of FIG.
The change in temperature of the substrate is shown in (c).

(Comparative Example 1) The procedure of Example 1 was repeated except that zirconia having a thermal expansion coefficient of 1.00 × 10 ^-5 (K ^-1 ) was used as the material of the substrate having the V-shaped groove (the material of the crimping sandwich plate). Is it okay to leave this as is?) A connection was created and the output change with respect to the temperature change was obtained in the same manner. The obtained results are shown in FIG. It can be seen from FIG. 3 that the use of the array of the present invention reduces the coupling loss by 0.97 dB as compared with the conventional case.

[0012]

Since the optical fiber array of the present invention is made of the same material as the optical waveguide, it becomes homogenous with respect to temperature changes, and it is possible to eliminate coupling loss depending on temperature changes.

[Brief description of drawings]

FIG. 1 is a sectional view of an optical fiber array. FIG. 2 is a cross-sectional view of an object in which the waveguide surface of the optical waveguide device substrate is covered with an end face block and then bonded to a metal base. FIG. 3 is a diagram showing changes in output of laser diode light with respect to changes in temperature, which are obtained in the embodiment of the present invention and the conventional example.

Claims (1)

[Claims] 1. A substrate having a V-shaped groove for fixing an optical fiber on its surface, and a crimping and clamping plate for crimping and clamping the optical fiber placed in the V-shaped groove, wherein the optical fiber and the optical waveguide type single crystal element are formed. In the optical fiber array used for connecting to each other, the substrate having the V-shaped groove and the crimping sandwiching plate are made of the same material as that of the optical waveguide type single crystal element substrate.