JPH08227055A - Method for joining optical isolator parts - Google Patents

Abstract

PURPOSE: To make it possible to join optical parts and their holding member without degrading the extinction performance of these optical parts by joining the optical parts and their holding member with solder or low melting glass and heating both under specific conditions, then gradually cooling both down to room temp. CONSTITUTION: The optical parts 2 which are optical isolator parts and their holding member 1 are joined by the solder 3 or the low melting glass. The joined body is then heated for one to five hours at a temp. lower by 5 to 100 deg.C than the m.p. of the solder 3 or the low melting glass and thereafter, the joined body is gradually cooled down to room temp. Namely, the holding member 1 and the optical parts 2 are joined by cooling and solidifying of the solder 3 molten by heat. The optical parts 2 and the holding member 1 are joined in such a manner. The shrinkage of the respective parts 1, 2 is relieved when the resulted joined body is gradually cooled down to room temp. after heating for specified time and, therefore, strains are hardly generated and the degradation in the extinction performance of the optical parts 2 is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of joining components incorporated in an optical isolator.

[0002]

2. Description of the Related Art In an optical communication system or the like, transmitted light oscillated from a laser light source may be reflected by an incident surface of various optical transmission components in an optical communication path and the reflected light may reach the laser light source. The reflected light disturbs the light emitting action of the light source and often causes noise. The optical isolator is installed between the light source and the optical transmission component, transmits only the light traveling in the direction of the transmission component, and selectively blocks the reflected light traveling in the direction of the light source.

To improve the performance of an optical isolator,
Optical components such as polarizers incorporated inside must be strongly bonded. The optical components were bonded with a resin adhesive, but the adhesive expands due to the temperature rise of the optical isolator and the temperature change of the outside, so that the joint may be displaced. Therefore, solder or low-melting glass is widely used as a bonding agent instead of the resin adhesive. A metal film is formed on the surface of the optical component so that solder or the like can be easily joined.

[0004]

When assembling the optical isolator, after joining the optical components to each other with solder or the like,
A holding member holds each optical component such as a polarizer and an analyzer. Specifically, the holding member and each optical component are soldered as in the case of joining the optical components. After the soldering is completed, the holding member and the optical component are cooled to room temperature and shrink together. However, since the thermal expansion coefficients are different, the shrinkage ratios are different. The distortion caused by this difference in contraction is concentrated on the optical component, and the extinction performance of the optical component after bonding is deteriorated. Even when a low melting point glass is used as the bonding agent, the extinction performance of the optical component is similarly deteriorated.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a method for joining an optical component and its holding member without deteriorating the extinction performance of the optical component. .

[0006]

In order to achieve the above-mentioned object, a method of joining optical isolator parts according to the present invention comprises an optical part which is an optical isolator part and a holding member for the optical isolator part by soldering or low melting point glass. This is a method of joining and heating the bonded body at a temperature 5 ° C. to 100 ° C. lower than the melting point of solder or low melting point glass for 1 hour to 5 hours, and then gradually cooling the bonded body to room temperature.

If the heating temperature is lower than the above temperature range, the extinction performance of the optical component after bonding will deteriorate,
If the temperature is higher than the above temperature range, the solder and the low melting point glass will be remelted. If the heating time is less than 1 hour,
The extinction performance of the optical component after bonding is deteriorated, and if it exceeds 5 hours, the effect of merely heating for a long time is not exhibited.

[0008]

The holding member 1 and the optical component 2 are joined by the solder 3 melted by heat being cooled and solidified. Generally, the holding member 1 has a higher coefficient of thermal expansion than the optical component 2, so that the holding member 1 has a larger shrinkage caused by cooling. When the contraction is different, the strain is concentrated on the optical component 2 which is weak in strength, and the extinction performance of the optical component 2 is deteriorated. When the optical component 2 and the holding member 1 are joined, and the obtained joined body is heated at a specific temperature for a certain period of time and then gradually cooled to room temperature, the shrinkage of each of the components 1 and 2 becomes gradual, so that distortion occurs. It is less likely to occur, and deterioration of the extinction performance of the optical component 2 is prevented.

[0009]

Embodiments of the present invention will be described below. FIG. 1 is a sectional view showing an embodiment of a bonded body obtained by the bonding method of the present invention. As shown in the figure, the optical component 2 is solder 3
Is joined to the holding member 1. The opening portion 4 of the holding member 1 serves as an optical path. The obtained bonded body becomes a component that constitutes an optical isolator.

The process of joining the optical component 2 and the holding member 1 will be described below. Solder 3 has a composition of 80% gold and 20 tin.
%, Au80-Sn20 having a melting point of 280 ° C., the optical component 2 is a polarizing glass (made by Corning Incorporated), and the holding member 1 is a stainless steel material (SUS 304). The surface of SUS 304 is plated with gold as a metal film for soldering. Polarized glass and SUS by Au80-Sn20
304 is joined, the obtained joined body is heated, and gradually cooled to room temperature.

The specific joining method is as follows. S
Au80-Sn20 is arranged in advance in US 304, the polarizing glass is fitted in SUS 304, and then the bonded portion is heated at a temperature of 300 ° C. or higher. After heating, the melted Au80-Sn20 is cooled and solidified, and the polarizing glass and SUS 304 are bonded. The obtained joined body was heated in a heating furnace at 260 ° C. for 3 hours and gradually cooled to room temperature over 2 hours.

When the temperature of the bonded body fell to room temperature, the extinction ratio of the polarizing glass was measured and compared with the extinction ratio before heating. The result is shown in FIG. The white plot in the figure is the extinction ratio of the polarizing glass when the holding member 1 is SUS 304. As shown in the figure, the extinction ratio before heating is 34.
The extinction ratio of the polarizing glass, which was 5 dB, was improved to 49.0 dB by holding it at a high temperature and gradually cooling it.

The holding member 1 was Kovar, and Kovar and the polarizing glass were joined with Au80-Sn20, and the obtained joined body was heated at 260 ° C. for 3 hours and then gradually cooled to room temperature over 2 hours. The extinction ratio of the polarizing glass was measured after completion of heating and compared with the extinction ratio before heating. The result is shown in FIG. The black plot in the figure is the extinction ratio of the polarizing glass when the holding member 1 is Kovar. As shown in the figure, the extinction ratio of the polarizing glass which was 38.0 dB before heating was maintained at high temperature and gradually cooled, so that the extinction ratio was 5%.
It improved to 0.0 dB.

[0014]

As described above in detail, according to the optical component joining method of the present invention, the extinction performance of the optical component joined to the holding member is improved as compared with that before joining. The optical isolator in which the obtained bonded body is incorporated has high performance and can effectively prevent the generation of noise in an optical communication system or the like.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of a bonded body obtained by a bonding method of the present invention.

FIG. 2 is a diagram showing a relationship between an extinction ratio of a polarizing glass before heating and an extinction ratio after heating.

[Explanation of symbols]

Reference numeral 1 is a holding member, 2 is an optical component, 3 is solder, and 4 is an opening.

Front page continuation (72) Inventor Toshihiko Nagao 2-13-1, Isobe, Annaka-shi, Gunma Shin-Etsu Chemical Co., Ltd. Precision Materials Research Laboratory

Claims (1)

[Claims] 1. An optical component, which is an optical isolator component, and a holding member thereof are joined together by solder or low melting point glass, and at a temperature 5 ° C. to 100 ° C. lower than the melting point of the solder or low melting point glass for 1 hour to 5 hours. After heating the conjugate over
A method of joining optical isolator parts, characterized in that the joined body is gradually cooled to room temperature.