JPH06230314A - Production of optical isolator - Google Patents

Abstract

PURPOSE:To provide a solder joining method which does not induce flaws on the surface of an optical element in the process for production of the metal joined isolator. CONSTITUTION:Metal joining is possible without requiring insertion of solder between the optical element 16 and a holder at the time of metal joining of the optical element 16 and the holder by forming an AuSn film 14 on the surface of the optical element by so-called physical vapor deposition methods, such as vapor deposition method, sputtering method and ion plating method, of an AnSn alloy.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing an optical isolator utilizing the Faraday effect.

[0002]

2. Description of the Related Art When a semiconductor laser is used as a light source for an optical signal transmission system for optical measurement or the like, a part of light emitted from the semiconductor laser is reflected at each connection portion of a transmission line or a transmission optical component and the semiconductor laser is reflected. When returned to, it may cause instability of oscillation characteristics of the semiconductor laser and increase noise.
An optical isolator is generally used to prevent the return light from returning. As shown in FIG. 3, the basic structure of the optical isolator includes a magneto-optical element (Faraday rotator) 3 having a Faraday effect, a polarizer 1, an analyzer 2, and a permanent magnet 4 for applying a magnetic field to the magneto-optical element. The magneto-optical element 3, the polarizer 1, and the analyzer 2 are each adjusted in optical axis. Then, the incident light propagating in the direction of the arrow a becomes linearly polarized light after passing through the polarizer 1 and is incident on the magneto-optical element 3. It is incident on the analyzer 2 in a state of being rotated by 45 °, and since the inclination of the analyzer 2 is set in advance to be equal to the inclination of 45 ° of the polarization plane of the incident light, this incident light is transmitted. On the other hand, the incident light propagating in the opposite direction as shown by the arrow b passes through the analyzer 2 and the magneto-optical element 3 to become linearly polarized light having a polarization plane inclined by 90 ° with respect to the polarization plane of the polarizer 1. In order to enter the polarizer 1,
This incident light in the opposite direction does not pass through the polarizer 1.

When manufacturing such an optical isolator, the structure shown in FIG. 2 is often used. In order to achieve miniaturization, a polar core (polarizing glass manufactured by Corning Co., Ltd.) that can be thinned is used for the polarizer 6 and the analyzer 7, and the permanent magnet 11 is an Sm-Co material which is a high Bs material, or N.
The d-Fe-B material is used. Further, when these are assembled, if the organic bonding method is used for bonding the parts, the durability is remarkably inferior, and thus the metal bonding method using metal solder is used. The metal bonding method is a method of bonding the respective parts through a metal solder. The metal solder is mainly made of Au / Sn alloy. Here, the end holder 8, the outer holder 10, the inner holder 12 and the permanent magnet 11 are plated on the entire surface by Ni plating or the like, so that surface treatment that is easy to get solder is performed. Although it is possible, the magneto-optical element 3 and the polarizing glass used for the polarizer and the analyzer are non-metallic and therefore cannot be plated. Therefore, the metallized sputtering method by masking is generally used.
In this method, a portion through which light of an optical element consisting of a magneto-optical element, a polarizer and an analyzer passes is masked, and an adhesive pattern is formed on the adhesive portion by sputtering such as Ni or Au. The inner holder is bonded onto these patterns via ring type solder. The melting point of solder is 2
Since the temperature is 80 ° C., the adhesion is completed by heating to 300 ° C. and then cooling. However, in the above manufacturing method,
It is difficult to accurately arrange the solder between the optical element and the holder, and a tool such as tweezers used when arranging the solder causes scratches and the like on the surface of the optical element to deteriorate the optical characteristics. Therefore, there are problems that the yield is lowered and the productivity is poor.

[0004]

Therefore, the present invention provides a solder bonding method that does not induce scratches or the like on the surface of an optical element, and improves the productivity of an optical isolator and ensures high optical characteristics. Can contribute to.

[0005]

[Means for Solving the Problems] In bonding an optical element for a metal junction isolator and a holder, an AuSn thin film is formed on the surface of the optical element by a so-called physical vapor deposition method such as a vapor deposition method, a sputtering method or an ion plating method. By forming a film, the above problems are solved.

[0006]

In the production of the metal-bonded isolator, the fixing of the optical element is generally completed by melting the ring-shaped solder between the optical element and the material to be bonded. However, when installing the solder between the optical element and the materials to be joined,
A tool such as tweezers and an auxiliary jig cause scratches and the like on the surface of the optical element, which causes deterioration of optical characteristics.
By using the optical element on which the AuSn solder of the present invention is formed, it is not necessary to interpose the solder between the optical element and the holder material, so that a high performance optical isolator can be obtained without deteriorating the optical characteristics of the optical element. Can be produced. Further, there is an advantage that the soldering process can be shortened.

[0007]

EXAMPLES The present invention will be described in detail with reference to examples.

(Embodiment) FIG. 2 is a block diagram of an isolator according to the present invention. Garnet was used for the magneto-optical element, and Polar core (polarizing glass manufactured by Corning Incorporated) was used for the polarizer and the analyzer. Garnet and polar core φ2m
It has been processed to m. The ring-shaped metallized pattern as shown in FIG. 1 was applied to the optical element including the magneto-optical element, the polarizer and the analyzer by masking. A sputtering apparatus is used as the film forming apparatus, and the film forming conditions are as follows: sputter power 200 W, sputtering pressure 0.5 Pa, target material Au.
Sn (= 80/20%), target-substrate distance 10
The film forming rate was 0 mm and the film forming rate was 600 angstrom / min. The film thickness was 5 μm. Furthermore, as other parts constituting the optical isolator, the end holder 8 has a Kovar,
SUS304 was used for the outer holder 10, SUS430 was used for the inner holder 12, and an SmCo magnet was used as the magnet. Each of these parts was plated with Ni. After the above components were aligned, they were heated to 320 degrees in an electric furnace to complete the joining, and an optical isolator was produced.

(Comparative Example) Cr, Ni, and Au were 0.35 μm and 0.3, respectively, on the surface of the optical element by sputtering.
An optical isolator was prepared in the same manner as in the example except that an optical element having a film thickness of 5 μm and a film thickness of 0.15 μm were used and a 0.4 mm wide ring type preform solder (AuSn = 80/20%) was used for soldering. It was made.

In order to confirm the reliability of the metal junction isolators produced in the examples and comparative examples, a heat cycle test was conducted with a profile as shown in FIG. The test determination method was set such that the reverse insertion loss deteriorated by 20% from the initial value. Table 1 shows the results of the heat cycle test.

[0011]

From the results of the heat cycle test,
Even when the comparative examples were compared, it was found that they had the same reliability. Therefore, when the present invention is used, a highly reliable metal junction isolator can be manufactured.

In each of the examples and comparative examples, 50 metal junction isolators were produced and the yield was calculated. The criterion is that the optical characteristics at the time of fabrication are 0.
The insertion loss was 5 dB or less and the insertion loss in the reverse direction was 38 dB or more. Table 2
The yield of the metal junction isolators produced in the examples and comparative examples is shown in FIG.

[0014]

From the results shown in Table 2, according to the manufacturing method of the present invention, it is possible to manufacture an optical isolator having high optical characteristics with a high yield as compared with the conventional manufacturing method (comparative example).

According to the present invention, a metal junction isolator having high performance and high reliability can be manufactured with high yield.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an optical element used in the present invention.
(A) is a plan view showing a metallized pattern on the surface of the optical element, and (b) is a sectional view showing the film-forming structure of (a).

FIG. 2 is a sectional view showing the structure of an optical isolator according to the present invention.

FIG. 3 is a schematic perspective view showing the configuration of a general optical isolator.

FIG. 4 is a diagram showing a profile of a heat cycle test.

[Explanation of symbols]

 1, 6 Polarizer 2, 7 Analyzer 3 Magneto-optical element (Faraday rotator) 4 Permanent magnet 5 Magneto-optical element (garnet film) 8 End holder 10 External holder 11 Permanent magnet 12 Inner holder 13 Solder adhesive part 14 Metallized film (AuSn film) 15 Transmission surface 16 Optical element a Arrow indicating propagation direction of incident light b Arrow indicating propagation direction of return light

Claims (1)

[Claims] 1. When bonding an optical element forming a metal-bonded isolator and a holder, Au is attached to the surface of the optical element.
A method for manufacturing an optical isolator, characterized in that a Sn alloy film is formed by a physical vapor deposition method.