JPH0667119A - Formation of optical isolator - Google Patents

Abstract

PURPOSE:To suppress the frequent occurrence of strain of an optical device at the time of sticking to a metal as small as possible by arraying to form metallized pattern in a concentric circular state at the outer circumference of the optical device except a light transmitting part in a metallizing treatment for adhesion-fixing metal to the optical device for an optical isolator. CONSTITUTION:Gadolinium.gallium.garnet is used as a magneto-optical device and a polar core is used as a pair of polarizer. Both are worked into a disk-like shape and the metallized patterns 2 are at positions made by dividing the circumference, which is described concentric on the disk of optical device 1 and has a prescribed diameter, into eight equal parts and are circular. The optical isolator is formed by soldering these optical devices 1. In this case, by regulating the total area of the metallized pattern of 5-20% of the area of the optical device 1, sufficient adhesive strength is attained and the characteristic deterioration caused by the strain of the optical device 1 is suppressed.

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 visible light 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 by a transmission line or each connection portion of transmission optical parts. When the semiconductor laser is fed back to the semiconductor laser, the oscillation characteristics of the semiconductor laser may become unstable and noise may increase. An optical isolator is generally used to prevent the return light from returning.

As shown in FIG. 3, the basic structure of an optical isolator is a magneto-optical element 5 having a Faraday effect, a pair of polarizer (1) 3 and polarizer (2) 4, and a magnetic optical element 5. And a magnet 6 for applying
The magneto-optical element 5, the polarizer (1) 3 and the polarizer (2) 4 have their optical axes adjusted. The incident light propagating in the direction of the arrow a is transmitted through the polarizer (1) 3, becomes linearly polarized light, and enters the magneto-optical element 5.
During the propagation of light, the light enters the polarizer (2) 4 with its plane of polarization normally rotated by 45 ° by the magnetic field formed by the magnet 6.
This polarizer (2) 4 has an inclination of 45 ° of the plane of polarization of the incident light in advance.
Is set equal to, so that this incident light is transmitted. On the other hand, the return light propagating in the opposite direction as shown by the arrow b is
By passing through the polarizer (2) 4 and the magneto-optical element 5, a linearly polarized light having a polarization plane inclined by 90 ° with respect to the polarization plane of the polarizer (1) 3 is formed, and the linear polarization is formed on the polarizer (1) 3. This return light in the opposite direction does not pass through the polarizer (1) 3 because it is incident.

When manufacturing such an optical isolator, the structure shown in FIG. 2 is often used. In order to achieve miniaturization, polarizable cores (polarizing glass manufactured by Corning Co., Ltd.) are used for the polarizer (1) 3 and the polarizer (2) 4, and the magnet 6 has a high saturation magnetic flux density Sm.
-Co material or Nd-Fe-B material is used. In the case of assembling an optical isolator using these members, if an organic adhesive is used to bond the parts, the durability is remarkably deteriorated. Therefore, 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. Metal solder is mainly Au / Sn (= 80/2
0) Alloy is used. Here, the end holder 8, the outer holder 9, the inner holder 7, and the magnet 6 can be surface-treated so as to be easily soldered by plating the entire surface with Ni plating or the like, but the magneto-optical element 5 and the polarizer (1 ) 3
Also, the polar core used for the polarizer (2) 4 is non-metallic and cannot be plated. So in general,
A metallized sputtering method using masking is used. In this method, a portion through which light of the optical element 1, which is a general term for the magneto-optical element 5 and the pair of polarizers (1) 3 and polarizers (2) 4, passes, is masked, and the bonding portion is metallized with Ni, Au, etc. by sputtering. To form a part. The optical element 1 and the inner holder 7 or the end holder 8 are solder-bonded to these metallized portions via a ring-type solder as shown in the solder-bonded portion 10 in FIG. Since the melting point of solder is 280 ℃, it is 300
The adhesion is completed by heating to ℃ and then cooling.

[0005]

However, since the thermal expansion coefficient of the optical element is different from that of the internal holder, the optical element is distorted during cooling and the isolator characteristic is deteriorated. An object of the present invention is to suppress the induction of distortion of an optical element at the time of metal adhesion as much as possible.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a metallization pattern 2 with the aid of FIG.
By arranging them at equal intervals on the concentric circles and setting the total area of the pattern to 5 to 25% of the cross-sectional area of the optical element 1, a bonding method that causes less distortion in the optical element during bonding is provided. . A method as claimed in each of the claims. That is, the present invention is characterized in that, in the metallization fixing metallization process for an optical element for an optical isolator, the metallization metallization pattern is formed concentrically on the outer peripheral portion of the optical element excluding the light transmitting portion. The method for producing an optical isolator according to claim 1, wherein the metallized pattern comprises at least four metallized patterns, wherein the total area of the metallized pattern is the light incident surface of the optical element. 2. The method for producing an optical isolator according to claim 1, wherein the area of the metallized pattern is 5 to 25% of the area of the optical isolator according to claim 1, wherein the metallized patterns are arranged at equal intervals. The method for producing an optical isolator according to claim 1, wherein the metallization pattern is circular. That.

[0007]

[Operation] When an optical isolator is manufactured by a metal bonding method using metal solder, a plurality of metallized patterns are concentrically arranged at equal intervals on the outer peripheral portion of the light incident surface of the optical element to bond the optical element and the holder. By applying the pattern so that the total area of the pattern is 5 to 25% of the area of the optical element, sufficient adhesive strength can be obtained and characteristic deterioration due to distortion of the optical element can be suppressed.

[0008]

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

[0009]

Embodiment 1 FIG. 1 shows the overall structure of metallization according to the present invention. Gadolinium gallium garnet was used as the magneto-optical element 5, and a polar core was used as the pair of polarizer (1) 3 and polarizer (2) 4. Both are 1.
It is processed into a 7 mm disk shape, and the metallized pattern is drawn concentrically on the disk of the optical element with a diameter of 1.6.
There are 8 equal divisions on the circumference of 5 mm, and φ0.2
It has a circular shape of mm. An optical isolator by soldering was manufactured using these optical elements.

[0010]

Example 2 An optical isolator was produced in the same manner as in Example 1, except that the diameter of the metallized pattern was φ0.3 mm.

[0011]

Example 3 An optical isolator was manufactured in the same manner as in Example 1 except that the diameter of the metallized pattern was changed to φ0.1 mm.

[0012]

[Example 4] An optical isolator was produced in the same manner as in Example 1 except that the metallized patterns were arranged at four equally divided positions on the circumference having a diameter of 1.65 mm.

[0013]

[Embodiment 5] An optical isolator was produced in the same manner as in Embodiment 1, except that the metallized patterns were arranged at 16 equally divided positions.

[0014]

Comparative Example 1 An optical isolator was manufactured in the same manner as in Example 1 except that the diameter of the metallized pattern was φ0.05 mm.

[0015]

Comparative Example 2 An optical isolator was manufactured in the same manner as in Example 1 except that the diameter of the metallized pattern was 0.4 mm.

[0016]

COMPARATIVE EXAMPLE 3 An optical isolator was manufactured in the same manner as in Example 1 except that the metallized pattern was arranged in two equally divided positions.

Regarding the above-mentioned examples and comparative examples, the number of metallization patterns arranged in equally divided positions, the presence or absence of crystal distortion, the ratio (%) of the total area of the metallization patterns to the optical element cross-sectional area, and The adhesive strength is shown in Table 1.

[0018]

[Table 1]

Generally, when a force is applied to an optical crystal adhered to a metal, the adhesive strength is not problematic as long as the adhesive surface is not peeled off and the crystal is destroyed, and the adhesive strength is 1
It is set to Kg / mm ² . For the distortion of the crystal, the contrast in the extinction state under the crossed Nicols condition was measured. Table 1
As a result, when the number of metallized patterns is 4 or more and the total area thereof is 5 to 25% of the optical element cross section, the metal bonded isolator can be manufactured by the metal bonding method with little crystal distortion and sufficient bonding strength. It shows that it is possible.

[0020]

According to the method of the present invention, it is possible to manufacture an optical isolator having less strain in the crystal and high reliability in strength.

[Brief description of drawings]

FIG. 1 is a plan view showing an overall configuration in which a light incident surface of an optical element is metallized.

FIG. 2 is an explanatory diagram showing a structure of an optical isolator.

FIG. 3 is an explanatory diagram showing a basic configuration of an optical isolator.

[Explanation of symbols]

 1 Optical Element 2 Metallized Pattern 3 Polarizer (1) 4 Polarizer (2) 5 Magneto-Optical Element 6 Magnet 7 Inner Holder 8 End Holder 9 External Holder 10 Solder Bonding Area a Direction of Incident Light b Direction of Return Light

Claims (5)

[Claims] 1. In the metallizing process for fixing metal adhesion to an optical element for an optical isolator, a metallizing pattern for metal adhesion is formed by concentrically arranging the metallizing pattern on the outer peripheral portion of the optical element except a light transmitting portion. Method for manufacturing optical isolator. 2. The metallized pattern is at least 4
The method for producing an optical isolator according to claim 1, wherein the optical isolator comprises a single piece. 3. The method for producing an optical isolator according to claim 1, wherein the total area of the metallized pattern is 5 to 25% of the area of the light incident surface of the optical element. 4. The method for manufacturing an optical isolator according to claim 1, wherein the metallized patterns are arranged at equal intervals. 5. The method for manufacturing an optical isolator according to claim 1, wherein the metallized pattern has a circular shape.