JPH1073786A - Parts for optical isolator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to save the amt. of a solder to be packed and to obtain sufficient joining strength with exact position accuracy in spite of the small amt. of the solder to be packed by inserting bridge members into the bow-shaped spaces generated in the clearance between the inner periphery of a cylindrical holder and an optical element and fixing the members with hot meltable binders. SOLUTION: Parts 10 for an optical isolator are formed by fitting a square polarizer 1 into the cylindrical holder 2 with a bottom 2b having a Faraday rotator 3, inserting the bridge members 8 into the bow-shaped spaces generated in the clearance between the inner peripheral 2a of the cylindrical holder 2 and the polarizer 1 and fixing the members with the solder 7. Namely, the polarizer 1 and the cylindrical holder 2 are fixed by the solder 7 via the bridge members 8. If the parts 10 for the optical isolator are coated with metallic films on the inner periphery 2a of the cylindrical holder 2 and the outer periphery of the polarizer 1 facing the inner periphery 2a, the fixing is more adequately executable. Further, the adequate fixing is executed if the bridge members 8 are spherical and at least the surfaces thereof are metallic.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical isolator which is disposed between a semiconductor laser, which is a light source for optical communication, and an optical transmission component and prevents laser light reflected by the optical transmission component from returning to the semiconductor laser. It relates to the components to be configured.

[0002]

2. Description of the Related Art When transmission light oscillated from a semiconductor laser enters an optical transmission component in a transmission line, it is reflected on the surface thereof, and the reflected light may return to the semiconductor laser. The reflected light disturbs the light emitting action of the semiconductor laser and causes noise. The optical isolator is provided in the transmission path to prevent such noise, and allows only light traveling in the transmission direction to pass therethrough and does not return reflected light traveling in the opposite direction to the semiconductor laser.

[0003] As in the current situation, when optical communication is gradually expanded from trunk line communication to branch line communication, the facility environment of optical transmission components used therein becomes poor, and the weather resistance of the optical transmission components is improved. It is an important issue. Improvements in weather resistance are also required for optical isolators, which are optical transmission components for optical communication.

An example of an optical isolator is shown in FIG. In the optical isolator of this example, a first polarizer ₁₁ , a Faraday rotator 3, and a second polarizer ₁₂ are sequentially arranged. First polarizer 1 ₁ is fixedly inserted into a cylindrical holder 2 ₁ constitutes a part 10 _1, a polarizer 1 ₂ of the second constitutes the part 10 ₂ is inserted and fixed to the cylindrical holder 2 _2, the Faraday rotation The child 3 is inserted and fixed in the cylindrical magnet 5 to form a component 9. Each of the optical isolator components 10 ₁ , 10 ₂ , and 9 is inserted into the outer cylinder 4 and fixed.

Conventionally, an organic adhesive (resin) has been mainly used as a bonding material for fixing each optical element of an optical isolator component. However, there is a problem that the resin is easily deteriorated at a high temperature and the optical surface is contaminated by gas generated from the resin. For these reasons,
Isolators that do not contain resin components are becoming mainstream. As a joining material instead of a resin, a solder that does not deteriorate at high temperatures or generate gas is used.

Normally, as shown in FIG. 3, the optical isolator component 10 has a rectangular polarizer 1 as an optical element and a cylindrical holder 2 as shown in FIG. Solder is filled in an arcuate space formed by fitting into the cylindrical holder 2, and the solder is heated and fused. In order to improve the wettability with solder, the outer peripheral side wall 1a of the polarizer 1 and the inner peripheral side wall 1a of the cylindrical holder 2 are coated with a metal thin film.

[0007]

In the case of soldering as described above, it is necessary to fill a sufficient amount of solder into the arcuate space.
Solder of a suitable shape is inserted in the bow-shaped space, and this is heated and melted. However, it is not easy to prepare a solder having a shape adapted to the bow-shaped space, that is, a solder having a bow-string or a shape close to the bow-string, and sacrifices mass productivity.

If the amount of the solder is insufficient, as shown in FIG. 4, the solder 7 does not spread over the entire arcuate space 6 and the portion where the polarizer 1 and the cylindrical holder 2 are close to each other (the rectangular polarizer 1).
(Only the corners of the joint), and the joining strength is weak. If the bottom surface 2b of the cylindrical holder 2 (see FIG. 3), that is, the mounting surface of the polarizer 1, is coated with a metal thin film for improving the wettability to solder, the bonding strength is improved. Get better. However, as shown in FIG. 5, since the amount of the solder 7 penetrating between the polarizer 1 and the bottom surface 2a of the cylindrical holder 2 is not constant, there is a problem in that the positional accuracy of the polarizer 1 may vary.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is possible to save the amount of solder filling, to obtain accurate positional accuracy and sufficient bonding strength even with a small amount of solder filling, and to achieve mass production. It is an object of the present invention to provide a component for an optical isolator having excellent characteristics.

[0010]

A component for an optical isolator according to the present invention, which has been made to achieve the above object, will be described with reference to FIG. 1 corresponding to an embodiment.

As shown in FIG. 1, an optical isolator component 10 to which the present invention is applied has a bottom 2b having a light transmitting opening 3.
A rectangular optical element 1 is fitted into a cylindrical holder 2 provided with a bridge member. A bridge member 8 is inserted into an arcuate space 6 formed in a gap between the inner periphery 2a of the cylindrical holder 2 and the optical element 1, and a heat-fusible adhesive 7 is used. It is fixed.

The component for an optical isolator of the present invention can be properly implemented when the inner periphery 2a of the cylindrical holder 1 and the outer periphery 1a of the optical element 1 facing the inner periphery 2a are covered with a metal film. Further, when the bridge member 8 is spherical,
Can be properly implemented. In addition, when the heat-meltable fixing agent 7 is an alloy solder, the bridge member is spherical, and at least the surface is made of metal, it can be properly implemented. More preferably, the alloy solder is an Au-based alloy solder. The heat-meltable fixing agent may be a low-melting glass.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which a component for an optical isolator of the present invention is a component in which a polarizer is fixed to a holder will be described in detail below.

As shown in FIG. 3, a rectangular polarizer 1 and a cylindrical holder 2 are prepared. The polarizer 1 is made of a polarizing glass or a birefringent crystal, and the outer peripheral side wall 1a is coated with a metal thin film for improving wettability with solder on all four surfaces. The material of the metal thin film coating is Cr, Ni, Ag, Au, Pt,
Co, Pd or the like, which is formed as a single layer or a stacked layer by vapor deposition, sputtering, electrolytic or non-electrolytic plating, for example. The cylindrical holder 2 is a cylindrical shape having a bottom 2b with a light transmission opening 3 formed therein, the inner diameter of the cylinder is slightly larger than the square diagonal diameter of the polarizer 1, and the inner peripheral side wall 1a of the cylinder is coated with a thin metal film. Have been. This polarizer 1 is attached to a cylindrical holder 2
When it is inserted into the inside, an arcuate space 6 surrounded by the inner peripheral side wall 1a of the cylindrical holder 2 and the outer peripheral side wall 1a of the polarizer 1 is formed.

The bridge member 8 is inserted into the arcuate space 6. The shape of the bridge member 8 is spherical in the illustrated example,
The material is selected so that the solder has good wettability and does not deform at the melting temperature of the solder. For example, a metal ball, a glass ball, or a ceramic ball plated with metal can be used. If the bridge member 8 is put into the arcuate space 6, and further solder is inserted and heated and melted and then cooled, the polarizer 1 and the cylindrical holder 2 are connected with the solder 7 through the bridge member 8 as shown in FIG. Fixed, optical isolator component 1
0 is completed. As solder, Au-based (for example, Au-Sn, Au-
Si, Au-Si) are preferable because of their excellent corrosion resistance and bonding ability.

When a low-melting glass is used as the heat-meltable fixing agent, it is not necessary to apply a thin film coating to the polarizer 1, the cylindrical holder 2, and the bridge member.

As shown in FIG. 2, two of the optical isolator components 10 ₁ and 10 ₂ completed above are turned upside down,
In the meantime, the optical isolator is completed by inserting the optical isolator component 9 in which the Faraday rotator 3 is inserted and fixed in the cylindrical magnet 5 into the outer cylinder 4.

An example in which the optical isolator component of the present invention is manufactured will be described below.

The polarizers 1 made of polarizing glass with gold plating on the outer peripheral side wall 1a are respectively fitted into 100 cylindrical Kovar cylindrical holders 2, and the gold-plated stainless steel (SUS-304) balls (bridges) are formed in the arcuate spaces 6. Member 8)
Were inserted per arcuate space (see FIG. 1), and further, a ball-shaped Au-Sn solder was inserted. For comparison, 100 pieces in which only the ball-shaped solder was inserted into the bow-shaped space were produced. These were heated in a vacuum at 320 ° C. for 10 minutes to perform a bonding process. After cooling, 100 optical isolator parts were completed.

An impact test was performed on all 200 optical isolator components under a load of 2000 G, and the number of the detached polarizing glasses was examined. In the optical isolator component of the present invention into which a stainless steel ball (bridge member) was inserted, none of the components had the polarizing glass removed. On the other hand, in the optical isolator component for comparison without using the bridge member, the polarizing glass was detached in 6 out of 100 components. This indicates that the use of the bridge member greatly improved the joining reliability between the optical element and the holder.

Also, it was confirmed that by forming the bridge member in a ball shape, there was no trouble that the bridge member was caught in the arcuate space, and the loading operation of the bridge member could be mechanized.

[0022]

As described above in detail, in the optical isolator component to which the present invention is applied, by providing a bridge member in the gap between the optical element and the holder, the amount of solder filling can be saved, and the amount of solder filling can be reduced. Even if the number is small, the positional accuracy is accurate, sufficient bonding strength can be obtained, and mass productivity is excellent.

[Brief description of the drawings]

FIG. 1 is a plan view and a sectional view of an embodiment of an optical isolator component to which the present invention is applied.

FIG. 2 is a cross-sectional view of an embodiment of the optical isolator.

FIG. 3 is a perspective view of an embodiment of an optical isolator component.

FIG. 4 is a plan view of a conventional optical isolator component.

FIG. 5 is a sectional view of a conventional optical isolator component.

[Explanation of symbols]

1 1 ₁ 1 ₂ is a polarizer, 2 is a cylindrical holder, 3 is a Faraday rotator, 4 is an outer cylinder, 5 is a cylindrical magnet, 6 is an arcuate space, 7 is a solder, 8 is a bridge member, 9 10 ₁・
10 ₂ is an optical isolator component.

Claims (6)

[Claims] 1. A component for an optical isolator in which a rectangular optical element is fitted in a cylindrical holder with a bottom having a light transmission opening, wherein a bridge member is formed in an arc-shaped space generated in a gap between the inner periphery of the cylindrical holder and the optical element. A component for an optical isolator, wherein a component is inserted and fixed with a heat-meltable fixing agent. 2. The optical isolator component according to claim 1, wherein a metal film is coated on an inner circumference of said cylindrical holder and an outer circumference of said optical element facing said inner circumference. 3. The component for an optical isolator according to claim 1, wherein said bridge member is spherical. 4. The component for an optical isolator according to claim 1, wherein the heat-meltable fixing agent is an alloy solder, the bridge member is spherical, and at least the surface is a metal. 5. The component for an optical isolator according to claim 4, wherein said alloy solder is an Au-based alloy solder. 6. The component for an optical isolator according to claim 1, wherein the heat-meltable fixing agent is a low-melting glass.