JPH05150188A - Optical isolator and its manufacture - Google Patents

Abstract

PURPOSE:To improve the moisture resistance of the optical isolator consisting of a polarizer, a 45 deg. Faraday rotator, an analyzer, and a magnet. CONSTITUTION:An optical isolator element where the polarizer 1, 45 deg. Faraday rotator 2, and analyzer 3 are fixed with a brazing material 5 at their outer peripheral parts across a support member 4 is cut in a state wherein a large polarizer, a 45 deg. Faraday rotator, and an analyzer are previously combined together, and fixed to the magnet 4 with brazing material 6 having a lower fusion point than the brazing material 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical isolator utilizing the magneto-optical effect used for optical communication, optical information processing and the like, and a method for manufacturing the same.

[0002]

2. Description of the Related Art The structure of a conventional optical isolator is shown in FIG.
Shown in (a) and (b). The optical isolator shown in FIGS. 3A and 3B includes a polarizer 15 and a Faraday rotator 1 of 45 degrees.
6, composed of an analyzer 17 and a magnet 18,
The Faraday rotator 16 includes a polarizer 15 and an analyzer 17.
Are adhered by an optical adhesive 19.

The light incident on the optical isolator is reflected by the polarizer 1.
A polarization component that matches the polarization plane of the polarizer 15 is selected by 5 and enters the 45-degree Faraday rotator 16.

Due to the Faraday effect, the 45-degree Faraday rotator 16 has the polarization plane of the incident light of 45 while the light passes through.
Since the length (or thickness) is determined so as to rotate by the degree, the polarization plane of the light after passing through the 45-degree Faraday rotator 16 is rotated by 45 degrees with respect to the incident light.

Therefore, if the polarization plane of the analyzer 17 is rotated by 45 degrees with respect to the polarization plane of the polarizer 15, the analyzer 1
At 7, light is emitted without any loss.

On the other hand, the returned light is 45 with respect to the polarizer 15.
After the light of the polarization plane rotated by a degree is selected by the analyzer 17, it is incident on the Faraday rotator 16 of 45 degrees, and the non-reciprocity of the Faraday effect (the rotation direction of the incident polarization plane is a property peculiar to the material of the Faraday rotator). And the direction of the light and the magnetic field are determined to be parallel or anti-parallel).

Therefore, only the polarization component rotated by 90 degrees with respect to the polarization plane of the polarizer 15 is incident on the polarizer 15, the component passing through the polarizer 15 is lost, and all the returning light is blocked. It will be.

The material of the Faraday rotator 16 is Y
IG (yttrium, iron, garnet) and (RBi)
IG (bismuth-substituted rare earth / iron / garnet) is often used in optical communication.

[0009]

However, in the conventional optical isolator shown in FIG. 3, when the polarizer and the analyzer and the 45 degree Faraday rotator are fixed, the optical surfaces are bonded and fixed with an optical adhesive. Therefore, there is a problem that the moisture resistance is poor and the use thereof is restricted especially under high temperature and high humidity conditions.

An object of the present invention is to provide an optical isolator having improved moisture resistance and a method for manufacturing the same.

[0011]

In order to achieve the above object, in an optical isolator according to the present invention, a polarizer, a 45 degree Faraday rotator, an analyzer and a magnet that gives a magnetic field to the 45 degree Faraday rotator are provided. An optical isolator having a structure in which a polarizer, a 45-degree Faraday rotator, and an analyzer are melted and fixed by brazing material at their outer peripheral portions.

In the method of manufacturing an optical isolator according to the present invention, a method of manufacturing an optical isolator having a polarizer, a 45 ° Faraday rotator, an analyzer and a magnet for giving a magnetic field to the 45 ° Faraday rotator. In addition, a grid-like metal film pattern is formed on the surface of the polarizer and the analyzer on the side of the 45-degree Faraday rotator and on both surfaces of the 45-degree Faraday rotator. A polarizer, a 45 ° Faraday rotator, and a 45 ° Faraday rotator are formed by a brazing material tablet formed in a lattice shape or a brazing material formed on the lattice-shaped metal film pattern.
After the Faraday rotator and the analyzer are fixed, a polarizer, a brazing material, a 45-degree Faraday rotator, a brazing material, along the grid-like metal film pattern, with a cutting margin sufficiently narrower than the grid line width, An optical isolator element composed of a polarizer, a 45 ° Faraday rotator, and an analyzer whose outer periphery formed by cutting the analyzer in order is fixed by a brazing material is attached to a magnet.

[0013]

As shown in FIG. 1, the polarizer, the 45-degree Faraday rotator and the analyzer have optical isolator elements fixed to each other at their outer peripheral portions by a brazing material.
The Faraday rotator and the analyzer are combined and cut out and fixed to the magnet by a brazing material having a melting point lower than that of the brazing material.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described below with reference to the drawings. FIG. 1A is a front view showing an embodiment of the optical isolator of the present invention, and FIG. 1B is a side sectional view.

1 (a) and 1 (b), a polarizer 1, a 45 ° Faraday rotator 2 and an analyzer 3 are fixed to each other by a brazing material 5 on the outer periphery thereof, and a brazing material 6 having a lower melting point than solder. It is fixed to the center of the magnet 4 by. Here, a metal film is formed on all the portions that are fixed to the brazing material 6 so that the brazing material 6 is easily fixed.

The plane of polarization of the analyzer 3 is rotated by 45 degrees with respect to the plane of polarization of the polarizer 1.

As the 45 ° Faraday rotator 2, a bismuth-substituted gadolinium / iron / garnet (GbBi) ₃ Fe ₅ O ₁₂ thick film grown by a liquid phase epitaxial method or a bismuth-substituted gadolinium / iron / aluminum /
Gallium garnet (GbBi) ₃ (FeAlGa) ₅
An O ₁₂ thick film or the like is used.

In general, bismuth-substituted rare earth / iron / garnet (RBi) IG has a large Faraday rotation coefficient and a small saturation magnetization, so that a small optical isolator can be realized. In the embodiment shown in FIG. 1, the diameter is 4 mm and the length is 2.5 m.
m optical isolator has been realized.

Gold / tin (Au / Sn) is used as the brazing material 5.
Since antimony-tin (Sb.Sn) solder having a melting point lower than that of gold-tin solder is used as the solder and brazing material 6, the brazing material 5 does not melt again when it is fixed to the magnet 4.

Further, an antireflection film for air is applied to all optical surfaces (light input / output surfaces) of the polarizer 1, the 45 ° Faraday rotator 2 and the analyzer 3.

Next, a method of manufacturing the optical isolator shown in FIG. 1 will be described with reference to FIGS.

As shown in FIG. 2 (a), a rectangular polarizer 7, a 45 ° Faraday rotator 9 and an analyzer 10 are provided, respectively.
Between the polarizer 7 and the 45 ° Faraday rotator 9 and between the 45 ° Faraday rotator 9 and the analyzer 10, a brazing filler metal tablet (for example, gold / tin tablet) 8 formed in a lattice shape is inserted and combined.

Since the analyzer 10 is formed in a rectangular shape in advance so that its polarization plane is rotated by 45 degrees with respect to the polarization plane of the polarizer 7, it is arranged between the polarizer 7 and the 45 degree Faraday. The analyzer 10 is arranged in the rotation direction of the polarization plane of the rotator 9.
Of the polarizers 7, 45 so that the rotation directions of the polarization planes of
It is necessary to overlap the Faraday rotator 9 and the analyzer 10. The optical surfaces of the polarizer 7, the 45 ° Faraday rotator 9, and the analyzer 10 are all provided with an antireflection film for air.

Further, the grid-shaped brazing material tablets 8 are fixed to the surfaces of the polarizer 7 and the analyzer 10 on the 45 ° Faraday rotator 9 side and both surfaces of the 45 ° Faraday rotator 9 when they are melted and fixed. A grid-like metal film pattern 9 ′ is formed so as to be in contact with the grid of the brazing material tablet 8 for ease of explanation.

In this way, after the polarizer 7, the lattice brazing material tablet 8, the 45 ° Faraday rotator 9, the lattice brazing material tablet 8 and the analyzer 10 are stacked in this order, about 300
The brazing filler metal tablet 8 is melted at a temperature of 10 ° C. to fix the polarizer 7, the 45 ° Faraday rotator 9, and the analyzer 10 (FIG. 2B).

After that, a blade having a width sufficiently narrower than the grid line width of the grid-shaped metal film pattern 9'formed on the polarizer 7, the 45-degree Faraday rotator 9, and the analyzer 10 is applied to the center of the grid line. Cut along the cutting line 11. Then,
Divided small-sized polarizers 7 and 4 as shown in FIG.
An optical isolator element is completed in which the 5 degree Faraday rotator 9 and the analyzer 10 are fixed to each other by the brazing material 8'on their outer peripheral portions.

The size of this optical isolator element is 2 mm on a side and about 2.5 mm in length. By fixing this optical isolator element on the central axis of the magnet 12 with a brazing material having a melting point lower than that of the brazing material 8 '(for example, antimony tin solder), a compact optical isolator as shown in FIG. 1 can be realized. (FIG.2 (d)).

[0028]

As described above, in the present invention, the polarizer, the 45 ° Faraday rotator, and the analyzer that constitute the optical isolator are melted and fixed by the brazing material at the outer peripheral portions of each, so that the moisture resistance is excellent. The effect is that stable characteristics can be obtained even under high temperature and high humidity conditions.

Further, there is an effect that such an excellent optical isolator can be mass-produced at once by a simple manufacturing method.

[Brief description of drawings]

FIG. 1 (a) is a front view showing an embodiment of the present invention,
(B) is a side sectional view.

2A to 2D are process diagrams showing a method for manufacturing an optical isolator according to the present invention.

3A is a front view showing a conventional optical isolator, and FIG. 3B is a side sectional view.

[Explanation of symbols]

 1 Polarizer 2 45 degree Faraday rotator 3 Analyzer 4 Magnet 5 Brazing material (including metal pattern) 6 Brazing material 7 Polarizer 8 Lattice brazing material tablet 8'Brazing material 9 45 degree Faraday rotator 9'Metal film pattern 10 Analyzer 11 Cutting Line 12 Magnet 15 Polarizer 16 45 Degree Faraday Rotor 17 Analyzer 18 Magnet 19 Optical Adhesive 20 Adhesive

Claims (2)

[Claims] 1. A polarizer and a 45 degree Faraday rotator,
An optical isolator having an analyzer and a magnet that gives a magnetic field to a 45-degree Faraday rotator, characterized in that a polarizer, a 45-degree Faraday rotator and an analyzer are melted and fixed by a brazing material at respective outer peripheral portions. Optical isolator. 2. A polarizer and a 45 degree Faraday rotator,
A method for manufacturing an optical isolator having an analyzer and a magnet for applying a magnetic field to a 45-degree Faraday rotator, comprising: a grating on the 45-degree Faraday rotator-side surface of the polarizer and the analyzer; A metal film pattern in the shape of a grid and a brazing filler metal tablet formed in advance in a grid pattern so as to match the grid metal film pattern or a brazing material formed on the grid metal film pattern, After the Faraday rotator and the 45-degree Faraday rotator and the analyzer are fixed, a polarizer, a brazing material, and a 45-degree along the grid-like metal film pattern with a cutting margin sufficiently narrower than the grid line width. Faraday rotator, brazing material, and analyzer are cut together in this order, and the outer circumference formed by it is fixed with brazing material, 45 degree Faraday rotator, and analyzer. The method of manufacturing an optical isolator to the optical isolator element, characterized in that attached to the magnet that.