JP2970159B2 - Optical isolator and method of manufacturing the same - Google Patents

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 a magneto-optical effect used for optical communication and optical information processing, and a method of manufacturing the same.

[0002]

2. Description of the Related Art The structure of a conventional optical isolator is shown in FIG. The optical isolator shown in FIG. 3 includes a polarizer 15, a 45-degree Faraday rotator 16, an analyzer 17, and a magnet 18. The 45-degree Faraday rotator includes the polarizer 15 and the analyzer 17 for optical use. It is adhered by an adhesive 19.

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

The 45-degree Faraday rotator 16 has a polarization plane of incident light of 45 degrees during the passage of light due to the Faraday effect.
Since the length (or thickness) is determined so as to rotate by degrees, 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 return light is directed to the polarizer 15 by 45
After the light of the polarization plane rotated by degrees is selected by the analyzer 17, it is incident on the 45-degree Faraday rotator 16, and the non-reciprocity of the Faraday effect (the rotation direction of the incident polarization plane depends on the material characteristic of the Faraday rotator). And the direction in which light travels and the magnetic field are determined by parallel or anti-parallel.).

Accordingly, only the polarized light component rotated by 90 degrees with respect to the polarization plane of the polarizer 15 is incident on the polarizer 15, no component passes through the polarizer 15, and all returned light is blocked. Will be.

The material of the Faraday rotator is YIG
(Yttrium / Iron / Garnet), (RBi) IG
(Bismuth-substituted rare earth / iron / garnet) is widely used in optical communication.

[0009]

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

An object of the present invention is to provide an optical isolator which is excellent in moisture resistance and has stable characteristics even under high temperature and high humidity conditions, and a method for manufacturing the same.

[0011]

To achieve the above object, an optical isolator according to the present invention comprises a polarizer, a 45 degree Faraday rotator, an analyzer, and a magnet for applying a magnetic field to the 45 degree Faraday rotator. Wherein the polarizer, the 45-degree Faraday rotator, and the analyzer are melted with low-melting glass via a support member having a thermal expansion coefficient substantially equal to these components at respective outer peripheral portions. It is stuck.

Further, a method of manufacturing an optical isolator according to the present invention is directed to an optical isolator comprising a polarizer, a 45-degree Faraday rotator, an analyzer, and a magnet for applying a magnetic field to the 45-degree Faraday rotator. Degree Faraday rotator and its 45 degree Faraday rotator and the analyzer are inserted between two preliminarily fired grid-like low melting point glass tablets with a grid-like supporting member. By melting the glass tablet, the polarizer and the 45-degree Faraday rotator, and the 45-degree Faraday rotator and the analyzer are fixed via the support member, and then cut along the grid line at a desired cutting margin. , Polarizer, low melting glass, support member, low melting glass, 45 degree Faraday rotator, low melting glass, support member, low melting glass, analyzer Collectively cutting, polarizers it outer peripheral portion formed by is fixed with low-melting glass, the support member,
An optical isolator element including a 45-degree Faraday rotator, a support member, and an analyzer is mounted on a magnet.

Further, the desired cutting margin is set to be sufficiently narrower than the grid line width.

[0014]

The polarizer, the 45-degree Faraday rotator, and the analyzer are melted and fixed with low-melting glass at the outer peripheral portion thereof via a support member having a thermal expansion coefficient substantially equal to those of these components.

[0015]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. FIG. 1A is a front view showing an embodiment of the optical isolator according to the present invention, and FIG. 1B is a side sectional view of the same.

1 (a) and 1 (b), a polarizer 1, a 45-degree Faraday rotator 2 and an analyzer 3 have a low-melting glass 6 at the outer periphery of each other with a supporting member 4 interposed therebetween.
And the low melting point glass 7 and the magnet 5
Is fixed at the center of

The plane of polarization of the analyzer 3 is arranged to be rotated by 45 degrees with respect to the plane of polarization of the polarizer 1. The 45-degree Faraday rotator 2, a bismuth-substituted gadolinium-iron-garnet grown by such liquid-phase epitaxial method (GbBi) ₃ Fe ₅ O ₁₂ thick and bismuth-substituted gadolinium-iron-aluminum-gallium garnet (Gb
Bi) ₃ (FeAlGa) ₅ O ₁₂ thick film or the like is used.

Generally, 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, an optical isolator having a diameter of 4 mm and a length of 2.5 mm is realized.

Since the low-melting glass 7 has a lower melting point than the low-melting glass 6, the low-melting glass 6 does not melt again when it is fixed to the magnet 5.

Further, the optical surfaces (the light entrance / exit surfaces) of the polarizer 1, 45-degree Faraday rotator 2, and analyzer 3 are all provided with an antireflection film for air.

Next, a method of manufacturing the optical isolator shown in FIG. 1 will be described with reference to FIGS. FIG.
As shown in (a), the square polarizer 8, the 45-degree Faraday rotator 11 and the analyzer 12 are respectively combined with the polarizers 8 and 45.
The supporting member 10 is sandwiched between two pieces of the preliminarily fired lattice-like low melting point glass tablets 9 between the Faraday rotator 11 and between the Faraday rotator 11 and the analyzer 12, and are combined.

Since the analyzer 12 is formed in a rectangular shape in advance so that its polarization plane rotates 45 degrees with respect to the polarization plane of the polarizer 8, a 45-degree Faraday disposed between the analyzer 12 and the polarizer 8 is provided. The analyzer 1 moves in the direction of rotation of the polarization plane in the rotator 11.
Polarizers 8, 4 so that the rotation directions of the polarization planes 2 are the same.
The Faraday rotator 11 and the analyzer 12 are superimposed five times.

Polarizer 8, 45-degree Faraday rotator 11,
The optical surfaces of the analyzer 12 are all provided with an antireflection film for air.

When the lattice-shaped low-melting glass tablet 9 is melted, the supporting member 10 does not cover the entire optical surfaces of the polarizer 8, the 45-degree Faraday rotator 11, and the analyzer 12 with the low-melting glass. It is used to make it.

In this manner, the polarizer 8, the lattice-like low melting point glass tablet 9, the support member 10, the lattice-like low melting point glass tablet 9, the 45 degree Faraday rotator 11, the lattice-like low melting point glass tablet 9, and the support member 10 , Lattice-like low melting point glass tablet 9, analyzer 12 and then 4
At a temperature of about 50 ° C., the lattice-shaped low melting glass tablet is melted, and the polarizer 8, the supporting member 10, the 45 ° Faraday rotator 11, the supporting member 10, and the analyzer 12 are fixed (FIG. 2).
(B)).

Thereafter, the center of the grid line is cut along a cutting line 13 by a blade having a width smaller than the grid line width of the grid-shaped support member 10. Then, as shown in FIG. 2C, the divided small polarizer 8, the supporting member 10, the 45-degree Faraday rotator 11, the supporting member 10, and the analyzer 12 are provided with a low-melting glass 9 'at the outer periphery thereof. As a result, the optical isolator element fixed is completed.

The size of the optical isolator element is about 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 14 with low melting point glass having a lower melting point than the low melting point glass 9 ', a small optical isolator as shown in FIG. 1 can be realized (FIG. 2). (D)).

[0030]

As described above, according to the present invention, the polarizer, the 45-degree Faraday rotator and the analyzer constituting the optical isolator have a support having a thermal expansion coefficient substantially equal to these components at their respective outer peripheral portions. Because it is melt-fixed with low-melting glass via members, it has excellent moisture resistance,
There is an effect 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 a time by an easy manufacturing method.

[Brief description of the drawings]

FIG. 1A is a front view showing one embodiment of the present invention,
(B) is the same longitudinal cross-sectional view.

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

FIG. 3A is a front view showing an example of a conventional optical isolator, and FIG. 3B is a longitudinal sectional view of the same.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 polarizer 2 45-degree Faraday rotator 3 analyzer 4 support member 5 magnet 6 low-melting glass 7 low-melting glass 8 polarizer 9 lattice-like low-melting glass tablet 9 ′ low-melting glass 10 support member 11 45-degree Faraday rotator 12 Analyzer 13 Cutting line 14 Magnet 15 Polarizer 16 45 degree Faraday rotator 17 Analyzer 18 Magnet 19 Optical adhesive 20 Adhesive

Claims (3)

(57) [Claims] 1. A polarizer, a 45 degree Faraday rotator,
An optical isolator having an analyzer and a magnet for applying a magnetic field to a 45-degree Faraday rotator, comprising: a polarizer, a 45-degree Faraday rotator, and an analyzer, each of which has a heat substantially equal to these constituent elements at an outer peripheral portion thereof. An optical isolator characterized by being fused and fixed with low-melting glass via a support member having an expansion coefficient. 2. An optical isolator comprising a polarizer, a 45-degree Faraday rotator, an analyzer, and a magnet for applying a magnetic field to the 45-degree Faraday rotator. The grid-like supporting member is inserted between two preliminarily fired grid-like low-melting glass tablets between the analyzer and the analyzer, and the grid-like low-melting glass tablet is melted to form a supporting member. Then, the polarizer, the 45-degree Faraday rotator, and the 45-degree Faraday rotator and the analyzer are fixed to each other. Thereafter, the polarizer,
Low melting glass, support member, low melting glass, 45 degree Faraday rotator, low melting glass, support member, low melting glass,
The analyzer is cut in the order of the analyzer, and an optical isolator element composed of a polarizer, a support member, a 45-degree Faraday rotator, a support member, and an analyzer whose outer peripheral portion is fixed with low-melting glass is attached to the magnet. A method for manufacturing an optical isolator. 3. The desired cutting margin is set to be sufficiently narrower than a grid line width.
3. The method for manufacturing an optical isolator according to 1.