JPH1068907A - Optical isolator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow optical isolators of a uniform characteristic with good precision as specified or better to be produced in quantity at inexpensive costs by a simple assembly process with a lowest parts count. SOLUTION: This isolator is provided with a grooved type holder 5, a permanent magnet 1 fitted to a center positioning recessed part 6 formed at the center part of the grooved type holder 5, a Faraday element 2 fitted into an opening part of the permanent magnet, a first polarizing plate 3a fitted to a first positioning recessed part 7 formed in the neighborhood of one end part of the grooved type holder 5, and a second polarizing plate 3b fitted to a second positioning recessed part 8 formed in the neighborhood of the other end of the grooved type holder 5. Since the recessed part 7 is made to be V-shaped and the recessed part 8 to be U-shaped, both polarizing plates are automatically shifted by 45 degrees when the polarizing plates are fitted to each recessed part. Thus, if a specified side is made parallel with a polarizing plane, the polarizing planes of both polarizing plates form an angle of 45 degrees automatically only by fitting the polarizing plates into the recessed parts.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical isolator used for preventing reflected light from returning to a laser light source in an optical communication device or an optical measuring device, and more particularly, to a Faraday element fixed in a cylindrical hole of a cylindrical magnet. And an optical isolator comprising two polarizers as polarizers and analyzers disposed on both sides thereof.

[0002]

2. Description of the Related Art FIG. 10 shows an example of the structure of a typical conventional optical isolator. As shown in FIG.
A Faraday element 2 of a rectangular plate is inserted and fixed in the opening of the Faraday rotator. One of the first polarizing plate 3a and the second polarizing plate 3b serves as a polarizer, and the other serves as an analyzer. Further, both polarizing plates 3a, 3b are mounted in openings of the polarizing plate holders 4a, 4b, respectively.

A polarizing plate holder 4a having a polarizing plate 3a is provided on both sides of the permanent magnet 1 having the Faraday element 2.
And a polarizing plate holder 4b having a polarizing plate 3b, respectively, to align their optical axes,
The polarization planes a and 3b are accurately shifted by a predetermined angle (usually 45 degrees) and positioned, and the whole is integrally fixed.

[0004]

However, the conventional structure shown in FIG. 10 has a problem that the number of parts is large and the assembly is complicated. Also,
Since the optical axis adjustment of the Faraday element 2 and the polarizing plates 3a and 3b and the rotation angle adjustment about the optical axis (the process of shifting the polarization planes of the polarizing plates 3a and 3b by 45 degrees) can be performed strictly, a highly accurate optical isolator Can be assembled,
Therefore, the point that the complicated positioning adjustment must be strictly performed greatly impairs productivity. In addition, there is another problem that improper positioning adjustment significantly reduces accuracy and performance.

SUMMARY OF THE INVENTION The present invention has been made in view of the above background, and has as its object to solve the above-mentioned problems and to provide an optical isolator having characteristics more than specified accuracy with a minimum number of parts and a simple structure. An object of the present invention is to provide a structure that can be mass-produced at a low cost by a simple assembling process.

[0006]

In order to achieve the above-mentioned object, in the optical isolator according to the first invention, a groove-shaped holder and a central positioning recess (6) formed in the center of the groove-shaped holder are provided. , A Faraday element inserted and fixed in the opening of the permanent magnet, and a first magnet formed near one end of the groove-shaped holder.
A first polarizing plate mounted in the positioning recess, and a second polarizing plate mounted in a second positioning recess formed near the other end of the groove-shaped holder, In addition, the first and second positioning recesses position the rotation positions of the two polarizing plates around the optical axis by mounting the first and second polarizing plates, and the polarization planes of the two polarizing plates are predetermined. It has a shape that forms an angle (claim 1).

An optical isolator according to a second aspect of the present invention comprises:
A grooved holder made of a permanent magnet, a Faraday element mounted in a central positioning recess formed in the center of the grooved holder, and a first positioning formed near one end of the grooved holder A first polarizing plate mounted in the recess, a second polarizing plate mounted in a second positioning recess formed near the other end of the groove-shaped holder, the Faraday element and the second A groove-shaped cover made of a permanent magnet integrated downwardly on the groove-shaped holder on which the first and second polarizing plates are mounted,
Further, the first and second positioning recesses are provided in the first and second positioning recesses.
By mounting the second polarizer and the second polarizer, the rotational positions of the two polarizers around the optical axis are positioned so that the polarization planes of the two polarizers have a predetermined angle (claim 2). .

That is, in the above two inventions, when the first and second polarizing plates are respectively mounted in the first and second positioning recesses, the angle between the polarizing surfaces of the two polarizing plates automatically becomes a predetermined angle. It is set to an angle (45 degrees in the embodiment).
In addition, the optical axes of the respective optical components also match. In other words, an optical isolator in which the polarization planes intersect at a predetermined angle with relatively high accuracy can be configured by a simple assembling operation such as simply mounting the optical disk in the concave portion. That is, unlike the related art, there is no need to perform positioning adjustment between the optical components.

In the second aspect, since the holder itself is made of a permanent magnet, it is not necessary to separately provide a magnet for applying a magnetic field to the Faraday element, and the number of parts can be further reduced.

In any of the first and second inventions, the first and second positioning recesses position the first and second polarizing plates at a rotational position about an optical axis, and at the same time, adjust the position of the first and second polarizing plates. A configuration that also regulates the position in the direction can be adopted (claim 3). With such a configuration, as described in detail in the fifth and sixth embodiments, it is possible to easily perform the axial alignment of each optical component.

The first and second positioning recesses are symmetrical with respect to the center positioning portion, so that either the first or second polarizing plate can be mounted at a predetermined angle. (Claim 4). With such a configuration, as described in detail in the second and eighth embodiments, the shapes of the two concave portions can be shared,
Processing becomes easy.

Further, a configuration may be adopted in which a positioning concave portion of an optical fiber ferrule is formed at at least one end of the groove type holder. With this configuration, as described in detail in the fourth and seventh embodiments, by simply mounting the ferrule in the recess, the ferrule with the optical axis aligned with each optical component can be easily positioned and fixed. Can be Therefore, it is not necessary to attach the optical isolator and the ferrule in a later process, and it is not necessary to adjust the relative positional relationship.

Still further, a configuration may be adopted in which legs for attaching and fixing to an external device are integrally formed on the outer periphery of the groove-shaped holder (claim 6). With such a configuration, as described in detail in the third and ninth embodiments, mounting can be easily performed.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Some embodiments of the first invention are shown in FIGS. 1 to 5, and some embodiments of the second invention are shown in FIGS. These embodiments will be described in order.

(1) Embodiment of FIG. 1 FIGS. 1A and 1B show the configuration of the first embodiment. The optical isolator includes a groove-shaped holder 5, a permanent magnet 1 fitted and mounted in a central positioning recess 6 formed in a central portion of the groove-shaped holder 5, and a fitting mounted in an opening of the permanent magnet 1. Element 2, a first polarizing plate 3 a fitted and mounted in a first positioning recess 7 formed near one end of the groove-shaped holder 5, and near the other end of the groove-shaped holder 5. And a second polarizing plate 3b fitted and mounted in the second positioning concave portion 8 formed at a predetermined angle (45 degrees) with respect to the first polarizing plate 3a. It is.

In FIG. 1, the directions of the polarization planes of the two polarizing plates 3a and 3b are the directions of a large number of straight lines described on the surfaces of the respective polarizing plates. It is a flat rectangular flat plate (the front shape is a square), and the direction of the polarization plane is parallel to a predetermined side of the plate.

The groove-shaped holder 5 has a shape in which a cylinder is divided in half, and is formed of a molded product such as plastic, metal or ceramic. The central positioning recess 6 is a semicircular groove corresponding to the cylindrical outer shape of the permanent magnet 1. The first positioning recess 7 has a square first
Is formed in a V-shaped groove so that each side of the polarizing plate 3a can be mounted at an angle of 45 degrees with respect to the horizontal. Further, the second positioning recess 8 is provided with the square second polarizing plate 3.
b is formed in a U-shaped groove so that the set b can be mounted in a posture in which one set of sides is horizontal. Note that, as described above, the groove-type holder 5 is not limited to a molded part, and may be manufactured by adding processing such as cutting to the molded part, or may be manufactured by cutting from the beginning. This is common to any of the following embodiments.

With this configuration, the permanent magnet 1 with the Faraday element 2 is inserted and fixed in the central positioning concave portion 6 of the groove type holder 5, and the first and second positioning concave portions 7, 8 are respectively inserted into the first and second positioning concave portions 7, 8. By inserting and fixing the two polarizing plates 3a and 3b, the Faraday element 2 and both polarizing plates 3
The optical axes of a and 3b are aligned, and the rotation positions of the polarization planes of both polarizing plates 3a and 3b around the optical axis are as specified. That is, as described above, the first and second positioning recesses 7, 8
Are made into a V-shape and a U-shape. When the square polarizing plates 3a and 3b are respectively inserted into the concave portions 7 and 8, the directions of the sides of the polarizing plates 3a and 3b are automatically set to 45 degrees. To intersect. Since the polarization planes of the respective polarizing plates 3a and 3b are parallel to the predetermined sides, the directions of the polarization planes are shifted by 45 degrees as in the direction of the sides. Thus, each of the optical components 1, 3 is simply placed in each of the concave portions 6, 7, and 8.
By a simple process of inserting a and 3b, the relative positional relationship of each optical component can be set to a predetermined state.

In the illustrated example, the optical components 1, 3a, 3b are mounted on the groove-shaped holder 5 having a substantially semicircular vertical section, and the upper part thereof is open. In this way, the cover may be left open, or a cover having the same shape as the groove-shaped holder 5 may be attached so as to cover each optical component. The shape of the cover to be mounted does not necessarily have to be the same as the shape of the groove-shaped holder 5, and the outer shape is arbitrary as long as the cover has an inner shape corresponding to the outer shape of each optical component. (The same applies to the following embodiments).

(2) Embodiment of FIG. 2 In the second embodiment shown in FIGS. 2 (a) and 2 (b), the first and second positioning recesses 7 and 8 in the groove type holder 5 are provided.
Is different from the embodiment of FIG. That is, in the present embodiment, the first positioning concave portion 7 and the second positioning concave portion 8 have shapes that are symmetric with respect to the center positioning portion 6,
Either the first polarizing plate 3a or the second polarizing plate 3b can be fitted and mounted at a predetermined angle posture.

That is, a V-shaped groove X in which a square polarizing plate is fitted so that each side is at 45 degrees to the horizontal, and a square polarizing plate is fitted in a position in which one set of sides are horizontal. A semi-star-shaped groove is formed by combining a U-shaped groove Y to be combined.

With this configuration, when the groove X is used when one of the polarizing plates is mounted and the groove Y is used when the other polarizing plate is mounted, the polarization planes of the polarizing plates are different from each other by 45 degrees. be able to. When combined with the first embodiment, the first positioning concave portion 7 actually uses the groove X portion, and the second positioning concave portion 8 actually uses the groove Y portion. Become.

(3) Embodiment of FIG. 3 FIG. 3 shows a modification of the groove type holder 5 of the second embodiment. Here, a leg 9 having a square cross section is integrally formed on the outer periphery of the groove-shaped holder 5 in order to facilitate attachment and fixing (mounting) to an external device.

As can be seen from the present embodiment, the outer shape of the groove-shaped holder 5 is not limited to a semi-cylindrical shape.
For example, a free form such as a square block type can be adopted according to the mounting object.

(4) Embodiment of FIG. 4 FIG. 4 shows a fourth embodiment of the present invention. In the present embodiment, one end portion (in the illustrated example, the second positioning concave portion 8 side) of the groove-shaped holder 5 is extended in the first embodiment, and the cylindrical portion of the optical fiber 10 is attached to the extended portion. A positioning recess 12 having a semicircular groove shape for mounting and positioning the mold ferrule 11 is formed. In the present embodiment, the coupling between the optical isolator and the optical fiber ferrule can be performed very easily.

(5) Embodiment of FIG. 5 FIG. 5 shows a fifth embodiment of the present invention. In the present embodiment, the first polarizing plate 3a in the groove type holder 5 is used.
The first positioning concave portion 7 for the second polarizing plate 3b and the second positioning concave portion 8 for the second polarizing plate 3b have a function of positioning the polarizing plate in the optical axis direction.

That is, the V-shaped groove of the first positioning recess 7 has a width corresponding to the thickness of the first polarizing plate 3a. The U-shaped groove of the second positioning recess 8 has a width corresponding to the thickness of the second polarizing plate 3b. According to the present embodiment, assembly and positioning can be performed more simply and accurately.

If the thickness of the polarizing plate to be mounted and the width of the concave portion are made the same as described above, accurate positioning in the optical axis direction can be easily performed. Even if the width is wider, if the polarizing plate has a protruding portion that comes into contact with the front or back surface, the polarizing plate is brought into contact with the protruding portion to make the relative positional relationship in the optical axis direction uniform. This includes the case in which this is possible.

(6) Embodiment of FIG. 6 FIG. 6 shows a sixth embodiment of the present invention. This embodiment is a basic mode of the second invention (except for the positioning mechanism in the optical axis direction), and includes a groove-shaped holder 50 made of a permanent magnet and a central portion of the groove-shaped holder 50. Faraday element 2 fitted and mounted in central positioning concave portion 60, first polarizing plate 3 a inserted and fixed in first positioning concave portion 7 formed near one end of groove type holder 50, and groove type The first polarizing plate 3 is inserted and fixed in a second positioning recess 8 formed near the other end of the holder 50.
a on the second polarizing plate 3b whose polarization axis forms a predetermined angle (45 degrees) with respect to a, and on the groove type holder 50 on which the Faraday element 60 and the first and second polarizing plates 3a and 3b are mounted. And a groove-shaped cover 51 made of a permanent magnet integrally combined by being combined downward.

The form of the permanent magnet / groove type holder 50 in the present embodiment is different from that of the first embodiment in the shape of the center positioning concave portion 60. That is, in the second invention, the Faraday element 2 is directly inserted into the center positioning concave portion 60 of the groove-shaped holder 50. The planar shape of the Faraday element 2 is a square like the polarizers 3a and 3b, and the Faraday element 2 is combined with the holder 50 at a 45-degree attitude, so that the central positioning recess 60 is a V-shaped groove. . Note that the concave portion 60 may have a U-shape.

The permanent magnet / groove type cover 51 has the same form as that of the permanent magnet / groove type holder 50, and a cylindrical permanent magnet is formed by combining them face to face. Is applied.

In the present embodiment, similarly to the fifth embodiment, the positioning recess 7 for the first polarizing plate 3a and the positioning recess 8 for the second polarizing plate 3b in the groove-shaped holder 50. Have a function of positioning the polarizing plate in the optical axis direction. That is, V of the first positioning recess 7
The U-shaped groove has a width corresponding to the thickness of the first polarizing plate 3a, and the U-shaped groove of the second positioning recess 8 has a width corresponding to the thickness of the second polarizing plate 3b. According to the present embodiment, assembly and positioning become extremely simple.

Further, since the holders 50 and 51 themselves have a magnet function for applying a magnetic field to the Faraday element 2, the permanent magnet 1 which is conventionally required separately becomes unnecessary, and the number of parts can be reduced. As in the first embodiment, it is of course not necessary to have a positioning mechanism in the optical axis direction.

(7) Embodiment of FIG. 7 FIG. 7 shows a seventh embodiment of the present invention. In the present embodiment, in the sixth embodiment described above, a semicircle for extending one end of the groove-shaped holder 50 and fitting and positioning the cylindrical ferrule 11 of the optical fiber 10 in the extended portion. A groove-shaped positioning recess 12 is formed.
The groove type cover 60 has the same form. That is, the present embodiment is obtained by adding the same functions as those of the fourth embodiment to the sixth embodiment. In this embodiment, the coupling between the optical isolator and the optical fiber ferrule becomes extremely easy.

(8) Embodiment of FIG. 8 FIG. 8 shows an eighth embodiment of the present invention. The first positioning concave portion 7 and the second positioning concave portion 8 of the groove-shaped holder 50 (the groove-shaped cover 51) in the present embodiment have shapes symmetrical with respect to the center positioning portion 60, and the first polarizing plate 3a. Alternatively, each of the second polarizing plates 3b can be fitted and mounted at a predetermined angle posture. That is, a V-shaped groove X in which a square polarizing plate is fitted at a position where each side is at 45 degrees with respect to the horizontal, and a square-shaped polarizing plate in which a pair of sides are fitted with a horizontal position. A semi-star-shaped groove is formed by combining the U-shaped groove Y.

(9) Embodiment of FIG. 9 FIG. 9 shows a ninth embodiment of the present invention. In the present embodiment, the groove-shaped holder 50 according to the eighth embodiment described above is used.
Are shown. Here, a leg 9 having a square cross section is integrally formed on the outer periphery of the groove-shaped holder 50 in order to facilitate attachment and fixing to an external device. As can be seen from the present embodiment, the outer shape of the permanent magnet / groove type holder 50 is not limited to a semi-cylindrical type, and may be a free type such as a square block type according to the mounting object. .

The present invention is not limited to the above-described embodiments, and it is needless to say that the main components of each embodiment may be appropriately combined.

[0038]

As described above, in the optical isolator according to the present invention, the polarization directions of both polarizing plates can be set to a predetermined angle only by inserting the polarizing plate into the concave portion formed in the groove type holder. As a result, optical isolators having characteristics more than specified accuracy can be mass-produced inexpensively with as few parts as possible and a simple assembling process.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a first embodiment of the present invention.

FIG. 2 is a configuration diagram of a second embodiment of the present invention.

FIG. 3 is a configuration diagram of a third embodiment of the present invention.

FIG. 4 is a configuration diagram of a fourth embodiment of the present invention.

FIG. 5 is a configuration diagram of a fifth embodiment of the present invention.

FIG. 6 is a configuration diagram of a sixth embodiment of the present invention.

FIG. 7 is a configuration diagram of a seventh embodiment of the present invention.

FIG. 8 is a configuration diagram of an eighth embodiment of the present invention.

FIG. 9 is a configuration diagram of a ninth embodiment of the present invention.

FIG. 10 is a configuration diagram of a conventional optical isolator.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Permanent magnet 2 Faraday element 3a, 3b Polarizing plate 4a, 4b Polarizing plate holder 5 Groove type holder 6 Center positioning concave part 7 First positioning concave part 8 Second positioning concave part 9 Leg 10 Optical fiber 11 Ferrule 12 For optical fiber ferrule Positioning concave part 50 Permanent magnet / groove type holder 51 Permanent magnet / groove type cover 60 Center positioning concave part

Claims (6)

[Claims] 1. A groove-shaped holder (5); a permanent magnet (1) mounted in a central positioning recess (6) formed in the center of the groove-shaped holder; A Faraday element (2) inserted and fixed, and a first polarizing plate (3a) mounted in a first positioning recess (7) formed near one end of the groove-shaped holder.
And a second polarizing plate (3b) mounted in a second positioning recess (8) formed near the other end of the groove-shaped holder.
And wherein the first and second positioning recesses are provided with the first
And an optical isolator characterized in that by mounting the second polarizing plate, the rotational positions of the two polarizing plates around the optical axis are positioned, and the polarizing surfaces of the two polarizing plates have a shape forming a predetermined angle. 2. A groove type holder (50) made of a permanent magnet.
A Faraday element (2) mounted in a central positioning recess (60) formed in the center of the groove-shaped holder; and a first positioning recess formed near one end of the groove-shaped holder. (7) First polarizing plate (3a) mounted inside
And a second polarizing plate (3b) mounted in a second positioning recess (8) formed near the other end of the groove-shaped holder.
And a groove-shaped cover (51) made of a permanent magnet integrated downward and integrated on the groove-shaped holder on which the Faraday element and the first and second polarizing plates are mounted. And the first and second positioning recesses are provided in the first positioning recess.
And an optical isolator characterized in that by mounting the second polarizing plate, the rotational positions of the two polarizing plates around the optical axis are positioned, and the polarizing surfaces of the two polarizing plates have a shape forming a predetermined angle. 3. The first and second positioning recesses,
3. The optical isolator according to claim 1, wherein the first and second polarizing plates are positioned at a rotational position about an optical axis, and at the same time, regulate an axial position. 4. 4. The first and second positioning recesses are symmetrical with respect to the center positioning portion, and the first and second positioning recesses are symmetrical to each other.
4. The optical isolator according to claim 1, wherein each of the second polarizers can be mounted at a predetermined angle posture. 5. 5. A positioning recess (12) for an optical fiber ferrule (11) at least at one end of the groove type holder.
The optical isolator according to claim 1, wherein the optical isolator is formed. 6. The device according to claim 1, wherein a leg (9) for attaching and fixing to an external device is integrally formed on an outer periphery of the groove-shaped holder. Optical isolator.