JP2001174752A - Optical isolator element and manufacturing method thereof - Google Patents

Abstract

(57) Abstract: Provided is an optical isolator which can be installed so that a light incident surface of an optical element is easily inclined with respect to incident light, and a method of manufacturing the same. A magneto-optical crystal plate serving as a Faraday element is provided.
Polarizing plates 52 and 53 serving as a polarizer or an analyzer are laminated on both surfaces of the substrate, respectively, so that the respective polarizing directions are adjusted to the rotation angle of the polarization plane by the Faraday element, thereby producing a laminated body 5 substrate. Next, the laminated body 5 is cut so that the cut surface 54 is perpendicular to the thickness direction of the laminated surface, and the cut surface 55 is perpendicular to the cut surface 54 and the cutting angle is inclined with respect to the thickness direction of the laminated surface. , And cut diagonally to cut out a plurality of optical elements 10 from the laminate substrate. Accordingly, when the optical isolator is arranged in the outer case, the incident surface of the optical element 10 is inclined at a certain angle with respect to the direction of the incident optical axis by holding and fixing the side cross section of the cut surface 55 as a reference surface.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shape of an optical isolator element in which a light incident surface can be easily installed on a holding side obliquely with respect to an incident optical axis, and a method of manufacturing the same.

[0002]

2. Description of the Related Art As information changes from data to images,
The development and improvement of optical communication-related technologies are rapidly progressing with the expansion of global network communication networks and the increase and speed of information data. The optical communication technology is a communication technology for transmitting a large amount of information quickly by transmitting light serving as an information transmission medium from an origin to a destination via an optical fiber.

[0003] In recent years, however, further technological innovation has been desired, and therefore, this enormous amount of information has been increased in density,
In order to transmit at a higher speed, it is necessary to cause a semiconductor laser element, which is a communication light source, to emit light with higher output and more stably. However, as shown in an example in FIG. 8, a semiconductor laser element is a laser diode module (not shown).
When incorporated into the optical fiber, the light emitted from the oscillating portion of the semiconductor laser element 20 is reflected by an optical path light receiving portion on the surface of an optical isolator or the like or in the optical path, or reflected by an optical fiber terminal portion (reflected light). ) Causes a problem that the laser emission becomes unstable.

For this reason, in order to prevent reflected return light and the like reflected at the input / output surface of the optical fiber terminal from returning to the semiconductor laser element and entering the semiconductor laser element, the laser emission light is placed in the intermediate position between the semiconductor laser element and the optical fiber. It is common to arrange an element having a special effect of passing only light in a direction, that is, a so-called “optical isolator” component.

An optical isolator 8 which is an example of this conventional general “optical isolator” holds an optical element 10 composed of three layers at the center position of a cylindrical magnet 3 as shown in FIG. The magnet 3 itself is fixed inside the cap-shaped outer case 100 having an opening in the center of the cylinder,
The optical element 10 is provided with an optical path system 30 for light through an opening at one end of the outer case 100.

The optical element 10 having the optical path system 30 is:
A plate-like polarizer 32 and an analyzer 33 are provided on both side surfaces of a Faraday element 31 serving as a plate-like Faraday rotator, respectively.
Are laminated, for example, in the outer case 100,
As shown in FIG. 9, it is used while being fixed in a direction perpendicular to the optical axis of the optical path system 30.

In the above-described structure, as described with reference to FIG. 8, the return light reflected from the semiconductor laser device 20 is reflected by the optical path light receiving portion 21 because the incident surface is perpendicular to the optical axis. Becomes larger. For this reason, in order to prevent reflected light from being incident on a semiconductor laser element (not shown) on the light source side, conventionally, an antireflection coating (AR coat) is applied to the optical surface of each element, or as shown in FIG. By arranging the outer case 100 itself at an angle to the direction of the incident optical axis, it is necessary to tilt the reflected light in a direction different from the direction of the incident optical axis.

[0008]

For this reason, as shown in the schematic diagram of FIG. 7, the normal direction of the optical surface of the optical path system light receiving section 21 is inclined by several degrees from the direction of the optical axis of the incident light toward the light receiving section. The arrangement with the inclination angle, in short, as a countermeasure for the above problem,
As in the internal structure of the optical isolator 7 shown in FIG. 6, an optical element in which the inclination angle of the optical element is set to the inner diameter of the outer case 100 and the inside of the case is machined has been used.

However, in such a method in which the optical element 10 is disposed obliquely with respect to the optical axis inside the outer case 100 or in a method in which the outer case 100 itself is disposed obliquely on the device mounting side, an optical isolator element ( It is necessary to increase the space (radial direction) required for the oblique arrangement of the optical element 10 (including the magnet), and the optical element 10 constituting the optical isolator is formed by, for example, inclining the inner wall surface of the outer case 100 and cylindrically obliquely grinding it. It was necessary to complicate the processing of other mounting members for holding.

Accordingly, the present invention provides an optical isolator element holding member for an optical isolator element and an optical isolator mounting member to a device or the like without complicating the structure thereof. It is an object of the present invention to provide an optical isolator element that can be installed obliquely with respect to an optical isolator element and a method of manufacturing the same.

[0011]

In order to solve the above-mentioned problems, the invention according to claim 1 comprises a rotator (for example, a Faraday element 11) for rotating a polarization plane of light, and a lamination on the incident side of the rotator. An integrated optical element (10) and an optical path system (30) formed from a polarizer (12) disposed and an analyzer (13) laminated on the emission side of the rotator; In addition, at least one side of the outer surface having the same outer shape in the optical axis direction of the optical element is inclined (for example, the side section 10a or 10b) with respect to the incident surface of the optical surface, and at the time of assembling, the magnet is located inside the magnet (4c). The optical surface (10c, 10d) can be obtained by simply arranging the side cross section of the one side parallel to the optical axis.
Laminate type optical isolator with slant angle (1)
Is obtained.

In the optical isolator according to the present invention, when the inclined portion of the side cross section is fixed to the inner wall of the outer case via a magnet, as shown in FIG.
Oc (optical surface) is structurally inclined with respect to the cylindrical inner wall and outer wall of the outer case 4. That is, the outer case 4
Even if the whole is arranged as usual in the direction perpendicular to the direction of the incident optical axis, the incident surface 10c can be arranged obliquely to the direction of the incident optical axis, and as a result, the reflection reflected by the incident surface 10c The light is reflected and travels in a direction deviating from the light source, and the reflected light returning to the optical path system 30 can be greatly reduced.

Therefore, at the time of assembling, it is not necessary to intentionally form and process the inner wall of the outer case or to arrange the outer case itself, which is a holding member of the optical isolator, obliquely with respect to the mounting device. The inclined arrangement of the optical isolator can be simplified without using complicated processing parts such as an inner diameter portion. Accordingly, the internal space (diameter dimension) can be made smaller, and the outer case of the optical isolator can be downsized, so that a compact and inexpensive optical isolator component can be manufactured while maintaining the performance characteristics more than before.

Here, for example, when the shape of the laminate optical isolator cut from the element substrate is polygonal,
At least one surface, preferably two surfaces facing each other, of the four side sections excluding the two optical surfaces may be inclined in parallel. In this case, the corresponding side cross-sectional portion of the element substrate may be cut obliquely and continuously at equal intervals in the same direction, or may be cut into small blocks, and several pieces may be stacked and cut diagonally from the end. You may.

Further, as the optical isolator element,
In addition to the optical element type that requires an external magnetic field (the magnet) for obtaining Faraday rotation, a so-called “latching-type optical isolator” that eliminates the need for an external magnetic field (magnet) by using a ferromagnetic material for the rotor itself. Naturally, the present invention can be applied to element components.

The optical element and the optical path system used in the optical isolator according to the first aspect of the present invention are, as described in the second aspect, provided on both surfaces of a plate-like member (for example, a magneto-optical crystal plate 51) serving as a rotor. Then, a polarizing plate (52 or 53) serving as a polarizer or an analyzer is laminated in accordance with the rotation direction of the polarization plane by the rotator to form a laminate (5) substrate. Put this laminate in a grid,
At least one of the X- and Y-axis directions of the optical surface serving as the substrate has an inclined angle (for example, the cut surface 55) in the cutting direction and is obliquely cut in the thickness direction, so that a pair of cut side surfaces facing each other can be formed. It is possible to manufacture an optical element (10) having a parallel optical path system.

That is, in the optical element used in the optical isolator according to the first aspect, a large-diameter substrate can be manufactured by laminating so-called individual element base materials by a laminating method, and the laminated substrates are formed in a lattice shape. , Just cut and cut out by dicing with a sword inclination angle,
This is a manufacturing method which enables multiple pieces each of which can be one isolator material (in the case of a latching type, an optical isolator itself). Therefore, the manufacturing cost of the optical isolator element according to the first aspect can be reduced.

Here, as shown in FIG. 1, for example, all of the cut surfaces 55 in the vertical direction (one direction) may be inclined cut surfaces at equal intervals, or all of the lattice-shaped cut surfaces (cut surfaces) may be used. (Including the direction of 54) may be an inclined cut surface. When these optical elements are installed at the target optical surface position having the inclined surface, preferably, the opposing two sides are made parallel to make the installation arrangement simpler.

In short, at least one of the side cross sections (four sides) of the optical element 10 excluding the optical surfaces on both sides has an inclined cross section, so that any optical surface can be used as an incident optical axis using the inclined cross section as a reference plane. It can be inclined at a constant angle to the direction.

In the invention according to claim 3,
When cutting the laminate, the cut shape of the upper and lower optical surfaces may be a quadrangle or more polygon. The optical surface of the optical element,
That is, the square shape shown in FIG. 1 which is the input / output surface (two surfaces) forming the optical path system is processed into a polygon (actually, a hexagon different from the hexagon shown in FIG. 5) from the beginning by a dicer at the time of cutting. Thus, a polygonal configuration in which the number of side cross sections is increased may be adopted.

In this case, if the optical surface shape of the optical path system of the cut optical element becomes a polygon, it becomes closer to a circle than a square. Usually, the optical path system of an optical isolator is used while being fixed to the end of the optical fiber together with the outer case holding the optical element, but the effective part involved in optical coupling with the optical path system such as an optical fiber terminal is an optical part. Since it is the central circular region in the cross section of the element, the diagonal corners of the angular optical element are substantially unnecessary for optical coupling.

Therefore, as the outer shape of the optical element becomes closer to a circle, the size of the outer size of the optical isolator can be made smaller and the diameter becomes smaller. Therefore, according to the third aspect of the invention, the space in the radial direction is further reduced and effectively used.
A small-diameter optical isolator can be manufactured.

Further, when the laminate substrate is cut in the thickness direction, it is cut obliquely at least in a lattice-like uniaxial direction with a certain angle of inclination so that a pair of cut surfaces facing each other are parallel, An approximately parallelogram rectangular parallelepiped optical element having two sides cut at the same angle can be manufactured.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A laminated optical isolator according to one embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 is a schematic perspective view for explaining a method of manufacturing the optical element 10 of the optical isolator 1 from the large-diameter substrate of the laminated body 5 of optical elements. FIG. 2 shows the substrate of the laminated body 5 from above. It is the schematic explaining the cutting method at the time of seeing. FIG. 3 is a schematic side sectional view of the inside of a free space type optical isolator for explaining a side sectional structure of the optical element 10, and FIG.

The optical isolator 1 shown in FIG. 4 has a configuration in which the optical element 10 is arranged at the center position of the cylindrical magnet 3 via a fixing member 6 on the outer peripheral section of the optical element 10. As schematically shown in FIG. 3, the cut optical element 10 is provided on both sides of a Faraday element 11 made of a magneto-optical crystal material typified by a well-known magnetic garnet single crystal substrate, on both sides of a well-known polarizing glass ( It is composed of a laminated body (laminate structure) in which a polarizer 12 and an analyzer 13 are formed by a polarizer such as a polar core, and the principle of light isolation (transmission, blocking) is the same as that of the conventional one. is there.

In the optical element 10, the entrance and exit surfaces (optical surfaces 10c and 10d) of the optical system are rectangular when viewed from the optical axis direction, and the side cross-sectional shapes are substantially parallelograms as shown in FIGS. Further, among the four side sections, the fixed reference planes of the side sections 10a and 10b at positions facing each other are shown in FIG.
As shown in the front view (B) of FIG.
Is in a state where an inclination angle is set obliquely with respect to the optical axis 30.

Next, a method for manufacturing the optical element 10 will be described.
This will be described with reference to the schematic diagrams of FIGS. Optical element 1
Numeral 0 is one of substantially dice-shaped chips cut out from a laminated substrate manufactured by a so-called laminating method.

That is, the polarizer 12 or the polarizer 12 shown in FIGS. 3 and 4 is provided on both upper and lower surfaces of a magneto-optical crystal plate 51 (Faraday element 11 in FIGS. 3 and 4) serving as an element substrate of a Faraday element material. The polarizing plates 52 and 53 serving as the analyzer 13 are laminated such that their respective deflecting directions are adjusted to match the rotation angle of the polarization plane by the Faraday element, and a large-diameter laminated body 5 of the laminated body 5 is manufactured.

Next, the laminated body 5 is divided into a plurality of optical elements 1 by using, for example, a dicing cutter called a dicer.
The optical isolator element parts are cut into 0 parts and cut into individual parts. Here, as shown in FIG. 2, the cut surface 5 indicated by a solid line
4 is a cut at an angle that remains perpendicular to the lamination plane in the thickness direction, but the cut plane 55 indicated by the dotted line is orthogonal to the cut plane 54 in a lattice shape, and On the other hand, the blade is cut diagonally with a blade angle.

That is, the cut surface 55 shown in FIG.
As shown in FIG. 3, side sections 10a and 10b are formed. Here, the inclination angle of the cut surface 55 is most preferably about 4 to 12 degrees with respect to the direction perpendicular to the thickness direction. When the tilt angle is 4 ° or less, the effect of preventing reflection is small. When the tilt angle is 12 ° or more, the refraction angle of the optical path system and other optical characteristics are out of an allowable range. is there.

Next, a structure for fixing the cut optical element 10 inside the outer case 4 will be described. The outer case 4 is, for example, a cylindrical cap-shaped metal case, and has a structure in which the cross-sectional shape is substantially L-shaped and step portions 4c and 4d are provided on the inner wall as shown in FIG. On the other hand, the cylindrical magnet 3 has the stepped portion 4c radially fixed to the stepped portion 4c and the stepped portion 4d abutted and fixed in the optical axis direction. Further, for example, a fixing member 6 made of a resin molded body or the like is used. A total of four opposing surfaces of the side sections 10a, 10b and 10e, 10f of the optical element 10 are fixed at the center position of the inner peripheral axis of the magnet 3.

In such a structure, as a method of fixing the optical element 10 serving as an optical isolator to the outer case 4 side, an optical element in which the cut optical element 10 is accurately arranged at the center position of the magnet 3 is assembled in advance. Then, the outer case 4 may be fixed by being pushed into the outer case 4 until it stops at the step 4d while being fitted into the inner step 4c from the opening insertion side of the outer case 4, or may be magnetized at the step in the outer case 4. The optical element 10 may be fixed together with the fixing member 6 after the element 3 is fixed in advance.

The present invention is not limited to the present embodiment, and may be arbitrarily modified without departing from the gist of the present invention. For example, the cross-sectional shape of the optical element 10 is not limited to a square, but may be a hexagon or an octagon. Here, when the cut shape of the optical element 10 is a hexagon, for example, as shown in a schematic top view of the cut shape in FIG.
It is also possible to cut by combining vertical cutting surfaces 56 and 57 in two directions that intersect at 60 ° and 120 ° in a grid pattern.

Further, although not shown in the figure, an octagon is formed, for example, after the laminate 5 shown in FIG. 2 is cut into a grid shape using the vertical It is also possible to newly provide a cut surface of 45 ° in the direction of chamfering the four corners of the shape to produce an octagon. Thus, by making the cut shape of the optical element 10 close to a circle, the entire outer case 4 can be made smaller.

In FIG. 2, not only the inclined cutting surface 55 but also the cutting surface 54 may be inclined, or one or both of the cutting surfaces 56 and 57 shown in FIG. 5 may be inclined. Good. Thereby, the optical element 10
Can easily set the inclination angle of the entrance / exit surface of the optical path system without providing the inclination angle with respect to the incident optical axis on the fixing member side on the element holding side, and mass-produce the optical element 10 efficiently only by cutting. In addition, the device can be manufactured at low cost by taking a large number of devices.

[0037]

As described above, according to the present invention, for example, the inner wall of the holding portion of the outer case is intentionally formed obliquely, or the outer case itself, which is the holding portion of the optical isolator, is obliquely attached to the mounting device. This eliminates the need to perform complicated processing of the holding components such as the outer case, thereby simplifying the inclined arrangement of the input / output surface of the optical isolator.

Thus, the light emitted from the semiconductor laser element is reflected by an optical surface such as an optical isolator and an optical fiber terminal, or an optical path light receiving unit in a path, or the like.
The so-called reflected return light can be reduced, and the oscillation operation of the laser light emitting element can be stably performed.

In addition, instead of performing fine processing of each optical element from a material as in the prior art, a large-diameter laminated substrate is manufactured by a laminating method using lamination, and cut and cut out at an inclined angle with a dicer or the like. Since it is possible to manufacture many pieces only by processing, the processing cost is low,
At the same time, the processing steps can be significantly reduced. Therefore, the manufacturing cost of the entire optical isolator including the outer case is reduced.

As described above, it is not necessary to perform special processing for arranging the optical isolator obliquely in the outer case, or to obliquely arrange the optical isolator in a device incorporating the outer case itself. In addition, the cost required for processing the parts can be reduced, and the space required for arranging the optical elements of the optical isolator can be reduced. This can contribute to the reduction in the diameter of the entire optical isolator and the space saving while maintaining the performance characteristics more than before.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view illustrating a method for manufacturing an optical element part of an optical isolator according to one embodiment of the present invention from a laminated substrate.

FIG. 2 is a schematic top view illustrating a cut shape of a laminated substrate.

FIG. 3 is a schematic side sectional view illustrating a laminated structure of an optical element.

FIG. 4 is a schematic side sectional view illustrating a fixing structure of an optical element in the optical isolator.

FIG. 5 is a schematic top view illustrating a method of cutting from a laminated substrate when the cut shape of the optical element is a hexagon.

FIG. 6 is a schematic side cross-sectional view illustrating a structure inside a conventional optical isolator of oblique arrangement.

FIG. 7 is a schematic diagram illustrating the relationship between the laser element emission and the reflection between the inclined optical path system light-receiving unit.

FIG. 8 is a schematic diagram illustrating the relationship between laser element light emission and reflection between an optical path light receiving unit.

FIG. 9 is a schematic side sectional view illustrating the structure inside an optical isolator, which is another example of the related art.

[Explanation of symbols]

 1, 7, 8 Optical isolator 3 Magnet 4 Outer case 5 Laminated body 6 Fixing member 10 Optical element 11 Faraday element (rotator) 12 Polarizer 13 Analyzer 51 Magneto-optical crystal plate 52, 53 Polarizing plate 54 Cutting surface 55 Inclined cutting surface

Claims (3)

[Claims] 1. A Faraday rotator for rotating a plane of polarization of light, a polarizer laminated on an incident side of the rotator,
An analyzer stacked on the emission side of the rotor, and an integrated optical element and an optical path system of light formed from the same, and the outer shape of the optical element has at least one side of the same outer surface in the optical axis direction. A laminated type optical isolator element characterized by being inclined by 4 ° to 12 ° with respect to an incident optical axis direction. 2. The method for manufacturing an optical isolator according to claim 1, wherein a polarizing plate serving as a polarizer or an analyzer is provided on both surfaces of a plate-shaped member serving as a rotator, and the polarizing directions of the polarizers or analyzers are different from each other. A single laminated substrate is prepared by laminating the layers while adjusting the angle of rotation of the polarization plane by the rotator, and the laminated body is further arranged in a lattice shape at least in one of the X and Y axis directions of the optical surface serving as the substrate. A method for manufacturing a laminated optical isolator element, wherein an optical element material in which a pair of cut side faces facing each other is made parallel by cutting obliquely in a thickness direction with an inclination angle in a cutting direction. 3. When cutting the optical element laminate with an angle of inclination in the cutting direction, the cut shape of the opposing optical surface is hexagonal or octagonal, and a pair of cut side faces facing each other are cut off. 3. The method according to claim 2, wherein the optical elements are parallel optical elements.