JP2003255268A - Optical isolator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical isolator which is easily and strongly assembled without using a solder or an organic adhesive. <P>SOLUTION: The optical isolator is provided with an optical isolator unit OIU, a first supporting frame 1 having a bottom plate part 1a which carries the optical isolator unit, a front plate part 1b which covers the front face of the optical isolator unit except a light transmission part, and a pair of side plate parts 1c which cover and elastically pinch and hold the both side faces of the optical isolator unit, a repulsion plate 2 which is placed on the bottom plate part 1a of the first supporting frame and repulsively pressurizes the optical isolator unit upward, and a second supporting frame 3 having a top plate part 3a which is adhered and fixed on the optical isolator unit to cover the top face of the unit, a front plate part 3b which is stacked to the front plate part 1b of the first supporting frame 1, and a back plate part 3c which covers the back face of the optical isolator unit except the light transmission part, and repulsively pressurizes the back face against the front plate part 1b of the first supporting frame 1. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical isolator using a laminate type optical isolator chip in which polarizers are arranged on both sides of a Faraday rotator and bonded with an adhesive, and in particular, stress due to adhesion is applied. The present invention relates to an optical isolator that does not generate and prevents generation of harmful gas.

[0002]

2. Description of the Related Art Conventionally, an optical isolator has been known as a non-reciprocal optical device having a function of allowing passage of light in one direction but blocking passage of light in the opposite direction. It is used for the purpose of blocking the reflected return light to the laser diode which is the light source. That is,
If there is reflected return light, the oscillation of the laser diode becomes unstable, so noise will be increased if it is the laser diode for excitation used in the fiber amplifier, and if it is the laser diode of the signal source, noise will also be generated. It will increase and, in the worst case, prevent accurate communication. Therefore, the optical isolator is an extremely important optical device that functions to cut off reflected return light in order to prevent these.

This optical isolator is composed of a polarizer, a Faraday rotator, a magnet and a holder or a substrate for holding them, and is roughly divided into a polarizer and a Faraday rotator, each of which is separated by a gap without using an adhesive. There is a so-called laminated type in which a fixed so-called adhesive-free type (organic free type) and an optical isolator chip in which a polarizer and a Faraday rotator are bonded with an adhesive are similarly fixed to a holder etc. with an adhesive. is there. Here, a chip in which a polarizer and a Faraday rotator are bonded together with an adhesive will be referred to as an optical isolator chip. If this optical isolator chip is of a high coercive force type, there is one that functions as it is as an optical isolator, but the other chip exerts a function as an optical isolator by applying a magnetic field in a predetermined direction.

In the surface mounting type assembly which is one form of the optical isolator, the optical isolator chip and the magnet of the component parts are adhered to the substrate with an organic adhesive, and the bonding surface of the component parts is sputtered or vapor-deposited. A method in which a metal thin film coating is applied and the substrate is similarly connected to the substrate by soldering is commonly used. In general, when an optical isolator with an exposed organic adhesive is used in a closed space for a long time, degassing from the organic adhesive may contaminate the inside of the module containing the optical isolator and adversely affect the laser light source. In the latter soldering method, stress is generated due to the difference in the coefficient of thermal expansion between the components to be soldered, and the optical isolator chip is cracked if the characteristics of the polarizer or the Faraday rotator are deteriorated. Occur. Further, it is necessary to add a process requiring a production facility for forming a metal thin film in vacuum before soldering.

[0005]

As described above, the optical isolator assembled by using the organic adhesive has a problem that degassing from the organic adhesive may contaminate the laser light emitting element. On the other hand, when assembling by solder connection, there is no danger of degassing, but it requires a metal thin film forming process using vacuum and production equipment for that, and also a polarizer and a Faraday rotator and a substrate to which they are connected. There is a problem that the optical characteristics are deteriorated due to the stress due to the difference in the coefficient of thermal expansion between the two, and that the polarizer and the Faraday rotator are cracked.

The present invention has been made in view of the above problems of the prior art, and an object of the present invention is to provide an optical isolator which can be assembled easily and firmly without using solder or organic adhesive. To provide.

[0007]

[Means for Solving the Problems] To achieve the above object,
The optical isolator according to the present invention is a laminate type optical isolator chip in which polarizers are respectively bonded to the front and rear sides of a Faraday rotator, and an optical isolator unit including a pair of permanent magnets that are closely adhered to the outer surfaces of the polarizer. ,
The bottom plate portion which carries the optical isolator unit and has an upward pressure suppressing means, the front plate portion which covers the front surface of the optical isolator unit except at least the light transmitting portion of the front side polarizer, and the both side surfaces of the optical isolator unit. A first holding frame body having a pair of side plate portions for covering and clamping the isolator unit by pressure, and a top plate portion that is attached and fixed to the first holding frame body and covers the top surface of the optical isolator unit. The first holding frame covers the rear surface of the optical isolator unit except for at least the light transmitting portion of the front polarizer overlapping the front plate of the first holding frame and the rear polarizer. And a second holding frame body having a rear plate portion that elastically presses toward the front plate portion of the frame body.

The optical isolator according to the present invention comprises a laminate type optical isolator chip having polarizers attached to the front and rear sides of a Faraday rotator, and a pair of permanent magnets attached to the outer surfaces of the polarizers. And an optical isolator unit including a bottom plate portion that carries the optical isolator unit and a front plate portion that covers the front surface of the optical isolator unit except at least the light transmitting portion of the front side polarizer and both side surfaces of the optical isolator unit. And a first holding frame body having a pair of side plate portions for elastically sandwiching the optical isolator unit, and a first holding frame body that is attached and fixed to cover the top surface of the optical isolator unit and the optical isolator. A top plate portion having an elastic means for elastically pressing the unit downward, a front plate portion overlapping the front plate portion of the first holding frame, and a front portion. A rear plate portion that covers the rear surface of the optical isolator unit except at least the light transmitting portion of the rear side polarizer and presses the optical isolator unit toward the front plate portion of the first holding frame. And two holding frames.

In the optical isolator according to the present invention, the Faraday rotator, the half-wave plate disposed on one side of the Faraday rotator and bonded, the other side of the Faraday rotator, and the side surface of the half-wave plate. And a laminated type optical isolator chip including a pair of parallel flat plate birefringent crystal plates bonded and arranged respectively, and a pair of permanent magnets closely adhered to the outer surfaces of the pair of parallel flat plate birefringent crystal plates. An optical isolator unit including the optical isolator unit and a bottom plate portion carrying the optical isolator unit upward and a front plate portion covering the front surface of the optical isolator unit except at least the light transmitting portion of the front side polarizer; A first holding frame body having a pair of side plate portions which cover both side surfaces of the isolator unit and elastically sandwich the optical isolator unit, and the first holding frame body. A top plate portion that is attached and fixed to the frame body and covers the top surface of the optical isolator unit, a front plate portion that overlaps with the front plate portion of the first holding frame body, and at least a light transmitting portion of the rear polarizer. Except for covering the rear surface of the optical isolator unit,
Second holding frame body having a rear plate portion for elastically pressing the holding frame body toward the front plate portion.

The optical isolator according to the present invention comprises a Faraday rotator, a half-wave plate disposed on one side of the Faraday rotator and bonded, and the other side of the Faraday rotator and the half-wave plate. A laminate type optical isolator chip including a pair of parallel flat plate birefringent crystal plates which are respectively arranged and adhered to the side surfaces, and a pair of permanent magnets which are closely attached to the outer surfaces of the pair of parallel flat plate birefringent crystal plates. An optical isolator unit including, a bottom plate portion that carries the optical isolator unit, a front plate portion that covers the front surface of the optical isolator unit except at least the light transmitting portion of the front side polarizer, and both side surfaces of the optical isolator unit. A first holding frame body that has a pair of side plate portions that cover the isolator unit and elastically sandwich the isolator unit; and a first holding frame body that is attached and fixed to the first holding frame body. A top plate portion that covers the top surface of the optical isolator unit and has an elastic pressure means for elastically pressing the optical isolator unit downward, a front plate portion that overlaps with the front plate portion of the first holding frame, and the rear polarizer. Second holding frame having a rear plate portion that covers the rear surface of the optical isolator unit except at least the light transmitting portion of the optical isolator unit and elastically presses the optical isolator unit toward the front plate portion of the first holding frame body. It has a body.

According to the present invention, the elastic pressure means is formed on the bottom plate portion or the top plate portion and bulges toward the optical isolator unit corresponding to the optical isolator chip and the pair of magnets, respectively. Is a raised portion, or is formed on a pressure plate interposed between the bottom plate portion and the bottom surface of the optical isolator unit or between the top plate portion and the top surface of the optical isolator unit, It is a raised portion that bulges toward the optical isolator unit corresponding to the isolator chip and the pair of magnets, respectively.

Further, according to the present invention, the optical isolator chip further includes a thin metal plate covering a side surface other than the light transmitting surface thereof.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, an embodiment of the present invention will be described based on illustrated examples. FIG. 1 is an exploded perspective view of an embodiment of the present invention. In the figure, F is a rectangular Faraday rotator,
P is a rectangular polarizer that is attached to both sides of the Faraday rotator F with an organic adhesive. These are optical isolator chips.
It comprises the OIC. Reference numeral M denotes a pair of permanent magnets of the same shape, preferably made of SmCo, which are closely attached to the opposing outer surfaces (vertical surfaces orthogonal to the light transmitting surface) of the optical isolator chip OIC, and these are horizontally long rectangular parallelepiped optical isolator units.
Configure OIU. The outer surface of the laminated type optical isolator chip OIC on which the organic adhesive appears is covered with a metal thin film formed by laminating a Cr film on the lowermost layer by a sputtering method or a vapor deposition method and an Au film thereon. .
This metal thin film may be made of a metal other than the above,
It may also be made of a ceramic material. The metal thin film may have a single layer structure.

Reference numeral 1 denotes a bottom plate portion 1a which is formed by pressing a steel plate SUS304 and has substantially the same shape and size as the bottom surface of the optical isolator unit OIU carrying the optical isolator unit OIU, and the bottom plate. Part 1
an upright front plate portion 1b which is bent from a and has a pair of projections 1b 'which covers the front surface of the front side of the optical isolator unit OIU except at least the light transmitting portion of the front side of the polarizer P, that is, the front surface of the optical isolator unit OIU; A first side plate having a pair of side plate portions which cover the outer side surface of the magnet M, that is, both outer side surfaces of the optical isolator unit OIU, and at least one of which has an inward projection 1c 'for elastically sandwiching the optical isolator unit OIU. It is a holding frame.

Reference numeral 2 is formed by pressing a steel plate SUS304, has the substantially same shape and size as the bottom plate portion 1a of the first holding frame body 1, and has an optical isolator chip.
The elastic plate has a bulge 2a that bulges upward at a position that can correspond to the OIC and the pair of magnets M, respectively. This oppression plate 2
Is placed between the bottom plate portion 1a of the first holding frame 1 and the bottom surface of the optical isolator unit OIU at the time of assembly, and is used to suppress the optical isolator unit OIU upward. The raised portion 2a is the bottom plate portion 1a of the first holding frame body 1.
May be provided in the same manner as above, in which case the above-mentioned pressure plate 2
Is unnecessary.

Reference numeral 3 denotes a top plate portion 3a which is formed by pressing a steel plate SUS304 and which substantially covers the top surface of the optical isolator unit OIU and has the same shape and size as the top surface of the optical isolator unit OIU. And the projection 1 of the front plate portion 1b when the front plate portion 1b of the first holding frame body 1 is folded and folded below the top plate portion 3a so as to be overlapped and assembled.
a front plate portion 3b having holes 3b 'respectively fitted in b', and the light except for at least a light transmitting portion of the rear surface of the polarizer P, that is, the optical isolator unit OIU, which is bent downward from the top plate portion 3a. An inward projection 3 that covers the rear surface of the isolator unit OIU and elastically presses the optical isolator unit OIU toward the front plate portion 1b of the first holding frame body 1.
It is the 2nd holding frame body provided with the back plate part 3c which has c '.

At the time of assembling the second holding frame 3, the bulging portion 2a facing downward is interposed between the top plate portion 3a and the upper surface of the optical isolator unit OIU with the pressure plate 2 being turned upside down. The optical isolator unit OIU may be configured so as to suppress the pressure downward. Further, without using the pressure plate 2, a downwardly bulging protruding portion is provided on the lower surface of the top surface portion 3a of the second holding frame body 3 to provide the optical isolator unit OIU.
May be repressed downward. In this case, the pressure plate 2 interposed between the bottom plate portion 1a of the first holding frame body 1 and the bottom surface of the optical isolator unit OIU, if necessary.
May be omitted. The front plate portion 1 of the first holding frame body 1
The protrusion 1b ′ provided on the b side and the hole 3b ′ provided on the front plate part 3b of the second holding frame body 3 may be exchanged with each other.

The above-mentioned steel plate SUS304 is hard to corrode without surface treatment, but if a rust-prone metal such as phosphor bronze is used in place of this material, Cr plating or Au plating should be applied to prevent corrosion. It is better to do it. Further, these holding frames may be made of synthetic resin having appropriate material properties.

Since the first embodiment is constructed as described above, when assembling the optical isolator, first, the optical isolator unit OIU, the first and second holding frame members 1 and 3, and the pressure plate are pressed. 2 and then the first holding frame 1
The oppression plate 2 is placed on the bottom plate portion 1a, the optical isolator unit OIU is placed on the bottom plate portion 1a, and the pair of side plate portions 1c elastically clamps it (see FIG. 2), and then the second holding frame body from above. Assembling can be completed by covering 3 and fitting the holes 3b 'of the front plate 3b to the projections 1b' on the front plate 1b of the first holding frame 1 respectively. At this time, the optical isolator unit OIU is elastically pressed toward the front plate portion 1b of the first holding frame body 1 by the inward protruding portion 3c ′ of the rear plate portion 3c of the second holding frame body 3 and, eventually, the optical isolator unit OIU. OIU
Is held by the first holding frame body 1, the second holding frame body 3 and the pressure plate 2 while being elastically pressed forward (y direction), upward (z direction) and leftward (x direction). The isolator is completed. The first holding frame body 1 and the second holding frame body 3 may be joined by laser welding.

As is apparent from this description, the optical isolator of the present invention is extremely simple to assemble, and at the time of assembly, the optical isolator unit OIU in which the magnets M are closely attached to both sides of the optical isolator touch OIC is assembled. Positioning is possible by aligning in the x-axis direction, and it is possible to absorb variations in the dimensions of these unit components. In addition, the pressurizing plate 2 with the bulged portion 2a that can be manufactured by press working makes it possible to align the components in the z direction and position them, and it is possible to absorb variations in the dimensions of the unit components. Further, the second holding frame body 3 with the protruding portion 3c 'which can be manufactured by press working allows the component parts to be aligned in the y direction and positioned, and also absorbs the dimensional variation of the unit component parts. You can

In the above embodiment, the optical isolator chip OI
As the C, a laminated type optical isolator chip in which the polarizers P are arranged and adhered on both sides of the Faraday rotator F is used, but as another embodiment, although not shown, one side of the Faraday rotator F is provided. It is possible to use a laminate type optical isolator chip in which a half-wave plate is arranged and bonded with an adhesive, and parallel plate birefringent crystal plates are respectively arranged on both sides thereof and bonded with an adhesive. This chip constitutes a so-called polarization-independent optical isolator. In this optical isolator, polarized light having an arbitrary polarization plane is separated into two polarized lights having polarization planes forming an angle of 90 degrees with each other. In addition, one polarized light is emitted with the same optical axis as the incident light, and the other polarized light is emitted with another optical axis parallel to the optical axis. It is characterized in that a Faraday rotator and a polarization rotator are sequentially arranged on the two optical paths between them.

In the conventional optical isolator, since it is necessary to match the polarization plane of the first polarizer with the polarization plane of the incident light, especially in an optical transmission system in which the polarization plane cannot be specified in advance. Has a drawback in that it cannot effectively exhibit its function. However, the polarization-independent optical isolator eliminates this drawback and can be used as an optical isolator without considering the polarization plane of incident light. There is an advantage that the function can be exhibited.

As is apparent from the above description, according to the present invention, the optical isolator chip and the permanent magnet, and the optical isolator unit and the first and second holding frame bodies are not connected to each other and are simply in contact with each other. Therefore, stress due to connection does not occur, so deterioration of characteristics and cracks due to it do not occur, and use an optical isolator chip with a metal thin film formed on the side surface other than the light transmitting surface. As a result, the organic adhesive exposed on the surface of the optical isolator is covered, and degassing harmful to the laser source can be prevented.

In the embodiment, the optical isolator chip is covered with a metal thin film so that the organic adhesive is not exposed on the surface. However, if degassing is not a problem, it goes without saying that this metal thin film is unnecessary. Nor. In addition, in the embodiment, the first and second holding frame bodies and the pressure plate are both manufactured by press working and combined, but the shape and the number of constituent parts are not limited to those in the embodiment because of requirements in assembly. , Can be designed with a certain degree of freedom.

[0025]

As described above, according to the present invention, it is possible to prevent outgassing from the optical isolator chip, prevent moisture and oxygen from entering the adhesive layer, and have a highly reliable optical isolator that does not cause characteristic deterioration. Can be provided at a relatively low price.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of an embodiment of an optical isolator according to the present invention.

FIG. 2 is a perspective view showing an assembling process of the embodiment shown in FIG.

[Explanation of symbols]

1 1st holding frame 1a Bottom plate part 1b, 3b Front plate part 1b 'Protrusion 1c Side plate part 1c', 3c 'Projection part 2 Repression plate 2a Bulging part 3 2nd holding frame part 3a Top plate part 3b' Hole 3c Rear plate Part F Faraday rotator P Polarizer M Permanent magnet OIC Optical isolator chip OIU Optical isolator unit

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yuji Umehara             Fuji Electronics 4-8-1 Higashishinden, Shizuoka City, Shizuoka Prefecture             Industry Co., Ltd. F-term (reference) 2H049 BA05 BA47 BB51 BC14 BC25                 2H099 AA01 BA02 CA11 DA05 DA07

Claims (7)

[Claims] 1. An optical isolator unit including a laminate type optical isolator chip in which polarizers are respectively bonded to front and rear sides of a Faraday rotator, and a pair of permanent magnets closely adhered to outer surfaces of the polarizer. A bottom plate portion carrying the optical isolator unit and having upward pressure suppressing means, a front plate portion covering the front surface of the optical isolator unit except at least the light transmitting portion of the front side polarizer, and both side surfaces of the optical isolator unit. A first holding frame body having a pair of side plate portions that cover and clamp the optical isolator unit, and a top plate portion that is attached and fixed to the first holding frame body and covers the top surface of the optical isolator unit. A rear surface of the optical isolator unit is removed except for at least a light transmitting portion of the front plate portion and the rear side polarizer which overlap with the front plate portion of the first holding frame body. The second holding frame and an optical isolator having a having a plate portion after the repression toward the light isolator unit to the front plate portion of the first retaining frame I. 2. An optical isolator unit including a laminate type optical isolator chip in which polarizers are adhered to the front and rear sides of a Faraday rotator, and a pair of permanent magnets adhered to the outer surfaces of the polarizer, respectively. A bottom plate portion that carries the optical isolator unit and a front plate portion that covers the front surface of the optical isolator unit except at least the light transmitting portion of the front side polarizer and both side surfaces of the optical isolator unit and suppress the optical isolator unit. A first holding frame body having a pair of side plate portions sandwiched between the first holding frame body and an elastic pressure which is attached and fixed to the first holding frame body to cover the top surface of the optical isolator unit and elastically press the optical isolator unit downward. A top plate portion having means, a front plate portion overlapping the front plate portion of the first holding frame, and at least a light transmitting portion of the rear polarizer. And a second holding frame body that covers the rear surface of the optical isolator unit and presses the optical isolator unit toward the front plate portion of the first holding frame body. . 3. A Faraday rotator, a half-wave plate disposed on one side of the Faraday rotator and bonded, and a half-wave plate disposed on the other side of the Faraday rotator and a side surface of the half-wave plate, respectively. A laminated type optical isolator chip including a pair of parallel flat plate birefringent crystal plates, and an optical isolator unit including a pair of permanent magnets respectively adhered to the outer surfaces of the pair of parallel flat plate birefringent crystal plates, A bottom plate part that carries an optical isolator unit and has an upward pressure suppressing means, and a front plate part that covers the front surface of the optical isolator unit except at least the light transmitting part of the front side polarizer and both side surfaces of the optical isolator unit. A first holding frame body having a pair of side plate portions for elastically sandwiching the optical isolator unit, and the optical isolator unit fixedly attached to the first holding frame body. A top plate portion that covers the top surface of the optical unit, a front plate portion that overlaps the front plate portion of the first holding frame, and a rear surface of the optical isolator unit except at least a light transmitting portion of the rear polarizer. And a second holding frame body having a rear plate portion that elastically presses the optical isolator unit toward the front plate portion of the first holding frame body. 4. A Faraday rotator, a half-wave plate disposed on one side of the Faraday rotator and bonded, and a half-wave plate disposed on the other side of the Faraday rotator and a side surface of the half-wave plate, respectively. A laminated type optical isolator chip including a pair of parallel flat plate birefringent crystal plates, and an optical isolator unit including a pair of permanent magnets respectively adhered to the outer surfaces of the pair of parallel flat plate birefringent crystal plates, A front plate portion that covers the front surface of the optical isolator unit except at least a light transmitting portion of the bottom plate portion that carries the optical isolator unit and the front side polarizer, and both side surfaces of the optical isolator unit are covered, and the optical isolator unit is elastically sandwiched. A first holding frame body having a pair of side plate portions, and covering the top surface of the optical isolator unit by being attached and fixed to the first holding frame body. Aside from the top plate portion having elastic means for elastically pressing the optical isolator unit downward, the front plate portion superposed on the front plate portion of the first holding frame, and at least the light transmitting portion of the rear polarizer. An optical isolator comprising: a second holding frame body that covers a rear surface of the optical isolator unit and has a rear plate portion that presses the optical isolator unit toward the front plate portion of the first holding frame body. 5. The elastic means is formed on the bottom plate portion or the top plate portion, and is a raised portion that bulges toward the optical isolator unit corresponding to the optical isolator chip and the pair of magnets, respectively. The optical isolator according to any one of claims 1 to 4. 6. The elastic pressure means is formed on an elastic pressure plate interposed between the bottom plate portion and the bottom surface of the optical isolator unit or between the top plate portion and the top surface of the optical isolator unit. The optical isolator according to any one of claims 1 to 4, wherein the optical isolator chip and the pair of magnets are raised portions that bulge toward the optical isolator unit, respectively. 7. The optical isolator according to claim 1, wherein the optical isolator chip further includes a metal thin film that covers the side surface of the chip except the light transmitting surface.