JP2551877B2 - Fiber-optic input/output type optical components - Google Patents

Description

Detailed Description of the Invention

[0001]

The present invention relates to a fiber input/output type optical component used in optical communications, optical measurement, etc. More specifically, it relates to a fiber input/output type optical component which comprises an optical element and fiber collimators with holders arranged on both sides of the optical element, and which supports the tip of one of the fiber collimators with a circular ridge, thereby enabling optical axis alignment by moving the holder.

[0002]

2. Description of the Related Art In optical communications, many optical components such as optical isolators, filters, and attenuators are used. When these optical components are used in a fiber transmission line, they are used in a fiber input/output type structure in which optical fibers are attached to the input/output ends. In such cases, it is technically essential to minimize the optical coupling loss between the two optical fibers.

[0003] The assembly is usually carried out in the following steps: Fix the optical element to the housing. Fix a lens to one end of a cylindrical sleeve, and insert and fix a ferrule with a fiber to the other end to assemble the fiber collimator. Adjust the position of the fiber collimator so that the optical coupling loss is minimized. Fix the fiber collimator to the housing.

[0004] These components are fixed in place by inserting a tapered block into the gap if the components are block-shaped, and by eliminating the gap by improving dimensional accuracy or by pressing them together with screws or the like if the components are cylindrical.

[0005]

[Problem to be solved by the invention] However, in order to align the optical axis, in addition to vertical and horizontal adjustment of the fiber collimator (adjusting the deviation perpendicular to the optical axis), subtle angle adjustment is also required. When the component is block-shaped, using a tapered block makes it difficult to make it compact and to adjust it, and the temperature characteristics become poor because the fixing points are not circularly symmetrical. Also, when the component is cylindrical, it is difficult to achieve precision, and even if precision is achieved, the inclination of the optical element or ferrule can cause the light to bend,
It is difficult to achieve a coupling without adjustment by shifting the lens in parallel. Even if a screw or other means is used to press the lens together, the optical axis alignment (positioning) is not necessarily easy.

SUMMARY OF THE PRESENT EMBODIMENT An object of the present invention is to provide a fiber input/output type optical component which overcomes the above-mentioned drawbacks of the prior art, allows easy alignment of the optical axis, and is small in size and highly reliable.

[0007]

[Means for solving the problems] The present invention is a fiber input/output type optical component in which fiber collimators are arranged on both sides of an optical element. In order to achieve the above object, the present invention comprises a housing having an annular ridge on the inner peripheral surface of a circular through hole extending in the optical axis direction and accommodating an optical element, and a holder for holding each fiber collimator on its outer peripheral side. One fiber collimator is inserted into the circular through hole of the housing and its holder end face is abutted against one end face of the housing, and the tip of the other fiber collimator is press-fitted into the annular ridge and its holder end face is abutted against the other end face of the housing, and both holders are fixed to the housing with their optical axes aligned.

In another embodiment of the present invention, a structure may be provided that includes a housing in which an optical element and one of the fiber collimators is mounted, a first holder having an annular ridge formed on the inner peripheral surface of a circular through hole, and a second holder that holds the other fiber collimator on the outer peripheral side. One end face of the first holder is abutted against the end face of the housing on the optical element side, the tip of the other fiber collimator is press-fitted into the annular ridge portion of the first holder, and the end face of the second holder is abutted against the other end face of the first holder, and both holders are fixed to the housing with their optical axes aligned.

The two fiber collimators are each provided with a lens at one end in a cylindrical sleeve and a ferrule with a fiber inserted and fixed from the other end. It is desirable to tape the outer circumferential surface of the tip of the fiber collimator.

[0010]

[Function] In the case of the former fiber input/output type optical component, the holder holding one of the fiber collimators is slid up, down, left and right to adjust the deviation in the vertical direction to the optical axis so that the optical coupling loss is minimized. Also, when the holder holding the other fiber collimator is slid while abutting against the end face of the housing, the tip of the fiber collimator is supported by the annular protrusion, so the inclination angle of the fiber collimator changes, and the inclination angle can be adjusted so that the optical coupling loss is minimized.

Next, in the case of the latter fiber input/output type optical component, the vertical deviation with respect to the optical axis can be adjusted by sliding the first holder that abuts against the end face of the housing up, down, left and right. Also, when the second holder that abuts against the end face of the first holder is slid, the tip of the fiber collimator is supported by an annular protrusion, so the inclination angle of the fiber collimator changes, and the inclination angle can be adjusted so that the optical coupling loss is minimized.

[0012]

[Embodiment] The present invention will be described below by taking as an example the case where it is applied to an optical isolator. There are various types of optical isolators, one of which is a fiber input/output type optical isolator that uses a uniaxial single crystal (birefringent polarizing plate) such as a wedge-shaped rutile single crystal as a polarizer, eliminating polarization dependency. This type of optical isolator has a 45
A 4-degree Faraday rotator is attached, and on both sides of it are polarizers made of wedge-shaped uniaxial single crystals, with their optical axes aligned 40 degrees apart.
There is a method in which the two optical fibers are offset by 5 degrees to form a non-reciprocal section, a collimator is made with a lens and a ferrule, and the non-reciprocal section is sandwiched between the collimators to couple light. This non-reciprocal section corresponds to the "optical element" in this invention. Here, technically, it is essential to minimize the coupling loss of light between the two optical fibers.

1 is a cross-sectional view showing one embodiment of a fiber input/output type optical isolator according to the present invention. This optical isolator incorporates a non-reciprocal part 10 and fiber collimators 20 located on both sides of the non-reciprocal part 10 in a housing 30, and each part is coupled by the spatial propagation of light. In this embodiment, one fiber collimator 20 (left hand side of the drawing) adjusts the positional deviation in the direction perpendicular to the optical axis, and the other fiber collimator 20 (right hand side of the drawing) adjusts the inclination angle with respect to the optical axis.

The non-reciprocal portion 10 is configured by mounting a 45-degree Faraday rotator 14 in a cylindrical permanent magnet 12, and arranging polarizers 16 made of wedge-shaped uniaxial single crystals (e.g., rutile single crystals) on both sides of the rotator. The fiber collimator 20 is configured by mounting a ball lens 2 at one end of a cylindrical sleeve 22.
The fiber collimators 20 are each structured such that a cylindrical holder 40 and an annular holder 42 are press-fitted into the fiber optics 22 and a ferrule 28 connected to an optical fiber 26 is inserted and fixed at the other end.
The housing 30 is cylindrical, and the inner diameter of the center of the circular through hole 32 is set to a size that matches the outer diameter of the non-reciprocal portion 10. The inner diameter of the circular through hole 32 on both fiber collimators 20 sides is set to a size that matches the outer diameter of the non-reciprocal portion 10.
The outer diameter is set to be larger than 0. Furthermore, a ring-shaped protrusion 34 is integrally formed on the inner periphery of the circular through hole 32.
The protrusion 34 has a rectangular or trapezoidal cross section, a width of about 1 mm, and an inner diameter set to a size that approximately matches the outer diameter of the cylindrical sleeve 22.
All of the components, such as the holders 40, 42, are constructed from a weldable material, such as stainless steel, or a material having a solderable surface.

First, the non-reciprocal portion 10 is fixed to the center inside the circular through hole 32 of the housing 30.
and the holders 40, 42 are fixed by welding or soldering. Then, one fiber collimator 20 is inserted into the circular through hole 32 of the housing 30, and the end face of the cylindrical holder 40 is abutted against one end face of the housing 30, while the tip of the other fiber collimator 20 is press-fitted into the annular protrusion 34, and the end face of the annular holder 42 is abutted against the other end face of the housing 30 to be temporarily fixed. Since the cylindrical holder 40 has a long axial length, sliding the cylindrical holder 40 up and down and left and right (perpendicular to the optical axis) moves the fiber collimator 20 in parallel, and the optical axis can be aligned so that the optical coupling loss is minimized. With the optical axis aligned, the cylindrical holder 40 is fixed to the end face of the housing 30 by welding or soldering. Next, when the temporarily fixed annular holder 42 is slid up, down, left, and right (perpendicular to the optical axis), the tip of the fiber collimator is supported by the annular protrusion 34, so the inclination angle of the fiber collimator varies with the protrusion 34 as a fulcrum. At this time, the movable range of the annular holder 42 is several tens of μm.
The angle is adjusted so that the optical coupling loss is minimized, and the annular holder 42 is fixed to the end face of the housing 30 by welding or soldering.

2 is a cross-sectional view showing another embodiment of the present invention. This optical isolator has a structure basically similar to that of the above embodiment, and has a fiber collimator 20 disposed on each side of the non-reciprocal portion 10. First, one of the fiber collimators 20 is inserted into the circular through hole 52 of the housing 50.
The inner diameter of the circular through hole 52 on the fiber collimator side is set to a dimension that matches the outer diameter of the fiber collimator 20, and the inner diameter on the non-reciprocal part side is set to a dimension that matches the outer diameter of the non-reciprocal part 10. The first holder 60 has an annular protrusion 62 formed on the inner peripheral surface of the circular through hole 61, and the second holder 70 has the other fiber collimator 2
One end of the first holder 60 is abutted against the end face of the non-opposite part of the housing 50. The tip of the other fiber collimator 20 is press-fitted into the annular protrusion 62 of the first holder 60, and the end face of the second holder 70 is abutted against the other end face of the first holder 60, and temporarily fixed.
The first holder 60 is slid up, down, left, and right (perpendicular to the optical axis) to align the optical axis so as to minimize the optical coupling loss, and the first holder 60 is fixed to the end face of the housing 50 by welding or soldering. Next, when the second holder 70 that was temporarily fixed is slid up, down, left, and right (perpendicular to the optical axis), since the tip of the fiber collimator is supported by the annular protrusion 62, the inclination angle of the fiber collimator varies with the protrusion 62 as a fulcrum. The angle is adjusted so as to minimize the optical coupling loss, and the second holder 70 is fixed to the end face of the first holder 60 by welding or soldering.

FIG. 3 shows another example of a fiber collimator. The outer peripheral surface of the tip of a cylindrical sleeve 80 has a taper 8.
The provision of the taper 82 makes it easy to press-fit the protruding portion, and even if the precision of the inner diameter of the protruding portion is low, the taper 82
The sleeve 80 can be held somewhere on the surface. Since the position in the optical axis direction has almost no effect on the characteristics, no problem occurs even if the distance between the non-reciprocal portion and the collimator changes due to the tapered surface.

[0018]

As described above, the present invention is provided with a holder that holds the outer circumference of the fiber collimator, so that the optical axis can be aligned relatively easily and reliably by abutting and sliding against the end face of the housing. And because the tip of the fiber collimator is supported by an annular protrusion, the tilt angle can be easily adjusted by abutting and sliding the holder against the end face of the housing or the end face of another holder. Furthermore, since the holder is fixed by welding or soldering, the joint reliability is high. Since no taper block is used for optical axis alignment, the device can be made compact.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing one embodiment of a fiber input/output type optical isolator according to the present invention.

FIG. 2 is a cross-sectional view showing another embodiment of a fiber input/output type optical isolator according to the present invention.

FIG. 3 is a cross-sectional view showing another example of a fiber collimator.

[Explanation of symbols]

REFERENCE SIGNS LIST 10 non-reciprocal portion 20 fiber collimator 30 housing 32 circular through hole 34 protrusion portion 40 cylindrical holder 42 annular holder

───────────────────────────────────────────────────────── Continued from the front page (72) Inventor: Akihiro Masuda Fuji Electric Chemical Co., Ltd. 5-36-11, Shinbashi, Minato-ku, Tokyo (56) References: JP 60-101507 (JP, A) JP 2-66503 (JP, A) Utility Model Application Publication No. 63-68625 (JP, U)

Claims (3)

(57) [Claims] [Claim 1] A fiber input/output type optical component having fiber collimators arranged on both sides of an optical element, comprising: a housing having an annular ridge portion on the inner peripheral surface of a circular through hole extending in the optical axis direction and accommodating the optical element; and a holder for holding each of the fiber collimators on its outer periphery, wherein one of the fiber collimators is inserted into the circular through hole of the housing and an end face of the holder is abutted against one end face of the housing, and a tip of the other fiber collimator is press-fitted into the annular ridge portion and an end face of the holder is abutted against the other end face of the housing, and both holders are fixed to the housing with their optical axes aligned. [Claim 2] A fiber input/output type optical component having fiber collimators disposed on both sides of an optical element, comprising: a housing in which the optical element and one of the fiber collimators are mounted;
a first holder having an annular ridge formed on the inner peripheral surface of a circular through hole, and a second holder for holding the other fiber collimator on its outer peripheral side, wherein one end face of the first holder is abutted against the end face of the housing on the optical element side, a tip of the other fiber collimator is press-fitted into the annular ridge of the first holder, and an end face of the second holder is abutted against the other end face of the first holder, and both holders are fixed to the housing with their optical axes aligned. 3. The fiber collimator according to claim 1 or 2, wherein the outer peripheral surface of the tip of the fiber collimator is tapered and press-fitted into the annular protrusion.
The fiber input/output type optical component described herein.