JP2001356235A - Method for manufacturing dual core polarization maintaining optical fiber and dual core polarization maintaining optical fiber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a dual core polarization maintaining optical fiber by which adjustment of a polarization direction, fixing work of the polarization maintaining optical fiber and ferrule assembling work can be surely and smoothly executed and to provide the dual core polarization maintaining optical fiber which can be favorably used to application utilizing relative relation of the polarization direction of optical fibers forming a pair. SOLUTION: The dual core polarization maintaining optical fiber is manufactured by a UV curing adhesive charging process in which a UV curing adhesive is charged inside a transparent fixing member after two covered polarization maintaining optical fibers are inserted into the fixing member; a polarization direction adjusting process in which polarization directions of the two optical fibers are adjusted after the process described above; an optical fiber fixing process in which the fixing member after the process described above is irradiated with UV rays to settle the adhesive, thereby the two optical fibers are fixed to the fixing member to form a polarization maintaining optical fiber fixed body; and a ferrule assembling process in which the adhesive is charged inside holes of a dual core ferrule, then the optical fiber fixed body is inserted thereinto and the adhesive is cured by heating.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing a two-core polarization maintaining optical fiber and a two-core polarization maintaining optical fiber.
More specifically, a method for manufacturing a two-core polarization-maintaining optical fiber, comprising fixing two polarization-maintaining optical fibers to one ferrule while adjusting the polarization direction to a fixed relative angle, and a two-core polarization-maintaining optical fiber Optical fiber.

[0002]

2. Description of the Related Art Conventionally, there has been known a two-core optical fiber in which two single-mode optical fibers or multi-mode optical fibers are inserted into and fixed to one ferrule. A conventional two-core optical fiber is manufactured as follows. (1) Fill the adhesive from the rear end side while sucking air with a vacuum pump from the front end side of a two-core ferrule having two holes. The reason why the air is sucked by the vacuum pump is to allow the air inside the two-core ferrule to escape and fill the adhesive without leaving air bubbles inside. (2) Insert two optical fibers from the rear end side of the two-core ferrule, and insert each into each hole. (3) The adhesive is cured.

[0003] On the other hand, a polarization maintaining optical fiber that can propagate linearly polarized light while maintaining the polarization direction is known. However, a two-core polarization-maintaining optical fiber in which two polarization-maintaining optical fibers are fixed to one ferrule is not conventionally known. Accordingly, a method of manufacturing a two-core polarization maintaining optical fiber has not been known.

[0004]

In a conventional two-core optical fiber, since a single mode optical fiber or a multimode optical fiber is used, linearly polarized light cannot be propagated while maintaining the polarization direction. It cannot be used for applications that make use of the relationship between the polarization directions of the paired optical fibers. Thus, a two-core polarization maintaining light in which a polarization maintaining optical fiber is used instead of a single mode optical fiber or a multimode optical fiber and the relative relationship between the polarization directions of the two polarization maintaining optical fibers is adjusted to be constant. Fiber is conceivable. However, when attempting to manufacture such a two-core polarization maintaining optical fiber by the above-described conventional method of manufacturing a two-core optical fiber, the adhesive filled in the hole of the two-core ferrule hinders smooth insertion of the polarization maintaining optical fiber. Therefore, there is a problem that the insertion work becomes troublesome. There is also a problem that the adhesive interferes with the adjustment operation for adjusting the relative relationship between the polarization directions of the two polarization maintaining optical fibers to be constant. SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned various problems of the related art, and has been made in order to make it possible to adjust and fix the polarization direction of a polarization maintaining optical fiber, and to perform a ferrule assembling operation reliably and smoothly. It is an object of the present invention to provide a method for manufacturing a two-core polarization maintaining optical fiber as described above, and a two-core polarization maintaining optical fiber that can be suitably used for an application utilizing the relative relationship between the polarization directions of the paired optical fibers.

[0005]

SUMMARY OF THE INVENTION As a first aspect, the present invention relates to a transparent fixing member comprising a transparent glass tube or a transparent plastic tube, or a transparent U-shaped glass sleeve or a transparent U-shaped plastic sleeve. After inserting the wave-holding optical fiber, the coating at one end of the optical fiber is peeled off for a predetermined length so that the polarization direction can be confirmed, and then the inside of the transparent fixing member is filled with an ultraviolet curing adhesive. A step of adjusting the polarization direction of the two coated polarization-maintaining optical fibers after the step of filling the ultraviolet-curable adhesive; and a transparent fixing member after the step of adjusting the polarization direction. Is irradiated with ultraviolet light to cure the ultraviolet curing adhesive, and the two coated polarization-maintaining optical fibers are fixed to a transparent fixing member to form a polarization-maintaining optical fiber fixed body. And after filling the inside of the ferrule hole of the two-core ferrule having two holes, inserting the polarization-maintaining optical fiber fixed body from the side from which the optical fiber coating has been peeled off, and heating the adhesive. And a ferrule assembling step of curing the optical fiber. As the shape of the transparent glass tube or transparent plastic tube, a circular shape, an elliptical shape, an oval shape,
Alternatively, a daruma shape or the like can be used. Further, as the shape of the transparent U-shaped glass sleeve or the transparent U-shaped plastic sleeve, the depth of the U-shaped portion can be used from shallow to deep depending on the purpose. As the plastic material of the transparent plastic tube or the like, various transparent plastic resins such as a transparent acrylic resin and a transparent polyvinyl chloride resin can be used. In the manufacturing method according to the first aspect, the operation of adjusting and fixing the polarization direction of the polarization-maintaining optical fiber is performed by the ultraviolet curing adhesive filling step, the polarization direction adjusting step, the optical fiber fixing step, and the ferrule assembling step. And ferrule assembly work can be performed reliably and smoothly.
A two-core polarization maintaining optical fiber having excellent characteristics can be manufactured.

As a second aspect, the present invention resides in a two-core polarization maintaining optical fiber obtained by the method for manufacturing a two-core polarization maintaining optical fiber according to the first aspect. Since the two-core polarization maintaining optical fiber of the second aspect is obtained by the manufacturing method of the first aspect, a two-core polarization maintaining optical fiber having excellent characteristics can be obtained. For this reason, for example, if the linearly polarized light is emitted from one of the two polarization-maintaining optical fibers, and the linearly polarized light after some processing is incident on the other, the relative angle in the polarization direction between the two is maintained. , It is possible to obtain a high SN ratio.

According to a third aspect of the present invention, the above-mentioned two-core polarization maintaining optical fiber is a symmetric type, and a symmetric single-row parallel polarization axis two-core polarization maintaining optical fiber, a symmetric two-row parallel polarization axis two-core polarization fiber. It is a holding optical fiber or a two-core polarization maintaining optical fiber which is a symmetric orthogonal polarization axis two-core polarization maintaining optical fiber. In the two-core polarization maintaining optical fiber according to the third aspect, a symmetric type can be easily obtained by the manufacturing method according to the first aspect, and a symmetric single-row parallel polarization axis two-core polarization maintaining optical fiber; A column-parallel polarization axis dual-core polarization-maintaining optical fiber or a symmetric orthogonal polarization axis dual-core polarization-maintaining optical fiber is obtained.

According to a fourth aspect of the present invention, the above-mentioned two-core polarization maintaining optical fiber is an asymmetric type, and the asymmetric one-row parallel polarization axis two-core polarization holding optical fiber, the asymmetric two-row parallel polarization axis two-core polarization fiber. The optical fiber is a holding optical fiber, an asymmetric inner orthogonal polarization axis two-core polarization maintaining optical fiber, or a two-core polarization maintaining optical fiber that is an asymmetric outer orthogonal polarization axis two-core polarization holding optical fiber. In the two-core polarization maintaining optical fiber according to the fourth aspect, the first fiber
The asymmetric type can be easily obtained by the manufacturing method according to the above aspect, and the asymmetric single-row parallel polarization axis dual-core polarization-maintaining optical fiber, the asymmetric double-row parallel polarization axis dual-core polarization-maintaining optical fiber, the asymmetric inner orthogonal polarization axis A two-core polarization maintaining optical fiber or an asymmetric outer orthogonal polarization axis two-core polarization maintaining optical fiber is obtained.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The contents of the present invention will be described below in more detail with reference to an embodiment shown in the drawings. Note that the present invention is not limited by this. -Embodiment 1- An embodiment of the manufacturing method of the present invention will be described with reference to FIG. First, in the ultraviolet curing adhesive filling step F1, two coated polarization maintaining optical fibers were inserted into a transparent fixing member made of a transparent glass tube or a transparent plastic tube, or a transparent U-shaped glass sleeve or a transparent U-shaped plastic sleeve. Thereafter, the coating at one end of the optical fiber is peeled off for a predetermined length so that the polarization direction can be confirmed, and then the inside of the transparent fixing member is filled with an ultraviolet curing adhesive. Note that the coating on one end of the optical fiber may be peeled off for a predetermined length before the two optical fibers are inserted. The next polarization direction adjusting step F2 is a step of adjusting the polarization directions of the two coated polarization-maintaining optical fibers after the ultraviolet curing adhesive filling step F1. In the next optical fiber fixing step F3, the transparent fixing member after the polarization direction adjusting step F2 is irradiated with ultraviolet rays to cure the ultraviolet curing adhesive, and the two coated polarization-maintaining optical fibers are fixed to the transparent fixing member. And a polarization maintaining optical fiber fixed body. In addition, the length of the polarization-maintaining optical fiber protruding from the transparent fixing member tip of the polarization-maintaining optical fiber fixed body may be adjusted to a predetermined length, and a step of removing a predetermined length of the coating at the tip may be provided. Good. In the next ferrule assembling step F4, after filling the inside of the ferrule hole of the two-core ferrule having two holes, the polarization-maintaining optical fiber fixed body is inserted from the side from which the coating of the optical fiber has been peeled off, and heated. To cure the adhesive, thereby obtaining a two-core polarization maintaining optical fiber.

Embodiment 2 In the manufacturing method of the present invention, a specific embodiment using a transparent glass tube (hereinafter, referred to as a glass tube) as a transparent fixing member will be described with reference to FIGS. 2 to 6 and FIG. This will be described in detail below. As shown in FIG. 2, inner diameter 0.5 mm, outer diameter 1.0 m
m, a glass tube (3a) having a length of 5 mm and a coated polarization maintaining optical fiber having an outer diameter of 250 μm (hereinafter referred to as a fiber core).
Insert two (2a). The coating (2) at one end of both fiber cores (2a, 2a) is peeled off for a predetermined length, and this end is cut so that the polarization direction can be confirmed. One is the first polarization maintaining optical fiber (1a)
And the other becomes the second polarization maintaining optical fiber (1b). UV curing adhesive (hereinafter referred to as UV adhesive) (4)
To the part of the fiber core (2a) where the glass tube (3a) is fixed.
Apply about mm. The glass tube (3a) is brought on it, and the inside of the glass tube is filled with the ultraviolet adhesive (4). Each of the fiber cores (2a) coming out of the glass tube (3a) is polarized by a microscope (101), a fiber fixing jig (102), and a rotating mechanism fine adjustment table (103) as shown in FIG. Set on the direction adjustment fixture (100). While confirming the fiber end face (or the side face) with the microscope (101), rotating the fine tuning table (103) rotates both fiber cores (2a, 2a) so that the polarization direction becomes necessary. Match. The glass tube (3a) filled with the ultraviolet adhesive (4) is irradiated with ultraviolet rays using an ultraviolet irradiator (not shown), and the adhesive (4) is cured, and the two optical fibers (2a, 2a) are cured. ) And glass tube
Fix (3a). A 10 mm portion is cut from the glass tube (3a), and the coating (2) on the portion is removed. This state is as shown in FIG. 3, which is a schematic diagram showing a fiber core fixed state (a polarization maintaining optical fiber fixed body) before the ferrule is inserted. As shown in the longitudinal sectional view of the main part of FIG. 4, a two-core ferrule having two holes therein, and a symmetric hole two-core ferrule (15) comprising a symmetric hole ceramic body (11) and a stainless steel tube (12) of its exterior. ) Is filled with an epoxy-based adhesive (5).
Are inserted from the first and second polarization maintaining optical fibers (1a, 1b). The symmetrical two-core polarization maintaining optical fiber (20) is completed by placing the symmetric hole two-core ferrule (15) into which the above-mentioned polarization maintaining optical fiber fixed body is inserted into a curing furnace and curing the adhesive (5). Let it. FIG. 5 shows a distal end face of the two-core polarization maintaining optical fiber (20).

As shown in the longitudinal sectional view of the main part of FIG. 4 and the end view of FIG. 5, the symmetric type two-core polarization maintaining optical fiber (20) of the present invention has a hole in the ferrule (15). The first polarization maintaining optical fiber (1a) and the second polarization maintaining optical fiber (1b) are inserted with the polarization direction fixed. The polarization maintaining optical fiber (1) has a core as shown in FIG.
(r), a clad (s), and two stressed portions (f, f). The portion inserted into the ceramic body (11) has the coating (2) removed. The symmetric two-core polarization maintaining optical fiber (20) can adjust the polarization direction as desired by the polarization direction adjusting step F2. The core polarization maintaining optical fiber can be easily and accurately manufactured.

FIG. 6 (a) shows a symmetric single-row parallel polarization axis double-core polarization maintaining optical fiber (20a). The polarization direction of the two polarization maintaining optical fibers (1a, 1b) is parallel to one row. is there. FIG. 2B shows a symmetric two-row parallel polarization axis two-core polarization maintaining optical fiber (2
0b), and the polarization directions of the two polarization-maintaining optical fibers (1a, 1b) are parallel in two rows. FIG. 3C shows a symmetric orthogonal polarization axis two-core polarization maintaining optical fiber (20c), and the polarization directions of the two polarization maintaining optical fibers (1a, 1b) are orthogonal to each other.
These two-core polarization maintaining optical fibers can be suitably used for applications utilizing the relative relationship of the polarization direction of the paired optical fibers.

Embodiment 3 In the manufacturing method of the present invention, a specific embodiment using a transparent U-shaped glass sleeve as a transparent fixing member will be described with reference to FIGS.
12 will be described in detail below. As shown in FIG. 7, a transparent U-shaped glass sleeve having a U-shaped portion having a depth of 0.5 mm, an outer diameter of 1.0 mm and a length of 5 mm (
Two fiber cores (2a) having an outer diameter of 250 μm are inserted into the sleeve (3b). The coating (2) at one end of both fiber cores (2a, 2a) is peeled off for a predetermined length, and this end is cut so that the polarization direction can be confirmed. One is the first polarization maintaining optical fiber (1a)
And the other becomes the second polarization maintaining optical fiber (1b). An ultraviolet adhesive (4) is applied to the entire length of the U-shaped portion of the sleeve (3b). The fiber core (2a) of the part to be fixed is taken on it, and the inside of the U-shaped part is filled with the ultraviolet adhesive (4). Each of the fiber cores (2a) protruding from the sleeve (3b) is set on a polarization direction adjusting fixture (100) shown in FIG. 12 similarly to the second embodiment. The polarization plane direction is adjusted to a necessary state in the same manner as in the second embodiment. The sleeve (3b) filled with the ultraviolet adhesive (4) is irradiated with ultraviolet rays using an ultraviolet irradiator (not shown) to cure the adhesive (4), and the fiber core (2a) and the sleeve ( 3b) is fixed. This state is shown in FIG. A 10 mm portion is cut from the sleeve (3b), and the coating (2) on the portion is removed. This state is as shown in FIG. 8, which is a schematic diagram showing the fiber core fixed state (the polarization maintaining optical fiber fixed body) before the ferrule is inserted. As shown in FIG. 9, a two-core ferrule having two holes inside, and epoxy-based bonding to an asymmetric two-core ferrule (15 ') composed of an asymmetric ceramic body (11') and a stainless steel tube (12) of its exterior. The agent (5) is filled, and the polarization-maintaining optical fiber fixed body shown in FIG. 8 is inserted from the first and second polarization-maintaining optical fibers (1a, 1b). The two-core ferrule (15 ') having the asymmetric hole into which the polarization-maintaining optical fiber fixing member is inserted is placed in a curing furnace and the adhesive is cured to complete the asymmetric type two-core polarization-maintaining optical fiber (30).

As shown in the longitudinal sectional view of FIG. 9 and the end view of FIG. 10, the asymmetric type two-core polarization maintaining optical fiber (30) of the present invention has a hole of an asymmetric two-core ferrule (15 '). The first polarization maintaining optical fiber (1a) and the second polarization maintaining optical fiber (1a)
b) is inserted with the polarization direction fixed. Although not shown in FIG. 9, as shown in FIG. 5, the polarization-maintaining optical fibers (1) and (1a, 1b) each include a core (r), a clad (s), and two stressed portions ( f). The part inserted into the asymmetric ceramic body (11 ') is covered with a coating.
(2) has been removed. The asymmetric type two-core polarization maintaining optical fiber (30) is provided in the polarization direction adjusting step F2.
Accordingly, the polarization direction can be adjusted as desired, and various asymmetric types of two-core polarization maintaining optical fibers as shown in FIG. 11 can be easily and accurately manufactured.

FIG. 11A shows an asymmetric single-row parallel polarization axis double-core polarization-maintaining optical fiber (30a). The polarization direction of the two polarization-maintaining optical fibers (1a, 1b) is parallel to one row. is there. FIG. 1B shows an asymmetric two-row parallel polarization axis two-core polarization maintaining optical fiber.
(30b), and the polarization directions of the two polarization-maintaining optical fibers (1a, 1b) are parallel in two rows. FIG. 4C shows an asymmetric inner orthogonal polarization axis two-core polarization maintaining optical fiber (30c), and the polarization directions of the two polarization maintaining optical fibers (1a, 1b) are inwardly orthogonal.
FIG. 2D shows an asymmetric outer orthogonal polarization axis two-core polarization maintaining optical fiber (30d), and the two polarization maintaining optical fibers (1d).
The polarization directions of a, 1b) are outwardly orthogonal. These two-core polarization maintaining optical fibers can be suitably used for applications utilizing the relative relationship of the polarization direction of the paired optical fibers.

[0016]

According to the manufacturing method of the present invention, the optical fiber is inserted into a transparent fixing member such as a transparent glass tube or a transparent plastic tube in a state where the outer periphery of the optical fiber is covered (fiber core wire), and the polarization direction is adjusted. After that, by irradiating an ultraviolet ray to an ultraviolet ray adhesive located in the middle of the fiber core wire and the transparent fixing member, the adhesive is cured, and the polarization direction is fixed. There is no need to rotate it while touching it directly. When the optical fiber is inserted into the ferrule when the optical fiber is inserted into the ferrule, the adhesive acts as a cushion between the ferrule and the optical fiber and does not directly hit the ferrule. By the above, disconnection of the optical fiber in the ferrule is reduced. Also, since the optical fiber is inserted into the ferrule after being fixed with the transparent fixing member, the inside of the ferrule may be filled with an adhesive (there is no need to check the polarization direction after insertion, so the fiber end face becomes dirty. The advantage is that the adhesive can be filled in the ferrule without using special equipment. Further, the two-core polarization maintaining optical fiber obtained by the manufacturing method of the present invention can be suitably used for applications utilizing the relative relationship of the polarization directions of the paired optical fibers. Therefore, the present invention has an extremely large effect of contributing to industry.

[Brief description of the drawings]

FIG. 1 is a chart showing an example of a method for manufacturing a two-core polarization maintaining optical fiber of the present invention.

FIG. 2 shows a state in which a transparent glass tube is used as a transparent fixing member and a fiber core is fixed with an ultraviolet-curing adhesive (a polarization-maintaining optical fiber fixed body) at the stage of manufacturing the two-core polarization maintaining optical fiber of the present invention. FIG. FIG. 1A is a front view, and FIG. 1B is a cross-sectional view of the glass tube.

FIG. 3 is a schematic view showing a fixed state of a fiber core before inserting a ferrule, in which a coating of a fiber core at a terminal part of the polarization maintaining optical fiber fixed body of FIG. 2 is removed and adjusted. FIG. 1A is a front view, and FIG. 1B is a cross-sectional view of the glass tube.

FIG. 4 is a longitudinal sectional view of a main part of a two-core polarization maintaining optical fiber (symmetric type) manufactured by the manufacturing method of the present invention.

FIG. 5 is an external view of the distal end of a two-core polarization maintaining optical fiber (symmetric type) manufactured by the manufacturing method of the present invention.

FIG. 6 is an external view of the distal end of various two-core polarization maintaining optical fibers (symmetrical type) manufactured by the manufacturing method of the present invention.
2A shows a symmetric single-row parallel polarization axis double-core polarization-maintaining optical fiber, FIG. 2B shows a symmetric two-row parallel polarization axis two-core polarization-maintaining optical fiber, and FIG. This is a two-core polarization maintaining optical fiber having an orthogonal polarization axis.

FIG. 7 is a schematic view showing a state in which a transparent U-shaped glass sleeve is used as a transparent fixing member and a fiber core is fixed (a polarization-maintaining optical fiber fixed body). FIG. 1A is a front view, and FIG. 1B is a cross-sectional view of a U-shaped glass sleeve portion.

FIG. 8 is a schematic view showing a fixed state of a fiber core before insertion of a ferrule, in which a coating on a terminal portion of the polarization maintaining optical fiber fixed body of FIG. 7 is removed and adjusted. FIG. 1A is a front view, and FIG. 1B is a cross-sectional view of a U-shaped glass sleeve portion.

FIG. 9 is a longitudinal sectional view of a main part of a two-core polarization maintaining optical fiber (asymmetric type) manufactured by the manufacturing method of the present invention.

FIG. 10 is an external view of the distal end of a two-core polarization maintaining optical fiber (asymmetric type) manufactured by the manufacturing method of the present invention.

FIG. 11 is an external view of the distal end of various two-core polarization maintaining optical fibers (asymmetric type) manufactured by the manufacturing method of the present invention. FIG. 3A shows an asymmetric single-row parallel polarization axis two-core polarization maintaining optical fiber, and FIG.
(C) is a two-core polarization-maintaining optical fiber with an asymmetric inner orthogonal polarization axis, and (d) is a two-core polarization-maintaining optical fiber with an asymmetric outer orthogonal polarization axis.

FIG. 12 is a schematic diagram illustrating a state in which the polarization direction of an optical fiber is adjusted using the polarization direction adjustment fixture of the present invention.

[Explanation of symbols]

 Reference Signs List 1 polarization-maintaining optical fiber 1a first polarization-maintaining optical fiber (polarization-maintaining optical fiber) 1b second polarization-maintaining optical fiber (polarization-maintaining optical fiber) 2 coating 2a coated polarization-maintaining optical fiber (fiber core fiber) 3) Transparent fixing member 3a Transparent glass tube 3b Transparent U-shaped glass sleeve 4 UV curing adhesive 5 Adhesive 11 Symmetric hole ceramic body 11 'Asymmetric hole ceramic body 12 Stainless steel tube 15 Symmetric hole 2 core ferrule 15' Asymmetric hole 2 core ferrule 20 Two-core polarization-maintaining optical fiber (symmetric type) 20a Symmetric single-row parallel polarization axis two-core polarization-maintaining optical fiber 20b Symmetric two-row parallel polarization axis dual-core polarization-maintaining optical fiber 20c Symmetric orthogonal polarization axis two-core polarization-maintaining Optical fiber 30 Two-core polarization-maintaining optical fiber (asymmetric type) 30a Asymmetric single-row parallel polarization axis 2-core polarization-maintaining optical fiber 30b Asymmetric two-row parallel polarization axis dual-core polarization-maintaining optical fiber 30c Asymmetric inner orthogonal Optical axis two-core polarization-maintaining optical fiber 30d asymmetrical outer orthogonal polarization axes 2 core polarization-maintaining optical fiber 100 polarization direction adjusting fixture 102 fiber fixing jig 103 rotating mechanism fine adjustment stage f stress unit j central axis r core s cladding

Claims (4)

[Claims] 1. After inserting two coated polarization-maintaining optical fibers into a transparent glass tube or a transparent plastic tube, or a transparent fixing member composed of a transparent U-shaped glass sleeve or a transparent U-shaped plastic sleeve, An ultraviolet curing adhesive filling step of peeling off the coating on one end for a predetermined length and filling the inside of the transparent fixing member with an ultraviolet curing adhesive so that the polarization direction can be confirmed; and after the ultraviolet curing adhesive filling step, A polarization direction adjusting step of adjusting the polarization direction of the two coated polarization-maintaining optical fibers; and irradiating the transparent fixing member after the polarization direction adjusting step with ultraviolet rays to cure the ultraviolet curing adhesive. An optical fiber fixing step of fixing the two coated polarization-maintaining optical fibers to a transparent fixing member to form a polarization-maintaining optical fiber fixed body; and a two-core ferrule having two holes. A ferrule assembling step of inserting the polarization-maintaining optical fiber fixed body from the side from which the coating of the optical fiber has been peeled off and then heating and curing the adhesive after filling the inside of the ferrule hole with the adhesive. A method for manufacturing a two-core polarization maintaining optical fiber, comprising: 2. A two-core polarization maintaining optical fiber obtained by the method for producing a two-core polarization maintaining optical fiber according to claim 1. 3. The two-core polarization maintaining optical fiber is of a symmetric type, and a symmetric single-row parallel polarization axis two-core polarization-maintaining optical fiber, a symmetric two-row parallel polarization axis two-core polarization-maintaining optical fiber, or a symmetric orthogonal. 3. The two-core polarization maintaining optical fiber according to claim 2, wherein the two-core polarization maintaining optical fiber is a polarization axis. 4. The two-core polarization-maintaining optical fiber is an asymmetric type, an asymmetric single-row parallel polarization axis two-core polarization-maintaining optical fiber, an asymmetric two-row parallel polarization axis two-core polarization-maintaining optical fiber,
3. The two-core polarization maintaining optical fiber according to claim 2, wherein the two-core polarization maintaining optical fiber is an asymmetric inner orthogonal polarization axis and a two-core polarization maintaining optical fiber.