JPH06242346A - Ferrule for polarization maintaining optical fiber and sleeve - Google Patents

Abstract

PURPOSE:To provide a connecting jig capable of aligning respective polarization axes only by inserting ferrules fixing polarization maintaining optical fibers into a butting sleeve. CONSTITUTION:Two ferrules 1 for polarization maintaining optical fibers are inserted from both the sides of the butting sleeve 5. Plane parts 3 are formed on the engaging parts 2 of respective ferrules 1 and the positions of the plane parts 3 in a rotational direction are regulated by a reference plane part 6 formed on the sleeve 5 so that respective plane parts 3 are allowed to butt against each other. Each polarization maintaining optical fiber is fixed in an optical fiber inserting hole 4 so as to hold prescribed positional relation between a polarization plane the plane part 3. Thereby the center axis of the fiber and the polarization axis can be aligned only by inserting the ferrules 1 from both the sides of the sleeve 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polarization-maintaining optical fiber ferrule and a sleeve, which connect the polarization-maintaining optical fibers with their central axes and polarization axes aligned with each other.

[0002]

2. Description of the Related Art It is known that an optical fiber has a single polarization characteristic when the refractive indexes of regions in two orthogonal directions in a cross section perpendicular to the longitudinal direction of the optical fiber are different from each other.
Such an optical fiber is called a polarization maintaining optical fiber.

FIG. 14 is a sectional view of an example of a polarization maintaining optical fiber, which is a so-called panda type. In the figure, 11 is a polarization maintaining optical fiber, 12 is a core, 13 is a clad, 14
Is a stress applying part, and 15 and 16 are polarization axes. A polarization imparting optical fiber 11 having a core 12 and a clad 13 is provided with a stress-applying portion 14 made of glass having a large thermal expansion coefficient on one diameter inside the clad 13 with the core 12 interposed therebetween. The stress imparting portion 14 causes a difference in refractive index in the directions of the two axes orthogonal to each other, and the polarization axes 15 and 16 are formed.

Unlike ordinary optical fibers, the polarization-maintaining optical fibers are connected not only to the mutual central axes of the polarization-maintaining optical fibers to be connected but also to maintain the characteristics of the polarization-maintaining optical fibers. It is necessary to match the wave axes and connect them. A conventional polarization-maintaining optical fiber connection jig uses a connector that can freely rotate the ferrule,
After inserting the ferrule into the sleeve and abutting them, the ferrule is rotated, and while checking the optical power, the polarization axes are aligned and connected.

When such a conventional connecting jig is used, not only the equipment and work for confirming the optical power when aligning the polarization axes are required, but also the polarization axes are matched each time the connection is made. There was a problem that I had to let them do it.

[0006]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and the polarization axes can be matched by simply inserting a ferrule having a polarization-maintaining optical fiber fixed into a butt sleeve. An object is to provide a connection jig that can be used.

[0007]

The present invention is a ferrule for a polarization-maintaining optical fiber, characterized in that at least one flat surface portion is provided in a fitting portion with a butt sleeve.

Further, in the polarization maintaining optical fiber sleeve, at least one reference flat surface portion for aligning the flat surface portions provided in the fitting portions of the mutual polarization maintaining optical fiber connecting ferrules to be connected is provided. It is characterized by.

The reference flat surface portion may be formed integrally with all or a part of the butt sleeve itself, may be formed into a half-cylindrical cylinder provided in the butt sleeve, or may be formed with a cutout portion in a part of the butt sleeve. It can be formed on a reference member provided in the cutout portion.

Further, in order to accurately align the polarization axes, the gap between the flat surface of the fitting portion of the ferrule and the reference flat surface of the butting sleeve must be several μm or less. Since it is difficult to insert the mating part into the butt sleeve while aligning the flat part and the reference flat part, make sure that the end of the flat part of the ferrule and both ends of the reference flat part near the insertion port of the mating part of the butt sleeve are It is also characterized in that it is tapered.

[0011]

According to the present invention, if the polarization axis-maintaining optical fiber is fixed to the connecting ferrule by aligning the polarization axis with the plane portion formed in the fitting portion of the ferrule for connecting optical fibers in advance, the fitting can be achieved. It is possible to align the central axis and the polarization axis of the mutual polarization axis holding optical fibers to be connected by aligning the flat section of the section with the reference flat section to be aligned and inserting it into the butt sleeve. .

Further, when the reference flat surface portion is formed by molding the butt sleeve, the reference flat surface portion is not displaced with respect to the sleeve, and the number of jigs required is small.

Further, when the half-split cylinder is inserted into the butt sleeve and the reference flat portion is formed by the flat portion of the half-split cylinder, the polarization-maintaining optical fiber is not processed into the existing connecting sleeve. It is possible to match the polarization axes of.

In the case where a suitable cutout portion is provided on the butt sleeve and a reference member such as a plate or a bar having a flat surface portion is inserted from the cutout portion to form the reference flat surface portion by the flat surface portion of the reference member. Since the reference flat surface portion can be inserted from the outside of the butt sleeve, the flat surface portion of the fitting portion and the reference flat surface portion can be aligned after the fitting portion of the ferrule is inserted into the butt sleeve.

Further, by making the tip end of the flat portion of the fitting portion of the sleeve and both ends of the reference flat portion tapered, it becomes easy to align the flat portion of the fitting portion with the reference flat portion, Connection in a shorter time becomes possible.

[0016]

FIG. 1 is a sectional view showing a state in which a ferrule for a polarization maintaining optical fiber according to an embodiment of the present invention is inserted into a butt sleeve. In the figure, 1 is a ferrule for a polarization maintaining optical fiber, 2 is a fitting portion, 3 is a flat surface portion, 4 is an optical fiber insertion hole, 5 is a butting sleeve, and 6 is a reference flat surface portion.
Two polarization-maintaining optical fiber ferrules 1 are inserted from both sides of a butt sleeve 5. A polarization maintaining optical fiber is positioned and fixed in the optical fiber insertion hole 4 of the polarization maintaining optical fiber ferrule 1 as described later. A flat portion 3 is formed on the fitting portion 2 of the two polarization-maintaining optical fiber ferrules 1, and the reference flat portion 6 provided on the butt sleeve 5 regulates the position of the flat portion 3 in the rotation direction. Then, the two polarization-maintaining optical fiber ferrules 1 are abutted at the positions where the respective plane portions 3 match.

FIG. 2 is a plan view of the tip of the ferrule for the polarization maintaining optical fiber of FIG. In the figure, 2 is a fitting portion, 3
Is a plane portion, 11 is a polarization maintaining optical fiber, 12 is a core, 1
Reference numeral 3 is a clad, 14 is a stress applying portion, and 15 and 16 are polarization axes. The outer shape of the fitting portion 2 is an arc, and the fitting portion 2 is fixed to the optical fiber insertion hole so that the center of the polarization maintaining optical fiber 11 coincides with the center thereof. When fixed, the polarization axis 15 of the polarization-maintaining optical fiber 11 is set to have a predetermined relationship with the plane portion 3, for example, the polarization axis 15 is parallel to the plane portion 3.

Therefore, as shown in FIG. 1, the reference plane section 6 is inserted into the butting sleeve 5 so that the plane section 3 of the ferrule 1 for polarization-maintaining optical fiber is aligned with the reference plane section 6, and in the state where they are butted, Both polarization-maintaining optical fibers have their respective central axes and polarization axes aligned with each other.

FIG. 3 is a perspective view of a first embodiment of a ferrule for a polarization maintaining optical fiber according to the present invention. In the figure, the same parts as those in FIG. In the polarization-maintaining optical fiber ferrule 1, a flat portion 3 is formed on a part of the fitting portion 2. At the tip of the flat part 3,
It may be tapered by chamfering or the like.

FIG. 4 is a perspective view of the second embodiment of the polarization-maintaining optical fiber ferrule of the present invention. In the figure, the same parts as those in FIG. In this embodiment, in the polarization-maintaining optical fiber ferrule 1, the flat surface portion 3 extends over the entire length of the fitting portion 2.

FIG. 5 is a perspective view of a first embodiment of a butt sleeve in the polarization maintaining optical fiber sleeve of the present invention. In the figure, the same parts as those in FIG. The reference plane portion 6 is formed on a part of the entire length by molding the butting sleeve 5 itself.

FIG. 6 is a perspective view of a second embodiment of the butting sleeve in the polarization maintaining optical fiber sleeve of the present invention. In the figure, the same parts as those in FIG. Also in this embodiment, the reference plane portion 6 is
The butt sleeve 5 itself is formed by molding, but is formed over the entire length. Since the reference plane portion 1 extends over the entire length of the butting sleeve 5, the reference plane portion 6 can be confirmed from the end of the butting sleeve 5 when the fitting portion of the polarization maintaining optical fiber ferrule is inserted. Compared to the matching sleeve 5 of the embodiment, there is an advantage that the flat surface portion of the fitting portion of the polarization maintaining optical fiber ferrule and the reference flat surface portion 6 in the matching sleeve 5 can be easily aligned.

FIG. 7 is a side sectional view of a third embodiment of the butting sleeve in the polarization maintaining optical fiber sleeve of the present invention. In the figure, the same parts as those in FIG. 7 is a tapered portion. In this embodiment, tapered portions 7 are formed on both ends of the reference plane portion 6. By providing the taper portion 7, it becomes easy to align the flat portion of the fitting portion of the polarization-maintaining optical fiber ferrule with the reference flat portion 6.

FIG. 8 is a perspective view of a fourth embodiment of a butting sleeve in the polarization maintaining optical fiber sleeve of the present invention. In the figure, the same parts as those in FIG. 8 is a half-cylinder. In this embodiment, the reference flat portion 6 is formed by inserting the half-split cylinder 8 into the butt sleeve 5 without processing the butt sleeve 5 that is generally used. The half-cylinder 8 may be simply inserted into the butting sleeve 5, but it is advantageous to fix it by adhesion or the like from the viewpoint of handling.

9 and 10 are perspective views of an example of the half-split cylinder 8 used in the fourth embodiment. FIG. 9 shows a shape obtained by cutting a part of a cylinder, and FIG. 10 shows a shape in which tapered portions 7 are formed at both ends of the half-divided cylinder of FIG.

FIG. 11 is a perspective view of a fifth embodiment of the butting sleeve in the polarization maintaining optical fiber sleeve of the present invention. In the figure, the same parts as those in FIG. 9 is a plate member. As the butt sleeve 5, a commonly used one for connection can be used, and a square hole is cut out at the bottom thereof,
The rectangular parallelepiped plate member 9 is inserted into the cutout hole as a reference member. The upper surface of the plate member 9 serves as the reference flat surface portion 6. In this embodiment, it is possible to insert the reference member after inserting the fitting portion of the polarization-maintaining optical fiber ferrule into the butting sleeve 5. Also in the reference flat surface portion 6 of the plate member 9, a tapered portion may be formed as in the above-described embodiment.

FIG. 12 is a side view of a sixth embodiment of the butt sleeve in the polarization maintaining optical fiber sleeve of the present invention. In the figure, parts similar to those in FIG. 11 are assigned the same reference numerals and explanations thereof are omitted. In this embodiment, in the fifth embodiment, both sides of the cutout hole are cut out in a triangular shape to form an insertion groove. Both sides of the plate member 9 may be formed in a triangular shape so as to fit the insertion groove, and the plate member 9 may be slid into the insertion groove for attachment.

In the above-mentioned embodiment, there is only one plane formed on the fitting portion of the polarization-maintaining optical fiber ferrule. However, a plurality of flat portions may be formed. FIG.
Is an embodiment in which two plane portions 3a and 3b are formed.
The reference flat portion of the butt sleeve is also the flat portion 3a, 3b.
Is formed in a shape corresponding to. If the flat portions 3a and 3b are formed in parallel, the polarization-maintaining optical fiber ferrule can be inserted into the butt sleeve without considering the upper and lower sides.

[0029]

As is apparent from the above description, according to the present invention, it is not necessary to check the optical power in order to align the polarization axes when the polarization maintaining optical fiber is connected, and it is possible to shorten the time. You can make connections that satisfy the desired characteristics. In addition, the polarization-maintaining optical fiber fixed to the ferrule for connecting the optical fiber has an effect that the central axis and the polarization axis can be easily connected in any combination.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a ferrule for a polarization-maintaining optical fiber according to an embodiment of the present invention inserted in a butt sleeve.

FIG. 2 is a plan view of a tip portion of the polarization-maintaining optical fiber ferrule 1 of FIG.

FIG. 3 is a perspective view of a first embodiment of a polarization-maintaining optical fiber ferrule of the present invention.

FIG. 4 is a perspective view of a second embodiment of the polarization-maintaining optical fiber ferrule of the present invention.

FIG. 5 is a perspective view of a first embodiment of a butting sleeve in the polarization maintaining optical fiber sleeve of the present invention.

FIG. 6 is a perspective view of a second embodiment of a butting sleeve in the polarization maintaining optical fiber sleeve of the present invention.

FIG. 7 is a perspective view of a third embodiment of a butting sleeve in the polarization maintaining optical fiber sleeve of the present invention.

FIG. 8 is a perspective view of a fourth embodiment of a butting sleeve in the polarization maintaining optical fiber sleeve of the present invention.

[Figure 9]

FIG. 10 is a perspective view of an example of a half cylinder used in the fourth embodiment.

FIG. 11 is a perspective view of a fifth embodiment of a butting sleeve in the polarization maintaining optical fiber sleeve of the present invention.

FIG. 12 is a side view of a sixth embodiment of a butting sleeve in the polarization maintaining optical fiber sleeve of the present invention.

FIG. 13 is a plan view of a tip end portion of another embodiment of the polarization-maintaining optical fiber ferrule.

FIG. 14 is a cross-sectional view of an example of a polarization maintaining optical fiber.

[Explanation of symbols]

 1 ferrule for polarization maintaining optical fiber 2 fitting part 3 plane part 4 optical fiber insertion hole 5 butt sleeve 6 reference plane part 7 taper part 8 half-cylinder 9 plate member 11 polarization maintaining optical fiber 12 core 13 clad 14 stress application Part 15, 16 Polarization axis

Claims (9)

[Claims] 1. A ferrule for a polarization-maintaining optical fiber, characterized in that at least one flat surface portion is provided in a fitting portion with a butt sleeve. 2. The polarization-maintaining optical fiber ferrule according to claim 1, wherein the tip of the flat surface portion is formed in a tapered shape. 3. A polarization-maintaining optical fiber sleeve having at least one reference flat surface portion for aligning the flat surface portions of the fitting portions of mutually connected polarization-maintaining optical fiber connecting ferrules. 4. The polarization maintaining optical fiber sleeve according to claim 3, wherein the reference flat surface portion is integrally formed on all or part of the butting sleeve itself. 5. The polarization maintaining optical fiber sleeve according to claim 4, wherein both ends of the reference flat surface portion are formed in a tapered shape. 6. The polarization-maintaining optical fiber sleeve according to claim 3, wherein a half cylinder having a reference plane portion is provided in the butting sleeve. 7. The polarization-maintaining optical fiber sleeve according to claim 6, wherein both ends of the reference plane portion of the half-cylinder are tapered. 8. The polarization maintaining optical fiber sleeve according to claim 3, wherein a cutout portion is formed in a part of the butting sleeve, and a reference member having a reference flat surface portion is provided in the cutout portion. . 9. The polarization maintaining optical fiber sleeve according to claim 8, wherein both ends of the reference flat surface portion of the reference member are formed in a tapered shape.