JPS60226425A - Preparation of optical fiber with constant polarized electromagnetic radiation - Google Patents

Abstract

PURPOSE:To obtain optical fiber with constant polarized electromagnetic radiation and nonsperical section simply and inexpensively, by collecting a core parent material and a stress imparting parent material in such a way that an external shape is nonsperical to form a preform rod, heating and spinning it. CONSTITUTION:The core parent material 4 having the core 5, the stress imparting parent materials 1 having the stress imparting parts 2, and the spacer parent materials 6 are prepared by VAD method, etc. Then, the sides 3 of the two stress imparting parent materials 1 are shaved off, the shaved faces are arranged opposing each other, the two spacer parent materials 6 are set in such a way that the core parent material 4 is sandwiched between the stress imparting parent materials 1, and they are collected so that the external shape is nonspherical, and the relationship of position of the stress imparting part 2 to the core 5 has a specific relationship of angle to the direction of preservation of plane of polarization, to form a preform rod. The rod is then heated, each parent material is thermally fused each other, and spun, to give the desired optical fiber with constant polarized electromagnetic radiation.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application This invention relates to a method for manufacturing a polarization-controlled optical fiber, and more particularly to a method for manufacturing a polarization-controlled optical fiber whose cross-section has a non-circular outer shape.

(b) Prior art Traditionally, non-circularly polarized optical fibers have been produced by first making a rod similar to a pre-7 ohm rod for a normal circularly polarizing optical fiber, and then cutting this rod into a non-circular shape. They were manufactured by adding new protrusions.

However, in the former method, which involves cutting out, the rod is cut out to the required non-circularity from a relatively thick rod.
The disadvantage is that it requires a considerable amount of cutting and takes a lot of time.

Also, the latter method of adding protrusions often requires adding protrusions with a similar diameter to the original preform rod in order to achieve the required non-circularity, and thus The diameter of the resulting polarized optical fiber is quite large, and due to manufacturing technology, it is necessary to use a quartz glass rod as the protrusion.
There are drawbacks such as increased manufacturing costs.

(C) Purpose This invention can significantly reduce the manufacturing process, easily adjust non-circularity, and also reduce manufacturing costs by reducing the manufacturing process and material costs. , an object of the present invention is to provide a method for manufacturing a non-circularly polarized optical fiber.

(D) Structure According to the present invention, first, a core base material having a core and a stress applying base material having a stress applying portion are prepared, and then these base materials are assembled to form a preform rod. However, at that time, the outer shape of the aggregate of these base materials is assembled into a non-circular shape that has a predetermined relationship with respect to the positional relationship of the stress applying part with respect to the core, and then the preform thus formed is The rod is heated and spun.

A polarization-constant optical fiber having a non-circular cross-sectional shape is manufactured.

(e) Example First, three types of rods 1 and 4.6 as shown in FIG. 1 are manufactured and prepared by the VAD method or the like.

The rod l is a stress-applying base material, and has a stress-applying part 2 doped with B, O, Gem, etc. in the center of S i O2, the outer diameter of which is 1'4 mm, and the stress-applying part 2 is The diameter is 6
．． 5■■, and the length was 200 mm. The side surface of this rod 1 is ground down by about 3 mm, that is, the lattice-like portion 3 of D=3 mm in the figure is ground off. The rod 4 was a core base material made of SiO2, had a core 5 doped with Gem, etc. in the center, and had an outer diameter of 3.5 mm and a length of 200 mm.

In addition, the rod 6 is made of Sioy and has an outer diameter of 3.5 mm.
This is a spacer base material with a length of 200 mm. Next, the stress-applying base material 1 prepared in this way is placed into two pieces of wood, and the core base material 4 is
A total of five wooden rods, one for spacer base material 6 and two for spacer base material 6, are arranged as shown in FIG. 2 to form a preform rod. That is, the stress-applying base material 1 is placed on both sides of the core base material 4 with the shaved surfaces facing the core base material 4.
, place l.

A spacer base material 6.6 is placed in the gap between these stress-applying base materials 1, 1 so as to sandwich the core base material 4 therebetween.

Here, at the stage of the preform rod, the outer shape is non-circular, and the non-circularity has a predetermined angular relationship with the stress applying portion 2, that is, a predetermined angular relationship with the polarization preservation direction. We should pay attention to Then, by heating this preform rod, the respective base materials are thermally fused to each other and spun. When a thin coating layer 7 with a thickness of approximately 2 m is provided on an optical fiber formed by spinning, as shown in FIG. A polarized optical fiber 8 was obtained.

The long axis A of the non-circular constant polarization optical fiber 8 obtained in this example was 129 long meters, and the short axis B was 74 long meters.

In the above, the core base material 4 is made circular and sandwiched between two spacer base materials 6, but as shown in FIG. good.

(F) Effect According to the present invention, each base material is assembled to form a preform rod so that the outer shape of the aggregate is non-circular, and this pre-2 ohm rod is spun to form a non-circular polarization constant optical fiber. Since the number of steps is small and it is possible to avoid scraping off a large amount of the base material, the time required for manufacturing the preform rod can be significantly shortened. In addition, the non-circularity can be easily adjusted by adjusting the diameter and amount of scraping of each base material constituting the preform rod. Furthermore, since a relatively small amount of material is required, and even if only a small amount is to be scraped off, material costs can be saved, and together with the simplification of the process, this can contribute to a reduction in manufacturing costs.

[Brief explanation of the drawing]

1, 2, and 3 show each step in a manufacturing method according to an embodiment of the present invention, and FIG. 1 is a perspective view of each base material constituting a preform rod, and FIG. 3 is a sectional view of the preform rod 7, FIG. 3 is a sectional view of the produced constant polarization optical fiber, and FIG. 4 is a sectional view of the preform rod in another embodiment. DESCRIPTION OF SYMBOLS 1... Stress applying base material 2... Stress applying part 3... Scraped-off part 4... Core base material 5... Core 6... Spacer base material 7... Coating layer 8...・Non-circular constant polarization optical fiber Applicant: Fujikura Electric Wire Co., Ltd. Representative, Patent Attorney Yusuke Sato AA=% Answer 1 Jun 2 F Minato 3 Calculation g Retrospection Z On

Claims (1)

[Claims] (1) A core base material having a core and a stress-applying base material having a stress-applying portion are formed into a non-circular shape such that the outer shape of the aggregate has a predetermined relationship with respect to the positional relationship of the stress-applying portion with respect to the core. A method for manufacturing a polarization-controlled optical fiber, which comprises the steps of assembling the preform rods to form a preform loft, and heating and spinning the preform rods.