JPS5913645A - Manufacture of optical fiber retaining plane of polarization - Google Patents

Abstract

PURPOSE:To manufacture the titled optical fiber free from central slip at the core and having a sufficient ellipticity, by deforming a quartz tube having film for cladding to a tube having an elliptical cross-section, forming a base material by a rod-in-tube system by using the deformed tube, and drawing the base material. CONSTITUTION:A film 2 of lower m.p. glass such as B2O3+SiO2 glass for outer cladding and a film 3 of higher m.p. glass such as high purity SiO2 glass for inner cladding are successively formed on the inner wall of a quartz tube 1, and the tube 1 is deformed to an elliptical tube 5 having 15-40% ellipticity by heating while evacuating the tube 1. A rod 6 for a core is put in the elliptical quartz glass tube 5 having the films 2, 3, and they are united in a body by heating while evacuating the tube 5 in accordance with the desired ellipticity. The resulting base material is drawn to obtain an optical fiber retaining the plane of polarization. The ellipticity of the outer clad of the fiber is >=40%.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a polarization maintaining optical fiber.
.

11 Wavefront preserving optical fibers are disclosed in Japanese Patent Application Laid-Open No. 56-99.
d3 in Publication No. 306 and Japanese Unexamined Patent Publication No. 57-37305
Its basic structure has already been disclosed, and here C
Although a detailed explanation of its functions and the like will be omitted, J5 is a cross-section (as shown in FIG. 1) in the present invention.
It is of I4 construction, and 11 is quartz jacket 1-1 and 12.
is the outer cladding, 13 is the inner cladding, and 16 is called the a.

A relatively reliable method for obtaining such a structure is the fleshed CV l) method as disclosed in Japanese Patent Application Laid-Open No. 56-125233.

By the way, in the above-mentioned ('J CV D method, the center part of 7. ) phenomenon occurs. This part is located in the center of the core and plays an important role in transmission, so such a phenomenon must be avoided as much as possible.

Therefore, the VAD method and Sl-settlement axis 1: J IJ > 1
．． Alternatively, use the Zorgul method etc. to produce a 1) C optical fiber with no center hole, and use the Radinch 1-j method to produce a C optical fiber.
・There is a method of manufacturing iba.

However, in the manufacture of optical fibers using the polarization commercial method, which include layers with an elliptical cross section, it is difficult to apply this method to medium-sized fibers.

In other words, in order to obtain a predetermined bond length, it is essential to perform CIE with a predetermined ellipticity as necessary. However, the rod inch 1-1 method (-) cannot necessarily control the ellipticity uniquely depending on the relationship between the glass composition and the amount of pressure reduction.
(iUru.

The cause of this will likely be gradually elucidated through future research, but even if a cylindrical glass tube with a membrane is inserted with a yen + 1" cutter and heated under reduced pressure, the desired result will be achieved. It is extremely difficult to obtain a polarization-maintaining optical fiber of
It is J-Noh.

Furthermore, a membrane-coated glass tube with an ellipticity of 5% was manufactured, a cylinder [A1-1] was inserted into it, and it was heated under reduced pressure to make it solid. However, it is almost impossible to control the ellipticity by changing the amount of pressure reduction. Moreover, the generally required ellipticity of a polarization maintaining optical fiber is 40% or more.

In view of such a situation, the present invention has no central () in ``ノ', and in order to control Φ by 1, the desired (11 yen rate is set to IB
The purpose of this invention is to provide a method for constructing a polarization-maintaining optical waveguide that can be used for C.

The configuration of the present invention will be explained in detail based on one embodiment with reference to the drawings.

In FIG. 3, 1 is made of English glass, and has an outer diameter of 18 mm and a wall thickness of 1.5 mm, which exceeds the thickness of 1.

A low melting point glass film 2 serving as an outer cladding is formed on the inner wall of this quartz glass tube 1.

This low melting point glass film 2 (4 days 3203+-8iQ2 type glass or 4J 1.3203, [-1[)20s
There is Karas-C, which contains two or more kinds of dopants such as GeO2, etc., and is structured in a ratio to the crystal layer (J, -, which has a low melting point). The thickness of this film (,1, for example, r 200μ7
1, which is about 11, this low) i11 point sword 2 is a high melting point glass that becomes the inner cladding further inside the i11 point sword! Form 3.

The high fusion power lath film 3 is made of high purity IUSiO2 containing high purity 5102b, and has a high 1i14 degree compared to the above-mentioned low 8゛, 1 sword lath film 2. It is not necessarily necessary that the melting point be higher than that of the quartz glass whistle 1 or the core rod described below.

The high melting point glass film 3 has a thickness of approximately 30 μmm, for example.

The inside of the membrane 4 is depressurized and heated to transform it into an elliptical tube 5 with an ellipticity of 15%.

After that, this elliptical membrane (= J quartz glass tube 5 is vertically
''/C (, as shown in FIG. 4, C'j) Insert the Drad 6.

] 7 a Rad 6 is a rod without a center (J) manufactured by a method such as the V A l) method, and has an outer diameter of 700 mm, for example.
There is 6 C of u m0 Yoshi.

State C'' as shown in Fig. 4, 11 depending on the desired ellipticity.
The base material is obtained by heating and integrating the two parts at fj4f.

In this case, the quartz glass tube 4 was made to have an ellipticity of 15% in advance, and the quartz glass tube 4 was made with a 1714-inch cope.
By controlling the amount of pressure reduction, it is possible to easily obtain f7J with an ellipticity of 40% or more. (The ellipticity of El material is /1
Although it is possible to write it as 0% or less, it is practically unnecessary C.
'be. ) To delineate the lrj IA obtained in this way,
It is easy to obtain a polarization-maintaining light beam with a predetermined inertia.
I can't wait to get rba.

In addition, the ellipse here is pure 1juki, f, l#
It does not necessarily mean an n-shape, but rather a relatively elliptical shape.

Furthermore, the inventors made the glass tube 4 into an oval shape to form an elliptical membrane A1 quartz glass tube with an ellipticity of 20%, and similarly =1A]1 Insert the tube 6, reduce the pressure and heat the base material 19.

In this case as well, it was possible to easily obtain a base material having an ellipticity of 40% or more.

To give an example, the inner diameter is ellipticity 20%? mm! 11 Circular membrane quartz glass tube 5 formed, external i ¥700 II
Insert the 6mm allotment vertically to ~''l/, = condition C to reduce the internal pressure to -20mm1-12C) and heat it.
, IjJ + A by iq1゜The pan wavefront preservation light beam obtained by drawing this base material has an ellipticity of 40% and a wavelength of 0. The bond length (a3[) at 33 μmm was /4 mm.

Since the ellipticity of the LLI wavefront-preserving optical fiber required for one communication is 40% I'C', the range where it is easy to control the amount of depressurization is -J inch:t -'l'<-t Oval membrane A
%~,, /1.0% (゛Yes, more desired), or to 20' 40! 'a There is a desirable range C.

The ellipticity used for d5ζ in the wood specification is (91 wavefront conserved light) In Iba and its base material, C is the outer cladding '12
Refers to the ellipticity of the external shape of the elliptical membrane (=J quartz glass tube 5 (
d3 indicates the ellipticity of the outer shape.

The manufacturing method of the present invention as described above produces the following significant effects.

fit Z-J -i' f in i = J CV l) Instead of forming by the [1tsuF'-(Nji1-bu method), 'I!A is created, so the (] in the center is do not have,.

(2) Membrane (NJ?; Arrow crow color with ellipticity of 15% ~
/'C to perform rod-in-tube after forming to IO%
', ellipticity of 4 can be easily achieved by controlling suspension during solid integration.
0% or more polarization-maintaining light) 1 wave is converted to 1q.

[Brief explanation of the drawing]

FIG. 1 shows the iq order ll11! according to the present invention. wave 1
Cross-sectional explanatory diagram showing the urinary condyle light horn and iva, Figure 2 1.1. Ii7 to explain centernu ()! The diagrams illustrating the l!J ratio, FIGS.
There is an i-side explanatory diagram C. 1: b English glass tube, 2: low FAl!
Lasuns membrane, 3: Takato Sadato'7 Su membrane, /l:ll! i
jIJi'+1<force'lys↑゛λ, 5; Oval formation phrase quartz glass tube, 6: 21 horn 1'tsu 1-6 numbness 1 l Figure 3 and Figure 2 (A) (B) Kidney 4 diagram

Claims (1)

[Claims] 1? : A low melting point glass film 2 is formed on the inner wall of the quartz glass tube 1 as an outer cladding, and a high melting point glass film 3 as an inner cladding is further formed on the inner wall of the quartz glass tube 1. The core rod 6 is inserted into the elliptical quartz glass tube 5, heated and depressurized to create an elliptic shape with an ellipticity of 15 to 40%.
i! is a polarization-maintaining optical fiber that has a solid base material, the base material is drawn, and the ellipticity of the outer crut is 40% or more. A method for manufacturing a polarization-maintaining optical fiber characterized by