JPH0361909A - Polymer clad fiber for light transmission - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to a polymer clad optical fiber having a core made of quartz glass and a cladding made of a polymer. The present invention relates to a polymer clad optical fiber used as an optical fiber.

(Prior Art) Conventionally, silicone resin (Japanese Patent Publication No. 56-2321), fluorocarbon resin, etc. have been used as TARAD polymers for polymer clad silica optical fibers (PCF), which have a core of quartz glass (or optical glass) and a polymer cladding. Alkyl methacrylate polymer (JP-A-58-12146
1), vinylidene fluoride/tetrafluoroethylene copolymer (Japanese Patent Publication No. 56-41966), polyether ester adze (Japanese Patent Publication No. 56-60402), ultraviolet curable fluorinated acrylate composition (U.S. Patent Publication No. 56-60402), Patent No. 4,211,209) and the like are used.

(Problems to be Solved by the Invention) However, these TARAD polymers do not meet the recently required properties such as low optical transmission loss, easy caulking type connector attachment, and stabilization of temperature characteristics of optical transmission loss. It is impossible to respond to increasing sophistication.

Since silicone resin has low mechanical properties, particularly low mechanical strength, optical transmission loss increases when the connector is attached by caulking. Fluoroalkyl methacrylate polymers are highly transparent but have poor adhesion to the core glass. Vinylidene fluoride/tetrafluoroethylene copolymer and polyether ester amide have large scattering and absorption, so they have poor light transmittance, and it is impossible to reduce the optical transmission loss of PCF. UV-curable fluorinated acrylate II oxides are cured with UV light after being applied onto the core glass, which makes it difficult to control the curing state, increases loss due to residual stress due to cladding shrinkage during curing, and increases fiber damage. There are problems such as difficulty in adjusting the outer diameter.

Further, the usage range for these PCFs is determined by the heat resistance of the polymer of the cladding material, and it is common that they cannot withstand the usage range of 200°C.

(Means for solving the problem in !1) The present inventors blended ladder-like polymethylsiloxane (A) with linear polymethylsiloxane (B) having an OH group as a cladding material for PCF. However, it was discovered that the cured product is particularly excellent in terms of low optical transmission loss characteristics, high mechanical strength, etc., and the present invention was developed.

That is, the present invention is: Reactive curing of a resin composition having a core of quartz glass or optical glass, and a ladder-like polymethylsiloxane (A) dissolved or dispersed in a linear polymethylsiloxane (B) having an OH group. The present invention provides a polymer clad fiber for optical transmission, which uses a material as a cladding material.

The linear polymethylsiloxane (B) having an OH group used in the present invention is a linear polymethylsiloxane represented by the general formula: % Formula % (1) having an OH group on the side chain or terminal. There are no particular restrictions.

Linear polymethylsiloxane (B) having this OH group
The number average molecular weight used is about 500 to 100.000, preferably about 1,000 to 20,000.

The refractive index of this linear polymethylsiloxane (B) is 1
．． 40 to 1.41, and after dissolving polymethylsilsesoxane and curing it by heating etc., it is 1.41
It has a refractive index of ~1.42, and is suitable as a cladding material for a polymer clad fiber whose core is quartz glass (optical glass) having a refractive index of about 1.45.

Next, the ladder-shaped polymethylsiloxane used in the present invention (
A) is produced by a known method such as that described in JP-A No. 53-88099, and typically has the following general formula: % Formula % This ladder-like polymethylsiloxane (A) is: Those having a number average molecular weight of 5,000 to 100,000 are preferred.

The ladder-shaped polymethylsiloxane (A) used in the present invention has a refractive index of 1.40 to 1.42, and has a polymer cladding having a core of quartz glass (optical glass) having a refractive index of about 1.45. Suitable as fiber cladding material.

The resin composition obtained by dispersing or dissolving the ladder-like polymethylsiloxane (A) of the present invention in the linear polymethylsiloxane (B) having an OH group is a viscous liquid at room temperature, and easily forms a silica-based glass ( It can be coated on a fiber core made of optical glass), and by heating, it can be applied between ladder-shaped polymethylsiloxane (A) or between ladder-shaped polymethylsiloxane (A) and linear polymethylsiloxane (OH group-containing). A condensation reaction occurs between B) and cures to form a tough and heat-resistant coating film.

In the present invention, the hardness and heat resistance of the cladding layer can be adjusted arbitrarily by adjusting the blending ratio of the ladder-like polymethylsiloxane (A) dispersed or dissolved in the linear polymethylsiloxane (B) having an OH group. can do. That is, when the blending ratio of ladder-like polymethylsiloxane (A) is increased, a cladding layer with high hardness and excellent heat resistance can be formed.

However, in general, the blending ratio of ladder-like polymethylsiloxane (A) and OH group-containing linear polymethylsiloxane is 95:5 to 5:95, preferably 80:
20-20:80.

The blending ratio of ladder polymethylsiloxane (A) is 95
% or more, a separate solvent will be required when coating the core, and there is a risk of bubbles occurring when the solvent is removed. Also, (A
) If the fi content is less than 5%, the heat resistance and mechanical strength will be insufficient.

The silicone resin composition of the present invention contains O in an amount that does not impair the function of the ladder polymethylsiloxane (A).
In addition to H group-containing linear polymethylsiloxane (B),
Other siloxane components such as diorganopolysiloxanes, alkoxyorganosilanes, etc. may be blended.

In addition, a catalyst, such as a platinum-based catalyst, may be used in the composition to assist the condensation/curing reaction, if necessary.

Furthermore, the core quartz-based or optical glass fiber may be similar to that used in conventional plastic-clad fibers, i.e., 0.05 diameter obtained by melt-spinning high-purity quartz-based or optical glass. ~0.
Approximately 5 ■ may be selected depending on the purpose of use, and there are no particular limitations other than that.

The production of the optical transmission polymer-clamped fiber of the present invention can be carried out by applying an in-shell coating technique.

For example, a quartz-based glass base material is melt-drawn, and a resin composition in which ladder-shaped polymethylsiloxane (A) is dispersed or dissolved in linear polymethylsiloxane (B) having OHM is placed on the base material using a die or the like. After application, it may be cured in a thermosetting oven to form a cured coating.

An outer covering of a thermoplastic resin such as polyethylene, polyamide, chlorinated polyethylene, polycarbonate, etc. may be provided around the outer periphery of the silicone resin cladding layer of the present invention in order to avoid destruction of the cladding layer during the cable forming process.

(Function) The polymer clad fiber for optical transmission of the present invention is made of resin &l whose main component is ladder-like polymethylsiloxane (^).
Since tc@IJ is used as the cladding layer, the core,
It is possible to realize a sufficiently large refractive index difference between the claddings, and the cladding layer has a small optical transmission loss, so it has excellent low optical transmission loss characteristics.

In addition, since the resin composition of the cladding layer, whose main component is ladder-like polysiloxane (A), has appropriate hardness and sufficient heat resistance, optical transmission loss increases when the connector is attached by caulking. It can withstand operating temperatures of 200°C or higher.

In addition, in the case of the present invention, using a resin &fl preservative in which ladder-like polymethylsiloxane (^) is dispersed or dissolved in linear polymethylsiloxane (B) having 01 (group),
Since no other solvent is used, there is no problem of bubbles being generated in the cladding material due to volatilization of the solvent when the resin composite acid is applied onto quartz glass and cured.

(Examples) Hereinafter, the structure and effects of the present invention will be explained in more detail based on Examples, but the present invention is not limited thereto.

Example 1 A flaky, ladder-like polymethylsiloxane with a refractive index of 1.42 and an average molecular weight of 6,000 was prepared with a refractive index of 1.41, a viscosity of 300 cps, an average molecular weight of 10°,000, and alcohol (ROM) at both ends. It is dissolved in linear dimethylsiloxane-based silicone oil at a weight ratio of 1:1 to give a refractive index of 1. 415, resin with viscosity 2.000 cps &
It was made from lI monooxide.

A core fiber with an outer diameter of 200 μm is drawn using an anhydrous synthetic quartz rod, and at the same time, the resin composition is coated with a die and heat-cured at about 200°C through a baking oven to form a fiber as shown in Figure 1. A polymer clad optical fiber with an outer diameter of 230 μm was obtained.

The wavelength of this fiber is 810 nm for a length of I km.
When the transmission loss was measured, it was found to be 3.5 dB/km, which was good.

Furthermore, even when the connector was attached by the caulking method, no increase in loss was observed, and the adhesion force of the connector to the fiber was 1.5 kg.

Furthermore, it has good adhesion with the core material, and is kept at 200°C at all times.
It was possible to use it even under the following conditions.

Furthermore, since no solvent was used, there were no problems such as air bubbles being mixed into the cladding material.

Comparative Example 1 Using an anhydrous synthetic quartz rod, a core fiber with an outer diameter of 200 μm was drawn, and at the same time the refractive index was 1.41 with a die.
, a linear thermosetting silicone resin made of polymethylsiloxane with a viscosity of 1.00 Or, ps is applied, and approximately 500
Heat curing was performed at °C to obtain a polymer clad fiber with an outer diameter of 230 μm.

The wavelength of this fiber is 810 nm for a 1km long fiber.
When the transmission loss was measured, it was found to be 3.6 dB/km, which was good.

When this fiber was used to attach a connector using the caulking method, an increase in loss of about 2 dB per connection was observed. In addition, in order to reduce the increase in losses,
By reducing the amount of caulking, the adhesion force between the connector and the fiber can be reduced.
, it weighed less than 1 kg and could not be used.

(Effects of the Invention) As explained above, the polymer clad fiber for optical transmission of the present invention has a ladder-like polymethylsiloxane (A) in the cladding layer, and a straight chain polymethylsiloxane (B) having an O) (group). Since it uses a reaction cured product of dissolved or dispersed resin and Irfi, it is extremely excellent in terms of transmission loss, strength in caulking type connector attachment, adhesion to the core, and heat resistance.

Furthermore, since no solvent is used, there is no problem of air bubbles occurring when the solvent evaporates.

[Brief explanation of drawings]

FIG. 1 shows a cross-sectional view of a specific example of a polymer clamped fiber for optical transmission according to the present invention. l... Core 2... Clad

Claims (1)

[Claims] (1) In a polymer clad fiber for optical transmission, which has a core made of quartz glass or optical glass and a polymer cladding, ladder-shaped polymethylsiloxane (A) is
A polymer clad fiber for optical transmission, characterized in that the cladding material is a reaction cured product of a resin composition dissolved or dispersed in a linear polymethylsiloxane (B) having an H group.