JPS5849845B2 - Plastic clad fiber end structure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an end structure for a plastic clad fiber.

Optical fibers used in various optical transmission systems etc. consist of a core and a cladding provided on the outer peripheral surface of the core.
An optical signal incident from the fiber end face travels inside the core while being reflected or meandering.

Since the refractive index of the cladding is smaller than the refractive index of the core,
Total reflection of light occurs at the boundary between the two, preventing light from being emitted.

There are various types of optical fibers, and while ordinary glass fibers have a core and cladding made of the same material, plastic clad fibers have a core made of glass and a cladding made of polymeric resin such as silicone resin. It is formed of.

Therefore, this plastic clad fiber has the advantage that the refractive index between the core and the cladding can be large, and a large diameter core can be used, so that a large diameter fiber can be realized.

However, on the other hand, the core and the clathode are made of different materials and have extremely different hardnesses, making it difficult to cut and polish, making it extremely difficult to connect fibers to each other or optically couple them with other optical components. Therefore, it is necessary to reinforce the ends in some way when using the product.

As shown in FIG. 1, the conventional end structure of a plastic clad fiber consists of removing an appropriate length of the plastic clad 2 and nylon coating 3 at the end of the plastic clad fiber 1 to expose the glass core 4. , the exposed part is inserted into a metal pipe 5 made of stainless steel or the like, and a hardening resin adhesive 6 which also serves as a cladding function is filled between the metal pipe 5 and the inserted glass core 4 to fix it. It is.

However, such a structure requires a long period of time for sufficient adhesion between the glass core and the metal pipe to harden, and there are problems with differences in adhesiveness, coefficient of thermal expansion, or hardness of each component. This has disadvantages such as eccentricity of the glass core with respect to the metal pipe, breakage and chipping of the glass core during end polishing, peeling of the adhesive, and protrusion or depression of the glass core at the end surface 7 due to temperature changes.

Another disadvantage is that the core moves significantly when the nylon coating is pulled or pushed by hand when operating the fiber.

The present invention solves these drawbacks by fusing a glass clad fiber to the end surface of a glass core of a plastic clad fiber, or by adding impurities to the outer peripheral surface of a glass core at the end of a plastic clad fiber. , only the end portion of the plastic clad fiber is made into a glass clad type fiber to make the end portion rigid.

One embodiment of the present invention will be explained with reference to FIG. 2. The plastic clad 2 and nylon coating 3 at the end of the plastic clad fiber 1 are removed over an appropriate length to expose the glass core 4 with a smooth end surface. Then, a glass clad fiber 10 consisting of a glass core 8 and a glass clad 9 and having smooth end faces is fused and bonded to the end face of the glass core 4 by a fusion method or the like with their axes aligned.

The glass clad fiber 10 used has the same diameter as the glass core 4 of the plastic clad fiber 1 and has a length of several mm.

Next, a new plastic cladding 11 is formed by attaching a polymeric resin such as silicone resin to the exposed outer periphery of the glass core 4 and the part where the glass clad fiber 10 is fused. The metal pipe 12 is integrated with the cladding 2, and a metal pipe 12 is placed over the fused portion for reinforcement, and an adhesive 13 is filled in the metal pipe 12 to fix the metal pipe 12.

In this way, only the end portion of the plastic clad fiber 1 becomes the glass clad 9.

As explained above, in this example, a glass clad fiber is fused to the end of a plastic clad fiber, and a new plastic clad is formed at the fused portion and the outer periphery of the exposed glass core of the plastic clad fiber. By doing so, a mechanically stable connection can be made without impairing the optical properties of the plastic clad fiber.

In other words, by fixing the glass clad fiber part, which is extremely easy to fix, it becomes possible to hold the tip of the plastic clad fiber optically and mechanically stable, and the glass core does not move when the fiber is manipulated. It is possible to eliminate the disadvantages such as

In addition, glass-clad fibers generally have better concentricity between the glass core and the outer periphery of the fiber than plastic-clad fibers, which improves the eccentricity of the glass core. It is also effective in preventing protrusion or depression at the end face due to temperature changes or the like.

In the above example, a glass clad fiber is fused to the end of a plastic clad fiber, but as another example, which is not shown, the cladding at the end of the plastic clad fiber is removed over an appropriate length. However, a glass crund may be formed on the outer circumferential surface of the glass core exposed thereby.

By doing so, the end of the plastic clad fiber becomes a glass clad fiber, so that the same effect as the embodiment shown in FIG. 2 can be obtained.

As explained above, the present invention makes the end part rigid by fusing the glass clad fiber to the core end face of the plastic clad fiber, so this glass fiber part physically strengthens the plastic clad fiber. In addition to being able to connect other fibers to the glass fiber, it is possible to connect plastic clad fibers together, to connect plastic clad fibers to other optical fibers, or to connect other fibers. This has the effect of facilitating optical coupling with optical components.

[Brief explanation of the drawing]

FIG. 1 is a side sectional view of a conventional example, and FIG. 2 is a side sectional view showing an embodiment of the present invention. 1...Plastic clad fiber, 2...
...Plastic clad, 3...Nylon coating, 4...Glass core, 8...Glass core, 9... ...Glaskland, 10...
...Glass clad fiber 11...Plastic clad, 12...Metal pipe, 13...
·····glue.

Claims (1)

[Claims] 1 The cladding at the end of a plastic clad fiber whose core is made of glass and whose cladding covering the core is made of polymeric resin is removed over an appropriate length, and a glass core is attached to the end face of the exposed core. 1. An end structure of a plastic clad fiber, characterized in that the end face of a certain glass clad fiber is fused to a glass clad, and a polymer resin is attached to the outer periphery of the fused fiber and to the outer periphery of the exposed core.