JPS58162906A - Optical fiber - Google Patents

Abstract

PURPOSE:To obtain a dummy fiber which uses no splice connection nor connector connection, by controlling a refractive index distribution in the radial direction and the lengthwise direction at the stage of preforming of a base material, elongating it, and optionally concatenating a step type and a graded type. CONSTITUTION:As for a base material, in a process for generating piled glass 4, a quartz pipe 3 is divided into pural areas (a), (b), (c)... in the lengthwise direction, and in each section, density of an addition oxide, for instance, that which raises a refractive index such as P2O5 or GeO2, or that which lowers a refractive index such as B2O3 is controlled, by which a refractive index distribution is controlled. In this case, the piled glass 4 is generated so that for instance, the area (a), the area (b), the area (c) and the area (d) become a step type, a graded type, a step type and a graded type, respectively. In this way, when a preformed base material is spun, that which concatenates the step type and the graded type is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Technical Field of the Invention The present invention relates to an optical fiber used as an exciter for measuring transmission characteristics of an optical fiber used in optical communications and the like.

(2) Prior art and problems There are various methods to measure the transmission characteristics of optical fibers, one of which is 8-G@8 (step-dare).
There is an excitation method (meaning ted-step).

Figure 1 is a diagram showing the excitation Dougie phi/excitation used in the conventional 8-G-8 excitation method, where 1 is the overall view, and b is the refractive index distribution in the cross section of parts A, B, and B in figure a. are shown respectively.

In the figure, the A and C portions of the optical fin 41 have a step-shaped refractive index distribution, and the mouth portion has a graded shape.

The stepped shape in the A part reduces the difference in the incidence conditions of the off-axis force, the grated shape in the mouth part removes excess light coming from the step part, and the step shape in the bottom part reduces the difference in the incidence conditions of the off-axis force. This has the effect of reducing the dependence on connection conditions.

Such a Dan-Fino example uses a splice method to connect a conventional step-type optical fiber and a Greterra P-type optical fiber. For this reason, the sheath for protecting the optical 7 eyelids is separated at the connecting portion, which has nine drawbacks: the connecting portion lacks strength and is easily broken, making it difficult to handle.

(3) Purpose of the Invention The present invention overcomes the above-mentioned drawbacks of the prior art, and aims to provide a single optical fiber transmission characteristic measurement method that does not use splice connections or connector connections. It is.

(4) According to the present invention, the structure and object of the invention is to control the refractive index distribution in the radial direction and longitudinal direction at the stage of preforming the base material, and to elongate the base material to form a stepped shape in the longitudinal direction. This is achieved by providing an optical fiber characterized by arbitrarily connecting and forming graded optical fibers Δ. .

[1] is a rounding diagram illustrating one method (inner q method) for creating an optical fiber Δ. In the figure, 2 is a gas flow rate control unit, 3 is quartz/4i/ which becomes the core of the base material, 4 is a deposited glass that is the core of the base material, and 5 is a shunsui bulk burner. There is.

In the figure, gas flow rate control Iku 2 is the main raw material silicon tetrachloride (lliCt4), which controls the KM refractive index, using oxygen as a carrier gas (1lrBtPOcj,,G@Cj
4 etc.) is added, and the composition and flow rate are controlled and supplied to the quartz t4 Ig 3. And quartz/dive 3
At the same time as it is rotated, it is heated with an external oxyhydrogen burner 5. When this happens, soot-like quartz and additive oxides are generated and deposited on the inner surface of the quartz pipe 3. Subsequently, this deposit is heated and melted to form transparent glass. After this, Quartz/Parable Eve 3
When the inside is reduced in pressure and heated to about 1750°C, the quartz/l tube is crushed by atmospheric pressure and the hollow part disappears. This process is called collapse. The base material thus prepared is heated from the end to about 2000° C. in a high-frequency heating furnace, electric furnace, oxyhydrogen flame, etc., and then spun to obtain an optical fiber.

In the case of 0.0, the refractive index can be easily controlled by the concentration of the added oxide, such as P2O, G.0. If it contains B20, the refractive index will be higher than that of pure quartz. If it is included, it will go down. Furthermore, the refractive index distribution can also be changed by changing the concentration of the added oxide according to the deposition thickness. FIG. 3 is a diagram for explaining the base material for producing the optical fiber according to the present invention. In the same figure, 3
/fi, quartz, and 4 indicate deposited glass, respectively. Then, in the step of producing the deposited glass 4, the main material is divided into a plurality of regions a and bl@- in the longitudinal direction of the quartz ΔI f3, and the concentration of the added oxide is controlled for each region, for example, in the region a. Ha, Ste! The deposited glass 4 is produced in such a manner that the b region is a grated shape, the C region is again a step shape, and the fourth region is a daleted shape.

By spinning the preformed base material in this manner, an optical fiber in which different modes of step type and graded type are connected can be obtained.

The optical fiber according to the present invention is formed by arbitrarily connecting different modes of step, tap, and graded modes in this way. As described above, the optical fiber of the present invention is
Since the Stiff type and Grated type are arbitrarily connected to form a single fiber, there are no splice connections or connector connections, and therefore it is possible to create a cable, and an excitation power source for adjusting transmission characteristics. It would be a great effect if it could be used in fiber optics to make electrical equipment extremely easy.

[Brief explanation of the drawing]

Fig. 1 is a rounded diagram to explain the excitation dummy fiber used for measuring the transmission characteristics of optical fiber, Fig. 2 is a diagram to explain the preforming of the base material of the optical fiber, and Fig. 3 is a diagram of the optical fiber according to the present invention. FIG. 3 is a diagram illustrating the creation of a base material for creating PhiΔ. In the drawings, 3 indicates quartz/4-beam, and 4 indicates deposited glass serving as the core. Patent Applicant: Fujitsu Limited Patent Application Agent Akira Aoki Patent Attorney Kazuyuki Tori Tate (Patent Attorney) 1) Yukio, Patent Attorney Akira Yamaguchi (G) (A) (B)
(c) ¥1) 2 Figure 31!1

Claims (1)

[Claims] 1. The refractive index distribution in the radial and longitudinal directions is controlled at the stage of preforming the base material, and the base material is stretched to arbitrarily connect the optical fibers in the stub, de, etc. shapes in the longitudinal direction. An optical fiber characterized in that it is formed by