JPS5855343A - Manufacture of optical fiber for long distance communication and optical fiber thereby - 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 The present invention relates to a method for manufacturing optical fibers for telecommunications, according to which a tubular preform having an axial channel is formed of a glass material, the surface of the channel is processing to form a light guiding region in the preform, the preform being heated such that it is crushed into a glass rod, a core of the rod being formed with the light guiding region; The fibers are stretched into thin fibers.

Fibers suitable for optical telecommunications are manufactured by conventional methods of molding glass tubes or preforms with axial channels therethrough, usually from pure quartz glass material. Various gases are introduced into the channels of the iron moldings as the preforms are heated simultaneously, and the gases mold the glass material between the insides of the tubes. Gas treatment of the preform produces a varying refractive index in the walls of the channels. When the preform treated in this way is densified by heating, it is crushed into a solid glass rod having a nine-beam waveguide region formed by the gas treatment at its center.

The refractive index of the glass changes gradually in the scissor region such that light rays directed into the finished fiber have a tendency to be refracted toward the center of the fiber and thus retained within the fiber. The crushed buttocks are then stretched into thin fibers, which are coated with the required insulation.

Two fibers prepared in this way can be used in a telecommunications channel, one fiber for transmitting and multiplexing and the other for receiving. A pair of fibers are made into a pair of conducting wires used in electric telecommunication cables.

The above-mentioned glass preform is supplied as a part having a length of about 1 layer and a thickness of about 20 m, and the thickness of the finished thin fiber is about 50 μ. The light guiding region may be applied to the preform in ways other than gas treatment, for example by various coating methods.

As mentioned above, when using this optical fiber for optical telecommunications, two fibers are always needed to form two information paths for duplex communication. The possibility of transmitting signals at different wavelengths in opposite directions or in the same direction on the same fiber was investigated, so as to eliminate two fibers. Technically, the solution based on multiple wavelengths has been found to be feasible, but uneconomical.

The object of the present invention is to provide a method for producing optical fibers which eliminates the above-mentioned drawbacks and which provides an optical fiber that alone allows duplex communication. This object is achieved in a method according to the invention, characterized in that at least two separate axial channels are formed in the tubular preform, each channel being treated to form a beam guiding region. be done.

The invention is based on the idea of forming at least two separate channels in a two-step preform instead of a single channel, so that the two separate cores providing the light guiding area are A glass preform is stretched to form a finished fiber. Due to the axillary fibers, signals can be transmitted along at least two separate paths without mutual interference or interdependent signals. For other manufacturing procedures,
The procedure is the same in the present invention as in conventional methods, i.e. the required light guiding regions are formed in each channel of the preform by a suitable process, and then the nucleon molding is It is crushed into rods, and the rods are stretched into fibers.

The shape of the glass preform with channels of 2t or more is such that the crushed but lath rod and the final fibers that are then drawn are shaped to suit each particular application, e.g. round or round. most appropriately found by

The present invention also relates to an optical fiber produced by the above-described method, characterized in that the skeleton fiber has at least two information paths formed by separate light-guiding regions.

The fiber of the invention has at least two telecommunications or data transmission paths, where each light beam signal passing through
Maintained within the beam guiding region associated with each path, different information paths do not interfere with each other. Thus, data can be transmitted independently along at least two individual communication paths over the same fiber. The present invention has the advantage of simpler and cheaper construction than known pairs or groups of separate fibers required for similar purposes. Another advantage is that the channels remain together and are easily fixable, which facilitates fiber extension and bonding.

The invention will be explained in more detail below with reference to the accompanying drawings.

The method shown in FIG.
7111) and the introduction of gas into each channel (step 1) when heating the preform to diffuse the gas into the quartz.
), and by increasing the density of the preform to form a solid glass rod (
5) heating the gas-treated glass preform so as to crush it 4 (procedure lid); and procedure V) stretching the lath rod into thin glass fibers 6.

As clearly shown in Figure 2, the glass preform 1 made according to the invention must have mutually spaced and parallel axial channels 2. The fiber 6, which is made to have the shape of a nucleon and is formed by circular stretching, has a circular shape as shown in FIG.

However, the circular shape is not essential to the invention. Preferably, the fibers are rather somewhat flat due to their bonding. In this case, the shapes are selected as shown in FIGS. 5 to 30.

Gas treatment of the channels in the glass preform crushed two light beam guiding regions 7 extending over the length of the rod such that two separate telecommunications channels B are formed in the stretched fiber. A solid rock Y is formed. The optical signals passing through the skeleton channel are maintained within the optical waveguide region and do not interfere with each other.

In this case, it is appropriate to manufacture the preform so that the stretched fibers 26 form a twisted structure as shown in FIG. In this embodiment, the preform has two channels and during the stretching procedure either the lath rod or the housing device is rotated, so that
The stretched fiber channel, B, is in a twisted configuration with respect to the central axis. This twist may be continuous or reversed. Advantages of the structure include better flexibility of flat fibers and protection of the telecommunications path from mechanical stress. In this type of construction, the stresses acting on the fibers are concentrated in the glass material located at the central axis of the fibers.

FIG. 5 shows a fiber 3 having four communication channels B, O, D.
Indicates B.

The drawings and related description are intended only to illustrate the concepts of the invention.

In detail, the method and the optical fiber of the invention may vary significantly within the scope of the claims. The method may be applied to all types of lath fiber cables. In particular, the method is suitable for producing so-called instrument fibers.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of the basic steps of a preferred embodiment of the method of the present invention, and FIG. 2, FIG. 2B, and FIG. 20 are diagrams of a preferred embodiment of the optical fiber of the present invention. 35, 3B, and 30 are cross-sectional views of the lath preform, the crushed two slots, and the stretched fiber during the manufacturing procedure, respectively, and FIG. 35 shows a second embodiment of the fiber. Figure 2, Figure 2B, Figure 2
Figure 4 shows a perspective view of a twisted nine fiber with two communication channels; Figure 5 shows a cross-sectional view of a twisted fiber with four communication channels (for illustrative purposes, the drawing The various figures are not mutually comparable with respect to their dimensions). 1.11... Tubular lath preform 2 - Axial channel 5.15... Glass rod T... Light beam guiding region m, a, n... Long distance communication path agent Akira Asamura 4 people

Claims (1)

Claims: (1) A tubular preform (1, 11) having an axial channel (2) is formed of a glass material, the surface of the channel forming a light guide region (7) in the nucleon molding. ), the nucleic acid molded article 1.11) is heated to be crushed into four pieces (5, 15);
The core of the rod is formed by the beam guiding region, and the cough glass rod (5, 15) is made of thin fibers (6, 16, 26).
In a method for producing an optical fiber for telecommunications, which is stretched to At least two separate axial channels (2) are formed in said tubular preform (1, 11), characterized in that the canyon channel is heated so as to form a beam guiding region (7). How to do it. (2) The tubular preform (1) is shaped so that the crushed but lath rod (5) and the fibers (6) drawn from the rod are circular. The method described in item 1. (3) The tubular preformed product (11) is formed so that the pressed glass rod (15) and the fibers (16) stretched from the four Y are flat. A method according to claim 1. 4. A method according to claim 5, characterized in that the flat glass rod is twisted about its longitudinal axis as it is drawn into fibers (26). (5) A method according to claim 4, characterized in that the glass rods are twisted in the same direction or in opposite directions. (6) Tubular preformed products made of glass materials (1, 11)
A telecommunication optic consisting of a scissor preform is crushed and drawn into a fiber (6, 16) having a telecommunication channel (mu) formed by a beam guiding region "'' (7) In a fiber, said fiber (6, 16, 26, 36) having at least two telecommunication channels (
A fiber characterized in that it has: ()) The fibers (6, 16) are connected to the light beam guiding region (7).
7. Fiber according to claim 6, characterized in that it is drawn from a preform (1, 11) having at least two separate axial channels (2) formed in the walls. (8) The long-distance communication path (Mu, B) is connected to the fiber (6,
16) Fiber according to claim 7, characterized in that it extends linearly within the fiber. (9) The long-distance communication path (MUeB) is connected to the fiber (2
6) The fiber according to claim 7, wherein the fiber is twisted in the same direction or in the opposite direction. α The fiber (26) is flat and the communication path (
10. The fiber according to claim 9, characterized in that the step B) is located around the central axis of the iron fiber.