JPS60186809A - Light distributor - Google Patents

Abstract

PURPOSE:To reduce losses of a light distributor, by giving a uniform intensity distribution at its output terminal to optical signals from its input terminal after mixing them at the inside of the distributor and outputting the optical signals to plural step-index type optical fibers equipped with plural transmission lines and having a small core diameter. CONSTITUTION:When light is inputted to a spiral mixer 4 composed of a core 5 and clad 6 from an input side transmission line 1 composed of a core 2 and clad 3, the output of the mixer 4 becomes a signal having uniform intensity at its output terminal. The signal is distributed to, for example, seven parts by coupling an optical fiber bundle 13 formed by bundling most closely one ends of seven optical fibers to the output terminal of the mixer 4. The core diameter 5 of the optical mixer 4 is set to one which includes all the cores 14 of the optical fiber bundle 13. The output terminal of the optical fiber bundle 13 is connected with an output transmission line 10 by making the core 14 of the bundle 13 coincident with the axis of the core 11 of the output transmission line 10. Therefore, the optical mixer 4 is coupled with the optical fiber bundle 13 in step index form and, as a result, loss of this light distributor can be reduced sharply.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention provides an optical splitter that is installed in a transmission line using optical fibers and distributes optical signals evenly to a plurality of transmission lines with low insertion loss. It's about traps.

[Prior art]

A conventional optical distributor of this type has a configuration shown in FIG. In FIG. 1, (l) is the input side transmission line.

(2) is the core of the input side transmission line, (3) is the cladding of the input side transmission line, (4) is the optical mixer, (5) is the core of the optical mixer, (6) is the cladding of the optical mixer, (7) is the output optical fiber, (8) is the core of the output optical fiber, (9) is the cladding of the output optical fiber, +l [I is the output side transmission line, al
1 is the core of the output transmission line, and a2 is the cladding of the output transmission line.

The optical signal propagated through the input side transmission line +11 was input to the core (5) of the optical mixer (4) at the input end of the optical mixer (4). The core (5) of this optical mixer is the core (5) of the transmission line (
It had a rectangular shape with a thickness d equal to the diameter of 2) and a width W equal to N times the diameter of the cladding (9) of the output optical fiber. However, N is the distribution number of the optical distributor. The optical signal input to the core (5) of the optical mixer is.

It reaches the output end of the optical mixer (4) while repeating total reflection at the boundary between the optical mixer core (5) and the optical mixer cladding (6) and the side surface of the optical mixer core (5), and reaches the output end of the optical mixer (4). The signal was uniformly distributed over the entire output end of the core (5). Further, at the output end of the optical mixer (4), N output optical fibers (7), which are the same as the transmission line, are arranged in a row, and the cores (8) of all the output optical fibers are connected to the core (5) of the optical mixer. The optical signals were evenly distributed by combining them so as to include them. The N output optical fibers (7) send out optical signals to the output side transmission lines ati connected to each one.

However, in the above configuration, the output 111j transmission line θG and the output optical fiber (7) are the same, so if the output side transmission line OI is a graded index type optical fiber, the optical mixer (4) is a step index type optical fiber. .

Output optical fiber (force is approximately 1.1
It had the disadvantage of causing a loss of dB. Also.

The optical mixer (4) is obtained by thermally fusing a glass optical mixer core (5) with a glass optical mixer glue → RAD (6) having a slightly lower refractive index than iL.

The core (5) of the optical mixer was also bonded together using an adhesive with a refractive index lower than that of the core (5), but the former required skilled technology and was expensive; The refractive index of the agent depends on the curing conditions and temperature! 7 changes, which has the disadvantage of low reliability.

[Summary of the invention]

In order to eliminate these drawbacks, this invention uses a step-index type 6 optical fiber with a small core diameter for the transmission line.
A graded-index optical fiber was used in a configuration in which the A17 Aibar bundle was coupled with an optical mixer made up of a step-index optical fiber having a core diameter that included the optical fiber; This device aims to reduce insertion loss in the transmission path, reduce cost, and improve reliability.The drawings will be described in detail below.

[Embodiments of the invention]

FIG. 2 is a fortune map according to an embodiment of this invention. In Figure 2, (vine) is the input 11+11 transmission line, +21 (3) is the cladding of the input side transmission line, (4)
is the optical mixer, (5) is the core of the optical mixer, (61t;i
: 9 mixer cladding, α1 is the output side transmission line, α0 is the output side transmission line core, H is the output side transmission line cladding,
Q3 is the original fiber bundle, 041 is the core of the optical fiber bundle,
(FJ Sakiko 7143 bundle cladding.

When an optical signal is input into the fc optical mixer (4) by spirally forming an optical fiber from the input side transmission path fi+, the optical mixer (4)
) becomes a signal with a uniform intensity distribution at the output end.

As an example, the optical signal can be distributed into one by coupling an optical fiber bundle a3, in which one end of one source fiber is bundled in the closest packing, to the output end of the optical mixer (4). At this time, if the core of one optical fiber constituting the optical fiber bundle 04 is referred to as the core α4 of the optical fiber bundle, the diameter of the core (5) of the optical mixer is as follows.

Core α of the optical fiber bundle at the bundled end of the optical fiber bundle
The size is set to include all 4. Further, the output end of the optical fiber bundle (13) is connected to the head of the output transmission line so that the central axes of the core I of the optical fiber bundle and the core aυ of the output transmission line coincide.

Now, when graded index optical fibers with a core diameter of 80 μm are used as the input transmission line fi+ and the output transmission line a1, in the optical splitter with the above configuration, the coupling surface between the optical mixer (4) and the optical fiber bundle Q3 In this case, there is no loss caused by the difference in refractive index distribution between the optical mixer (4) and the output optical fine nozzle (7), which occurs in the conventional configuration. However, loss occurs due to the difference in refractive index distribution between the optical fiber bundle θ and the output side transmission line.

FIG. 3 shows the relationship between this loss and the diameter of the core I of the optical fiber bundle. Here, the optical fiber bundle a has a core diameter of 50μ
m optical fiber, 0.05Ji from Figure 3.
It can be seen that this results in a loss for B. Therefore, compared to the conventional configuration, the insertion loss of the optical splitter is 1.1 dB and 0.05 dB.
This has the advantage of being able to reduce the difference by 1.05 dB. Further, the spirally formed optical mixer (4) can be easily formed into a desired shape by using a multi-component glass optical fiber, so it is inexpensive and highly reliable.

FIG. 4 is a block diagram of another embodiment of the present invention.

Figure 4 shows that in Figure 2, a straight optical fiber is used as the one-source mixer (4), a ring-shaped bundle of optical fibers is used as the optical fiber bundle α, and an optical mixer (4) is used.
At the input end of the optical mixer, an optical signal is input from the input side transmission line fil to the periphery of the core (5) of the optical mixer.

In the configuration shown in FIG. 4, input 9I++ transmission line fil 1
"The original signal input to the optical mixer (4) is
At the output end of the signal, a signal has a uniform annular intensity distribution biased toward the periphery of the optical mixer core (5), as shown by diagonal lines in FIG. Therefore, the core of the optical mixer (5
As an example, using an optical fiber bundle Q3 in which one optical fiber bundle Q3 is wrapped in an annular shape so as to fit inside the optical mixer (
By coupling to the output end of 13, the optical signal having the annular intensity distribution can be efficiently distributed. The optical distributor having the configuration shown in FIG. 4 can also reduce the insertion loss for the same reason as the optical distributor having the configuration shown in FIG.

Note that although the case where two or more optical signals are distributed once has been described, the present invention is not limited to this and may be used for any number of distributions. t7t, Although the above description has been made for the case where there is one 1-length transmission path on the input side, this invention is not limited to this, and can be used when there are multiple transmission paths on the input side. The case has been described in which an optical fiber with a core diameter of 80 μm is used as the output side transmission line, and the optical fiber bundle is composed of optical fibers with a core diameter of 50 μm. However, this invention is not limited to this, and can be applied to a transmission line with an arbitrary core diameter of Ω. It may also be used when forming an optical fiber bundle using optical fibers having a small core diameter as well as the transmission line. Furthermore, although the above description has been made of the case where the input side transmission line and the output side transmission line are the same optical fiber, the present invention is not limited to this, and the output 911 transmission line is a graded index type optical fiber regardless of the input side transmission line. It may also be used when it is a fiber.

〔Effect of the invention〕

As described above, in the optical splitter according to the present invention.

The original signal is distributed by an optical fiber bundle made up of step-index optical fibers with a core diameter smaller than that of the output transmission line, which reduces insertion loss when the output transmission line is a crepey index fiber. Furthermore, since a step index type optical fiber is used as the optical mixer, it has the advantage of being low-cost and highly reliable.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a conventional optical splitter, Fig. 2 is a block diagram of an embodiment of an optical splitter according to the present invention, and Fig. 3 is a diagram showing the connection loss between the optical fiber bundle and the output side transmission line and the optical fiber bundle. FIG. 4 is a diagram showing the relationship between the core diameter and the core diameter, and FIG. 4 is a configuration diagram of another embodiment of the optical distributor according to the present invention. FIG. 5 is a diagram showing the intensity distribution of the optical signal at the output end of the optical mixer used in the embodiment of FIG. 4. In the figure (11 is the input side transmission line, (2) is the core of the input side transmission line, (3) is the cladding of the input side transmission line, (4) is the optical mixer, (5) is the core of the optical mixer, (6) is the cladding of the input side transmission line, and (4) is the optical mixer. ) is the cladding of the optical mixer. (7) is the output optical fiber, (8) is the core of the output optical fiber. (9) is the cladding of the output optical fiber, α1 is the output side transmission line, and aυ is the core of the output side transmission line. , a is the cladding of the output transmission line, (I3 is the optical fiber bundle, I is the core of the optical fiber bundle, and a!19 is the cladding of the optical fiber bundle. Note that the same or equivalent parts in Figure 1 are designated by the same reference numerals. Agent Masuo Oiwa Figure 3 (ctB) Q 102050405060708090 (Core diameter of microfiber Figure 5

Claims (3)

[Claims] (1) In an optical splitter used in communications using optical fiber as a signal transmission path, the optical signal propagated through the transmission path is distributed equally to multiple transmission paths and sent out, and is transmitted at the input end. an optical mixer for receiving an optical signal from the optical path and mixing it internally to form a uniform intensity distribution at the output end;
An optical fiber bundle made up of a plurality of step-index optical fibers with a smaller core diameter than the plurality of transmission lines mentioned above is connected to the output end of the original mixer and is used to distribute optical signals to a plurality of transmission lines. Optical distributor with a % sign that it has been configured. (2) As the optical fiber bundle, optical fibers are arranged and bundled in a close-packed manner, and as the optical mixer, step-index optical fibers having a core diameter included in the optical fiber bundle are formed in a spiral shape. An optical distributor according to claim 1, characterized in that the optical distributor uses an optical distributor. (3) The optical fiber bundle is a bundle of optical fibers arranged in an annular shape, the optical mixer is a step index type optical fiber having a core diameter in which the optical fibers are inscribed, and Claim (1) characterized in that the transmission line is connected to the peripheral part of the core of the optical mixer at the input end of the optical mixer.
Optical distributor as described in section.