JPS6236611A - Active Star Katsupura - 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 Field of the Invention The present invention relates to an active star coupler using a local area network (hereinafter referred to as LAN) K using optical fibers.

2. Description of the Related Art Conventionally, when configuring a star type LAN using optical fibers, terminals (32-1, 32-2, 32-3) are connected as shown in FIG.
) to optical transmitters (33-1, 33-2, 33-
3) is converted into an optical signal and inputted to the input section of the pass-through star coupler 31 through the optical fiber 35. In the pass-through star coupler 31, light entering from any input end is equally distributed to all output ends and supplied to all optical receivers (34-1, 34-2, 34-3) via optical fibers. . These receivers only accept signals with their own address. This method is generally known as a carrier sensing multiple access method with collision detection (Detection = C3MA/CD), so its explanation will be omitted (References rc
"Study of 32 Mb/7g optical star transmission system using sMA/CD control" Oguchi et al. NTT, C383-110),
.

In this method, two round trip fibers are used for one terminal. Furthermore, as the number of input/output ports increases, the loss of the star coupler increases, making it impossible to achieve long transmission distances.Problems the invention aims to solve Two fibers are used to connect to a star coupler for transmission and reception, but this requires many fibers, connectors, etc., and is uneconomical. The present invention aims at integrating these fibers.

In addition, the passive star coupler has a large loss, which is a problem in system design (for example, the loss in the case of 8 people and 8 outputs is 12 to 14 dB). The present invention also aims to reduce this loss.

Means for Solving the Problems According to the present invention, in order to perform round-trip transmission using a single wire, optical transmission is performed using light emitting elements having two different wavelengths.

That is, the direction of upstream (terminal → star coupler) and the direction of downstream (
In order to transmit different wavelengths in the direction (from star coupler to terminal), the star coupler performs a type of wavelength conversion. The configuration means for performing the wavelength conversion is the main point of the invention.

Function: As a means of wavelength conversion, the upstream optical signal is once converted into electricity, amplified, and sent out in the downstream direction using a light-emitting element of another wavelength, so the star coupler as a whole has an amplifying effect, reducing loss. It becomes less.

This is a so-called active star coupler.

Embodiment First, the structure of an active star coupler 1 of the present invention will be explained using FIG. An optical fiber 6 for signal input/output and a fiber 8 for inputting the light emission output of λ2 to the mixing rod are fixed to one end of the mixing rod 2. On the other hand, the other end of the mixing rod is provided with an optical filter 3 that allows wavelength λ1 to pass through and reflects wavelength λ2.

On the outside of the rod lens on the side where the optical filter 3 is attached,
A light receiving element is fixed so as to receive all the light that has passed through the optical filter. The electrical output of the light-receiving element is supplied to a light-emitting element that emits wavelength λ2 via an amplifier circuit 6. An optical fiber 8 is coupled to the light output of the light-emitting element, and the other end of the light-emitting element is connected to an optical fiber 8 such that the light enters one end of the mixing rod 2. combined.

The active star coupler of the present invention is realized by the above configuration.

Next, its operation will be explained with reference to FIGS. 1 and 2. Second
The figure shows a LAN using the active star coupler of the present invention.
FIG. The output signal of a certain terminal device 22 is converted into an optical signal with a wavelength of λ by the optical transmitter 23 and sent to the demultiplexer/multiplexer 2.
6, the active star coupler 1 is reached. In the star coupler 1, light with a wavelength λ1 that is incident on the mixing rod 2 from the fiber 5 passes through the optical filter 3, is converted into an electrical signal by the light receiving element 4, is amplified by the amplifier circuit 6, and is sent to the light emitting element 7 with the wavelength λ2. is converted into an optical signal and guided to the mixing rod 2 by the fiber 8. This wavelength λ
The two optical signals are averaged by the mixing rod, reflected by the optical filter 3, and reach the demultiplexer/multiplexer 26 at each terminal via the fiber 5. In this demultiplexer/multiplexer 26, the wavelength λ2
Only the signal of is supplied to the optical momme receiver 24. The optical receiver 24 output is supplied to the terminal device 22 as an input signal to the terminal device.

Which terminals can communicate with each other is determined by the so-called C
Controlled by 8MA/CD communication protocol.

This protocol is a general one and is not directly related to the present invention, so its explanation will be omitted. Effects of the Invention According to the present invention, in a star type optical LAN, a single fiber is used between the terminal and the star coupler to make a round trip. Can exchange signals, is easy to construct, and is economical.

Both will be excellent.

Furthermore, since the star coupler itself has an amplifying section, the overall loss is lower than that of a passive star coupler. Therefore, in loss distribution in the entire system, the reduction in coupler loss increases the transmission distance and increases the margin, which simplifies system design.

[Brief explanation of drawings]

Fig. 1 is a principle diagram of an active star coupler according to an embodiment of the present invention, Fig. 2 is a principle diagram of a star type LAN using the same active star coupler, and Fig. 3 is a principle diagram of a conventional star type LAN. . 1... Active star coupler, 2...
...Mixing rod, 3...Optical filter,
4... Light receiving element, 5, 8... Optical fin (, e... Amplifying circuit, 7... Light emitting element. Name of agent: Patent attorney Medium Toshio Oo and 1 other person 1st
Figure I Active star coupler Figure 2

Claims (1)

[Claims] A mixing rod portion having an optical filter on its end face that allows a first wavelength to pass through and reflects a second wavelength, a light receiving element that receives a signal of the passed first wavelength, and an output electric signal of the light receiving element. an amplification circuit that amplifies; a light emitting element that is driven by the output of the amplification circuit and emits a second wavelength;
An active star characterized by comprising an optical waveguide that guides the output of the light emitting element to the end face of the mixing rod on the side not provided with the filter, and a plurality of input/output fibers on the side of the mixing rod not provided with the filter. Cupra.