JPH03250932A - Optical amplifier relay system - 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] [Summary] An optical amplification and repeating system that amplifies and relays optical signals in submarine optical cable transmission systems and the like, and which can significantly reduce equipment costs for submarine optical cable transmission systems and the like. In order to provide a system, a plurality of optical direct amplifiers that directly amplify optical signals are provided, each of the optical direct amplifiers is connected with a wooden optical fiber 2, and the optical direct amplifiers are connected in the upstream direction. a one-way gain control circuit for controlling the gain of
The optical direct amplifiers are provided alternately in the plurality of optical direct amplifiers.

[Industrial application field]

This invention is applicable to submarine optical cable transmission systems, etc.
The present invention relates to an optical amplification and relay system that amplifies and relays optical signals.

In long-distance optical signal transmission such as undersea optical cables, in order to compensate for the attenuation of optical energy in the transmission path,
It is necessary to place several optical amplification repeaters along the way.

[Conventional technology]

In the conventional optical amplification and repeating system, optical amplification and repeating is performed using a so-called 3R circuit that once converts an optical signal into an electrical signal and then performs signal wave shaping, retiming, and regeneration.

[Problem to be solved by the invention]

However, in the 3R circuit, each circuit is arranged in series, and moreover, an optical/electrical conversion must be performed at the beginning, and an opposite electric/optical conversion must be performed at the end.

Therefore, in the 3R circuit, the direction of signal propagation is limited to one direction. Therefore, in submarine optical cable transmission systems and the like, it is necessary to provide completely separate uplinks and downlinks, resulting in high equipment costs.

SUMMARY OF THE INVENTION An object of the present invention is to provide an optical amplification repeater system that can eliminate such conventional drawbacks and significantly reduce equipment costs for submarine optical cable transmission systems and the like.

[Means to solve the problem]

In order to achieve the above object, the optical amplification repeater system of the present invention, as shown in FIG. Each is connected by one optical fiber 2, and includes an upstream gain control circuit 3A for controlling the upstream gain in the optical direct amplifier l, and a downstream gain control circuit for controlling the downstream gain. The circuit 3B is provided alternately in the plurality of optical direct amplifiers l.

[Effect]

The optical signal transmitted through the optical fiber 2 is transmitted through the optical direct amplifier 1
This amplifies both the upper and lower directions.

Further, gain control circuits 3A for upstream and downstream directions are provided alternately in the plurality of optical direct amplifiers 1.

3B, the gain in the upstream direction and the gain in the downstream direction are alternately controlled, and homogeneous amplification and relay is performed in both directions as a whole.

〔Example〕

Examples will be described with reference to the drawings.

FIG. 2 shows an optical direct amplifier l using an erbium-doped fiber 11. Reference numeral 2 denotes an optical fiber through which optical signals are transmitted, and bidirectional optical signals in the up and down directions are transmitted within the same optical fiber 2. However, in the up direction and the down direction, the wavelength of the signal light is λ1. λ2 is slightly different.

Optical fibers 1 disposed across the optical direct amplifier 1 are connected by an erbium-doped fiber 11 within the optical direct amplifier 1. At the connection between each optical fiber 2 and the erbium-doped fiber 11, an optical coupler 12 is placed on one side, and a beam splitter 31 is placed on the other side.

Excitation light enters the optical coupler 12 from a laser diode 14 disposed on the side, and the excitation light is sent into the erbium-doped fiber 11. The pumping light directly amplifies the optical signal within the erbium-doped fiber 11, and both the upstream and downstream optical signals are amplified.

In the beam splitter 31, part of the energy of the optical signal in the upstream direction is split, enters the photoelectric converter 32, and is converted into an electrical signal. Then, the automatic gain control circuit 33 is activated by the output signal from the photoelectric converter 32.
The intensity of the excitation light generated by the laser diode 14 is controlled so that the output A of the optical signal in the upward direction is always constant.

Note that the output from the automatic gain control circuit 33 is input to a drive circuit for the laser diode 14, but the drive circuit is not shown.

In this way, in the optical direct amplifier l shown in FIG. 2, bidirectional optical signals in the upstream and downstream directions are directly amplified, and the output value of the optical signal in the upstream direction becomes a constant level. Automatic gain control is performed as follows. The gain of the downstream optical signal is directly affected by the automatic gain control performed on the upstream optical signal, and changes depending on the input level of the upstream optical signal.

Although not shown, if the optical direct amplifier 1 shown in FIG. 2 is connected in reverse directions for up and down, automatic gain control is performed so that the output value of the optical signal in the down direction is constant. Of course, upstream optical signal amplification is also performed.

FIG. 3 shows an optical direct amplifier 1 (la) as described above.

This shows an optical amplification repeating system in which a plurality of tb, . 2
0.21 is an optical signal transmitter and receiver for uplink. 22.
23 is a downstream optical signal transmitter and receiver. 24
is an optical coupler for inputting a downstream optical signal into the optical fiber 2. 25 is a beam splitter for branching a downstream optical signal from the optical fiber 2.

The plurality of optical direct amplifiers l are alternately provided with gain control circuits 3A for controlling the gain in the upstream direction and gain control circuits 3B for controlling the gain in the downstream direction. That is, lb and ld in FIG.

If the optical direct amplifier l has a gain control circuit 3 for the upstream direction.
A is provided, and a downstream gain control circuit 3B is provided for the optical direct amplifiers 1a, lc, and le.

In this way, optical signals in each direction up and down are transmitted through one optical fiber 2, and each optical direct amplifier la, lb, .
Both directions of optical signals are amplified in..., and the gain of optical amplification in each direction is determined by a plurality of optical direct amplifiers 1a, lb,...
・Performed every other time. Therefore, if amplification without gain control is performed on both the upper and lower optical signals, the output of the optical signal will always be amplified to a predetermined constant level by gain-controlled amplification. Both can perform stable amplification.

FIG. 4 shows an example in which a semiconductor laser optical amplifier 41 is used as an optical direct amplifier instead of an erbium-doped fiber. As the semiconductor laser amplifier 41 for direct optical amplification, a so-called traveling wave optical amplifier or the like can be used, and the same functions and effects as in the embodiment shown in FIG. 2 can be obtained. 42 is a semiconductor laser amplifier 41
drive circuit. 43 is a convex lens for focusing the signal light on the semiconductor laser amplifier 41.

In addition to the optical direct amplifier, an optical amplifier using stimulated Raman scattering can be used, but in that case, a large amount of power is required.

〔Effect of the invention〕

According to the optical amplification and repeating system of the present invention, by using multiple optical direct amplifiers, long-distance bidirectional optical signal transmission can be performed with a single optical fiber, which reduces equipment costs for submarine optical cable transmission systems, etc. It has an excellent effect of significantly reducing

[Brief explanation of drawings]

Figure 1 is a diagram of the principle of the present invention. FIG. 2 is a partial configuration diagram of the embodiment, FIG. 3 is an overall configuration diagram of the embodiment, FIG. 4 is a partial configuration diagram of the second embodiment. In the figure, 1... optical direct amplifier, 2...optical fiber, 3A...gain control circuit, 3B...Gain control circuit. °ko: Ton Pebe bebe

Claims (1)

[Claims] A plurality of optical direct amplifiers (1) that directly amplify optical signals are provided, and each of the optical direct amplifiers (1) is connected with a single optical fiber (2), and the optical An upstream gain control circuit (3A) for controlling the upstream gain in the direct amplifier (1), and a downstream gain control circuit (3A) for controlling the downstream gain in the direct amplifier (1).
B) is provided alternately in the plurality of optical direct amplifiers (1).