JPS6084034A - Optical agc system - Google Patents

Abstract

PURPOSE:To keep always a loss of an optical transmission line constant independently of its connection path by calculating a loss between two points with an output luminous amount of a monitor optical signal obtained at one end of optional two points between which an optical transmission line is set and giving a gain in response to the loss to a wavelength carrying information. CONSTITUTION:Information in the optical transmission line ranging from one end of an optical fiber cable 100 to other end of an optical fiber cable 112 is carried by using an optical signal having a wavelength lambda1, and the optical loss of the optical transmission line of the wavelength lambda1 to the optical signal is represented as a difference L-G between the loss L of the optical fiber cable 104 and the gain G of an optical amplifier 105. On the other hand, a light emitting element 101 emits continuous light having a wavelength lambda2 and a prescribed luminous amount and the continuous light of the wavelength lambda2 is transmitted to an photoelectric converting circuit 109 provided to a receiving end. A differential amplifier 111 controls the gain G of the optical amplifier 105 so that an output voltage of the photoelectric converting circuit 109 is equal to an electromotive force Vref of a reference voltage source 110.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides an optical
This invention relates to an optical AGC method that amplifies an optical signal according to the loss of the symbol.

Nowadays, optical fiber cable transmission systems using optical fiber cables as transmission paths are being introduced into various communication networks, both public and private, in place of thin, broadband, and conventional coaxial cable transmission systems. G) Switching equipment, which is another important component in such communication networks, converts optical signals sent through optical fiber cables into electrical signals, performs switching connections, and performs writing. Currently, the signal is converted into an optical signal and sent to an optical fiber group.

However, in recent years, examples include the 1985 Hikiko Communication Society General Conference Financial Papers Volume 7.170 [Basic Experiments on Time-Division Optical Switching] and the Shigeko Communication Society Technical Research Report V. l, -
78, pp. 73-79 1. Attempts on space-division optical switching equipment - An optical system that exchanges and connects optical signals sent by optical fiber cables as they are, and sends them out to optical fiber cables. As research and development of switching equipment continues, it is expected that in the near future optical communication systems that will be able to transmit and exchange optical signals as they are will emerge.

In such optical communication m, desired two
An optical amplifier that compensates for loss in an optical transmission line set between points is indispensable for MI.

An object of the present invention is to provide an optical AGC that can provide an optical signal carrying information with a gain corresponding to the loss of an optical transmission line set within an optical communication network without converting the optical signal into an electrical signal.
The goal is to provide a method.

According to the present invention, in an optical communication set that transmits and exchanges optical signals, an optical transmission path has a wavelength different from a wavelength that carries information and a predetermined amount of light between any two points set up. The optical signal for monitoring is transmitted to one end of the two points, and the loss between the two points is calculated based on the output light amount of the optical signal for monitoring obtained at one end of the two points, and the gain corresponding to the loss is applied to the wavelength that carries the information. Optical AGC system characterized by giving % formula % Next, regarding this invention, refer to the drawings 1. I will explain.

FIG. 1 is a diagram showing a first embodiment of the present invention.

Group 10υ has a wavelength formula and is predetermined t
A light emitting element 101 that emits continuous light at L/c source, an optical fiber couple 102 into which one end of the light emitting element 1010 output 9 is input, and the fiber coupler 10 of the source fiber 10.
The optical multiplexer 103 has one input end connected to the other end of 0 and the other input end contacts the other end of the cable 102, and the optical multiplexer 1 (one end contacts the direct output end of +3). 7-eye fiber cable 104, a nine-wave chair 107 whose input end is in contact with the other end of the optical fiber coupler 104, and a nine-wavelength chair 107 whose input end is in contact with the other end of the optical fiber coupler 104; an optical fiber couple 108 whose one end is in contact with the end surface of the optical fiber cable 108;
A reference voltage source 110 with a negative terminal connected to the earth with the reference voltage source 110 on the other hand, one human power is applied to the positive terminal of this reference voltage source 110, and the other human power is applied to the output of the optical-electric conversion circuit 109. , a differential amplifier 111 whose vj power is connected to the control input terminal of the amplifier 105, and an optical fiber group 112 whose one end is in contact with the end face of the optical demultiplexer 1070 from which the optical signal is output. including.

In FIG. 1, information is conveyed in the optical transmission line from one end of the optical fiber cable 100 to the other end of the original fiber cable 112 by an optical signal having a wavelength formula. The optical loss of the optical transmission line for the signal is the loss of the optical fiber cable 104 and the optical amplifier 1.
It can be expressed as the difference L−G in the gain G of 0.05.

On the other hand, the light emitting element 101 emits continuous light having a wavelength of λ and a predetermined amount of light.
Optical fiber cable 104 - optical amplifier 105 - optical demultiplexer 108 - optical-to-electric conversion regeneration force Vref and force Z' provided at the receiving end in the path of optical fiber cable 108
The gain G of the optical amplifier 105 is controlled so that they are equal. Therefore, if the loss of the optical fiber cable 104 and the gain G of the optical amplifier 105 are approximately equal to the wavelength λ and the input, the wavelength λ1 from one end of the optical fiber cable 100 to the other end of the optical fiber cable 112 is
The loss L-G for the optical signal of optical fiber 1
It is possible to always set it constant regardless of the loss I. Here, the loss LG is the amount of light from the light emitting element 101, and b is the reference voltage #, and the output voltage of 110 is 7'J V
It can be set to a desired value using ref.

Although FIG. 1 shows only the optical fiber cable 104 as an optical transmission path from one end of the optical fiber cable 100 to the optical fiber cable 112, for example, see IEICE technical research report VoJ1; The loss is always kept constant even when different connection paths are selected depending on the current situation, even when multiple optical exchanges are constructed of optical fiber cables with a number of links, as seen in ``A Trial of Split Optical Switching''. be able to.

Further, as a means for detecting optical loss from one end of the optical fiber cable 100 to the other end of the optical fiber cable 112, a part of the optical signal of wavelength λ carrying information is obtained by an optical branch circuit and used. However, in this case, a loss is caused to the optical signal of wavelength X, and deterioration of p87N is caused. Furthermore, since the optical signal having the wavelength table is an optical signal modulated by information, the optical-to-electrical conversion circuit 109 is required to have a function such as peak value detection, resulting in a complicated configuration of the optical-to-electrical conversion circuit 109.

As described above, according to the first embodiment of the present invention shown in FIG. Therefore, an optical AGC system that is always constant and has a simple nine-electric conversion circuit 1090 circuit configuration can be obtained.

FIG. 2 is a diagram showing a second embodiment of the present invention.

In FIG. 2, the same numbers as in FIG. 1 indicate the same components as in FIG.
A multiple optical element 101 different from the first Q embodiment shown in the figure is provided at the same receiving end as the optical-to-electrical conversion circuit 109.

In FIG. 2, the wavelength table emitted from the light emitting element 101,
The continuous light having...-7 mirrors 200-optical fiber cable 108-optical demultiplexer 107-optical fiber cable 106-optical amplifier 105-optical fiber.

Eyeper cable 104 - reaches the output end of the optical fiber cable 102 through the path of the optical multiplexer 103. After this optical signal with the wavelength λ is reflected by the mirror 201, the optical fiber cable 102-optical multiplexer 103-optical fiber cable 104-optical amplifier 105-optical fiber cable 106-optical demultiplexer 107-optical fiber cable 108 - Directing the path of the half mirror 200 - optical fiber cable 203 and optical-electrical conversion circuit 109
The differential amplifier 111 is added to the 0 input terminal, and the optical amplifier 105 is connected to the optical amplifier 105 so that the output voltage of the optical-to-electrical conversion circuit 109 and the electromotive force Vref of the reference voltage source 110 become equal, as in the first embodiment shown in FIG. The gain G of is controlled. In the second embodiment of the present invention shown in FIG. 2, a light emitting element 101 and a wavelength ^7. The optical-to-electrical conversion circuit 109 for detecting continuous light, the reference voltage source 110, the differential amplifier 109, etc. can be provided in the same station.

As a result, even if the amount of light emitted from the light emitting element 101 changes due to fluctuations in the power supply, the influence of power fluctuations can be offset by using the same power source as the reference voltage source 110 for the light emitting element.

In the second embodiment of the present invention shown in FIG. 2, bidirectionality is required for the nine optical amplifiers 105, which is different from the first embodiment shown in FIG.

As the optical amplifier 105 shown in FIGS. 1 and 2, for example, a traveling wave amplifier in which anti-reflection treatment is applied to the cleavage plane of a double heterojunction laser diode is known, and the gain of this traveling wave amplifier is It can be electrically controlled by injection current.

For details on the above traveling wave amplifier, please refer to IBWB Journal
ofQuantum Electronics, Y
o i, QE-11, 65-69 Shellfish 1lGaAs
-Double -1(eterostructure
La5ers asOptical A, 1y+pl
iNers''.

Note that the first and second embodiments of the present invention shown in FIG. 1 and FIG.
In both embodiments, the optical amplifier 105 is replaced by the optical multiplexer 10.
3 and the optical demultiplexer 105. For example, this optical amplifier 105 can be connected to the wavelength table.

By providing the optical demultiplexer 107 in front of the optical signal having the wavelength table, it is also possible to amplify only the optical signal having the wavelength table.

As described above, according to the present invention, it is possible to always keep the loss of the light beam path set to any two-point curve as necessary in the communication network to be constant regardless of the connection path. An optical AGC system can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a first embodiment of the present invention;
The figure is a block diagram showing a second embodiment of the present invention. In the figure, °C, 101 is a light emitting element, 103 is a multiplexer, 1
05 is an optical amplifier, 107 is a demultiplexer, 109 is an electric-to-optical conversion circuit, 111 is a left-handed amplifier, 200 is /...-Fumi-
Each represents a 1201Fi mirror. Agent buj4jj+in 1 "ri line"

Claims (1)

[Claims] In an optical communication system that transmits and exchanges optical signals, an optical transmission line is used to superimpose a monitoring optical signal with a predetermined amount of light and a wavelength different from the wavelength that carries information between any two points set up. , calculating the loss between the two points based on the output light amount of the monitoring optical signal obtained at one end of the two points,
Optical AGC method 2, characterized in that a gain corresponding to the loss is given to nine wavelengths carrying the information.