JP2002353940A - Optical transmission system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem of a WDM system configuration becoming complicated, due to separate optical fiber transmission lines or components being required for incoming transmission and outgoing transmission. SOLUTION: This optical transmission system is provided with at least two optical transmission terminal stations, composed of a plurality of optical transmission/reception parts for respectively transmitting/receiving optical signals, a plurality of diffusion and compensation parts for respectively dispersion-compensating optical signals from the optical transmission/reception parts and optical signals to the optical transmission/ reception parts by using bidirectional dispersion and compensation functions, a wavelength multiplexing/demultiplexing part for multiplexing the optical signals from a plurality of dispersion and compensation parts, outputting a WDM optical signal, demultiplexing the inputted WDM optical signal and respectively outputting resultant optical signals to a plurality of dispersion and compensation parts, and an optically amplifying part for amplifying the WDM optical signal from the wavelength multiplexing/demultiplexing part and the WDM optical signal to the wavelength multiplexing/demultiplexing part, by using a bidirectional optical amplifying function; and an optical fiber transmission line for transmitting the WDM optical signal, by connecting the optical transmission terminal stations.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to wavelength division multiplexing (WDM: Wavelength Division) applied to a large-capacity long-distance backbone system in the field of optical communication.
The present invention relates to an optical transmission system of a multiplexing type.

[0002]

2. Description of the Related Art In an optical transmission system, a WDM system is known as a means for expanding a transmission capacity without adding a transmission line. In the WDM system, a plurality of optical signals having different center wavelengths are multiplexed by an optical multiplexer arranged on a transmitting side to form a WDM optical signal, and the WDM optical signal is divided by an optical demultiplexer arranged on a receiving side into each wavelength. By dividing into optical signals, the transmission capacity is increased without increasing the number of optical fiber transmission lines.

[0003] The basic configuration of a conventional optical transmission system based on the WDM system is such that optical transmission terminal stations are connected using separate optical fiber transmission lines on the upstream side and the downstream side, respectively. It has a dispersion compensation function, a wavelength multiplexing function, a wavelength separation function, an optical amplification function, an optical repeater amplification function, and the like.

FIG. 9 is a diagram showing a configuration of a conventional optical transmission system. In FIG. 9, reference numerals 110X and 110Y denote optical transmission terminal stations, 120 denotes an optical relay amplification station, and 130, respectively.
F is an upstream optical fiber transmission line, and 130B is a downstream optical fiber transmission line. The optical transmission system in FIG. 9 includes optical transmission terminal stations 110X and 110Y, a plurality of optical repeater amplification stations 120, and optical fiber transmission lines 130F and 130F.
30B.

[0005] The transmission system of the optical transmission terminal stations 110X and 110Y includes a plurality of optical transmitters 111F and 111B for converting an electric signal into a plurality of optical signals having different center wavelengths and transmitting the electric signal.
And dispersion compensators 112F and 112B for compensating chromatic dispersion generated in the optical fiber transmission lines 130F and 130B before transmission.
And optical signal multiplexers 113F and 113B for multiplexing a plurality of optical signals and outputting them as WDM optical signals, and for amplifying the WDM optical signals before transmission and for optical fiber transmission lines 130F and 130B.
, And optical fiber amplifiers 114F and 114B for outputting the signals to the optical fibers.

The receiving system of the optical transmission terminal stations 110X and 110Y includes an optical fiber amplifier 115 for amplifying a WDM optical signal received from the optical fiber transmission lines 130B and 130F.
B, 115F, and optical signal demultiplexers 116B, 116 for demultiplexing the WDM optical signal for each wavelength and outputting as a plurality of optical signals.
F and dispersion compensators 117B and 117 for compensating chromatic dispersion generated in the optical fiber transmission lines 130B and 130F after transmission.
F and a plurality of optical receivers 118B and 118F that receive a plurality of optical signals having different center wavelengths and convert the signals into electric signals.
Respectively.

[0007] The optical repeater amplifying station 120 has an optical fiber transmission line 130F, 1 for the purpose of compensating the transmission loss of the WDM optical signal.
It is appropriately installed on 30B. In FIG. 9, an optical fiber amplifier 121F for compensating for the loss of the WDM optical signal generated in the upstream optical fiber transmission line 130F and an optical fiber amplifier 121B for compensating for the loss of the WDM optical signal generated in the downstream optical fiber transmission line 130B. Are provided in plurality.

[0008]

Since the conventional optical transmission system is configured as described above, optical fiber transmission lines and components are individually required for upstream transmission and downstream transmission. There are problems that the system configuration becomes complicated and the cost of the WDM system increases.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and has been developed without changing the transmission capacity.
It is an object to configure an optical transmission system that can simplify the system configuration and reduce the cost of the WDM system.

[0010]

SUMMARY OF THE INVENTION An optical transmission system according to the present invention includes a plurality of optical transmission / reception units for transmitting an optical signal and receiving an optical signal, an optical signal from the optical transmission / reception unit, and an optical transmission / reception unit. A plurality of dispersion compensating units for respectively compensating optical signals to the optical signal by a bidirectional dispersion compensating function, and multiplexing optical signals from the plurality of dispersion compensating units by a wavelength multiplexing function to output a WDM optical signal; A wavelength division multiplexing / demultiplexing unit for demultiplexing the separated WDM optical signal by a wavelength demultiplexing function and outputting each of the optical signals to a plurality of dispersion compensating units; a WDM optical signal from the wavelength division multiplexing / demultiplexing unit; At least two optical transmission terminals comprising an optical amplifier for amplifying a signal by a bidirectional optical amplification function; an optical amplifier for one optical transmission terminal; and an optical amplifier for the other optical transmission terminal. By connecting the parts is obtained so as to include an optical fiber transmission line for transmitting a WDM optical signal.

An optical transmission system according to the present invention is provided with an optical repeater amplifying station for repeating and amplifying a WDM optical signal by a bidirectional optical repeater amplifying function on an optical fiber transmission line.

An optical transmission system according to the present invention comprises: an optical transmitter for transmitting an optical signal; an optical receiver for receiving an optical signal;
An optical transmitter / receiver is constituted by an optical circulator that outputs an optical signal from an optical transmitter to a dispersion compensator and outputs an optical signal from the dispersion compensator to an optical receiver.

In the optical transmission system according to the present invention, the dispersion compensator is an optical fiber.

[0014] In the optical transmission system according to the present invention, the dispersion compensator is an optical fiber grating.

In the optical transmission system according to the present invention, the wavelength division multiplexing / demultiplexing unit is an AWG type WDM filter.

In the optical transmission system according to the present invention, the wavelength division multiplexing / demultiplexing unit is a dielectric multilayer WDM filter.

An optical transmission system according to the present invention includes a plurality of dielectric multilayer narrow band filters each having a pass band of a wavelength of an optical signal passing through a plurality of dispersion compensators, and a plurality of dielectric multilayer narrow band filters. And multiplexes the optical signals that have passed through and outputs a WDM optical signal to the optical amplifier.
A wavelength multiplexing / demultiplexing unit is constituted by a WDM optical signal input from the optical amplifying unit, and a star coupler which equally divides the WDM optical signal and outputs the divided signals to the dispersion compensating unit via a plurality of dielectric multilayer narrow band filters. .

The optical transmission system according to the present invention has a WDM
A first optical fiber amplifier and a second optical fiber amplifier for amplifying optical signals, respectively, and a WDM from a wavelength division multiplexer.
A first optical circulator for inputting an optical signal to the first optical fiber amplifier and inputting a WDM optical signal from the second optical fiber amplifier to the wavelength division multiplexing / demultiplexing unit; A second optical circulator for inputting the WDM optical signal from the first optical fiber amplifier to the optical fiber transmission line while inputting to the fiber amplifier constitutes an optical amplifier.

An optical transmission system according to the present invention has a WDM
A first optical fiber amplifier and a second optical fiber amplifier for respectively amplifying an optical signal, and a WDM optical signal from one of the optical fiber transmission lines being input to the first optical fiber amplifier, and a WDM optical signal from the second optical fiber amplifier. A first optical circulator for inputting a signal to one optical fiber transmission line, and a second optical circulator for transmitting a WDM optical signal from the other optical fiber transmission line to a second optical circulator.
An optical repeater amplifying unit comprising an optical fiber amplifier and a second optical circulator for outputting a WDM optical signal from the first optical fiber amplifier to the other optical fiber transmission line is provided in the optical repeater amplifying station. It was done.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below. Embodiment 1 FIG. FIG. 1 is a diagram showing a configuration of an optical transmission system according to Embodiment 1 of the present invention. In FIG. 1, 1
0X and 10Y are optical transmission terminal stations, 20 is an optical repeater amplifier station, and 30 is an optical fiber transmission line.
The optical transmission system shown in FIG.
And a plurality of optical repeater amplification stations 20 and an optical fiber transmission line 30
It is composed of The optical transmission terminal stations 10X, 10
Y, the numbers of the optical repeater amplification stations 20 and the optical fiber transmission lines 30 are not particularly limited. If the transmission loss can be ignored, the optical repeater amplification station 20 may be omitted.

In the optical transmission terminal stations 10X and 10Y of FIG. 1, 11X and 11Y are a plurality of optical transmission / reception units (only one is shown in FIG. 1) for transmitting and receiving optical signals of respective wavelengths. Numeral 12Y denotes a plurality of dispersion compensators (only one is shown in FIG. 1) having a bidirectional dispersion compensation function by non-directional devices, and 13X and 13Y denote wavelength multiplexing functions and wavelength separation functions by non-directional devices. (Wavelength multiplexing / demultiplexing function), 14X and 14Y are optical amplifiers having a bidirectional optical amplification function by devices having no directivity.

Further, in each optical repeater amplifying station 20 of FIG. 1, reference numeral 21 denotes an optical repeater amplifying unit having a bidirectional optical repeater amplifying function by a device having no directivity.

First, from the optical transmission terminal 10X to the optical transmission terminal 10
The transmission operation to Y will be described. In FIG. 1, an optical signal transmitted from an optical transmitting / receiving unit 11X of an optical transmission terminal 10X is input to a dispersion compensating unit 12X via an optical fiber, and dispersion compensation before transmission is performed. The optical signal output from the dispersion compensator 12X is transmitted to the wavelength multiplexing / demultiplexing unit 13 via an optical fiber.
X, where a plurality of optical signals are multiplexed into a WDM optical signal. This WDM optical signal is input to the optical amplifier 14X via an optical fiber, amplified, and output to the optical fiber transmission line 30.

The WDM optical signal transmitted through the optical fiber transmission line 30 is input to the optical repeater 21 of the optical repeater 20. The optical repeater 21 repeats and amplifies the WDM optical signal and outputs the signal to the next optical fiber transmission line 30. Hereinafter, the WDM optical signal output from the optical transmission terminal station 10X reaches the optical transmission terminal station 10Y while repeating the transmission of the optical fiber transmission line 30 and the relay amplification of the optical relay amplification station 20.

The WDM optical signal reaching the optical transmission terminal 10Y is amplified by the optical amplifier 14Y. The amplified WDM optical signal is input to the wavelength division multiplexing / demultiplexing unit 13Y via an optical fiber, where it is demultiplexed as a plurality of optical signals for each wavelength.
Each of the demultiplexed optical signals is input to a dispersion compensator 12Y via an optical fiber, and after performing dispersion compensation after transmission,
The data is received by the optical transceiver 11Y via the optical fiber.

Next, the optical transmission terminal 10Y to the optical transmission terminal 10Y
The transmission operation to X will be described. In FIG. 1, an optical signal transmitted from an optical transmission / reception unit 11Y of an optical transmission terminal 10Y is input to a dispersion compensation unit 12Y via an optical fiber, and dispersion compensation before transmission is performed. The optical signal output from the dispersion compensator 12Y is transmitted to the wavelength multiplexing / demultiplexer 13 via an optical fiber.
Y, and a plurality of optical signals are multiplexed into a WDM optical signal. The WDM optical signal is input to the optical amplifier 14Y via an optical fiber, amplified, and output to the optical fiber transmission line 30.

The WDM optical signal transmitted through the optical fiber transmission line 30 is input to the optical repeater 21 of the optical repeater 20. The optical repeater 21 repeats and amplifies the WDM optical signal and outputs the signal to the next optical fiber transmission line 30. Hereinafter, the WDM optical signal output by the optical transmission terminal station 10Y reaches the optical transmission terminal station 10X while repeating the transmission of the optical fiber transmission line 30 and the relay amplification of the optical relay amplification station 20.

The WDM optical signal reaching the optical transmission terminal 10X is amplified by the optical amplifier 14X. The amplified WDM optical signal is input to the wavelength division multiplexing / demultiplexing unit 13X via an optical fiber, where it is demultiplexed as a plurality of optical signals for each wavelength.
Each of the demultiplexed optical signals is input to the dispersion compensator 12X via an optical fiber, and after performing dispersion compensation after transmission,
It is received by the optical transceiver 11X via the optical fiber.

As described above, in the optical transmission system according to the first embodiment, the dispersion compensators 12X and 12Y, the wavelength multiplexing / demultiplexing units 13X and 13Y, the optical amplifiers 14X and 14Y, and the optical repeater amplifier 21 are connected to the optical fiber transmission line. 30 and the same optical fiber transmission line 30 for upstream transmission and downstream transmission.
Is also used. Each of these components has a bidirectionality in a dispersion compensation function, a wavelength division multiplexing / demultiplexing function, an optical amplification function, and an optical repeater amplification function, so that the WDM system configuration is simplified as shown in FIG. , The cost can be reduced by the simplified amount. Note that components realizing each function in FIG. 1 will be described in Embodiments 2 to 8.

As described above, according to the first embodiment, a plurality of optical transmitting / receiving units 11X and 11Y for transmitting optical signals and receiving optical signals, respectively, and light from optical transmitting / receiving units 11X and 11Y. Signal and optical transceiver 1
A plurality of dispersion compensators 12X, 12X each of which compensates the optical signal to 1X, 11Y by a bidirectional dispersion compensation function.
Y and the optical signals from the plurality of dispersion compensators 12X and 12Y are multiplexed by the wavelength multiplexing function to output a WDM optical signal, and the input WDM optical signal is demultiplexed by the wavelength demultiplexing function to generate a plurality of dispersion signals. Wavelength multiplexing / demultiplexing units 13X and 13Y for outputting optical signals to the compensating units 12X and 12Y, respectively;
Optical amplifiers 14X, 1 which amplify the WDM optical signals from the wavelength multiplexing / demultiplexing units 13X, 13Y and the WDM optical signals to the wavelength multiplexing / demultiplexing units 13X, 13Y by a bidirectional optical amplification function.
4Y, and the optical amplifier 14X (1Y) of one of the optical transmission terminals 10X (10Y).
4Y) and the optical amplifying unit 14Y (14X) of the other optical transmission terminal 10Y (10X), and the optical fiber transmission line 30 for transmitting the WDM optical signal. In this case, the optical fiber transmission line 30 can be shared for transmission, and the effect of simplifying the WDM system configuration without changing the transmission capacity can be obtained, and the effect of reducing the cost of the WDM system can be obtained.

Further, according to the first embodiment, the optical repeater amplification station 20 for repeating and amplifying the WDM optical signal by the bidirectional optical repeater amplification function is provided on the optical fiber transmission line 30. And in the downstream direction, the long-distance optical fiber transmission line can be shared and transmitted,
The advantage is that the WDM system configuration can be simplified without changing the transmission capacity, and that the cost of the WDM system can be reduced.

Embodiment 2 FIG. FIG. 2 is a diagram showing a configuration of an optical transmission system according to Embodiment 2 of the present invention. FIG.
The same reference numerals are the same or equivalent. In the optical transmission / reception units 11X and 11Y of FIG. 2, 11A is an optical transmitter for transmitting an optical signal, 11B is an optical receiver for receiving an optical signal,
11C is an optical circulator having a port I, a port II, and a port III.

Next, the operation will be described. Optical transmitter 11
The optical signal transmitted from A is input to port I of optical circulator 11C. The optical circulator 11C outputs an optical signal input to the port I from the port II, and outputs the optical signal to the dispersion compensators 12X and 12Y via an optical fiber.
The optical signals input from the dispersion compensating units 12X and 12Y to the port II via the optical fibers are transmitted to the optical circulator 1
1C, output from the port III, the optical receiver 11
B.

As described above, the optical transmission / reception units 11X and 11Y of the second embodiment transmit the optical signals transmitted by the transmitter 11A via the ports I and II to the dispersion compensation units 12X and 12Y.
Y, and the optical signals from the dispersion compensating units 12X and 12Y are received by the optical receiving unit 11B through the ports II and III, so that the optical signals are transmitted and received by one optical fiber connected to the port II. And the configuration can be simplified.

As described above, according to the second embodiment, the optical transmitter 11A for transmitting an optical signal, the optical receiver 11B for receiving an optical signal, and the optical signal from the optical transmitter 11A are dispersion-compensated. The optical circulator 11C which outputs the optical signals from the dispersion compensators 12X and 12Y to the optical receiver 11B while outputting the signals to the optical transmitters and receivers 11X and 12Y.
Since X and 11Y are configured, the effect of simplifying the WDM system configuration without changing the transmission capacity is obtained, and the effect of reducing the cost of the WDM system is obtained.

Embodiment 3 FIG. 3 is a diagram showing a configuration of an optical transmission system according to Embodiment 3 of the present invention. FIG.
The same reference numerals are the same or equivalent. In the dispersion compensators 12X and 12Y of FIG. 3, 12A is an optical fiber for chromatic dispersion compensation. In the optical transmission system according to the third embodiment, the dispersion compensators 12X and 12Y according to the first embodiment are used.
Are realized by the optical fiber 12A. Even in this case, the same effect as in the first embodiment can be obtained.

As described above, according to the third embodiment, by using the optical fibers 12A for the dispersion compensators 12X and 12Y, the dispersion compensation before transmission and the dispersion compensation after transmission are the same. Therefore, the effect of simplifying the WDM system configuration without changing the transmission capacity can be obtained, and the effect of reducing the cost of the WDM system can be obtained.

Embodiment 4 FIG. FIG. 4 is a diagram showing a configuration of an optical transmission system according to Embodiment 4 of the present invention. FIG.
The same reference numerals are the same or equivalent. In the dispersion compensators 12X and 12Y of FIG. 4, 12B is an optical fiber grating. In the optical transmission system according to the fourth embodiment, the bidirectional dispersion compensation function in the dispersion compensators 12X and 12Y according to the first embodiment is realized by the optical fiber grating 12B. Even in this case, the same effect as in the first embodiment can be obtained.

As described above, according to the fourth embodiment, the dispersion compensation before transmission and the dispersion compensation after transmission are the same by using the optical fiber grating 12B for the dispersion compensators 12X and 12Y. Since the operation can be performed by the grating 12B, the effect that the WDM system configuration can be simplified without changing the transmission capacity can be obtained, and the effect that the cost of the WDM system can be reduced can be obtained.

Embodiment 5 FIG. 5 is a diagram showing a configuration of an optical transmission system according to Embodiment 5 of the present invention. FIG.
The same reference numerals are the same or equivalent. In the wavelength division multiplexing / demultiplexing units 13X and 13Y of FIG.
(Arrayed Waveguide Gritin
g, array waveguide diffraction grating) type WDM filter.
In the optical transmission system of the fifth embodiment, the first embodiment
The wavelength multiplexing function and the wavelength demultiplexing function in the wavelength multiplexing / demultiplexing units 13X and 13Y are realized by the AWG-type WDM filter 13A. Even in this case, the first embodiment
The same effect can be obtained.

As described above, according to the fifth embodiment, the wavelength division multiplexing / demultiplexing units 13X and 13Y are AWG-type WDM filters 13A. And the input WDM
Since the demultiplexing of the optical signal into a plurality of optical signals for each wavelength can be performed by the same AWG-type WDM filter 13A, the effect of simplifying the WDM system configuration without changing the transmission capacity is obtained. In addition, there is an effect that the cost of the WDM system can be reduced.

Embodiment 6 FIG. FIG. 6 is a diagram showing a configuration of an optical transmission system according to Embodiment 6 of the present invention. FIG.
The same reference numerals are the same or equivalent. In the wavelength division multiplexing / demultiplexing units 13X and 13Y of FIG. 6, reference numeral 13B denotes a dielectric multilayer WDM filter. In the optical transmission system according to the sixth embodiment, the wavelength division multiplexing / demultiplexing unit 13 according to the first embodiment is used.
The wavelength multiplexing function and the wavelength separation function in X and 13Y are realized by the dielectric multilayer WDM filter 13B. Even in this case, the same effect as in the first embodiment can be obtained.

As described above, according to the sixth embodiment, the wavelength division multiplexing / demultiplexing units 13X and 13Y are formed by the dielectric multilayer film WD.
By using the M filter 13B, a plurality of input optical signals are multiplexed into a WDM optical signal, and
Demultiplexing a DM optical signal into a plurality of optical signals for each wavelength can be performed by the same dielectric multilayer WDM filter 13B.
The advantage is that the system configuration can be simplified and the cost of the WDM system can be reduced.

Embodiment 7 FIG. FIG. 7 is a diagram showing a configuration of an optical transmission system according to Embodiment 7 of the present invention. FIG.
The same reference numerals are the same or equivalent. In the wavelength division multiplexing / demultiplexing units 13X and 13Y of FIG. 7, 13C is a star coupler, and 13D is a plurality of dielectric multilayer narrow band filters (only one is shown in FIG. 7). In the optical transmission system according to the seventh embodiment, the wavelength division multiplexing / demultiplexing unit 1 according to the first embodiment is used.
The wavelength multiplexing function and the wavelength demultiplexing function in 3X and 13Y are provided by a star coupler 13C and a dielectric multilayer film narrow band filter 1.
This is realized by a combination with 3D. Even in this case, the same effect as in the first embodiment can be obtained.

Next, the operation will be described. Dispersion compensator 1
The optical signals output from the 2X and 12Y are input to the dielectric multilayer narrow band filter 13D via the optical fiber. Since the pass band of the dielectric multilayer narrow band filter 13D is adjusted to the wavelength of the optical signal from the dispersion compensating units 12X and 12Y, noise outside the optical signal band is removed by the dielectric multilayer narrow band filter 13D. You. The optical signal from which the out-of-band noise has been removed is input to the star coupler 13C and multiplexed with the optical signal from the other dielectric multilayer narrow-band filter 13D to become a WDM signal. This WDM optical signal is input to the optical amplifiers 14X and 14Y via the optical fiber.

The WDM optical signals output from the optical amplifiers 14X and 14Y are connected to the star coupler 1 via an optical fiber.
3C, where it is equally divided into the number of ports of the star coupler 13C. Each equally divided WDM optical signal is input to the dielectric multilayer narrow band filter 13D via an optical fiber. Here, the optical signal and noise outside the optical signal band are removed, and the optical signal is demultiplexed as a plurality of optical signals for each wavelength. The demultiplexed optical signals are input to the dispersion compensators 12X and 12Y via optical fibers.

As described above, according to the seventh embodiment, a plurality of dielectric multilayer thin-film filters 13D whose pass bands are the wavelengths of optical signals passing through the plurality of dispersion compensators 12X and 12Y, respectively, The optical signals that have passed through the plurality of dielectric multilayer thin-film filters 13D are multiplexed to form a WDM
While outputting the optical signal to the optical amplifiers 14X and 14Y,
The WDM optical signals input from the optical amplifiers 14X and 14Y are equally divided and output from the star coupler 13C to the dispersion compensators 12X and 12Y via a plurality of dielectric multilayer narrow band filters 13D. , 13Y, the input optical signals are multiplexed and WD
Making the M optical signal and demultiplexing the input WDM optical signal into a plurality of optical signals for each wavelength are performed by the same set of the dielectric multilayer thin film narrow band filter 13D and the star coupler 13C. Therefore, the effect that the WDM system configuration can be simplified without changing the transmission capacity can be obtained, and the effect that the cost of the WDM system can be reduced can be obtained.

Embodiment 8 FIG. FIG. 8 is a diagram showing a configuration of an optical transmission system according to Embodiment 8 of the present invention. FIG.
The same reference numerals are the same or equivalent. 8, 14A and 14B are optical fiber amplifiers, respectively, and 14C and 14D are optical circulators having ports I, II and III, respectively. In the optical repeater amplifying section 21 of FIG.
1A and 21B are optical fiber amplifiers, 21C and 2 respectively.
1D is an optical circulator having a port I, a port II, and a port III, respectively.

In the optical transmission system according to the eighth embodiment,
The optical amplification function in the optical amplification units 14X and 14Y of the first embodiment is realized by a combination of the optical fiber amplifiers 14A and 14B and the optical circulators 14C and 14D.
The optical repeater amplifying function in the optical repeater amplifying unit 21 of the first embodiment is realized by a combination of the optical fiber amplifiers 21A and 21B and the optical circulators 21C and 21D. Even in this case, the same effect as in the first embodiment can be obtained.

Next, the operation will be described. Optical transmission terminal 1
At 0X and 10Y, the wavelength multiplexing / demultiplexing units 13X and 13Y
The WDM optical signals input from the optical amplifiers 14X and 14Y to the optical amplifiers 14X and 14Y are input to the port II of the optical circulator (first optical circulator) 14C via the optical fiber. Port I
The WDM optical signal input to I is output from the port III by the optical circulator 14C and input to the optical fiber amplifier (first optical fiber amplifier) 14A via the optical fiber.

The optical fiber amplifier 14A receives the input W
Amplify the DM optical signal. The amplified WDM optical signal is input to port I of an optical circulator (second optical circulator) 14D via an optical fiber. The WDM optical signal input to port I is output from port II by optical circulator 14D, and input to optical fiber transmission line 30.

The WDM optical signals input from the optical fiber transmission line 30 to the optical amplifiers 14X and 14Y are input to the port II of the optical circulator 14D via the optical fiber. The WDM optical signal input to the port II is output from the port III by the optical circulator 14D, and is output via an optical fiber to an optical fiber amplifier (second optical fiber amplifier).
Input to 14B.

The optical fiber amplifier 14B receives the input W
Amplify the DM optical signal. The amplified WDM optical signal is input to port I of optical circulator 14C via an optical fiber. The WDM optical signal input to the port I is output from the port II by the optical circulator 14C, and is input to the wavelength division multiplexing / demultiplexing units 13X and 13Y via the optical fiber.

In the optical repeater amplifying station 20, the signals are output from the optical transmission terminal stations 10X and 10Y and the optical fiber transmission line 30 is output.
Is input to the port II of the optical circulator (first optical circulator) 21C. The WDM optical signal input to port II is transmitted to optical circulator 21
The signal is output from the port III by C and input to the optical fiber amplifier (first optical fiber amplifier) 21A via the optical fiber.

The optical fiber amplifier 21A receives the input W
The DM optical signal is relay-amplified. The relay-amplified WDM optical signal is input to port I of an optical circulator (second optical circulator) 21D via an optical fiber. Port I
The WDM optical signal input to is output from the port II by the optical circulator 21D, transmitted through the optical fiber transmission line 30, and directed to the optical transmission terminal stations 10Y and 10X.

The WDM optical signal input from the optical fiber transmission line 30 between the optical relay amplifier stations 20 to the optical relay amplifier 21 is input to the port II of the optical circulator 21D.
The WDM optical signal input to the port II is output from the port III by the optical circulator 21D, and is output via the optical fiber to the optical fiber amplifier (second optical fiber amplifier) 21.
Input to B.

The optical fiber amplifier 21B receives the input W
The DM optical signal is relay-amplified. The relay-amplified WDM optical signal is input to the port I of the optical circulator 21C via an optical fiber. The WDM optical signal input to the port I is output from the port II by the optical circulator 21C, transmitted through the optical fiber transmission line 30, and
Go to X, 10Y.

As described above, according to the eighth embodiment, the optical fiber amplifiers 14A and 14B amplify the WDM optical signal, respectively, and the WDM optical signals from the The input to the amplifier 14A and the optical fiber amplifier 14B
The optical circulator 14C inputs the WDM optical signal from the optical fiber amplifier 14B to the wavelength division multiplexing / demultiplexing units 13X and 13Y, and inputs the WDM optical signal from the optical fiber transmission line 30 to the optical fiber amplifier 14B.
By configuring the optical amplifiers 14X and 14Y from the optical circulator 14D that outputs an optical signal to the optical fiber transmission line 30, the optical fiber transmission line can be shared and transmitted in the upstream and downstream directions, so that the transmission capacity is changed. The advantage is that the configuration of the WDM system can be simplified without any problem, and the effect that the cost of the WDM system can be reduced can be obtained.

According to the eighth embodiment, the WDM
An optical fiber amplifier 21A and an optical fiber amplifier 21B for respectively amplifying an optical signal, and a WDM optical signal from one optical fiber transmission line 30 is input to the optical fiber amplifier 21A, and the WDM optical signal from the optical fiber amplifier 21B is
An optical circulator 21C for inputting an optical signal to one of the optical fiber transmission lines 30 and a WDM optical signal from the other optical fiber transmission line 30 to the optical fiber amplifier 21B, and a WDM optical signal from the optical fiber amplifier 21A. By providing the optical amplifying unit 21 including the optical circulator 21D for outputting to the other optical fiber transmission line 30 in the optical relay amplification station 20, the long-distance optical fiber transmission line is shared in the upstream and downstream directions. Since transmission can be performed, the effect that the WDM system configuration can be simplified without changing the transmission capacity can be obtained, and the effect that the cost of the WDM system can be reduced can be obtained.

[0060]

As described above, according to the present invention, a plurality of optical transmission / reception units for transmitting an optical signal and receiving an optical signal, respectively, the optical signal from the optical transmission / reception unit and the transmission / reception to the optical transmission / reception unit are provided. A plurality of dispersion compensators for respectively compensating optical signals by a bidirectional dispersion compensation function, and multiplexing optical signals from the plurality of dispersion compensators by a wavelength multiplexing function to output a WDM optical signal and input the WDM optical signal; A wavelength division multiplexing / demultiplexing unit for demultiplexing a WDM optical signal by a wavelength separation function and outputting the optical signal to each of a plurality of dispersion compensating units; and a WDM optical signal from the wavelength division multiplexing / demultiplexing unit and a WDM optical signal to the wavelength division multiplexing / demultiplexing unit. At least two optical transmission terminals, each of which comprises an optical amplifier for amplifying by a bidirectional optical amplification function, are connected to an optical amplifier of one optical transmission terminal and an optical amplifier of the other optical transmission terminal. I An optical fiber transmission line for transmitting WDM optical signals is provided, so that the optical fiber transmission line can be shared and transmitted in the upstream and downstream directions, thereby simplifying the WDM system configuration without changing the transmission capacity. And the WDM
The effect that the cost of the system can be reduced is obtained.

According to the present invention, the optical repeater amplifying and relaying the WDM optical signal by the bidirectional optical repeater amplifying function is provided on the optical fiber transmission line. The transmission can be performed by sharing the transmission path, whereby the effect of simplifying the WDM system configuration without changing the transmission capacity can be obtained, and the effect of reducing the cost of the WDM system can be obtained.

According to the present invention, an optical transmitter for transmitting an optical signal, an optical receiver for receiving an optical signal, and an optical signal from the optical transmitter are output to the dispersion compensating section, and the optical signal from the dispersion compensating section is output from the dispersion compensating section. An optical circulator that outputs an optical signal to an optical receiver constitutes an optical transmitting and receiving unit, and the optical transmitter and the optical receiver are integrated into one, so that W can be changed without changing the transmission capacity.
The effect that the DM system configuration can be simplified is obtained,
Further, the effect that the cost of the WDM system can be reduced is obtained.

According to the present invention, by using an optical fiber as the dispersion compensator, dispersion compensation before transmission and dispersion compensation after transmission can be performed on the same optical fiber. The advantage is that the WDM system configuration can be simplified, and the cost of the WDM system can be reduced.

According to the present invention, since the dispersion compensator is an optical fiber grating, dispersion compensation before transmission and dispersion compensation after transmission can be performed by the same optical fiber grating. The advantage is that the WDM system configuration can be simplified without any change, and the effect that the cost of the WDM system can be reduced can be obtained.

According to this invention, the wavelength division multiplexing / demultiplexing unit is
By using a G-type WDM filter, it is possible to combine a plurality of input optical signals into a WDM optical signal and to split the input WDM optical signal into a plurality of optical signals for each wavelength. Since the same AWG-type WDM filter can be used, the effect of simplifying the WDM system configuration without changing the transmission capacity can be obtained, and the effect of reducing the cost of the WDM system can be obtained.

According to the present invention, the wavelength division multiplexing / demultiplexing unit is a dielectric multilayer WDM filter, so that a plurality of input optical signals are multiplexed into a WDM optical signal, and the input WDM optical signal is used. Since the signal can be split into a plurality of optical signals for each wavelength by the same dielectric multilayer WDM filter, the WDM system configuration can be simplified without changing the transmission capacity. And W
The effect that the cost of the DM system can be reduced is obtained.

According to the present invention, each of the plurality of dielectric multilayer narrow band filters having a pass band of the wavelength of the optical signal passing through each of the plurality of dispersion compensators, and each of the plurality of dielectric multilayer narrow band filters passes. Multiplexed optical signals and WDM
The optical signal is output to the optical amplifying unit, and the WDM optical signal input from the optical amplifying unit is equally divided and wavelength-division multiplexed from a star coupler which outputs the optical signal to the dispersion compensating unit through a plurality of dielectric multilayer narrow band filters. By configuring the demultiplexing unit, combining the input optical signals into a WDM optical signal and demultiplexing the input WDM optical signal into a plurality of optical signals for each wavelength, Since the same dielectric multilayer narrow band filter and star coupler can be used, the WDM system configuration can be simplified without changing the transmission capacity, and the cost of the WDM system can be reduced. The effect is obtained.

According to the present invention, the first optical fiber amplifier and the second optical fiber amplifier for respectively amplifying the WDM optical signal, and the WDM optical signal from the wavelength division multiplexer are inputted to the first optical fiber amplifier. A first optical circulator for inputting a WDM optical signal from a two-optical fiber amplifier to a wavelength division multiplexing / demultiplexing unit, and a WDM optical signal from an optical fiber transmission line.
The optical signal is input to the second optical fiber amplifier, and the second optical circulator that outputs the WDM optical signal from the first optical fiber amplifier to the optical fiber transmission line constitutes an optical amplifying unit, so that the upstream and downstream directions are formed. Since the transmission can be performed by sharing the optical fiber transmission line in the direction, the effect that the WDM system configuration can be simplified without changing the transmission capacity can be obtained, and the effect that the cost of the WDM system can be reduced can be obtained.

According to the present invention, the first optical fiber amplifier and the second optical fiber amplifier for amplifying a WDM optical signal, and the WDM optical signal from one of the optical fiber transmission lines are input to the first optical fiber amplifier. A first optical circulator for inputting the WDM optical signal from the second optical fiber amplifier to one optical fiber transmission line, and a WDM optical signal from the other optical fiber transmission line to the second optical fiber amplifier; WD from one optical fiber amplifier
By providing an optical repeater amplifying section comprising a second optical circulator for outputting the M optical signal to the other optical fiber transmission line in the optical repeater amplifying station, the long distance optical fiber transmission line is shared in the upstream and downstream directions. Can be transmitted
The advantage is that the WDM system configuration can be simplified without changing the transmission capacity, and that the cost of the WDM system can be reduced.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of an optical transmission system according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of an optical transmission system according to a second embodiment of the present invention.

FIG. 3 is a diagram showing a configuration of an optical transmission system according to a third embodiment of the present invention.

FIG. 4 is a diagram showing a configuration of an optical transmission system according to a fourth embodiment of the present invention.

FIG. 5 is a diagram showing a configuration of an optical transmission system according to Embodiment 5 of the present invention.

FIG. 6 is a diagram showing a configuration of an optical transmission system according to Embodiment 6 of the present invention.

FIG. 7 is a diagram showing a configuration of an optical transmission system according to a seventh embodiment of the present invention.

FIG. 8 is a diagram showing a configuration of an optical transmission system according to an eighth embodiment of the present invention.

FIG. 9 is a diagram showing a configuration of a conventional optical transmission system.

[Explanation of symbols]

10X, 10Y optical transmission terminal, 11A optical transmitter, 11
B optical receiver, 11C optical circulator, 11X, 11
Y optical transceiver, 12A optical fiber, 12B optical fiber grating, 12X, 12Y dispersion compensator, 1
3A AWG type WDM filter, 13B dielectric multilayer WDM filter, 13C star coupler, 13D dielectric multilayer narrow band filter, 13X, 13Y wavelength division multiplexing / demultiplexing unit, 14A, 14B optical fiber amplifier, 14C, 1
4D optical circulator, 14X, 14Y optical amplifier,
20 optical repeater amplification station, 21 optical repeater amplifier, 21A, 2
1B optical fiber amplifier, 21C, 21D optical circulator, 30 optical fiber transmission line.

Claims (10)

[Claims] A plurality of optical transmission / reception units for transmitting an optical signal and receiving the optical signal, respectively, and transmitting the optical signal from the optical transmission / reception unit and the optical signal to the optical transmission / reception unit in two directions. A plurality of dispersion compensators each of which performs dispersion compensation by a dispersion compensation function, and multiplexes the optical signals from the plurality of dispersion compensation units by a wavelength multiplexing function to WD
A wavelength multiplexing / demultiplexing unit that outputs an M optical signal and outputs the optical signal to a plurality of the dispersion compensating units by demultiplexing the input WDM optical signal by a wavelength demultiplexing function; At least two optical transmission terminals, each of which comprises an optical amplifier for amplifying the WDM optical signal and the WDM optical signal to the wavelength division multiplexing / demultiplexing unit by a bidirectional optical amplifying function; An optical transmission system, comprising: an optical fiber transmission line that connects the optical amplification unit of a station and the optical amplification unit of the other optical transmission terminal to transmit the WDM optical signal. 2. A WDM system using a bidirectional optical repeater amplification function.
2. The optical transmission system according to claim 1, further comprising an optical repeater amplifying the optical signal on the optical fiber transmission line. 3. An optical transmitter / receiver, comprising: an optical transmitter for transmitting an optical signal; an optical receiver for receiving the optical signal; and outputting the optical signal from the optical transmitter to a dispersion compensator; The optical transmission system according to claim 1, further comprising: an optical circulator that outputs the optical signal from a dispersion compensator to the optical receiver. 4. The optical transmission system according to claim 1, wherein the dispersion compensator is an optical fiber. 5. The optical transmission system according to claim 1, wherein the dispersion compensator is an optical fiber grating. 6. The optical transmission system according to claim 1, wherein the wavelength division multiplexing / demultiplexing unit is an AWG type WDM filter. 7. The wavelength division multiplexing / demultiplexing unit includes a dielectric multilayer film WDM.
The optical transmission system according to claim 1, wherein the optical transmission system is a filter. 8. A wavelength division multiplexing / demultiplexing unit comprising: a plurality of dielectric multilayer narrow band filters each having a pass band of a wavelength of an optical signal passing through each of the plurality of dispersion compensating units; Combine the optical signals that have passed through the optical amplifier, output a WDM optical signal to the optical amplifier, and input the WDM optical signal input from the optical amplifier.
2. The optical transmission system according to claim 1, further comprising a star coupler that equally divides an optical signal and outputs the optical signal to the dispersion compensator through the plurality of dielectric multilayer narrow band filters. 9. An optical amplifier, comprising: a first optical fiber amplifier and a second optical fiber amplifier for respectively amplifying a WDM optical signal; and inputting the WDM optical signal from a wavelength division multiplexer to the first optical fiber amplifier. And a first optical circulator for inputting the WDM optical signal from the second optical fiber amplifier to the wavelength division multiplexing / demultiplexing unit, and inputting the WDM optical signal from the optical fiber transmission line to the second optical fiber amplifier. 2. The optical transmission system according to claim 1, further comprising a second optical circulator for outputting said WDM optical signal from said first optical fiber amplifier to said optical fiber transmission line. 10. An optical repeater amplifying station, comprising: a first optical fiber amplifier and a second optical fiber amplifier for respectively amplifying a WDM optical signal; and the first optical fiber amplifier for transmitting the WDM optical signal from one of the optical fiber transmission lines. A first optical circulator for inputting the WDM optical signal from the second optical fiber amplifier to the one optical fiber transmission line, and a second optical circulator for inputting the WDM optical signal from the other optical fiber transmission line to the second optical fiber transmission line. A second optical circulator for inputting to the optical fiber amplifier and outputting the WDM optical signal from the first optical fiber amplifier to the other optical fiber transmission line. The optical transmission system according to claim 2, wherein