KR100384998B1 - Apparatus for bidirectional spectral inversion - Google Patents

Abstract

PURPOSE: A bidirectional spectral inverter is provided to compensate a chromatic dispersion and nonlinear phenomenon occurring in a bidirectional optical communication system by enabling a spectral inversion for both two signals inputted from two ways by using a single spectral inverter. CONSTITUTION: A waveguide type photocoupler(110) receives by both input terminals thereof an optical signal outputted from transmitters(101,127) positioned at both directions through optical fibers of each direction, generates a spectral inversion light, and outputs the spectral inversion light through both output terminals. Wavelength division multiplexers(103,109,124) receive signals outputted to two output terminals of the waveguide type photocoupler(110) and excited light supplied from an excitation light source after being divided into 1/2 through a Y-type branching filter and inputs them to nonlinear mediums(115,116). The nonlinear mediums(115,116) generate s fresh light signal component through the operation of the signal light and the excited light source inputted through the inter terminals by using a nonlinear phenomenon such as a 4-light wave mixture. Reflectors(117,118) changes proceeding direction of a spectral inversion light signal generated by the nonlinear mediums.

Description

Bidirectional spectral inversion device {Apparatus for bidirectional spectral inversion}

The present invention relates to an apparatus for bidirectional spectral inversion, and when using spectral inversion light by four-wave mixing occurring in a nonlinear medium, color dispersion and nonlinear phenomena occurring in an optical communication system can be compensated for.

However, all of the related technologies up to now have been applicable only to unidirectional optical communication systems.

Therefore, in order to apply to a two-way optical communication system, a device having the same function has to be used in each direction.

1 is a block diagram of a conventional unidirectional spectral inverting device, which is unidirectional using an apparatus consisting of an excitation light 3, a wavelength division multiplexer 4 and a nonlinear medium 5 used to combine an excitation light and a signal light. Only the spectral inversion signal light is generated.

Accordingly, for the bidirectional spectral inversion, as shown in FIG. 2, the optical circulators 9 and 12, the nonlinear media 10 and 11, the excitation light sources 7 and 14, and the wavelength division multiplexers 8 and 13, respectively, are used. Since two independent spectral inversion devices must be configured by two to perform spectral inversion in each direction, the implementation of the device is complicated and economically disadvantageous.

Accordingly, the conventional color dispersion compensating apparatus using the inverted light is only able to operate in one-way optical communication.

In order to solve the above disadvantages, the present invention, by using a spectrum inverting device to enable the spectrum inversion for both signals input in both directions to compensate for the color dispersion and nonlinear phenomenon of the optical fiber generated in the bidirectional optical communication system It is an object to provide a bidirectional spectral inversion device.

In order to achieve the above object, the present invention is a waveguide type optical coupler for receiving the optical signal output from the transmitter located in both directions through the optical fiber in each direction through the input terminal on both sides to generate spectral inverted light and output through both output terminals; A wavelength division multiplexer for splitting the signals output to the two output stages of the waveguide optical coupler and a Y-type splitter and receiving the excitation light supplied from the excitation light source into a nonlinear medium; The non-linear medium for generating a new optical signal component through the action of the signal light input through the input terminal and the excitation light source using the same non-linear phenomenon and the reflector for changing the traveling direction of the spectral inverted optical signal newly generated by the non-linear medium Characterized in that it comprises a.

1 is a block diagram of a conventional unidirectional spectral inversion device;

2 is a block diagram of a conventional bidirectional spectrum inversion apparatus;

3 is a block diagram of a novel bidirectional spectrum inversion device to which the present invention is applied.

* Explanation of symbols for main parts of the drawings

101, 127: transmitter 102, 126: receiver

103, 109, 124: wavelength division multiplexer 104, 125: filter

105, 123: transmission optical signal 106: spectrum inversion reception optical signal

107, 121: optical fiber 108: excitation light source

110: waveguide optical fiber coupler 111: one side input of the device

112: other input terminal of the device 113: one output terminal of the device

114: other output terminal 115, 116: nonlinear medium

117, 118: reflectors 119, 120: spectral inversion signal light

122: spectral inverted received signal light 128: Y-type splitter

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

3 is a block diagram of a novel bidirectional spectral inversion device to which the present invention is applied, and includes a waveguide optical coupler, a reflector, a nonlinear medium, an excitation light source, a wavelength division multiplexer, and a waveguide for connecting these devices.

The operation of the new bidirectional spectrum inversion device configured as described above is as follows.

First, the optical signal 105 output from the transmitter 101 located at one side of FIG. 3 is input to one input terminal 111 of the waveguide optical coupler via the optical fiber 107.

The input optical signal is divided into 1/2 and output through the output terminals 113 and 114 of the waveguide optical coupler.

At this time, the signal output to the output terminal 113 of the waveguide optical coupler does not change the phase, but the signal output to the other output terminal 114 of the waveguide optical coupler to the adjacent channel from the inside of the waveguide optical coupler Coupling occurs and the phase of the output signal is delayed by π / 2.

Meanwhile, signals output to the two output terminals 113 and 114 of the waveguide optical coupler are input to two nonlinear media 115 and 116 together with excitation light separately supplied through the wavelength division multiplexer 109.

The excitation light is input into the nonlinear media 115 and 116 through the wavelength division multiplexer 109 after the output of the excitation light source 108 is divided into 1/2 through the Y-type splitter 128.

The wavelength division multiplexer 109 does not cause a phase change with respect to the signal.

In the nonlinear media 115 and 116, new optical signal components 119 and 120 are generated by the action of the input signal light and the excitation light source by nonlinear phenomena such as four-wave mixing. The signal is a spectral inverted light whose phase is changed by 180 ° compared with the original optical signal 105, and the wavelength of the signal light input from the transmitter 101 is changed. , The wavelength of the excitation light The wavelength of the spectral inverted light In this case, the wavelength of the spectral inverted light is given by Equation 1 below.

[Equation 1]

On the other hand, the spectral inverted light by nonlinear phenomenon has the characteristic of taking the information regarding the phase of the original signal light as it is.

Therefore, compared to the phase of the spectral inverted light 119 generated by the action between the signal input to the nonlinear medium 115 through the output terminal 113 of the waveguide optical coupler and the excitation light, the other output terminal 114 of the waveguide optical coupler The spectral inverted light 120 by the signal input to the nonlinear medium 116 has a phase delay of π / 2.

If a waveguide path formed of one output terminal 113, nonlinear medium 119, reflector 117, nonlinear medium 119, one output terminal 113 of the waveguide optical coupler and the other output terminal 114 of the waveguide optical coupler, The length of the waveguide formed by the nonlinear medium 116, the reflector 118, the nonlinear medium 116, and the other output terminal 114 is the same, and if there is no phase difference, it is input to one output terminal 113 of the waveguide optical coupler. When the spectral inverted light signal 119 is output to the other input terminal 112, since the coupling to the adjacent channel occurs inside the waveguide type optical coupler, it has a phase delay of π / 2.

On the other hand, if the spectral inverted light signal 120 inputted to the other output terminal 114 of the waveguide optical coupler already has a phase delay of π / 2, but this signal is output to one input terminal 112 of the waveguide optical coupler No additional phase delay will occur.

Therefore, both signals have a phase retardation of π / 2, and since the two signals have the same phase, they are inputted to one input terminal 111 of the waveguide optical coupler, and the spectrum is inverted. The output terminal 113 of the waveguide optical coupler is then returned. , And the signals 119 and 120 input to the 114 are output to the other input terminal 112 of the waveguide optical coupler.

On the other hand, in one input terminal 111 of the waveguide optical coupler, the phase difference between the spectral inverted light inputs to the two output terminals is π, so that there is no light output.

The output spectral inverted light is input to the other receiver 126 via the optical fiber 121 and the filter 125, where the filter is used to pass only the spectral inverted light.

Meanwhile, the optical signal 123 output from the transmitter 127 located at the other side of FIG. 3 is input to the other input terminal 112 of the waveguide optical coupler 110 and then newly generated spectrum through the same process as the above case. The inverted light is output only to one input terminal 111 of the waveguide optical coupler.

The spectral inverted light is received by the receiver 102 through the optical fiber 107 and the filter 103.

Therefore, when the device is configured with the elements of the excitation light source 108 to the reflector 118 of FIG. 3, the spectral inverted signal of the optical signal input from one transmitter 101 is input to the other receiver 126. The signal input from the other transmitter 127 can be used to send the spectrum inverted signal to one receiver 102 using the same structure.

Therefore, it is possible to generate spectral inverted light for all the optical signals transmitted in both directions within one device.

As described above, when compensating for color dispersion occurring in a bidirectional optical communication system using a conventional spectral inversion device, it is economically disadvantageous because two expensive optical rotators and two excitation light sources are used, but in the present invention, the conventional optical rotator Instead, it has the effect of constructing a bidirectional spectral inverting device using only one low cost waveguide type optical coupler and one excitation light source.

Claims (4)

An apparatus for preventing chromatic dispersion and nonlinear phenomenon occurring in a bidirectional optical communication system, A waveguide type optical coupler which receives optical signals output from transmitters located in both directions through optical fibers in each direction and generates spectral inverted light and outputs them through both output terminals; A wavelength division multiplexer for splitting the signals output to the two output ends of the waveguide optical coupler and the Y-type splitter and receiving the excitation light supplied from the excitation light source into a nonlinear medium; A nonlinear medium generating a new optical signal component through the action of the signal light input through the input terminal and the excitation light source using a nonlinear phenomenon such as four-wave mixing; And a reflector for changing a traveling direction of a spectral inverted optical signal newly generated by the nonlinear medium. The method of claim 1, wherein the waveguide optical coupler A bidirectional spectral inverting device which generates spectral inverted light having information on the phase of the original signal light as it is by nonlinear phenomenon. The method of claim 1, And a filter is used to pass only the spectral inverted light in the signal received by each of the wavelength division multiplexers. The method of claim 1, wherein the waveguide optical coupler And spectral inverted light due to a difference between the wavelength of the excitation light supplied from the excitation light source and the wavelength of the optical signal input from the one side transmitter.