OPTICAL TRANSMISSION SYSTEM, PHASE CONJUGATE CONVERTER AND PHASE SENSITIVE AMPLIFIER
Provided is an optical transmission system including: a phase conjugate conversion device that performs optical parametric amplification, monitors power of a first polarization component and a second polarization component of first pilot light, synchronizes phases of harmonics and the first pilot light by controlling a phase of pump light to cause each optical power of the first pilot light to be maximum, and matches optical lengths of paths of a first optical parametric amplification unit and a second optical parametric amplification unit by controlling a transfer device arranged in at least one of the paths to cause an interference waveform of components of second pilot light to be maximum when the second pilot light is caused to pass in a second direction, the second pilot light having at least a wavelength or optical power different from that of the first pilot light; and a phase-sensitive amplification device that performs phase-sensitive amplification of an optical signal included in an optical transmission signal and idler light by optical parametric amplification using the pump light controlled by using the first pilot light included in the optical transmission signal.
1 . An optical transmission system comprising:
a phase conjugate conversion device including: a first splitter configured to split pump light; a multiplexer configured to multiplex first pilot light that is generated on a basis of the pump light split by the first splitter and propagates in a first direction, and an optical signal transmitted from an optical transmitter; a second splitter configured to split the pump light split by the first splitter; a plurality of transferer configured to respectively perform phase control on a plurality of pieces of the pump light split; a plurality of harmonic generators configured to convert the plurality of pieces of the pump light subjected to phase control by the respective plurality of transferers into harmonics; a divider configured to divide the first pilot light and the optical signal that are multiplexed by the multiplexer into two polarization components orthogonal to each other; a first optical parametric amplifier configured to perform optical parametric amplification on a basis of a first polarization component of the first pilot light and a first polarization component of the optical signal that are divided by the divider, and the harmonics converted by the plurality of harmonic generators; a second optical parametric amplifier configured to perform optical parametric amplification on a basis of a second polarization component of the first pilot light and a second polarization component of the optical signal that are divided by the divider, and the harmonics converted by the plurality of harmonic generators; a combiner configured to generate an optical transmission signal by multiplexing the first polarization component of the first pilot light and the first polarization component of the optical signal that are amplified by the first optical parametric amplifier, and the second polarization component of the first pilot light and the second polarization component of the optical signal that are amplified by the second optical parametric amplifier; a first monitor unit configured to monitor power of the first polarization component of the first pilot light amplified by the first optical parametric amplifier; a second monitor configured to monitor power of the second polarization component of the first pilot light amplified by the second optical parametric amplifier; a first controller configured to synchronize phases of the harmonics and the first pilot light by controlling phases of the pump light input to the plurality of harmonic generators to cause each of optical power of the first pilot light amplified by the first optical parametric amplifier and optical power of the first pilot light amplified by the second optical parametric amplifier to be maximum on a basis of monitoring results by the first monitor and the second monitor; a second pilot light source configured to output second pilot light in which at least a wavelength or optical power is different from that of the first pilot light; a circulator configured to propagate the second pilot light output from the second pilot light source in a second direction that is an opposite direction to the first direction, and externally outputs the optical transmission signal output from the combiner; and a second controller configured to match optical lengths of paths of the first optical parametric amplifier and the second optical parametric amplifier by controlling a transfer device arranged in at least one of the paths to cause an interference waveform of components of the second pilot light caused to pass in the second direction to be maximum;
an optical transmitter configured to transmit the optical transmission signal output from the phase conjugate conversion device; and
a phase-sensitive amplification device configured to perform phase-sensitive amplification of the optical signal and idler light included in the optical transmission signal by optical parametric amplification using the pump light controlled by using the first pilot light included in the optical transmission signal.
2 . The optical transmission system according to claim 1 , wherein
the phase-sensitive amplification device includes:
a pump light source configured to output pump light for optical parametric amplification by performing optical injection locking to the pump light source by using the first pilot light included in the optical transmission signal;
a third splitter configured to split the pump light output from the pump light source;
a plurality of transferers configured to respectively perform phase control on a plurality of pieces of the pump light split;
a plurality of harmonic generators configured to convert the plurality of pieces of the pump light subjected to phase control by the respective plurality of transferers into harmonics;
a divider configured to divide the optical signal included in the optical transmission signal into two polarization components orthogonal to each other;
a third optical parametric amplifier configured to perform optical parametric amplification on a basis of the first polarization component of the optical signal divided by the divider and the harmonics converted by the plurality of harmonic generators;
a fourth optical parametric amplifier configured to perform optical parametric amplification on a basis of the second polarization component of the optical signal divided by the divider and the harmonics converted by the plurality of harmonic generators;
a combiner configured to multiplex the first polarization component of the optical signal amplified by the third optical parametric amplifier and the second polarization component of the optical signal amplified by the fourth optical parametric amplifier;
a third monitor configured to monitor power of the first polarization component of the optical signal amplified by the third optical parametric amplifier;
a fourth monitor configured to monitor power of the second polarization component of the optical signal amplified by the fourth optical parametric amplifier;
a third controller configured to synchronize phases of the harmonics and the optical signal by controlling phases of the pump light input to the plurality of harmonic generators to cause each of optical power of the optical signal amplified by the third optical parametric amplifier and optical power of the optical signal amplified by the fourth optical parametric amplifier to be maximum on a basis of monitoring results by the third monitor and the fourth monitor;
a third pilot light source configured to output third pilot light in which at least a wavelength or optical power is different from that of the first pilot light;
a circulator configured to propagate the third pilot light output from the third pilot light source in a second direction that is an opposite direction to the first direction; and
a fourth controller configured to match optical lengths of paths of the third optical parametric amplifier and the fourth optical parametric amplifier by controlling a transfer device arranged in at least one of the paths to cause an interference waveform of components of the third pilot light caused to pass in the second direction through each of the third optical parametric amplifier and the fourth optical parametric amplifier to be maximum.
3 . The optical transmission system according to claim 2 , wherein the phase-sensitive amplification device includes:
a fourth splitter configured to split the optical transmission signal output from the phase conjugate conversion device; and
a filter configured to extract the first pilot light from the optical transmission signal split by the fourth splitter,
and
the pump light source outputs pump light for optical parametric amplification by performing optical injection locking of the first pilot light extracted by the filter to the pump light source.
4 . The optical transmission system according to claim 2 , wherein the phase-sensitive amplification device further includes:
a demultiplexer configured to demultiplex the first pilot light from the optical transmission signal output from the phase conjugate conversion device;
a fifth splitter configured to split the pump light output from the pump light source at a stage before the third splitter; and
a second combiner configured to multiplex the first polarization component of the optical signal and the second polarization component of the optical signal that are multiplexed by the combiner, and the pump light split by the fifth splitter.
5 . A phase conjugate conversion device comprising:
a first splitter configured to split pump light;
a multiplexer configured to multiplex first pilot light that is generated on a basis of the pump light split by the first splitter and propagates in a first direction, and an optical signal transmitted from an optical transmitter;
a second splitter configured to split the pump light split by the first splitter;
a plurality of transferers that respectively performs phase control on a plurality of pieces of the pump light split;
a plurality of harmonic generators configured to convert the plurality of pieces of the pump light subjected to phase control by the respective plurality of transferers into harmonics;
a divider configured to divide the first pilot light and the optical signal that are multiplexed by the multiplexer into two polarization components orthogonal to each other;
a first optical parametric amplifier configured to perform optical parametric amplification on a basis of a first polarization component of the first pilot light and a first polarization component of the optical signal that are divided by the divider, and the harmonics converted by the plurality of harmonic generators;
a second optical parametric amplifier configured to perform optical parametric amplification on a basis of a second polarization component of the first pilot light and a second polarization component of the optical signal that are divided by the divider, and the harmonics converted by the plurality of harmonic generators;
a combiner configured to generate an optical transmission signal by multiplexing the first polarization component of the first pilot light and the first polarization component of the optical signal that are amplified by the first optical parametric amplifier, and the second polarization component of the first pilot light and the second polarization component of the optical signal that are amplified by the second optical parametric amplifier;
a first monitor configured to monitor power of the first polarization component of the first pilot light amplified by the first optical parametric amplifier;
a second monitor configured to monitor power of the second polarization component of the first pilot light amplified by the second optical parametric amplifier;
a first controller configured to synchronize phases of the harmonics and the first pilot light by controlling phases of the pump light input to the plurality of harmonic generators to cause each of optical power of the first pilot light amplified by the first optical parametric amplifier and optical power of the first pilot light amplified by the second optical parametric amplifier to be maximum on a basis of monitoring results by the first monitor and the second monitor;
a second pilot light source configured to output second pilot light in which at least a wavelength or optical power is different from that of the first pilot light;
a circulator configured to propagate the second pilot light output from the second pilot light source in a second direction that is an opposite direction to the first direction, and externally outputs the optical transmission signal output from the combiner; and
a second controller configured to match optical lengths of paths of the first optical parametric amplifier and the second optical parametric amplifier by controlling a transfer device arranged in at least one of the paths to cause an interference waveform of components of the second pilot light caused to pass in the second direction through each of the first optical parametric amplifier and the second optical parametric amplifier to be maximum.
6 . A phase-sensitive amplification device comprising:
a pump light source configured to output pump light for optical parametric amplification by performing optical injection locking to the pump light source by using first pilot light included in an optical transmission signal transmitted from a phase conjugate conversion device configured to perform optical parametric amplification;
a third splitter configured to split the pump light output from the pump light source;
a plurality of transferers configured to respectively perform phase control on a plurality of pieces of the pump light split;
a plurality of harmonic generators configured to convert the plurality of pieces of the pump light subjected to phase control by the respective plurality of transferers into harmonics;
a divider configured to divide an optical signal included in the optical transmission signal into two polarization components orthogonal to each other;
a third optical parametric amplifier configured to perform optical parametric amplification on a basis of a first polarization component of the optical signal divided by the divider and the harmonics converted by the plurality of harmonic generators;
a fourth optical parametric amplifier configured to perform optical parametric amplification on a basis of a second polarization component of the optical signal divided by the divider and the harmonics converted by the plurality of harmonic generators;
a combiner configured to multiplex the first polarization component of the optical signal amplified by the third optical parametric amplifier and the second polarization component of the optical signal amplified by the fourth optical parametric amplifier;
a third monitor configured to monitor power of the first polarization component of the optical signal amplified by the third optical parametric amplifier;
a fourth monitor configured to monitor power of the second polarization component of the optical signal amplified by the fourth optical parametric amplifier;
a third controller configured to synchronize phases of the harmonics and the optical signal by controlling phases of the pump light input to the plurality of harmonic generators to cause each of optical power of the optical signal amplified by the third optical parametric amplifier and optical power of the optical signal amplified by the fourth optical parametric amplifier to be maximum on a basis of monitoring results by the third monitor and the fourth monitor;
a third pilot light source configured to output third pilot light in which at least a wavelength or optical power is different from that of the first pilot light;
a circulator configured to propagate the third pilot light output from the third pilot light source in a second direction that is an opposite direction to the first direction; and
a fourth controller configured to match optical lengths of paths of the third optical parametric amplifier and the fourth optical parametric amplifier by controlling a transfer device arranged in at least one of the paths to cause an interference waveform of components of the third pilot light caused to pass in the second direction through each of the third optical parametric amplifier and the fourth optical parametric amplifier to be maximum.