Apparatus for dual-polarization QAM and optical communications system using the same cross-reference to related application

An integrated receiving apparatus for optical communication, receiving a transmitted optical signal modulated between multiple amplitude states, multiple phase states and between two states of polarization of the optical beam, comprising:

• a first waveguide receiving a first optical input beam;
• the first optical input beam being a first transmitted S optical beam modulated between multiple phase states and between different states of polarization;
• a second waveguide receiving a second optical input beam;
• the second Lo optical input beam being a Local Oscillator polarized at 45 degrees relatively to the TE and TM polarizations of the waveguide;
• a first splitter dividing the first optical input beam into a third and a fourth optical beams;
• a second splitter dividing the second optical input beam into a fifth and a sixth optical beams;
• a first phase-shifter, applied to the third optical beam;
• the first phase-shifter affecting the TE optical mode exclusively, within the third optical beam;
• a second phase-shifter, applied to the fourth optical beam;
• the second phase-shifter affecting the TM optical mode exclusively, within the fourth optical beam;
• a first 3 dB coupler, mixing the third optical beam and the fifth optical beam;
• the first 3 dB coupler, outputting a seventh and an eighth optical beams;
• a second 3 dB coupler, mixing the fourth optical beam and the sixth optical beam;
• the second 3 dB coupler, outputting a ninth and a tenth optical beams;
• a first polarization splitter;
• the first polarization splitter having the seventh optical beam as an input and producing a first output of TE polarization and a second output of TM polarization;
• a second polarization splitter;
• the second polarization splitter having the eighth optical beam as an input and producing a third output of TE polarization and a fourth output of TM polarization;
• a third polarization splitter;
• the third polarization splitter having the ninth optical beam as an input and producing a fifth output of TE polarization and a sixth output of TM polarization;
• a fourth polarization splitter;
• the fourth polarization splitter having the tenth optical beam as an input and producing a seventh output of TE polarization and an eighth output of TM polarization;
• a first balance detector, detecting the first output of TE polarization and the third output of TE polarization;
• a second balance detector, detecting the second output of TM polarization and the fourth output of TM polarization;
• a third balance detector, detecting the fifth output of TE polarization and the seventh output of TE polarization;
• a fourth balance detector, detecting the sixth output of TM polarization and the eighth output of TM polarization;
• the first balance detector and the third balance detector being used to recover a transmitted data in TE polarization;
• the second balance detector and the fourth balance detector being used to recover a transmitted data in TM polarization.

An optical communication system for data transmission, comprising:

• a synthesizer transmitting an encoded optical beam to a receiver, the synthesizer comprising:
• Y-branch dividing the light beam from the light source and producing a first and a second transmitting beams;
• the first and the second transmitting beams entering a first M-PSK modulator and a second M-PSK modulator producing a first and a second PSK-modulated output beams;
• a first and a second polarization controllers receiving the first and the second output modulated beams, respectively, and creating a third and a fourth beams having polarization state orthogonal to each other;
• the first PSK-modulated beam is reflected from a first mirror prior to entering the first MZ modulator, and the second PSK-modulated beam is reflected from a second mirror prior to entering the second MZ modulator, wherein the first and the second mirrors located on the back output surface of a planar chip;
• the first MZ modulator producing the first QAM-beam and the second MZ modulator producing the second QAM-beam;
• the first QAM-beam is reflected from a third mirror prior to entering the polarization combiner, and the second QAM-beam is reflected from a fourth mirror prior to entering the polarization combiner, wherein the third and fourth mirrors located on the front surface of the planar chip, the first, the second, the third and the fourth mirrors providing compactness critical to the synthesizer formation on the single chip;
• the polarization combiner outputting a dual-polarization QAM signal;
• the synthesizer formed as a part of a single planar chip.