Patent ID: 8384977

Claim:
A light extracting device comprising: a dual light generating unit for receiving an input optical signal and a control signal, and for generating from the input optical signal first and second optical signals that have a phase difference there between, the phase difference being associated with the control signal, said dual light generating unit including a light separator having a separator input end and first and second separator output ends, said light separator being adapted for receiving the input optical signal at said separator input end, separating the input optical signal into two optical signals having substantially equal power, and outputting the two optical signals at said first and second separator output ends, respectively, and an optical phase shifter having a shifter input end coupled to said first separator output end, a shifter output end, and a control end, said optical phase shifter being adapted for receiving the control signal at said control end, and adjusting phase of one of the two optical signals received at said shifter input end to result in the first optical signal that is outputted at said shifter output end; and a first order Bragg grating unit for receiving the first and second optical signals from said dual light generating unit, and for causing optical interference to occur between the first and second optical signals within a predetermined wavelength range to result in first and second output optical signals, said first order Bragg grating unit including a first light circulator having a first end coupled to said shifter output end to receive the first optical signal therefrom, a second end for outputting the first optical signal, and a third end a second light circulator having a first end coupled to said second separator output end of said light separator to receive the second optical signal therefrom, a second end for outputting the second optical signal, and a third end, and a first order Bragg grating having a first end coupled to said second end of said first light circulator, and a second end coupled to said second end of said second light circulator, said first order Bragg grating receiving the first and second optical signals from said second ends of said first and second light circulators and providing the first and second output optical signals to said second ends of said first and second light circulators such that said first and second light circulators output the first and second output optical signals at said third ends thereof, respectively.