Patent ID: 8238747

Claim:
A method for generating a differential quadrature phase shift keying (DQPSK) code optical signal, comprising: splitting an optical signal to obtain two polarized optical signals; modulating one of the two polarized optical signals to obtain a polarized and modulated optical signal, and phase-shifting the polarized and modulated optical signal to obtain a phase-shifted and polarized optical signal; modulating the other of the two polarized optical signals to obtain another polarized and modulated optical signal; combining the phase-shifted and polarized optical signal and the another polarized and modulated optical signal to obtain a polarization multiplexed optical signal; and polarizing the polarization multiplexed optical signal to obtain the DQPSK code optical signal, comprising: acquiring light intensity ratio information of the phase-shifted and polarized optical signal and the another polarized and modulated optical signal; calculating a direction angle according to the light intensity ratio information; and polarizing the polarization multiplexed optical signal according to the direction angle to obtain the DQPSK code optical signal.