| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an optical receiver that becomes polarization-independent, the optical receiver being configured to demodulate a DQPSK-modulated optical signal into a multi-level phase-modulated signal. <P>SOLUTION: The optical receiver includes: a polarization branching means for branching a DQPSK-modulated optical signal into two optical waves with polarization planes orthogonal to each other; a branch rotating means for further branching each of split beams into two optical waves and passing them through a 1/4 wavelength plate at 45°; a one-bit delay circuit means separating each of four optical waves through the branch rotating means into two optical waves with polarization planes orthogonal to each other; a rotation branching means for passing the two optical waves, that have passed through the one-bit delay circuit means, through the 1/4 wavelength plate at 45°, further rotating the polarization planes at 22.5°, and branching them for each of the two optical waves with polarization planes orthogonal to each other; and a multiplexing means for passing the specific four optical waves, that have been passed through the rotation branching means, through a half wavelength plate at 45° and multiplexing resultant eight optical waves while maintaining polarization planes in a specific combination. <P>COPYRIGHT: (C)2011,JPO&INPIT |
