| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an optical receiver hard to be influenced by disturbance such as temperature change, using a simple space optical system, which decodes a DQPSK modulated optical signal to a multi-level phase modulated signal in the optical receiver. <P>SOLUTION: In the optical receiver where a DQPSK modulated optical signal A is decoded to a multi-level phase modulated signal, an optical system is configured using a polarized beam splitter 2 at least. The optical system branches the DQPSK modulated optical signal to two optical waves of a different polarization plane while generating a delay of 1 bit at one branched light, and multiplexes both. As for an optical wave emitted from the polarized beam splitter, an 1/4 wave plate (8 and 9) is provided for fixing relatively phase relation between an I component signal and a Q component signal. <P>COPYRIGHT: (C)2011,JPO&INPIT |
