| 摘要 |
<P>PROBLEM TO BE SOLVED: To obtain a demodulator for a small-sized DMPSK modulation mode without using an asymmetric MZI as a means of providing delay time and phase shift. <P>SOLUTION: The demodulator 1 in an optical communication system of a differential M phase shift modulation mode which is M=2<SP>n</SP>(n is a natural number of 2 or more) in this invention comprises two optical waveguides of different physical lengths which receive an input modulated light, two input ports connected to the two optical waveguides, M pieces of output ports, (2M-4) pieces of optical waveguides, and a phase shift part 200 having (3M/2-2) pieces of optical couplers. The phase shift part 200 includes a phase shift means of adding phase shift to the optical signal to be propagated, and in addition has a photoelectric conversion device 300 to which the output light of the phase shift part 200 is incident. A difference in the physical length between the two optical waveguides has a difference in the optical path length corresponding to a symbol period of data modulated light. <P>COPYRIGHT: (C)2008,JPO&INPIT |
