| 摘要 |
PROBLEM TO BE SOLVED: To solve the problem that in the case of suppressing PDFS when making a demodulator for a differential phase shift keying signal, assembly adjustment is complicated or variation in characteristics among individual components is increased in a conventional way of solving the problem.SOLUTION: In a delay interferometer inside the demodulator, the polarization state of two split beams 303 and 304 of light to be interfered with each other, is set so that p polarization and s polarization are reversed by a half beam splitter 302 and, further, multiplexing is performed again by the half beam splitter 302 used for splitting to generate interference light 309 and 310. |
