OPTICAL FIBER MACH-ZEHNDER INTERFEROMETER HAVING ASYMMETRICAL COUPLER

摘要

PROBLEM TO BE SOLVED: To provide an asymmetrical optical fiber Mach-Zehnder interferometer and a multiplexer demultiplexer equipped with it. SOLUTION: This asymmetrical optical fiber Mach-Zehnder interferometer 10 is equipped with a 1st optical fiber 20 and a 2nd optical fiber 22. Those 1st and 2nd optical fibers 20 and 22 are coupled together in a 1st coupling area 12 and a 2nd coupling area 14. The 1st and 2nd optical fibers 20 and 22 form interference arms 16 and 18 between the 1st and 2nd coupling areas 16 and 18. To obtain asymmetry, the propagation constant for the part of the 1st optical fiber 20 in one coupling area is different from that of the 2nd optical fiber 22 in the coupling area. An asymmetrical structure provides 30 dB insulation over a large wavelength span.