COMPOSITE MACH-ZEHNDER INTERFEROMETER AND RECEIVER FOR QUANTUM KEY DELIVERY

摘要

PROBLEM TO BE SOLVED: To provide a composite Mach-Zehnder interferometer which can be operated as an asymmetrical Mach-Zehnder interferometer not having polarization state dependency.SOLUTION: An input system 42 branches input light into two, and outputs a first polarization component b1 and a second polarization component b2. A bidirectional asymmetrical Mach-Zehnder interferometer 40 includes a first multiplexer/demultiplexer 11, and a second multiplexer/demultiplexer 12, and in which two optical paths of a first arm X1 and a second arm X2 connecting the first multiplexer/demultiplexer 11 and second multiplexer/demultiplexer 12, are formed. The first polarization component b1 is inputted to the bidirectional asymmetrical Mach-Zehnder interferometer 40 from the first multiplexer/demultiplexer 11, and the second polarization component b2 is inputted to the bidirectional asymmetrical Mach-Zehnder interferometer 40 from the second multiplexer/demultiplexer 12. The first output light d1 outputted from the bidirectional asymmetrical Mach-Zehnder interferometer 40 is outputted from a first output system 44, and the second output light d2 is outputted from a second output system 46.SELECTED DRAWING: Figure 2