SAGNAC LOOP TYPE ASYMMETRICAL MACH-ZEHNDER INTERFEROMETER, AND RECEIVER FOR QUANTUM KEY DISTRIBUTION

摘要

PROBLEM TO BE SOLVED: To realize polarization state independence.SOLUTION: A Mach-Zehnder interferometer comprises: a first optical arm including a first Sagnac loop 10-1 equipped with a first polarization rotator 5; a second optical arm including a second Sagnac loop 10-2 equipped with a second polarization rotator 6; a semi-transparent mirror 1, and an optical circulator 2. The semi-transparent mirror has: a first input/output terminals 1-1; a second input/output terminal 1-2 and a third input/output terminal 1-3 which split light input from a first input/output terminals and outputs the light; and a fourth input/output terminal 1-4 (first interference light output terminal) which outputs first interference light formed by multiplexing output lights from the first and second optical arms. Further, the optical circulator has: an input terminal 2-1; a first input/output terminal 2-2 which outputs input light input from the input terminal, and inputs second interference light formed by multiplexing output lights from the first and second optical arms which are output from the first input/output terminal of the semi-transparent mirror; and a second input/output terminal 2-3 (second interference light output terminal) which outputs the second interference light.SELECTED DRAWING: Figure 2