Symmetrical low-noise sagnac interferometer based on wavelength division multiplexing

Abstract

A kind of symmetric low-noise Sagnac interferometer based on wavelength division multiplexing, applied to non-contact ultrasonic detection field, its all-fiber non-contact ultrasonic detection optical path includes: communication waveband broadband light source, first polarization controller, non-polarization-maintaining ring, first wavelength division multiplexer, first polarization beam splitter, second polarization beam splitter, third polarization beam splitter, second polarization controller, non-polarization-maintaining long optical fiber ring, fourth polarization beam splitter, fifth polarization beam splitter, sixth polarization beam splitter, second wavelength division multiplexer, polarization-maintaining optical fiber focusing mirror, 1 / 4 glass, third polarization controller, seventh polarization beam splitter, balanced detector.The application can realize π / 2 phase bias and maximum fringe contrast while maintaining a very low noise level of detection by combining wavelength division multiplexing, controlling the high symmetry design of different interference light maintaining orthogonal and using the method of differential detection of balanced detector, and then realizing high-sensitivity non-contact ultrasonic detection.

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