Cascade interferometer optical fiber temperature sensor based on vernier effect

The invention belongs to an optical fiber temperature sensor in the technical field of sensing, and particularly relates to a cascaded interferometer optical fiber temperature sensor based on a vernier effect. The sensor comprises a pumping source, a wavelength division multiplexer, an erbium-doped optical fiber, an optical isolator, an optical fiber Sagnac interferometer, an M-Z interferometer and a spectrograph, pump light output by the pumping source passes through the wavelength division multiplexer and then is input into the erbium-doped optical fiber, the pump light is amplified by the erbium-doped optical fiber to form a wide-spectrum light source, the wide-spectrum light source passes through the optical isolator and then sequentially passes through the optical fiber Sagnac interferometer and the M-Z interferometer, laser signals with envelopes are formed after two times of filtering, and the spectrograph displays an output spectrum. The erbium-doped optical fiber is adopted as a gain medium, the opti