Reflecting type full-optical fiber current sensor

The invention discloses a reflective all-optical fiber current sensor, which is characterized in that a sagnac interference system which consists of a polarization maintaining optical fiber coupler adopts two 1/4 wave plates and a Faraday rotator as the phase bias of light waves and adopts a single polarization maintaining optical cable as a transmission line and the reflective end surface of an optical fiber sensing ring to commonly form the reflective sensing system. An interference optical circuit further adopts a polarization multiplexer, one port thereof is welded by 90 degrees, and two polarizers are additionally added at the port of the polarization maintaining optical fiber coupler, thereby eliminating the polarization noise of a plurality of devices during the polarization transformation and the transmission. The reflective all-optical fiber current sensor with the optical circuit structure has stable light wave phase bias. Interference signals have very high signal-to-noise ratio. The circuit proces