The invention discloses an
all optical-
fiber current sensor based on magnetic fluid and a multi-mode interference structure. The
all optical-
fiber current sensor comprises a
signal detection unit and a sensing unit. The
signal detection unit comprises an SLD
light source, a 50:50
optical fiber beam splitter, an adjustable
optical fiber attenuator, a photoelectric balance
detector, a data collection card, a computer, a power-on coil and a programmable power source. The sensing unit comprises a multi-mode coreless
optical fiber arranged in a
quartz capillary tube, the portion between the
quartz capillary tube and the multi-mode coreless optical
fiber is filled with magnetic fluid, the two ends of the multi-mode coreless optical fiber are respectively connected with single-mode input and output optical fibers in a
welding mode, and the two ends of the
quartz capillary tube are sealed by optical solidification glue. According to the
all optical-fiber
current sensor based on magnetic fluid and the multi-mode interference structure, the sensitivity of the
magnetic field generated by the magnetic fluid to the currents and the multi-mode
interference theory are used, the change relation between
light intensity and currents is directly detected and output to achieve the purpose of detecting currents, and the defect that the polarized
light detection method adopted by a traditional all optical-fiber current sensor is not stable is overcome.