The invention discloses a high-sensitivity all-
fiber current measuring device and method with a dual-cycle structure. The device comprises a
broadband light source, a
polarizer, a
polarization controller, a first
polarization beam splitter, a first coupler, a
circulator, a second coupler, a sensing
optical fiber ring, a current-carrying conductor, a first
Faraday rotator mirror, a second
Faraday rotator mirror, a second
polarization beam splitter, a first photoelectric
detector and a second photoelectric
detector. According to the sensor, the
polarization beam splitter, the first coupler, thedouble Faraday rotating mirror and the second coupler are combined to form a double-circulation structure, so that optical signals are circulated for multiple times in a sensing
optical path, the sensitivity of the sensor is improved while the stability of a
system is enhanced, and the influence of a
linear birefringence effect is reduced.