Abstract: A Fiber-optic current sensor for sensing electric current carried in an electric conductor (18). Its optical section comprises: a light source (1); a directional coupler (2) with two ports (2A, 2B) of two arms each; a radiation polarizer (3); a polarization modulator (4); a fiber line (17) coupled to a current-sensing fiber loop (11); a mirror (10); and a photodetector (22). The first port of the coupler (2) is coupled to the light source (1) and to the photodetector (22). Its second port is coupled via the radiation polarizer (3) to the polarization modulator (4). The polarization modulator comprises a magneto-sensitive element (5), around which a solenoid (6) is wound. The fiber loop (11) comprises a magneto-sensitive optical fiber with embedded linear birefringence. An electronic section comprises a signal generator (21) which drives the solenoid (6); and a signal processing unit which receives the optical signal from the photodetector (22).

Abstract: Method for manufacturing optical fibers, comprising cutting mirror-symmetrical grooves (2, 3) on a preform rod (1) which is inserted into a tube (4) of optical material; fusing the perform rod and the tube in a nonworking area; pulling the fused perform rod and tube into a perform which has longitudinal channels defined by the grooves (2, 3) and the tube (4); cutting the perform (5) into segments; etching the longitudinal channels; sealing segment end(s), assembling segments with a capillary tube and tubular process holder; joining the segment and capillary tube on a side opposite to the tubular process holder; drawing the perform segment into an optical fiber, and applying a protective strengthening coating on the drawn optical fiber. As a result, an optical fiber is produced, which has birefringent properties influenced by dimensions of the mirror-symmetrical grooves and the etching step.

Abstract: A Fiber-optic current sensor for sensing electric current carried in an electric conductor (18). Its optical section comprises: a light source (1); a directional coupler (2) with two ports (2A, 2B) of two arms each; a radiation polarizer (3); a polarization modulator (4); a fiber line (17) coupled to a current-sensing fiber loop (11); a mirror (10); and a photodetector (22). The first port of the coupler (2) is coupled to the light source (1) and to the photodetector (22). Its second port is coupled via the radiation polarizer (3) to the polarization modulator (4). The polarization modulator comprises a magneto-sensitive element (5), around which a solenoid (6) is wound. The fiber loop (11) comprises a magneto-sensitive optical fiber with embedded linear birefringence. An electronic section comprises a signal generator (21) which drives the solenoid (6); and a signal processing unit which receives the optical signal from the photodetector (22).