An optical current transducer with the compensation for the polarization and the temperature disturbance

This paper presents a novel bulk type of optical current transducer (OCT), in which a single-mode fiber to multi-mode fiber coupling configuration is adopt to reduce the optical loss and to restrain the random mode-coupling noise in a conventional multi-mode fiber to multi-mode fiber coupling structure. A special design is used to automatically compensate the changes of the State of Polarization (SOP) of the optical fiber. Experiment shows that about 10 times of precision improvement can be achieved compared with conventional sensing element without SOP compensation. The OCT system employs microcomputer together with corresponding software to accomplish signal processing. The overall performance of the OCT system is tested experimentally. The results show that the system has good long-term stability - the precision during 100 hours is 0.3%, and temperature compensation can considerably improve the temperature characteristic of the system.