The New All-fiber Current Sensor Optical Structure

This article introduced the principle of all-fiber optic current sensor (AFOCS), analyzed and compared several kinds of common AFOCS. According to the practical difficulty, a improved in-line AFOCS has been proposed. Through the theoretical analysis of the imperfect of optical component (polarizer, phase modulator, 90 degree splice, polarization maintaining coupler, quarter wave-plate as well as sensor fiber and so on) in the system , the method of polarization state evolution, which is used to analyse polarized errors qualitatively, has been proposed . This method can indicate the errors simply and clearly. Theoretic analyzing the errors which are caused by the imperfect of optical component in detail,using the method of polarization state evolution and Jones matrix,works out the corresponding error curves.The experiment system of optical path has been established,and the experiment study to confirm the theory result mentioned above has been carried out. Theoretic and experimental analysis indicate the improved system can avoid using the birefringent phase modulator, reduce the require of the polarizer extinction ratio and phase modulator.So the improved system is easier to realize.This article also introduced the manufacture craft of the key optical component: fiber quarter wave-plate and sensor fiber. And the reverse method to manufact fiber quarter wave-plate in laboratory has been proposed.The method of polarization state evolution and the Jones matrix computation simulation will be helped in the AFOCS theoretical analysis;The improved system and manufacture of fiber quarter wave-plate in laboratory will be helped in the AFOCS practical study.