Fading-free Polarization-Sensitive Optical Fiber Sensing

Conventional polarization-sensitive optical fiber sensors (POFS) sometimes can hardly detect external disturbances at some special locations where the polarization state of light has little change with the fixed analyzer. This phenomenon is the so-called polarization-induced signal fading that leads to alarm missing in the forward transmission POFS system and deteriorates locating accuracy in the polarization optical time-domain reflectometry system. To eliminate the fading phenomenon and maintain the high sensitivity along the whole sensing fiber, we propose a forward transmission polarization-sensitive optical fiber sensing scheme using polarization-maintaining fiber with the slow axes 45° aligned splicing at both the input and detection ends. Theoretical and experimental results indicate that the system works at the most sensitive state and the signal fading phenomenon is eliminated. This system promises potential applications in perimeter security and physical parameters measurement.