Depolarizer improvement for optical fiber vibration sensor

An optical signal with a polarization dependence behaves as a noise signal in a vibration sensing optical fiber. To remove the noise signal, the optical fiber vibration sensor needs to have a depolarizer. Fusion splicing the polarization maintaining fiber with a 45 degree angle offset is a common method to produce the depolarizer. In this paper, we present a method to improve the depolarizer for the vibration sensor through the use of fusion splicing. We succeeded to reduce the noise with the improved depolarizer that uses a method to observe the fiber end surface of polarization maintaining fiber for analyzing the polarization plane.