摘要
A torsion sensor based on the near-helical(NH)long period fiber grating(LPFG)is fabricated by using a high frequency pulsed CO_(2) laser.Each groove of the NH-LPFG is spirally written in the four sides of a single-mode fiber.The NH-LPFG has a helical periodic vertical index modulation.This is different from the screw-type index modulation of the common helical LPFGs(H-LPFGs)fabricated in a twisted fiber.The torsion and temperature characteristics of the NH-LPFG are experimentally investigated.The temperature sensitivity is about0.0668 nm/℃.The torsion sensitivity is 0.103 nm/(rad/m)and independent of the polarization state of incident light.
基金
supported by the National Natural Science Foundation of China(Nos.61377084,41174161,and 61775044)
the Joint Research Fund in Astronomy(No.U1631239)under cooperative agreement between the National Natural Science Foundation of China(NSFC)and the Chinese Academy of Sciences(CAS)
in part by the Aeronautical Science Foundation of China(No.201608P6003)
