A new phase-shifted long-period fiber grating for simultaneous measurement of torsion and temperature

A novel phase-shifted long-period fiber grating(PS-LPFG) for the simultaneous measurement of torsion and temperature is described and experimentally demonstrated. The PS-LPFG is fabricated by inserting a pretwisted structure into the long-period fiber grating(LPFG) written in single-mode fiber(SMF). Experimental results show that the torsion sensitivities of the two dips are -0.114 nm/(rad/m) and -0.069 nm/(rad/m) in the clockwise direction, and -0.087 nm/(rad/m) and -0.048 nm/(rad/m) in the counterclockwise direction, respectively. The temperature sensitivities of the two dips are 0.057 nm/℃ and 0.051 nm/℃, respectively. The two dips of the PS-LPFG exhibit different responses to torsion and temperature. Simultaneous measurement of torsion and temperature can be implemented using a sensor. The feasibility and stabilization of simultaneous torsion and temperature measurement have been confirmed, and hence this novel PS-LPFG demonstrates potential for fiber sensing and engineering applications.