A Temperature-Insensitive Twist Sensor by Using Low-Birefringence Photonic-Crystal-Fiber-Based Sagnac Interferometer

An optical fiber twist sensor is proposed by using solid core low birefringence photonic crystal fiber (LB-PCF)-based Sagnac interferometer. The twist effects on the fiber are theoretically analyzed. The results show that the dip wavelength of the transmission spectrum shifts with the twist angle with a high sensitivity and resolution of 1.00 nm/
⁰
and 0.01
⁰
, respectively. The sensor is also insensitive to environmental temperature change with an ultralow thermal dependent coeffiecient of -0.5 pm/
⁰
C.