Temperature and twist characteristics of cascaded long-period fiber gratings written in polarization-maintaining fibers

Temperature and twist characteristics of cascaded long period fiber gratings (LPFGs) written in PANDA polarization-maintaining fibers have been experimentally investigated. The temperature sensitivity of the proposed structure reaches 102.6 pm °C−1. The amplitude of the peak decreases as the structure is rotated clockwise, whereas it increases as the structure is rotated counterclockwise. The resonance wavelength responds linearly to the twist ratio with a sensitivity of 0.072 nm (rad m−1)−1 for a range of ±21 rad m−1. The proposed structure could be employed for twist and temperature sensing applications. (paper)