Simultaneous Temperature and Strain Measurement Using Two Types of High-Birefringence Fibers in Sagnac Loop Mirror

A fiber sensor configuration capable of simultaneous measurement of temperature and strain is newly presented and investigated. Two different types of high-birefringence fibers (HBFs) spliced together are inserted in a Sagnac loop mirror to act as the sensing head for temperature and strain discrimination. Unlike an individual HBF, the two wavelength dips used as detected parameters in the transmission spectrum of the Sagnac loop mirror may have opposite sensitivity responses to temperature and/or strain variation, which depends on the relative angle between the primary axes of the two sections of HBFs and rotation angle of the polarization controller in the Sagnac loop mirror.