Simultaneous measurement of temperature and strain using a Lyot fiber filter incorporated with a fiber Bragg grating in a linear configuration

We report a fiber sensor capable of simultaneously measuring temperature and strain. A fiber Bragg grating (FBG) was incorporated in a Lyot fiber filter (LFF) by fusion splicing an FBG and a section of high birefringence fiber (PM fiber), which is an elliptical core side-hole fiber, and then placing them between two polarizers. Measured in the transmission mode, the fringe resulting from the LFF and the resonance wavelength dip of the FBG have different responses when a variation of temperature or strain is applied. The proposed device can therefore measure both strain and temperature simultaneously.