Simultaneous measurement of strain and temperature with a long-period fiber grating inscribed Sagnac interferometer

► Sagnac interferometer with a long-period fiber grating(LPG) inscribed in polarization maintains fiber (PMF)for simultaneous measurement of strain and temperature. ► Transmission spectrum of Sagnac interferometer was modulated by the transmission spectrum of LPG. ► The PMF is longer than the LPG so that applied strain contribution to wavelength shift can be neglected. ► High temperature-sensitivity of Sagnac interferometer can compensate the cross effect of strain measurement, which improves the measurement accuracy of sensor.