Temperature independent strain sensor based on intensity measurement using a highly birefringent photonic crystal fiber loop mirror

A fiber-optic strain sensor is demonstrated by using a short length of highly birefringent photonic crystal fiber (PCF) as the sensing element inserted in a fiber loop mirror (FLM). Due to the ultralow thermal sensitivity of the PCF, the proposed strain sensor is inherently insensitive to temperature. When a DFB laser passes through the FLM, the output power will only be affected by the transmission spectral change of the FLM caused by the strain applied on the PCF. Based on intensity measurement, an optical power meter is adequate to deduce the strain information and an expensive optical spectrum analyzer (OSA) would not be needed.