Temperature-Independent Humidity Sensor Based on Polarization Maintaining Fiber Loop Mirror

A relative humidity sensor based on two polarization maintaining fibers loop mirror with temperature compensation is presented. The proposed sensors are created through coating a thin layer of polyvinyl alcohol (PVA) onto a polarization maintaining fiber (PMF1) from which a portion of the cladding is etched. The relative humidity optical fiber sensor which shows a linear response to parameter and compensates for temperature is tested with different surrounding humidity level from 20% to 80%. The sensitivity of the relative humidity measurement of 0.98nm/%RH and the temperature sensitivity of -0.323nm/°C is experimentally achieved.