A U-shaped microfiber interferometer coated with MoS2 film for simultaneous measuring relative humidity and temperature

This letter presents and validates a simultaneous relative humidity (RH) and temperature (T) measurement system comprising a U-shaped microfiber interferometer covered with a thin film of molybdenum disulfide (MoS2). Along with changes in RH and T in the external environment, the adsorption of MoS2 on the fiber surface induces a refractive index response, which generates an interferometer wavelength drift. Results show that the designed sensors have RH sensitivities of 0.116 nm/%RH (wavelength) and −0.201 dB/%RH (intensity) at 51%–80% RH and T sensitivities of −0.013 nm/°C (wavelength) and −0.017 dB/°C (intensity) at 30 °C–65 °C. The proposed sensor can be used to simultaneously measure both the RH and T.