Agarose coated single mode fiber bend for monitoring humidity
A relative humidity (RH) sensor measuring wide range of humidity variations based on a bent single mode optical fiber coated with Agarose is reported. When exposed to moisture the change in refractive index of the Agarose layer results in changes in the degree of coupling of the core mode to cladding modes and corresponding changes in the output power are observed in the transmission spectrum of the Agarose coated bent fiber. The sensor shows linear response in the range 25 %- 90 % RH. We show that humidity sensitivity of the sensor is wavelength dependant and high sensitivity is observed at higher wavelengths. The sensor response is fast, stable and reversible in nature. 2011 SPIE.