Fiber temperature and humidity sensor based on photonic crystal fiber coated with graphene oxide

A temperature and humidity sensor based on photonic crystal fiber(PCF) coated with graphene oxide (GO) cascaded with two spherical structures is presented and demonstrated. The principle of this sensor is based on Mach–Zehnder interferometer (MZI), and the interference spectrum is sensitive to the change of temperature and humidity. Because of the hydrophilic property of GO, refractive index (RI) of the fiber surface changes significantly with the variation of humidity. Therefore, the GO film deposited on the PCF surface can improve the humidity sensitivity of the sensor. Experimental results show that the temperature sensitivities are 0.063 nm/°C and 0.086 nm/°C from 10°C to 70°C. The humidity sensitivities are 0.128 nm/%RH and 0.159 nm/%RH from 30% to 70%. Moreover, it also contains the following advantages: low cost, simple construction, and high sensitivity.