A methylcellulose coated humidity sensor based on Mach-Zehnder interferometer with photonic crystal fiber

A methylcellulose (MC) coated humidity sensor by using photonic crystal fiber (PCF) based Mach-Zehnder interferometer (MZI) is proposed and experimentally demonstrated. It is fabricated by sandwiching a PCF between two standard single mode fibers (SMFs) with the air holes of the PCF in the fusion splicing region being fully collapsed. Experimental results show that this structure can not only carry on the intensity modulation, but also carry on the wavelength modulation, and the sensitivity in high humidity region is 0.57nm/%RH(relative humidity unit), 0.608dB/%RH respectively. We can be seen that the sensor has high sensitivity in high humidity area. It also shows that the humidity sensitive film of the wet characteristics of good, good stability, so it can be applied to humidity measurement.