Ultrahigh Temperature Sensitivity Using Photonic Bandgap Effect in Liquid-Filled Photonic Crystal Fibers

We theoretically and experimentally investigate the temperature responses of two liquid-filled polarization maintaining photonic crystal fibers (PM-PCFs). The guidance mechanism of liquid-filled PM-PCFs is a hybrid of the modified total internal reflection and photonic bandgap (PBG) principles. According to the wavelength shifting of photonic band edges, a sensitivity of -10.033 nm/°C from 38 °C to 45 °C was achieved in the glycerol-filled PM-PCF, whereas an ultrahigh sensitivity up to -76.197 nm/°C from 59 °C to 63 °C was obtained in the toluene-filled PM-PCF. High temperature sensitivities stem from the high transmission window located in the first PBG. The thermal tunable filled PCFs with PBG effect properties will offer great potential for temperature sensing, as well as tunable bandpass filters.