Selectively Infiltrated Photonic Crystal Fiber With Ultrahigh Temperature Sensitivity

By selective filling of one of the air holes in the photonic crystal fiber, the fundamental core mode can be effectively coupled to the fundamental mode of the adjacent liquid rod waveguide at the resonant wavelength with extremely high temperature sensitivity. The spectral power of the rod mode can be filtered out by fusion splicing the selectively infiltrated photonic crystal fiber with conventional single-mode fiber, resulting in a sharp dip in the transmission spectrum. Such a device is demonstrated in our experiment by filling standard 1.46 refractive index liquid into one of the air holes of the commercially available photonic crystal fiber by use of femtosecond laser-assisted selective infiltration technique. The average temperature sensitivity achieved is ~54.3 nm/°C.