High temperature photonic crystal fiber tip sensor

We demonstrate a temperature sensor consisting of a 2-dimensional, Silicon (Si), Photonic Crystal (PC) attached to the facet of a standard single-mode optical fiber. The 2-D PC sensors are fabricated on standard Si wafers, using a single mask and a combination of isotropic and anisotropic etching, and micro-assembled onto the facets of the optical fibers by Si welding. The temperature of the Si-PC sensor is monitored by measuring its reflectance spectrum in the 1250 nm to 1650 nm wavelength range. The measured reflectivity peak shifts from 100°C to 700°C is 0.1036 nm/°C. The observed spectral shift and temperature sensitivity are significantly higher than other high temperature fiber Bragg grating sensors, and comparable to long-period fiber gratings sensors. The high sensitivity along with the compactness and robustness gives these sensors the strong potential for use in harsh environments.