Thermally Controllable Silicon Photonic Crystal Nanobeam Cavity without Surface Cladding for Sensing Applications

Photonic crystal nanobeam cavities with high-quality factors are very sensitive to the dielectric properties of their surroundings. Combining this high sensitivity with a specially designed heater, we experimentally demonstrate a very sensitive optical sensor, capable of simultaneously providing heat and interrogating the refractive index of its surroundings. The structure presents experimental sensitivity of 98 nm/RIU and signal-to-noise ratio of 3.88 × 10 –4 RIU and provides approximately 100 °C of temperature variation in the sensing area, with a temperature switching time of a few microseconds.