Multiple Modes of a Photonic Crystal Cavity on a Fiber Tip for Multiple Parameter Sensing

Measuring resonant wavelengths of different modes of a luminescent semiconductor photonic crystal cavity placed on the tip of an optical fiber is proposed and demonstrated for simultaneous measurement of multiple parameters, and is applied to the measurement of temperature and refractive index in the temperature range of 77-370 K. The operation principle is supported by the finite-element method simulations. The robustness of a simple mounting scheme without adhesives is proven experimentally. The simplicity, extremely small size, and high sensitivity to both refractive index and temperature makes this concept an ideal fiber-optic sensor for a multitude of applications.