All-Optical On-Chip Sensor For High Refractive Index Sensing

A highly sensitive sensor design based on two-dimensional photonic crystal cavity is demonstrated. The geometric structure of the cavity is modified to gain a high quality factor, which enables a sensitive refractive index sensing. A group of slots with optimized parameters is created in the cavity. The existence of the slots enhances the light-matter interactions between confined photons and analytes. The interactions result in large wavelength shifts in the transmission spectra and are denoted by high sensitivities. Experiments show that a change in refractive index of Delta n similar to 0.12 between water and oil sample 1 causes a spectral shift of 23.5 nm, and the spectral shift between two oil samples is 5.1 nm for Delta n similar to 0.039. These results are in good agreement with simulations, which are 21.3 and 7.39 nm for the same index changes. (C) 2015 Author(s).