Optofluidic Fano resonance photonic crystal refractometric sensors

Abstract

We report an ultra-compact surface-normal optofluidic refractometric sensor based on a two-dimensional silicon photonic crystal on insulator. In contrast to the conventional symmetric Lorentzian resonance that is prevalently used in the label-free sensors, the asymmetric lineshape and steep peak-to-dip transition of a Fano resonance enable the enhanced detection sensitivity. The detection limit of 1.3 × 10−6 refractive index units is achieved, which is among the lowest reported experimentally in the defect-free photonic crystal sensors.