Design of a new two-dimensional optical biosensor using photonic crystal waveguides and a nanocavity

Abstract In this paper, a two-dimensional photonic crystal biosensor for medical applications based on two waveguides and a nanocavity is presented. The waveguides and nanocavity are created by introducing line and point defects into a photonic crystal, respectively. It could be shown that by injecting an analyte into a sensing hole, and thus changing its refractive index, may shift the resonant wavelength. The proposed structure is designed for the wavelength range of 1.5259–1.6934 μm. Sensitivity, the most important biosensor parameter, was studied and found to be approximately equal to 83.75 nm/refractive index units (RIU). An important specification of this structure is its very small dimensions. Two-dimensional finite-difference time domain and plane-wave expansion methods were used for both to simulate the proposed structure and to obtain the band diagrams.