Study of photonic crystal microcavities coupled with waveguide for biosensing applications

摘要

In this paper, we propose a two-dimensional photonic crystal biosensor implemented by waveguide and microcavity. The optical sensing characteristics of the structure are analyzed by using two-dimensional finite difference time domain method. Biomole-cules, e.g., DNAs, trapped in selected holes cause resonant wavelength shifting at the output terminal. The quality factor and the sensitivity of the proposed structure are about 6776 and 3.4 nm/fg, respectively, with a minimum detectable biomolecule weight in a sensing hole of 0.029 fg. We have also investigated the structure for use in bulk refractive index sensing. A sensitivity and detection limit of 210 nm/RIU and 8.92 × 10~(-5) were obtained respectively. Furthermore, to overcome the single purpose capacity of the sensor, a multichannel optofluidic sensor has been designed. The structure is made up of three microcavities connected in series and coupled to a waveguide. Simulation results indicate that the response of each detection unit to the refractive index variation (from 1.330 to 1.371) was completely independent. These features make the designed device a promising element for performing label-free multiplexed detection in monolithic substrate for medical diagnostics and environmental monitoring.