Hybrid Photonic Crystal Cavity as a Sensitive Label-Free Biosensor

In this paper, a two-dimensional (2D) photonic crystal (PC) structure with a triangular lattice is designed for using as a biosensor. It has the ability to detect bio-targets with refractive indices between 1.33 (water) and 1.5. As the refractive indices of sensitive holes change, a significant shift in the peak of transmission is observed. This structure consists of air holes in silicon slab with 0.48a thickness and 10 $a$ × 10a µm2 active area which has band gap and waveguide modes for TE polarization. Finite difference time domain (FDTD) and plane wave expansion (PWE) methods have been used for the analysis. We've used effective refractive index of silicon for 2D simulation. The simulation results yield a maximum sensitivity of 300 nm/RIU and a quality factor of 418. These results compared with previous experimental or simulated results show considerable improvements.