Label Free Chemical and Biochemical Sensing Using Photonic Crystal Waveguide at Sodium D-Line

Photonic crystal waveguide (PCW) sensors represents an efficient and accurate solution for chemical and biochemical sensing. Here, we propose a design of photonic crystal waveguide sensor for chemical sensing applications. The proposed PCW sensor is patterned on 10x10 mu m silicon on insulator (SOI) wafer. PCW designed with circular air holes of radius r = 0.35a where a is the lattice constant of 0.45 mu m, arranged in hexagonal structure. The principle of measurement is based on variation in refractive index of sample that causes change in effective refractive index (ERI) in guided mode leading to blue shift. Experimental results of refractive indices are used in sensing analysis. Proposed design is capable of allowing sodium doublet line (Sodium D-Line) wavelength through structure to work as chemical and biochemical sensor. Better results are achieved after optimization of center cavity.