Computational study on high sensitive silicon based two dimensional photonic crystal waveguide with circular holes for biochemical sensing

A study has been made using finite difference time domain (FDTD) method to investigate the performance of silicon (Si) based two-dimensional (2-D) photonic crystal waveguide (PCW) for biochemical sensing. Circular type of PCW has been analyzed by removing a single row of holes from a 2-D Si photonic crystal (PC) slab. Sensors contained hexagonal lattice with particular geometric configurations trapped different amount of biomolecules e.g. DNA. The transmission spectrums of the sensor with different cover refractive indices are calculated. The calculation results show that a change in cover refractive index (RI) is apparent. A shift in light wavelength is found at the output end of the sensor which is monitored to evaluate sensing performance. The sensing scheme is based on monitoring the wavelength shifts resulting from the attachment of DNA molecules to the sensor holes. The diameter of the circular holes localized at each side of the line defect was optimized to realize high sensitivity, wide measurement range and improved transmission. Approximately 18% improvement in sensitivity has been found for circular holes than that of elliptical holes.