Optofluidic sensor using two-dimensional photonic crystal waveguides

Photonic crystal (PC) waveguide is one class of PC devices that has been demonstrated for RI measurements. In this paper, we have reported a new design of infiltrated optofluidic sensors based on 2D photonic crystal slab with triangular lattice pattern of ring-shaped holes. The properties of the sensor are simulated using the finite-difference time-domain (FDTD) method. The transmission spectra have been measured by changing the refractive index of holes and it has been found that with increasing refractive index, wavelength position of transmission spectrum shifts. The radius and the shape of the air holes localized at each side of the line defect are optimized to realize high sensitivity, wide measurement range and improved transmission. An improved optofluidic sensor design is also described and a 210 nm wavelength position of upper band edge shift was observed corresponding to a sensitivity of more than 636 nm per refractive index unit (RIU).