Optimizing the Performance of 1D Photonic Crystal Based Biosensors Containing Gradient Refractive Index Materials

In this work, we have optimized the performance of the 1D photonic crystal based biosensor. The photonic crystal contains the layers A, B and F which are ZnSe, SiO2 and a microfluidic channel, respectively. Also, there is a radial gradient refractive index defect layer in the center of the structure. By irradiating a plane beam to the proposed structure, a ring-shaped intensity profile is achieved on the output plane of the structure. Any changed in the effective refractive index of the fluid inside of microfluidic channels can cause a change in the radius of the intensity ring. There are different parameters such as number and thickness of the layers and the rate of the refractive index variation in the D layer that can effect the sensitivity. Optimizing these parameters, it is possible to sense the refractive index changes of 10^-5 .