Optics and Photonics Society of Iran

 In this paper, we introduce a novel biosensor based on defective one-dimensional photonic crystals in total internal reflection (TIR) geometry, where a gradient refractive index (GRIN) defect layer is located at the end of the structure. By using the GRIN defect in the structure due to its special refractive index distribution function, the concentric ring-shaped reflectance distribution appears on the output plane of the structure that their radius is highly dependent to the refractive index of the Analyte at the end of the structure. Using the transfer matrix method (TMM) the sensitivity of this biosensor has been calculated for each ring.