Sensing improvement of 1D photonic crystal sensors by hybridization of defect and Bloch surface modes

Abstract

There are enormous efforts to make new optical sensors based on photonic crystals with improved features. In this paper, we utilize the coupling behavior of two different localized modes of a one-dimensional photonic crystal to promote the sensing performance of sensors based on Bloch surface waves. Defect modes are appeared by embedding a periodic Dirac semimetal material-Dielectric layers into a one-dimensional photonic crystal. The dispersion relations of surface and the defect modes are obtained using the transfer matrix method. The hybridization of the defect and surface modes are examined and optimized by the period number and also the position of the defect layers, physical parameters of Dirac semimetal and the distance of defect layers from the prism. The sensing characteristics are studied under the Kretschmann configuration with the reflectance spectrum. The Bloch surface waves are excited in Kretschmann configuration and the sensing characteristics such as the angular sensitivity and the figure of merits are investigated by the reflection spectrum changes. The results reveal that foregoing parameters have great influences on the sensor performances. Besides, the results are compared with those of the structures with ordinary periodic dielectric- dielectric layers (no Dirac semimetal). Considerable improvement of sensor performance is achieved in these structures and consequently, our findings can be present promising applications of Bloch surface wave based sensors.