Photonic crystal based biosensor with the irregular defect for detection of blood plasma

Abstract

Truncated 1D photonic crystals-based biosensors with aperiodic defects under the Kretschmann configuration are investigated for sensing the refractive index changes in an aqueous solution polluted with blood components like plasma (n=1.35). The aperiodic defect cells are three types of Fibonacci sequences (S2, S3, and S4) made of two Dirac semimetal and dielectric materials. Dirac semimetal materials have considerably tunable permittivities and conductivities and evidence have shown that light-matter coupling is stronger than previously known materials like graphene. The Bloch surface waves and defect modes are the results of breaking the periodicity in an ordinary 1D photonic crystal that appeared in the photonic band gaps. The influence of the irregular, periodic defect layer on the hybridization of the defect and surface modes and the performance of the proposed biosensors are investigated by using the well-known transfer matrix method. The effect of the defect layer thicknesses is also taken into account. Plotting the electric field profile shows that the modes in the crossing region change their roles and those following the slope of the modes in the defectless structure have better sensing performance than farther ones. In addition, results show that the figure of merit of the structures (N′=2, N=4) using the aperiodic defect with mentioned Fibonacci sequences (FOM(S3)=525 and FOM(S4)=508) is considerably better than those made of periodic defects (FOM(S2)=406).