Terahertz plasmonic frequency selection metasurface based on Na-GaAs complementary symmetrical split-rings for refractive index sensing

Abstract

A Terahertz (THz) plasmonic frequency selection metasurface based on Na-GaAs complementary symmetrical split-ring (PFSM-NCSS) is demonstrated for bulk refractive index (RI) sensing. The sensing performances of the PFSM-NCSS is studied by finite element method (FEM). The results show that the PFSM-NCSS has reflection peaks at 9.25 and 4.4 THz for the TM and TE incident lights, respectively. The parameter optimizations indicate that the reflection peak moves towards lower frequency when P decreases or r increases, and shifts to higher frequency when w1 or w2 increases. The PFSM-NCSS with two loaded dielectrics has minimum relative frequency offset with various θ, which means it has good angular stability. The sensing structure based on the PFSM-NCSS has RI sensitivities of −969.8 and −651.1 GHz/RIU for the TM and TE incident lights, meanwhile DLs of 9.8 × 10−4 and 3.2 × 10−4RIU can be achieved. The PFSM-NCSS provides a feasible THz RI sensing scheme for the cost-effective, real-time biosensors and immunosensors, along with strong light–matter​ interaction, good electromagnetically induced transparency characteristics, and compatibility with the CMOS technology.