Ultra-compact and highly sensitive refractive index sensor based on a chalcogenide suspended slot hybrid plasmonic microring resonator

A microring resonator based on chalcogenide suspended slot hybrid plasmonic waveguide (CSSHPW) is designed for the refractive index (RI) sensing. The CSSHPW consists of a suspended Si nanowire with a nanoscale air gap and a Cu film deposited on a chalcogenide support layer. The mode characteristics of the suspended slot hybrid plasmonic mode (SSHPM) in the CSSHPW are simulated by using the finite element method (FEM). The simulation results show that the waveguide sensitivity (Swg) as high as 0.8 and the optical propagation loss as low as 0.08 dB/µm are obtained by optimizing the structure. The RI sensitivity (S), detection limit (DL), and detection range (DR) of the CSSHPW-based microring resonator (MRR) with a radius of 2 µm are 511.5 nm/RIU, 4.72 × 10−5 RIU, and 0.158 RIU, respectively. These superior performances as well as the fully complementary metal-oxide-semiconductor (CMOS) compatibility pave the way for CSSHPW-based biochemical sensors to realize on-chip high-S waveguide sensors. Moreover, the CSSHPW-MRR has a small size, high modulation depth, large Swg, and Cu cap of easy electrode formation, it facilitates the fabrication of a high-performance electro-optic (EO) modulator by infilling the slot with EO material.