Mos2 Surface Plasmon Resonance Based High-Resolution Terahertz

Abstract

Currently, the field of terahertz bio-detection faces challenges in terms of sensitivity, efficiency, and anti-interference.Achieving high-sensitivity independent multi-channel terahertz (THz) optical fiber detection is the key to overcome these bottlenecks. Here, a high-resolution terahertz biosensor based on surface plasmon resonance (SPR) of molybdenum disulfide (MoS2) is achieved by depositing layers of MoS2 on polishing surfaces of a dual-channel micro-structured fiber (MSF). To enhance the coupling efficiency between fundamental mode and surface plasmon polariton mode, a thin zinc oxide (ZnO) dielectric film is sputtered between the excitation layer and analytes, which also improves the THz detection sensitivity. The dual D-shaped channels are completely separated by support arm claddings to ensure the detection independence of each channel. The performance of SPR-MSF is optimized by finite element method, with its structural parameters set to provide the optimal transmission performance. The results show that the proposed biosensor presents high amplitude sensitivity (AS) up to 384.80 RIU-1 and high wavelength sensitivity (WS) of about 223.45 μm/RIU, corresponding to sensing resolution (SR) of about 4.47×10-7 RIU. Furthermore, the dual-channel WS andSR can be improved to 602.52 μm/RIU and 1.65×10-7 RIU, respectively, by introducing ZnO thin film on the excitation layer in the detection channel. In addition, the special dual-channel design introduces self-referencing, which reduces the measurement bias caused by environmental changes and improves the detection accuracy. Therefore, with its advantageous performance, the proposed SPR-MSF can potentially advance the development of THz biosensing technology.

Keywords: Surface plasmon resonance, terahertz, Micro-structured fiber biosensor, MoS2, ZnO, Resolution