Fluoride fiber plasmonic sensor with multilayer variants of tungsten disulfide (WS2): Seeking enhanced figure-of-merit via thermo-optic tuning of radiation damping

Abstract

Abstract A multilayered fiber SPR sensor is studied with as many as five design variants governed by different number (N varied from 1 to 5) of WS2 monolayer for ethanol detection. The sensor design variants are simulated and analyzed at 785 nm wavelength. The dynamic radiation damping in terms of variable temperature and Ag layer thickness is enforced on the sensor variants to lead to possible sensing performance enhancement. Further, an attempt is made to more comprehensively evaluate the sensor’s performance by including the power loss curve characteristics. At an optimum radiation damping (ORD) condition (23 °C temperature and 55.5 nm thick Ag layer at 785 nm wavelength), the figure of merit (FOM) of the fiber (ZBLAN core and NaF clad) SPR sensor with WS2 bilayer has the potential to reach to an ultrahigh magnitude of 27563.575 RIU−1 while the overall figure of merit (FOM*) reaches to 62293.68 RIU−1. The next best combination (i.e., with 4 monolayers of WS2, 29.1 °C temperature, and 54.6 nm thick Ag layer at 785 nm wavelength) provides FOM of 27028.217 RIU−1 and FOM* of 61813.53 RIU−1). The results are explained in terms of physical concepts such as light absorption, Rayleigh scattering and thermo-optic effects in sensor constituents (Ag and WS2, in particular) converging at dynamic nature of radiation damping in plasmonic structures. The proposed sensor can be an important milestone in developing highly sensitive and accurate fiber optic chemical sensors.