Common path interferometeric analysis of a planar polymer optical waveguide having adlayer of 2D materials for biosensing applications

Abstract

Sensitivity of a planar polymer optical waveguide having adlayer of MoS2, WS2, MoSe2, WSe2 are estimated using common path Mach-Zehnder interferometer analyses. Dispersion relation and reflectivity equation of proposed waveguide is obtained by matching the electric and magnetic field at various boundaries. The obtained cutoff film thickness of the waveguide is approximately same in the presence of monolayer thickness of transition metal dichalcogenides materials. The cutoff film thickness 84.2 nm of this waveguide is approximately same for TE0, TM0 mode at wavelength 300 nm, these cutoff film thicknesses increases and become 304.6 nm at 1200 nm wavelength. In the proposed common path interferometer analysis, the superposition of TE0 and TM0 modes is considered as sensing signal. It is observed that the difference of their propagation constant is slightly decreased with increase of cover refractive index. Further the maximum phase change is obtained near the propagation constant maxima value hence around this value the output interference signal shows maximum shift with cover refractive index. In the considered wavelength range the maximum sensitivity 0.019 is obtained at wavelength 936nm, when a monolayer of WSe2 material is used as adlayer. © 2021, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.