MoS2-functionalized analyte-defect-cavity Si/SiO2 one-dimensional photonic crystal biosensor for chemical detection with thermo-optic response.

A MoS2-functionalized Si/SiO2 one-dimensional photonic crystal (1D-PC) biosensor is proposed for chemical sensing applications and analyzed using the transfer matrix method (TMM). The structure consists of alternating Si/SiO2 dielectric layers forming top and bottom Bragg mirrors, with a central MoS2-functionalized analyte defect cavity introduced between them to generate a localized defect-mode resonance and enhance analyte interaction. The sensing mechanism is governed by concentration-induced refractive-index modulation within the analyte defect cavity, where the MoS2 monolayer acts as an active functional interface that improves light-matter interaction. The designed sensor exhibits a sharp resonance at ∼807.6 nm with a narrow linewidth (FWHM ≈ 1.8 nm) and a high Q-factor (∼448), indicating strong optical confinement. A sensitivity range of 292-302 nm RIU-1 with excellent linearity (R 2 ≈ 0.9998) is achieved. Furthermore, combined independent thermo-optic and concentration-dependent refractive-index corrections are introduced to evaluate how temperature variations influence the resonance response under more representative numerical sensing conditions. The results show a predictable thermo-optic shift and concentration-dependent response within the investigated operating range. The proposed platform combines dielectric Bragg-mirror engineering with a MoS2-functionalized analyte defect cavity, offering a promising numerical framework for chemically responsive photonic biosensing.