Design of Low Dispersion Silicon Nanowire Optical Rectangular Waveguide for Label-Free Biosensing Applications

This paper presents an in-depth investigation into silicon nanowire optical rectangular waveguides designed specifically for label-free biosensing applications. Silicon nanowire waveguides possess numerous advantageous characteristics, making them highly suitable for applications in both communication and sensing within photonic integrated designs. These optical rectangular waveguides efficiently guide light through optimized dimensions of low refractive index gaps. Employing a finite-element method for numerical analysis provides substantial evidence to validate the guiding properties of these waveguides. In exploring their sensing capabilities, it is crucial to understand various influential factors. The initial phase of this exploration focuses on how nanowire waveguides, guided by low refractive indices, propagate and exhibit sensing behavior. The results underscore the importance of surface sensing. Examining the impact of functionalization layer coverage on silicon wire surfaces, as reflected in the waveguide confinement factor, highlights enhanced interaction with sensing analytes when the functionalization layer fully covers the surface. Thus, integrating a functionalization layer over the waveguide sensing surface is imperative for devising label-free surface sensing optical devices. Ultimately, the silicon nanowire optical rectangular waveguide proves instrumental in facilitating efficient sensing within the advancing domain of photonics.