Homogeneous sensitivity of sol-gel derived planar waveguide structures - Theoretical analysis

Rib waveguides are the key components of integrated optical devices including evanescent wave chemical and biochemical sensors. The sol-gel method allows the SiO₂:TiO₂ rib waveguides with very low attenuation to be fabricated by means of selective etching of the SiO ₂:TiO₂ parent slab waveguides deposited on glassy substrates. The present work focuses on theoretical investigation into both the influence of selected rib waveguide geometrical parameters and wavelength on the homogeneous sensitivity of the rib waveguides. The homogeneous sensitivity spectral characteristics of rib waveguides are compared with the ones for the parent slab waveguides. Moreover, there is investigated the influence of additional, sol-gel based amorphous silica layer, which separates rib sidewalls from an ambient on effective index and homogeneous sensitivity characteristics. Analysis was carried out using effective index method.