Effect of patterns and inhomogeneities on the surface of waveguides used for optical waveguide lightmode spectroscopy applications

It has been found that patterns acid inhomogeneities on the surface of the waveguide used fur optical waveguide lightmode spectroscopy applications ca n produce broadening and fine structure in the incoupled light peak spectra . During cell spreading on the waveguide, a broadening of the incoupling pe aks is observed, while regular microstructures on the incoupling grating pr oduce shifts and splitting of the peaks. A theoretical model, based on the zigzag wave representation of light propagation in a planar optical wavegui de has been developed in order to understand the physical background of the observed effects. Numerical results are given for the different cases obse rved, and they are compared with the experimental data. Several possible ap plications of these effects are considered.