Study and Analysis of Light Scattering Loss in Irregular Integrated Optical Waveguides

Abstract

Results are presented that have been obtained in numerical and experimental investigations of three-layer single-mode and multimode polystyrene, liquid, and liquid-crystal integrated optical waveguides. Numerical simulation results are presented and compared to the experimental data. The form of the scatter diagram from both the coordinates of the observation points and the waveguide phase slow-down factor is investigated. Characteristic experimental scatter diagrams in the plane transverse to the plane of incidence are given for TE- and TM-polarization. Calculated and experimental scatter diagrams are found to be in satisfactory agreement. Measurement of optical loss in the waveguides has allowed determining, in particular, the root-mean-square roughness height of the substrates of the polystyrene and liquid waveguides, which fairly corresponds to the known surface finish. In the liquid-crystal waveguide, the investigations have been focused on the features of the TE- and TM-mode scattering in a wide range of the phase slow-down factor variation. Complicated nonlinear processes of radiation field transformation beyond the waveguide are observed experimentally and through numerical simulation. Statistical parameters obtained for the irregularities of the investigated waveguides are presented. In addition, the root-mean-square estimates are given for spatial fluctuations of the director and compared to the average correlation radius for fluctuations of local orientation of nematic liquid crystal molecules.