SCATTERING LOSSES IN A HIGH Δn WAVEGUIDE SYSTEM FOR SILICON MICROPHOTONICS

摘要

In this study, we investigate the scattering losses of planar dielectric waveguides as a function of sidewall roughness and core/cladding index difference (Δn). We constructed a loss contour map showing the interdependence of sidewall roughness and transmission loss, using a theoretical approach. This map assists users in their design of an optimal waveguide fabrication process that minimizes loss. We use both theoretical and experimental approaches to investigate the effect of Δn on loss. By adding the trend of the minimum bending radius as a function of Δn, we constructed an index engineering plot that addresses the size/performance tradeoff in waveguide material selection. There is an optimal range of Δn bound by the lower limit from bending radius and the upper limit from scattering losses. The design flexibility in waveguide materials is increased by raising the upper limit for the optimal Δn with a processing technology that yields low scattering losses.