Abstract

Low-loss semiconductor waveguides and bends are essential for integrating optical guided-wave devices with electronic circuitry. We have fabricated rib waveguides on GaAs/AlGaAs single heterostructures with losses as low as 0.25 dB/cm and much greater optical confinement (effective index difference Δn = 0.012) than in previously reported semiconductor guides of comparable loss (Δn ≤ 0.003).^1,2 Scattering from rib roughness is a significant loss contribution in ion-milled rib waveguides; the loss is described by a rib roughness of 50 nm using a simple formula³ for the scattering loss. Smoother rib walls can be obtained by other etching methods, however. The effect of rib geometry and fabrication method on the scattering loss is discussed. Bends with low radiation loss (≤0.6 dB/rad) and small radius (several millimeters) were fabricated with such guides.

© 1987 Optical Society of America