Propagation loss study of very compact GaAs/AlGaAs substrate removed waveguides

Abstract

Very compact GaAs/AlGaAs optical waveguides with propagation loss as low as 0.9 dB/cm at lambda=1.55 microm were demonstrated using substrate removal and evaporated Si for index loading. Loss components were identified and minimized through process and waveguide design. Process induced roughness contributed significantly to overall propagation loss. Therefore a low damage process in addition to proper waveguide design is needed for loss minimization.