Low-loss GaAs/AlGaAs waveguide phase modulator using a W-shaped index profile

Abstract
We demonstrate a low-loss semiconductor optical waveguide phase modulator for the 1.5 μm wavelength region. The device, based on a p-i-n diode/heterostructure waveguide, utilizes a novel epilayer structure to reduce propagation losses associated with doped electrode layers. Propagation loss below 1 dB/cm, significantly lower than previously reported values for conventional semiconductor waveguide phase modulators, was achieved without sacrificing modulator efficiency.