Electroabsorption in GaAs and its application to waveguide detectors and modulators

Abstract

The electroabsorption coefficient of GaAs has been measured in uniform electric fields at wavelengths from 0.91 to 0.93 μm. These measurements were made using Schottky barrier contacts on low-loss GaAs waveguides consisting of high-purity epitaxial GaAs grown on heavily doped GaAs substrates. The experimental results are in good agreement with theoretical calculations of the Franz-Keldysh effect. Electroabsorption detectors with subnanosecond response time and 100% internal quantum efficiency have been integrated into these waveguides. Small values of avalanche gain have been obtained without any intentional guard-ring structure. Integrated electroabsorption modulators with greater than 20-dB depth of modulation were also fabricated.