Intensity and Phase Modulators at 1.55 μm in GaAs/AlGaAs Layers Directly Grown on Silicon

We report for the first-time electro-optic phase and amplitude modulators in GaAs/AlGaAs epitaxial layers grown on misaligned silicon substrates containing germanium buffer layers. Epilayer has a npin doping profile and is equivalent to a pin diode. The 4-mm long electrode Mach–Zehnder modulators have 7.4- and 3.6-V Vπ under single-arm and push–pull drive conditions corresponding to 1.5 ± 0.1 V-cm modulation efficiency. Data on 7-mm long electrode Fabry–Perot phase modulators indicate 2.3- V Mach–Zehnder modulators are possible. These data also indicate less than 1-dB/cm on-chip propagation loss under 5-V reverse bias.