Orientation dependence of the phase modulation in a p-n junction GaAs/AlxGa1−xAs waveguide

Abstract
Phase modulation has been measured in a reverse‐biased PiN GaAs/AlxGa1−xAs double heterostructure with heavily doped (N, P∼1018 cm3) AlxGa1−xAs layers. These measurements were performed at two wavelengths (1.09 and 1.15 μm), for both TE and TM modes and with light propagating in the [110] and [11̄0] directions. We found that the effective quadratic electro‐optic coefficients R11 and R12 have approximately the same magnitude and sign. The values are −(40±10)×1017 cm2/V2 and −(54±10)×1017 cm2/V2 for λ=1.15 μm and λ=1.09 μm, respectively. The contribution of the plasma effect due to the free carrier is comparable and has the same sign.