Nonlinear phase matching in THz semiconductor waveguides

Waveguide phase matching of a frequency conversion process within an isotropic semiconductor is studied. The three-wave interaction involves pump and signal beams in the near infrared, and the idler at THz frequencies, i.e. with a wavelength greater than 50 mum in GaAs. Phase matching is obtained by exploiting modal dispersion and, for energies below the reststrahlen region, the semiconductor anomalous dispersion. This original phase matching scheme provides simultaneously a long interaction length, due to waveguide confinement, and efficient wave mixing because only the fundamental modes are involved in a modal phase matching process. Two different types of waveguides are studied: bulk semiconductor rods and plasmon waveguides.