Optical THz-wave generation with periodically-inverted GaAs

We overview methods of THz-wave generation using frequency down-conversion in GaAs with periodically-inverted crystalline orientation. First, we compare different nonlinearoptical materials suitable for THz generation, analyze THz generation process in quasi-phase-matched crystals and consider theoretical limits of optical-to-THz conversion. Then, we review single-pass optical rectification experiments with feratosecond pump pulses, performed in periodically-inverted GaAs, where monochromatic THz output tunable in the range 0.9-3 THz was produced. Finally, we describe a novel approach to create a compact highly efficient tunable (0.5-3.5 THz) room temperature monochromatic THz source, based on the concept of intracavity THz generation via resonantly-enhanced difference frequency mixing. This approach allowed generating of 1 mW of average THz power, potentially scalable to 10-100 mW.