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 nonlinear‐optical 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 femtosecond 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. We overview methods of THz‐wave generation using frequency down‐conversion in GaAs with periodically‐inverted crystalline orientation. First, we compare different nonlinear‐optical 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 femtosecond 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. Conceptual scheme of resonantly‐enhanced THz‐wave generation. Near‐degenerate doubly‐resonant PPLN optical parametric oscillator 2 μm. THz output is produced at the beat frequency between these two waves, via frequency mixing in periodically‐inverted GaAs.