Transform-limited, narrow-linewidth, terahertz-wave parametric generator

An injection-seeded nanosecond terahertz (THz) wave parametric generator was demonstrated using nonlinear crystals that were pumped by a single frequency Nd:yttrium–aluminum–garnet laser. Spectrum narrowing to the Fourier transform limit (ν=1.58 THz, Δν<200 MHz) was achieved by injection seeding the idler wave (near-infrared Stokes). This resulted in a THz-wave output power (900 pJ/pulse, >100 mW peak) approximately 300 times higher than that of a conventional THz-wave parametric generator, which has no injection seeder. This compact system operates at room temperature and promises to be a widely tunable THz-wave source that will compete with free-electron lasers and p-Ge lasers.