Achromatically injection-seeded terahertz-wave parametric generator.

An achromatically injection-seeded terahertz-wave parametric generator was constructed with MgO:LiNbO3 crystals and a tunable seeder in a stationary dispersion-compensated optical arrangement. Without readjusting the mirrors, we obtained smooth tuning of the terahertz wave over the 0.6–2.6 THz range by adjusting the seeder wavelength alone. We have successfully demonstrated the feasibility of this system for terahertz-wave absorption measurements over a wide frequency range by using low-pressure water vapor.