Tunable terahertz waves from 4-dimethylamino-N′-methyl-4′-stibazolium tosylate pumped with dual-wavelength injection-seeded optical parametric generation

Abstract

We developed a widely tunable terahertz (THz)-wave source covering the sub-THz frequency by difference frequency generation using a 4-dimethylamino-N′-methyl-4′-stibazolium tosylate (DAST) crystal. Near-infrared waves generated by dual-wavelength injection-seeded β-BaB2O4 optical parametric generation (is-BBO-OPG) were used for pumping the DAST crystal, which had separated wavelengths in the spectrum with a difference frequency of sub-THz. Furthermore, the non-collinear phase-matching condition was designed to compensate the walk-off effect of the BBO crystal. Consequently, tunable THz-waves from 0.3 to 4 THz were generated by tuning the wavelength of one of the seeding beams. The generated sub-THz-waves were monochromatic (dν < 33 GHz) with a maximum energy of 80 pJ at 0.65 THz.