title: Ultrabright continuously tunable terahertz-wave generation at room temperature.
abstract: The hottest frequency region in terms of research currently lies in the 'frequency gap' region between microwaves and infrared: terahertz waves. Although new methods for generating terahertz radiation have been developed, most sources cannot generate high-brightness terahertz beams. Here we demonstrate the generation of ultrabright terahertz waves (brightness ~0.2 GW/sr·cm(2), brightness temperature of ~10(18) K, peak power of >50 kW) using parametric wavelength conversion in a nonlinear crystal; this is brighter than many specialized sources such as far-infrared free-electron lasers (~10(16) K, ~2 kW). We revealed novel parametric wavelength conversion using stimulated Raman scattering in LiNbO3 without stimulated Brillouin scattering using recently-developed microchip laser. Furthermore, nonlinear up-conversion techniques allow the intense terahertz waves to be visualized and their frequency determined. These results are very promising for extending applied research into the terahertz region, and we expect that this source will open up new research fields such as nonlinear optics in the terahertz region.
authors.affiliation: RIKEN, 519-1399 Aramakiaoba, Aoba, Sendai 980-0845, Japan.
authors.forename: Shin'ichiro
authors.initials: S
authors.lastname: Hayashi
authors.affiliation: RIKEN, 519-1399 Aramakiaoba, Aoba, Sendai 980-0845, Japan.
authors.forename: Kouji
authors.initials: K
authors.lastname: Nawata
authors.affiliation: Institute for Molecular Science, 38 Nishigo-Naka, Myodaiji, Okazaki 444-8585, Japan.
authors.forename: Takunori
authors.initials: T
authors.lastname: Taira
authors.affiliation: Nihon Univ., 1 Nakagawara, Tokusada, Tamura, Koriyama 963-8642, Japan.
authors.forename: Jun-ichi
authors.initials: J
authors.lastname: Shikata
authors.affiliation: 1] RIKEN, 519-1399 Aramakiaoba, Aoba, Sendai 980-0845, Japan [2] Nagoya Univ., Furo-cho, Chikusa, Nagoya 464-8603, Japan.
authors.forename: Kodo
authors.initials: K
authors.lastname: Kawase
authors.affiliation: RIKEN, 519-1399 Aramakiaoba, Aoba, Sendai 980-0845, Japan.
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Minamide