Using a λ=2.8 μm pump makes it possible to take full advantage of notable nonlinear optical properties of the infrared crystals ZnGeP<sub>2</sub>, CdSe, and GaSe to achieve efficient mid-infrared frequency downconversion. Traveling-wave optical parametric generators with angular tuning were pumped by single 100-ps 2.8-μm Er, Cr:YSGG laser pulses. The continuous tuning range achieved was 3.9–10 μm (ZnGeP<sub>2</sub>), 3.57–4.3 and 8–13 μm (CdSe), and 3.3–19 μm (GaSe), with a quantum conversion efficiency of typically 10% and the lowest, to the author’s knowledge, threshold ever obtained for a traveling-wave optical parametric generator. A dual-wavelength optical parametric generator was used for nonlinear spectroscopy of intersubband transitions of conduction-band electrons, quantum confined in semiconductor quantum wells, as well as for the study of intersubband-based resonantly enhanced χ<sup>(2)</sup> in quantum wells.
© 1999 Optical Society of America
(140.5680) Lasers and laser optics : Rare earth and transition metal solid-state lasers
(190.0190) Nonlinear optics : Nonlinear optics
(190.2620) Nonlinear optics : Harmonic generation and mixing
(190.4720) Nonlinear optics : Optical nonlinearities of condensed matter
(190.4970) Nonlinear optics : Parametric oscillators and amplifiers
K. L. Vodopyanov, "Mid-infrared optical parametric generator with extra-wide (3–19-μm) tunability: applications for spectroscopy of two-dimensional electrons in quantum wells," J. Opt. Soc. Am. B 16, 1579-1586 (1999)