We show that it is possible to use backward optical parametric oscillation in GaSe to obtain tunable output in the 13–20-μm range with the minimum threshold intensity as low as a few 10<sup>8</sup> W/cm<sup>2</sup>. We may be able to use this configuration to achieve large amplification factors for a coherent weak beam in the far-infrared region. It is also possible to generate coherent far-infrared waves in the presence of pump and signal waves.
© 1998 Optical Society of America
(190.2620) Nonlinear optics : Harmonic generation and mixing
(190.4400) Nonlinear optics : Nonlinear optics, materials
(190.4410) Nonlinear optics : Nonlinear optics, parametric processes
(190.4970) Nonlinear optics : Parametric oscillators and amplifiers
Y. J. Ding and J. B. Khurgin, "Generation of tunable coherent far-infrared waves based on backward optical parametric oscillation in gallium selenide," J. Opt. Soc. Am. B 15, 1567-1571 (1998)