We report high-resolution saturated-absorption spectra recorded by use of a few microwatts of radiation generated in a single pass by difference-frequency mixing. These results were obtained without the use of buildup cavities for the nonlinear mixing or for the saturation spectroscopy. We show high-quality saturated-absorption signals for the fundamental rovibrational band of CO<sub>2</sub> near 4.3 μm. Convenient sources and frequency-conversion devices open new possibilities for sub-Doppler spectroscopy in the infrared.
© 2000 Optical Society of America
(190.2620) Nonlinear optics : Harmonic generation and mixing
(300.6320) Spectroscopy : Spectroscopy, high-resolution
(300.6340) Spectroscopy : Spectroscopy, infrared
(300.6390) Spectroscopy : Spectroscopy, molecular
(300.6460) Spectroscopy : Spectroscopy, saturation
D. Mazzotti, P. De Natale, G. Giusfredi, C. Fort, J. A. Mitchell, and L. Hollberg, "Saturated-absorption spectroscopy with low-power difference-frequency radiation," Opt. Lett. 25, 350-352 (2000)