Inverse Lamb dip spectroscopy using microwave modulation sidebands of CO2 laser lines

Abstract
We report the observation of infrared Lamb dips using a widely tunable laser source. The microwave sidebands generated on CO2 laser lines provide sufficient power (∼0.5 mW) and spectral purity (Δν≲100 kHz) for saturation spectroscopy. Application of this infrared source to the observation of infrared Lamb dip spectra of CH3F and SiF4 is reported.