Saturation spectroscopy for optically thick atomic samples

Abstract

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SUPER RESOLUTION LASER RADAR WITH BLINKING ATMOSPHERIC PARTICLES ---- APPLICATION TO INTERACTING FLYING INSECTS (Invited Paper)

“…However, during recent decades this limitation has been circumvented through various approaches. In stimulated emission depletion (STED) fluorescence microscopy, the point spread function can be narrowed beyond the diffraction limit through the usage of a secondary toroidal depletion laser beam [23][24][25], whereby optical resolution is pushed to few tens of nanometers (A somewhat related improved resolution in the spectral domain is obtained in high-contrast Doppler-free transmission spectroscopy [26,27], also relying on a non-linear response-saturation).…”

Saturation spectroscopy in optically thick three-level gas media

“…Theoretical descriptions of the SAS experiments in the new regime have also been given, based either on a simple hole-burning model 3 or on a more accurate analysis in terms of Maxwell-Bloch-type equations. 4 Both these models predict that subnatural linewidths can be reached, but since they consider samples of Dopplerbroadened two-level atoms, there still remains the interesting question of whether SAS in the new regime can be used to resolve spectral features that lie within the natural linewidth.…”

Investigation of shifts and interaction of signals in high-contrast transmission spectroscopy

“…Although the applications are more limited than for polarization spectroscopy the extreme simplicity of the set-up offers advantages. Although not evidenced in the early measurements [1,2], shifts in the recorded Doppler-free signals cannot be excluded under the rather extreme experimental conditions of high-contrast transmission spectroscopy. One of the purposes of the present work was to closer examine this point in a comparative study between the new approach and the established ones.…”

“…Recently the high-contrast transmission version of saturated absorption laser spectroscopy was introduced [ 1,2]. In normal saturated absorption spectroscopy [3,4] a gaseous sample of moderate absorption is used and a weak pumping beam is used to avoid power broadening of the Doppler-free signals.…”

“…Since the wings of the Doppler-free signal is more strongly attenuated than the central part, narrow and even subnatural linewidths can be obtained at the same time as extreme contrast (background rejection) is attainable. Various experimental aspects of the technique were demonstrated in [1,2] and a theoretical model was used in [2] to explain the observations. Although the applications are more limited than for polarization spectroscopy the extreme simplicity of the set-up offers advantages.…”