Spectroscopy in an extremely thin vapor cell: Comparing the cell-length dependence in fluorescence and in absorption techniques

Abstract

We compare the behavior of absorption and of resonance fluorescence spectra in an extremely thin Rb vapor cell as a function of the ratio of L / , with L the cell thickness ͑L ϳ 150-1800 nm͒ and the wavelength of the Rb D 2 line ͑ = 780 mn͒. The Dicke-type coherent narrowing [G. Dutier et al., Europhys. Lett. 63, 35 (2003)] is observed only in transmission measurements, in the linear regime, with its typical collapse and revival, which reaches a maximum for L = ͑2n +1͒ /2 (n integer). It is shown not to appear in fluorescence, whose behavior-amplitude, and spectral width, is more monotonic with L. Conversely, at high-intensity, the sub-Doppler saturation effects are shown to be the most visible in transmission around L = n.

Dicke coherent narrowing in two-photon and Raman spectroscopy of thin vapor cells

“…therein), with respect to the transient nature of the atom-light interaction. In linear optical absorption, a particular coherent narrowing has been experimentally observed for a λ/2 cell thickness [3,4], analogous to the one first mentioned by Romer and Dicke [5] in the microwave domain. The purpose of this note is to show that the main features of this coherent Dicke narrowing can be extended to two-(or multi-) photon transitions, as long as an effective two-level model can be considered, and for a normal incidence condition now referring to the sum of photon wave-vectors  i k r ∑  .…”

“…It exhibits a logarithmic singularity (in the limiting case ku >> γ 21 ), originating in the 1/v z contribution of fast atoms. Also, in spite of a mismatching brought by the Doppler detuning [3,4], all velocity groups interfere constructively up to the λ/2 thickness.…”

“…For v z < 0 , z/v z is replaced by (z -L)/v z . The transmission lineshape strongly depends on the L thickness [3,4,8]: it oscillates, with a pseudo-periodicity λ, from a sub-Doppler width (for L = (2n+1)λ/2) to a Doppler-broadened one (for L = nλ). The narrowest lineshape is for the λ/2 thickness as in the situation analyzed by Romer and Dicke [5].…”

“…Even if the Dicke narrowing may remain only of a marginal interest for precision spectroscopy (the fabrication of ETCs [4,10] requires thick windows for a small active thickness), several possible applications can be envisioned. ETCs are already an interesting tool for the probing of atom-surface interaction, notably for the effective analysis of the spatial dependence of long-distance atom-surface interaction [11].…”

Hilbert transform: Applications to atomic spectra

“…Theoretical spectra of n(ω) are generated using a model of the complex susceptibility that takes the Doppler broadened transitions and applies self-broadening [28], Dicke narrowing [29,30], atom-surface interactions [18], and reflectivity effects [31]. The fit compares the transmission line shape to the theoretical line shape from χ I (ω).…”