Infiltrating a thin or single-layer opal with an atomic vapour: Sub-Doppler signals and crystal optics

¹ Laboratoire de Physique des Lasers, Université Paris13 - Sorbonne-Paris-Cité - 99 Av. JB Clément, 93430 Villetaneuse, France
² UMR 7538 du CNRS - 99 Av. JB Clément, 93430 Villetaneuse, France
³ Moscow Institute of Physics and Technology (State University) - Institutskiy Pereulok 9, 141700 Dolgoprudny, Russia
⁴ P.N. Lebedev Physics Institute - 53 Leninskii prospekt, 119991 Moscow, Russia

^(a) daniel.bloch@univ-paris13.fr (corresponding author)

Received: 19 June 2014
Accepted: 15 September 2014

Abstract

Artificial thin glass opals can be infiltrated with a resonant alkali-metal vapour, providing novel types of hybrid systems. The reflection at the interface between the substrate and the opal yields a resonant signal, which exhibits sub-Doppler structures in linear spectroscopy for a range of oblique incidences. This result is suspected to originate in an effect of the three-dimensional confinement of the vapour in the opal interstices. It is here extended to a situation where the opal is limited to a few- or even a single-layer opal film, which is a kind of bidimensional grating. We have developed a flexible one-dimensional layered optical model, well suited for a Langmuir-Blodgett opal. Once extended to the case of a resonant infiltration, the model reproduces quick variations of the lineshape with incidence angle or polarization. Alternately, for an opal limited to a single layer of identical spheres, a three-dimensional numerical calculation was developed. It predicts crystalline anisotropy, which is demonstrated through diffraction on an empty opal made of a single layer of polystyrene spheres.