Sculpting shadows. On the spatial structuring of fields & atoms: a tale of light and darkness

QC Physics

Clark, Thomas William ; Franke-Arnold, Sonja

University:University of Glasgow

Department:School of Physics and Astronomy

关键词: optics, atomic physics, eit, spatial eit, hologram generation, optical switching, magnetic sensing.;   

Others  :  http://theses.gla.ac.uk/8029/7/thesis_coversheet.pdf

来源: University of Glasgow

【 摘 要 】

Whether in art or physics, two dimensions are better than one.And in this context, we consider the spatial shaping of opticalfields and atomic polarisations.This work begins with a comprehensive review of how toaccurately and arbitrarily modulate transverse beam profilesusing six different methods. The methods are presented in thecontext of a general complex input beam and the shaping andmeasuring of the input beam with a single SLM is discussed anddemonstrated.A simple setup is then considered that allows for the rapidswitching between arbitrary profiles, using only a single holo-graphic component and an acousto-optical modulator (AOM). Inthis setup, a switching speed of approximately 10 kHz is demon-strated explicitly, limited by the current detection system, butwhere speeds of up to 20 MHz are estimated to be possible.The following discussion then concentrates on the spatialstructure of atoms, reviewing the conceptual tools needed tomeasure and interpret an atomic cloud in the presence of a mag-netic field from fundamental concerns, both in theory and inpractice: assuming a classical light field and a quantum atomicsystem. The specific implementation of both a magneto-opticaltrap and a holographically-shaped dynamic dark SpOT follows.The crux of the work then concerns how polarisation-structuredlight can be used to create spatial patterns of transparency (spa-tial EIT) within an atomic cloud. Beginning with a review of EITin general, with particular focus on an F = 1 → F = 0 transition,the spatial modulation of absorption, dispersion, polarisationrotation and change in ellipticity is predicted for systems in thepresence of a transverse magnetic field. The depth of this mag-netic field dependency is then explored in some detail, where therelationship between observed patterns and applied magneticfield suggests the possibility of a visual magnetometer. The finalsection then considers how linearly polarised light and a q-platewas used to demonstrate spatially dependent transparency in areal atomic cloud.