Construction and characterisation of ultra-thin alkali-metal vapour cells

• Main Author: Whittaker, Kate Avril
• Published: Durham University 2017
• Subjects: 539.7
• Online Access: https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.716276

This thesis presents the study of thermal alkali-metal vapours confined in a layer with a sub-micron thickness. This confinement enables the study of high density media without the loss of signal present in usually thermal vapours, but also has additional effects on spectra acquired from the system. Such effects include the suppression of the Doppler broadening and the interaction of the atoms with nearby surfaces. Herein, we present a study of this atom-surface interaction in both Rubidium and Caesium atoms, demonstrating that the interaction follows a power law of $1/r^\alpha$, where $\alpha = 3.02 \pm 0.06$. We also study Rabi oscillations at high densities, driving GHz Rabi oscillations in a Rb vapour at densities up to $10^17$~cm$^{-3}$. We find that the results do not have sufficient agreement with an optical Bloch simulation, but Maxwell Bloch simulations indicate the possible presence of simultons; simultaneously propagating solitons. Such phenomena have not yet been observed out of crystalline media. We also present a study of causality relations in atomic media. We first discuss the equivalency of the Hilbert transform to the Kramers-Kronig relations, well known in signal processing, but rarely applied in atomic physics. We then demonstrate that the Hilbert transform can be applied to atomic transmission spectra to quickly generate refractive index spectra. The final section of this thesis fully details the successful design and fabrication of vapour cells with a thickness of 500-1500~nm. The cells are assembled using a combination of traditional scientific glass blowing techniques and thermally annealed optically contacted plates. We fully outline the production process, and then present evidence of their successful functionality and longevity.