Nonlinear optical effects in cold atomic gases

  • James McKelvie

Student thesis: Doctoral Thesis


In this thesis the Collective Atomic Recoil Laser (CARL) model of Bonifacio et al., which described CARL by two-level atoms, is extended to describe three-level atoms with ladder and ᴧ energy level configurations. It is shown that, in contrast to the case of two-level atoms where the CARL instability is quenched at high pump rates with significant atomic excitation, CARL instabilities involving 3-level atoms can persist at high pump rates due to transitions between the populated states being dipole forbidden. It is also demonstrated for the ladder configuration that, when the system is operated in the two-photon superfluorescent regime,introduction of centre of mass motion and atomic bunching result in symmetry breaking in the sign of detuning from field-atom resonance. CARL instabilities involving three-level atoms with ᴧ energy level configurations are investigated for two distinct cases : in the first the two ground states are degenerate, whereas in the second the ground states are non-degenerate. It is demonstrated that in the degenerate case, it is possible to decouple the atomic centre of mass motion from the internal atomic degrees of freedom. It is also demonstrated that for the non-degenerate case it is possible for the the atomic motion to be decoupled from the atomic coherence but not the atomic population. The population difference remains constant throughout the interaction, so the population inversion acts as a parameter in the equation for the force experienced by the atoms. Consequently,for both the degenerate and non-degenerate ᴧ configurations, CARL instabilities can occur at higher pump intensities than for the case of two-level atoms.
Date of Award19 Sept 2016
Original languageEnglish
Awarding Institution
  • University Of Strathclyde

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