Frequency up- and down-conversion by parametric and non-parametric processes in warm rubidium vapour

This thesis presents an experimental study of nonlinear frequency up- and down-conversion in warm rubidium vapour at modest intensities of the applied laser light. We studied the properties and optical amplification of the amplified spontaneous emission. Our results may improve the performance of the laser-guide-star technique. Our examination also reveals that despite continuous-wave (cw) and quasi-cw two-photon excitation, the directional blue emission generated by parametric four-wave mixing exhibits a spiking behaviour. This needs to be considered in emerging applications in the field of quantum information and technology. Additionally, we explored the usage of a laser as an optical switch.