Quantentechnologie

In this thesis I present experiments done with optical fibres tapered down to submicrometre diameters. In such an optical microfibre, OMF, the light is strongly confined over a large length with a strong evanescent field propagating outside of the OMF. With this high light intensity in the surrounding medium of the OMF over a length of several millimetres, OMFs offer excellent conditions for light-matter interaction experiments. Linear absorption spectroscopy of hot caesium vapour using OMFs has already been done in our group [1]. The goal of my work was to investigate the possibilities of further spectroscopic methods. After presenting the considerations about pump - probe spectroscopy of caesium vapour using OMFs, I will introduce the optical setup I built. It offers the possibility for saturated absorption and polarisation spectroscopy using OMFs with a great flexibility. In first experiments the setup proofed to work, but transmission losses due to chemical reactions of the caesium with the surface of the OMFs prevented further investigations. To overcome this problem, the surface of the OMF had to be protected. I will present the surface passivation method which fulfils all of our demands and the developed treatment procedure of an OMF. This treatment procedure can now be applied and an OMF with a chemically passivated surface can be connected to the ready to use optical setup for pump - probe spectroscopy of hot atmoic caesium vapour.