Setup and Characterization of a Single-Focused Beam Optical Trap for Lithium

Lars Heinen

Published Jan 1, 2017• 0 citations

Abstract

Within the MOTREMI experiment at the Max-Plank-Institut für Kernphysik a new optical trap was constructed. A already installed magneto-optical trap cools 6Li atoms down to temperatures on the order of 100 μK. From the corresponding atoms an ultracold lithium gas is trapped inside the center of the main vacuum chamber. In the further course of the experiment, ionization measurements with a degenerate quantum gas will be carried out. In order to create theses gases, one needs to surpass the temperature limit of the magneto-optical trap. Traps using a high intensity, far red-detuned focused laser beam are able to achieve temperatures on the order of 100 nK. An intensity stabilization which is able to extend the lifetime of trapped gas was constructed in the scope of this thesis. With the use of two different photodiodes, every intensity level of the laser is covered. The high laser powers which are needed for the trap, can lead to thermal effects in the entire setup. Consequently, the properties of the laser and the optical elements the laser is passing through can change. Therefore, a quantitative analysis of these thermal effects has been carried out. Besides the shift and reduction of the focused laser beam, the thermal effect on the trap size was obtained.

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