arXiv subjects
Publications and source records attributed to A. Koglbauer.
A stable, continuous wave, single frequency fiber amplifier system at 1015 nm with 10W output power is presented. It is based on a large mode double clad fiber cooled to liquid nitrogen temperature. The amplified light is frequency quadrupled to 254 nm and used for spectroscopy of the 6^1S - 6^3P transition in mercury.
We demonstrate a reliable continuous-wave (cw) laser source at the 1\,$S$--2\,$P$ transition in (anti)hydrogen at 121.56\,nm (Lyman-$α$) based on four-wave sum-frequency mixing in mercury. A two-photon resonance in the four-wave mixing scheme is essential for a powerful cw Lyman-$α$ source and is well investigated.
We have measured the AC-Stark shift of the $14D_{5/2}$ Rydberg state of rubidium 87 in an optical dipole trap formed by a focussed CO$_2$-laser. We find good quantitative agreement with the model of a free electron experiencing a ponderomotive potential in the light field. In order to reproduce the observed spectra we take into account the broadening of the Rydberg state due to photoionization. The extracted cross-section is compatible with previous measurements on neighboring Rydberg states.
Cooling antihydrogen atoms is important for future experiments both to test the fundamental CPT symmetry by high-resolution laser spectroscopy and also to measure the gravitational acceleration of antimatter. Laser-cooling of antihydrogen can be done on the strong 1S-2P transition at the wavelength of Lyman-alpha (121.6nm). A continuous-wave laser at the Lyman-alpha wavelength based on solid-state fundamental lasers is described. By using a two-photon and a near one photon resonance a scan across the whole phasematching curve of the four-wave mixing process is possible. Furthermore the influence of the beam profile of one fundamental beam on the four-wave mixing process is studied.