A high-stability semiconductor laser system for a 88Sr-based optical lattice clock
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- Tarallo, M.G., Poli, N., Schioppo, M. et al. Appl. Phys. B (2011) 103: 17. doi:10.1007/s00340-010-4232-2
We describe a frequency-stabilized diode laser at 698 nm used for high-resolution spectroscopy of the 1S0–3P0 strontium clock transition. For the laser stabilization we use state-of-the-art symmetrically suspended optical cavities optimized for very low thermal noise at room temperature. Two-stage frequency stabilization to high-finesse optical cavities results in measured laser frequency noise about a factor of three above the cavity thermal noise between 2 Hz and 11 Hz. With this system, we demonstrate high-resolution remote spectroscopy on the 88Sr clock transition by transferring the laser output over a phase noise-compensated 200-m-long fiber link between two separated laboratories. Our dedicated fiber link ensures a transfer of the optical carrier with frequency stability of 7×10−18 after 100 s integration time, which could enable the observation of the strontium clock transition with an atomic Q of 1014. Furthermore, with an eye toward the development of transportable optical clocks, we investigate how the complete laser system (laser+optics+cavity) can be influenced by environmental disturbances in terms of both short- and long-term frequency stability.