Stuttgart 2012 – wissenschaftliches Programm
Q 3.6: Vortrag
Montag, 12. März 2012, 11:45–12:00, V47.02
Comparison of reference cavities for an optical clock with improved short-term stability — •Jonas Keller1, Stepan Ignatovich2, Maksim Okhapkin1,2, Stephen Webster3, David-M. Meier1, Karsten Pyka1, and Tanja E. Mehlstäubler1 — 1Physikalisch-Technische Bundesanstalt, 38116 Braunschweig — 2Institute of Laser Physics, 630090 Novosibirsk — 3National Physical Laboratory, Hampton Road, Teddington
Our work is targeted on the development of an optical frequency standard with a relative short term stability below 10−15 in 1s based on Coulomb crystals of 115In+ and 172Yb+ ions in a linear segmented Paul trap. This requires two highly stable lasers for interrogating the 1S0↔3P0 clock transition in 115In+ and the 2S1/2↔2D5/2 transition in 172Yb+ for studying and controlling the dynamics of the ion crystals. To achieve these stabilities, we are experimentally comparing two different designs for reference cavities with ULE® spacers and fused silica mirrors. A simple setup using a horizontally mounted cavity of 12 cm length yielded a thermal time constant of 44 h and allowed the stabilization of a diode laser to a relative frequency instability of 6·10−16. The second cavity has a length of 30 cm, giving a thermal noise limit of 1·10−16. Its spacer design is based on FEM calculations to ensure a sufficiently low vibration sensitivity. In order to refine this experimentally, the support points can be moved freely along the optical axis. For this adjustment, the short cavity can act as a reference.