摘要
We report on studies of an optical lattice for a strontium clock performed at the National Time Service Center. Follow-ing tw o-stage laser cooling and trapping,88 Sr cold atoms w ith population of 105 and a longitudinal temperature of 8. 4 μK are loaded into a one-dimensional optical lattice. Spectroscopic analysis of the1S0-3P0 transition gives a linew idth of 180 Hz measured using magnetic field-induction,w hich mixes the3P1 state w ith the3P0 state. Rabi oscillations are observed. Because of the inhomogeneous excitation among the atoms,the Rabi π-pulse excitation at 5 ms show s a near 65% excitation of atoms. The transverse velocity distribution of the atomic beam and the absolute frequencies of the four inter-combination transitions of the isotopes w as measured precisely using velocity-selective fluorescence spectroscopy. By optical injection of tw o cascade external-cavity diode lasers,a single comb line at 689 nm from an optical femtosecond laser comb is filtered and amplified w ith a 37-d B side-mode suppression and a linew idth of less than 240 Hz. We describe recent w ork on a space optical clock concerning the physical vacuum system,thermal analysis,and a permanent-magnet Zeeman slow er for a space strontium optical clock. The first six mode frequencies are obtained and the corresponding oscillation modes are described in detail. We also simulate and analyze thermal profiles for both the physical and optical units installed in the cooling system. When the injected cooling w ater has a temperature of 21℃ or28℃,the units meet operational requirements for temperatures in a space environment. Using a series of permanent magnets,a Zeeman slow er is built that can w ithstand space launching and operating conditions for the space optical clock.
We report on studies of an optical lattice for a strontium clock performed at the National Time Service Center. Follow-ing tw o-stage laser cooling and trapping,88 Sr cold atoms w ith population of 105 and a longitudinal temperature of 8. 4 μK are loaded into a one-dimensional optical lattice. Spectroscopic analysis of the1S0-3P0 transition gives a linew idth of 180 Hz measured using magnetic field-induction,w hich mixes the3P1 state w ith the3P0 state. Rabi oscillations are observed. Because of the inhomogeneous excitation among the atoms,the Rabi π-pulse excitation at 5 ms show s a near 65% excitation of atoms. The transverse velocity distribution of the atomic beam and the absolute frequencies of the four inter-combination transitions of the isotopes w as measured precisely using velocity-selective fluorescence spectroscopy. By optical injection of tw o cascade external-cavity diode lasers,a single comb line at 689 nm from an optical femtosecond laser comb is filtered and amplified w ith a 37-d B side-mode suppression and a linew idth of less than 240 Hz. We describe recent w ork on a space optical clock concerning the physical vacuum system,thermal analysis,and a permanent-magnet Zeeman slow er for a space strontium optical clock. The first six mode frequencies are obtained and the corresponding oscillation modes are described in detail. We also simulate and analyze thermal profiles for both the physical and optical units installed in the cooling system. When the injected cooling w ater has a temperature of 21℃ or28℃,the units meet operational requirements for temperatures in a space environment. Using a series of permanent magnets,a Zeeman slow er is built that can w ithstand space launching and operating conditions for the space optical clock.
