Abstract

Ionic Ytterbium (Yb⁺) is one candidate for future microwave and optical-frequency stand ards based on trapped, laser cooled ions. Recently, a novel optical-excitation scheme for laser cooling of Yb⁺ has been demonstrated^[1] which permits large technical simplifications with respect to earlier solutions.^[2] The scheme makes use of the specific rare-earth energy level structure of Yb⁺: The metastable 4f¹⁴5d ²D_3/2 level, to which ions decay upon excitation of the ²S_1/2 - ² p _1/2 resonance transition, is coupled to a rapidly decaying fourth energy level by a transition at λ = 935 nm that is allowed by configuration mixing (see Fig. 1). With optical power densities of a few mW-mm^–2 at λ = 935 nm, depletion of the ²D_3/2 level is sufficiently rapid to obtain the large fluorescence scattering rates required for laser cooling of ions in Paul traps.^[1]

© 1992 IQEC