Spin coherence excitation and rephasing with optically shelved atoms

We investigate the use of resonant optical Raman pulses to excite and rephase ground state spin coherences via the partial storage or shelving of atoms. Unlike direct-rf-excited spin echoes or off-resonant Raman echoes, the resonant Raman optical field efficiently excites and rephases the spin coherence using π and 2π pulses, respectively. In a crystal of (Formula presented) doped (Formula presented) we experimentally observe spin echo efficiency as high as 46% of the free induction decay signal.