Optical pumping by a laser pulse traveling in a cavity

We have developed a general method to perform optical pumping by a pulsed laser with the aid of an optical cavity (cavity-assisted optical pumping). Optical pumping is achieved by repetitive interaction of a single laser pulse with a target material in the cavity. This method is demonstrated for manganese ions, Mn⁺, stored in a linear radio-frequency ion trap; about 10⁸ ions are spin polarized by a 5-ns laser pulse via ⁷PJ←⁷S₃ ($J=3$ or 4) transition in the ultraviolet region. The linewidth of the pulsed light source is broad enough to transfer the populations of lower hyperfine levels to the highest one $(F=11/2)$ in the ⁷S₃ ground state; the nuclear spin is polarized as well.