Optical pumping of thulium ground-state sublevels

V. G. Domelunksen, I. V. Zhurkin, A. Yu. Nikolaev +1 more

H. Liening

E.S. Fedorova, Artem A. Golovizin, Dmitry O. Tregubov +5 more

Because of the low sensitivity of a thulium optical clock to black-body radiation and good accuracy and stability estimations, it is considered as a promising transportable optical clock. One of the leading systematic effects for Tm clock transition, i.e., the second-order Zeeman effect, can be canceled by probing two clock transitions between different hyperfine levels of ground and metastable states during clock operation. Herein, we demonstrate efficient optical pumping into the ${m}_{F}=0$ state of both ground hyperfine levels using single-frequency radiation at 418.8 nm. We prepared the atoms in both target states simultaneously and excited two clock transitions alternately. The resulting population of ${m}_{F}=0$ states of ground hyperfine levels was 36% and 3.8% of the initial number of atoms with less than 4% and 0.4% on nonzero magnetic sublevels, respectively. We performed numerical simulations of the optical pumping process, which is able to explain experimental results well.

J. Brossel

Anne Louchet-Chauvet, Romain Lauro, Philippe Goldner +3 more

Thulium-doped crystals are considered for programmable filtering. Such a filter can be achieved by Spectral Hole Burning (SHB). One optically pumps the active ions into a long-lived shelving state, opening a narrow transparency window in the crystal absorption band. We investigate a new shelving scheme in Tm:YAG where the thulium ions are pumped into a ground state nuclear Zeeman sublevel, instead of their natural 10ms-lifetime metastable state. The shelving time is increased to several seconds, reducing the residual population in the transparency window by orders of magnitude. This should enhance the filter's dynamic range, which is essential in demanding filtering applications like ultrasound optical tomography.

J. C. White, Jeffrey Bokor A, Don O. Henderson

A thulium vapor column is irradiated with the fourth harmonic of a Nd:YAG laser at 266 nm. The near coincidence with a dipole allowed transition from ground state results in efficient optical pumping yielding 87 simultaneous superfluorescent laser transitions from 300 to 900 nm. Many of the emissions are due to inversions to the ground state of both neutral and singly ionized Tm atoms.