Optical pumping

The technique was developed by the 1966 Nobel Prize winner Alfred Kastler in the early 1950s.

For the simplest case of coherent two-level optical pumping of an atomic species containing a single outer-shell electron, this means that the electron is coherently pumped to a single hyperfine sublevel (labeled

), which is defined by the polarization of the pump laser along with the quantum selection rules.

In practice, completely coherent optical pumping may not occur due to power-broadening of the linewidth of a transition and undesirable effects such as hyperfine structure trapping and radiation trapping.

[3] An optical pumping experiment is commonly found in physics undergraduate laboratories, using rubidium gas isotopes and displaying the ability of radiofrequency (MHz) electromagnetic radiation to effectively pump and unpump these isotopes.