Laser cooling of barium monofluoride molecules using synthesized optical spectra

We will report on the laser cooling of barium monofluoride molecules. Due to its high mass, a comparably narrow linewidth and resolved hyperfine structure of the excited state, as well as potential branching losses through an intermediate electronic state this molecular species is notoriously difficult to cool. We use serrodynes to synthesize time-sequenced optical spectra that can be precisely tailored to the hyperfine structure of this species. By optimizing these spectra, we realize strong Sisyphus laser cooling forces that can efficiently collimate a molecular beam. Our approach is an important step towards using intense beams of barium monofluoride for precision measurement applications, and will also be useful for cooling other molecular species with complex level structure.