title: Sub-Doppler bandwidth atomic optical filter.
abstract: We demonstrate what is to our knowledge the first atomic optical filter that uses velocity selection to achieve a passband width that is less than the Doppler width of the filtering transition. A narrow-linewidth pump laser is used to induce circular birefringence in a narrow velocity class of atoms in a dense potassium vapor for 694-nm light resonant with the 4P(3/2)-6S(1/2) transition. The filter displays a single 170-MHz passband at a peak transmittance of 9.5%. The bandwidth is an order of magnitude lower than that of previously demonstrated atomic optical filters.
authors.forename: L D
authors.initials: LD
authors.lastname: Turner
authors.forename: V
authors.initials: V
authors.lastname: Karaganov
authors.forename: P J O
authors.initials: PJ
authors.lastname: Teubner
authors.forename: R E
authors.initials: RE
authors.lastname: Scholten