title: Subkilohertz linewidths measured by heterodyne-detected coherent population trapping in sodium vapor.
abstract: Subkilohertz spectroscopy by coherent population trapping (CPT) has been performed in Na atomic vapor. The system employs a frequency-swept acousto-optic modulator for bichromatic excitation as well as a heterodyne-lock-in detection technique that permits the direct measurement of the CPT dispersion curves at a good signal-to-noise ratio. A CPT linewidth of -400 Hz was measured as well as a steep refractive-index dispersion of as much as 3.3 x 10(-10) Hz(-1), corresponding to a group velocity of 1800 m/s.
authors.affiliation: Department of Physics, Faculty of Science, Kumamoto University, 2-39-1 Kurokami, Kumamoto-shi, Kumamoto 860-8555, Japan.
authors.forename: Koji
authors.initials: K
authors.lastname: Motomura
authors.forename: Takanori
authors.initials: T
authors.lastname: Koshimizu
authors.forename: Ken-ichi
authors.initials: K
authors.lastname: Harada
authors.forename: Hirotaka
authors.initials: H
authors.lastname: Ueno
authors.forename: Masaharu
authors.initials: M
authors.lastname: Mitsunaga