Physical Review A
Sub-Doppler and subnatural narrowing of an absorption line induced by interacting dark resonances in a tripod system
Chana Goren, A. D. Wilson‐Gordon, M. Rosenbluh, Harry Friedmann
Abstract
A method is presented for obtaining sub-Doppler and subnatural narrowing and increased absorption of a spectral line. The ultranarrow spectral line is confined between two closely spaced electromagnetically induced transparency windows in a nearly degenerate tripod atomic system formed by an ${F}_{g}=1\ensuremath{\rightarrow}{F}_{e}=0$ transition, split by a magnetic field. The system is driven by a $\ensuremath{\sigma}$-polarized pump and probed by a tunable $\ensuremath{\pi}$-polarized laser. It can be used to measure small magnetic fields and also as a magneto-optic switch.