title: Extra resonances in degenerate four-wave mixing triggered by pressure-induced decay of the lower state.
abstract: By using the Schenzle-Brewer model, in which the ground state of a two-level system also has a finite lifetime, it is shown that two pressure-induced extraresonant degenerate four-wave mixing signals are obtained. The first extra resonance is similar to that predicted and observed by Bogdan et al. [Opt. Lett. 6, 82, 348 (1981)]. It is characterized by a linewidth equal to the inverse lifetime of the upper state and appears only in the presence of collisional redistribution. The second extra resonance is characterized by a linewidth equal to the inverse lifetime of the ground state and does not depend on collisional redistribution for its appearance.
authors.forename: A D
authors.initials: AD
authors.lastname: Wilson-Gordon
authors.forename: H
authors.initials: H
authors.lastname: Friedmann