title: Nonlinear dispersion of avalanche upconversion.
abstract: Two-beam coupling measurements of an avalanche upconversion transition in concentrated Tm:LiYF (4) confirm that, despite the resonant nature of the excited-state optical interaction, the induced response is strongly dispersive. This surprising characteristic is shown to be a general feature of avalanche polarization, with an off-resonant process dominating the resonant response.
authors.forename: Q
authors.initials: Q
authors.lastname: Shu
authors.forename: H
authors.initials: H
authors.lastname: Ni
authors.forename: S C
authors.initials: SC
authors.lastname: Rand