Adiabatic Following in Two-Photon Transition

Abstract

Renewed interest has been generated recently in coherent multiphoton transitions in many-level systems [1–5]. Coherent two-photon propagations, exhibiting self-induced transparency when twice the propagating frequency is resonant with a two-level system, have been analyzed [1,2], and the one- and two-photon resonant fields were shown to obey together an area theorem [2]. Tan-no et al. [3] reported the observation of coherent propagations based on a two-photon transition which involved the interaction of two optical pulses of different frequencies with a gaseous three-level system. Further, self-transparency in a resonant two-photon absorption with a two-level system was observed [4]. In this work, we consider the effect of relaxation on the response of a three-level system to a smoothly varying, near resonant, two-photon field.