Comment on the relationship between an exact two-photon solution and a two-photon vector model

The exact pulse solution of Brewer and Hahn for optical two-photon transitions is shown to reduce in the adiabatic limit to the two-photon vector model used by Grischkowsky, Loy, and Liao. The connection between the two approaches is explained and the complementary relationship between the two papers is discussed. © 1977 The American Physical Society.