ROTATIONAL LINE STRENGTHS IN DEGENERATE 4-WAVE-MIXING

In this paper we present a derivation of the rotational line strengths involved in fully resonant degenerate four wave mixing processes (DFW M). General expressions are gi ven for diatomic molecules with differe nt Hund's coupling cases. More precisely, we tabulated the rotational line strengths for the electronic transition 2SIGMA+-2PI of OH and NO. For the ground state, Hund's cases (b), (a) and the intermediate case (a-b) are considered. We also stress the dependence of the line stren gths with respect to the geometry and to the polarization of the incid ent beams. So, we consider the optical phase conjugation (OPC) geometr y and the forward (FDFWM) one. We also give expressions for the line s trengths in different polarization arrangements, i.e. parallel or cros sed polarized beams. A comparison is made between these cases. Finally , theoretical simulations, using our line strengths calculations, are compared with experimental spectra of OH obtained in a methane air fla me using OPC and FDFWM.