We have developed a framework for investigating the effects of level degeneracies on rotational Raman scattering. The density matrix equations describing the response of the medium are described within the multipole expansion formalism. The advantages of this technique over the conventional |jM〉 representation are (1) correct and straightforward incorporation of collisional widths, (2) transparent description of polarization effects, and (3) the reduction of a full set of equations to a conventional two-level nondegenerate system which still has the effects of polarization. Our formalism allows a general treatment of saturation effects, pump depletion, ac Stark shifts, arbitrary polarization, transient response, coupling of multiple Stokes, and anti-Stokes orders.

© 1989 Optical Society of America

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