Wideband pulse propagation: single-field and multi-field
approaches to Raman interactions

P. Kinsler, G.H.C. New

    Department of Physics, 
    Imperial College London,
    Prince Consort Road,
    London SW7 2BW, 
    United Kingdom.

    Phys.Rev.A72, 033804 (2005). 

    We present a model of two-colour laser fields interacting 
with a Raman transition in the kind of scheme currently used 
to generate the ultra broadband light fields needed to create
ultrashort pulses.  In contrast to the usual approach using
separate field envelopes for the pump, Stokes, and anti-Stokes
spectral lines, we use a {\em single} field envelope.  This
requires the inclusion of few-cycle corrections to the pulse
propagation.  Our single-field model makes fewer approximations
and is mathematically (and hence computationally) simpler,
although it does require greater computational resources to
implement.  The single-field theory reduces to the traditional
multi-field one using appropriate approximations.