  We model the process of ultra broadband light generation in which a pair of
laser pulses separated by the Raman frequency drive a Raman transition. In
contrast to the usual approach using separate field envelopes for the different
frequency components, we treat the field as a single entity. 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.
