despite my best efforts, may contain occasional mistakes. Please contact me if you have any comments, corrections or queries.* ]{}

\[\*\] I worked at this institution while doing the bulk of this calculation. My main project was with Jon Marangos & Prof. GHC New on ultrabroadband multifrequency Raman generation, and I was funded with money from the EPSRC.

 

WWW: QOLS Group <http://www.qols.ph.ic.ac.uk/>\
WWW: Physics Dept. <http://www.ph.ic.ac.uk/>\
WWW: Imperial College <http://www.ic.ac.uk/>\
Email: Paul Kinsler <Dr.Paul.Kinsler@physics.org>\
Email: G.H.C. New <g.new@ic.ac.uk>

Introduction {#s-intro}
============

An important aim of current wideband Raman experiments is to try to efficiently generate few-cycle pulses [@Harris-S-1998prl; @Sokolov-WYYH-2001prl; @Hakuta-SKL-2000prl; @Sali-MTHM-2004ol]. If driven strongly enough, the two-photon Raman transition modulates the incoming field by adding sidebands separated by the transition frequency. Wideband fields are generated as these sidebands generate sidebands of their own (and so on), thus generating a wide comb of frequency components separated by the transition frequency. If a scheme can be implemented that adjusts the phases of each component appropriately, then few- or single- cycle optical pulses can be obtained (see e.g. [@Sokolov-WYYH-2001prl]). Standard theoretical treatments of this process split the field into fields components centred on the teeth of this comb. The approach has the advantage 