The slowly varying envelope approximation in non-linear optics

Of the various simplifying assumptions made for analysing non-linear interactions in waveguides one of the most important, and frequently used is the slowly varying envelope approximation (SVEA). The authors investigate the method and discover that it is not necessary to invoke this approximate technique at all, and that an exact analysis is actually simpler and more straightforward, and reveals in a very clear way the circumstances under which the SVEA can be used