Four-wave mixing instabilities in tapered and photonic crystal fibers
  We present an analytical study of four-wave mixing instabilities in tapered fibers and photonic crystal fibers. Our approach avoids the use of Taylor expansion for the linear susceptibility and the slowly-varying envelope approximation. This allows us to describe the generation of sidebands strongly detuned from the pump wave with simultaneous account for the entire dispersion characteristic of a fiber, which is found to be important for describing properly the key role of the parametric instabilities in the supercontinuum generation in these kind of fibers. 
Fabio Biancalana, Dmitry V. Skryabin, Arturo Ortigosa-Blanch