deletions | additions       diff --git a/section_Four_wave_mixing_Bragg__.tex b/section_Four_wave_mixing_Bragg__.tex  index 29c650b..fdf635d 100644  --- a/section_Four_wave_mixing_Bragg__.tex  +++ b/section_Four_wave_mixing_Bragg__.tex 
...
In the approximation $\Delta\Omega \gg \Delta\omega \gg \epsilon$ we obtain a simpler expression for the process momentum conservation  $$ \kappa(\epsilon) L \simeq \beta^{(3)} \Delta\omega \Delta\Omega \epsilon + \beta^{(4)}/24 (8\Delta\omega\Delta\Omega^3) = (\epsilon + \Delta\Omega)/\delta\omega_{bs}$$  in which we can identify the process acceptance-bandwidth $\delta\omega_{bs}$, and the frequency separation from symmetric point $\delta\epsilon = \frac{\beta^{(4)}}{3 \beta^{(3)}} \Delta\Omega^2$ due to higher-order dispersion \cite{Provo_2010}.  One prominent feature of FWM-BS, already noticed in \cite{Inoue_1994, Marhic_1996} is highlighted by equation \ref{eq:ph}, that is translation for any given pair of signal and idler frequency can be exactly phasematched by choosing the appropriate pumps: this gives the flexibility of tuning the parameters of the interaction withoutthe  modifying thedispersion of the  nonlinear medium. medium dispersion.