Pulse compression and amplification by stimulated Raman scattering in a nonlinear periodic structure

Summary form only given, as follows. It has been predicted theoretically and demonstrated experimentally that the large negative group velocity dispersion and the intensity-dependent refractive index associated with nonlinear periodic structures can enable pulse compression and the propagation of novel solitons. We show that the grating feedback also makes it possible to generate intense ultrashort pulses through backward stimulated Raman scattering. Here an intense pump pulse at a wavelength far detuned from the Bragg resonance can amplify and compress a weak Stokes-shifted signal whose wavelength is in the vicinity of the grating stop band. Once the backward stimulated Raman pulse begins to grow, its temporal behavior is known to be quite different from that of the forward scattering component. This is because a backward traveling pulse continuously encounters undepleted pump light, and its leading edge can be amplified to values in excess of the pump intensity, thus resulting in pulse steepening. In addition, if the Stokes wavelength lies in a region of negative grating dispersion, the cross-phase modulation due to the pump can interact with this dispersion to further compress the pulse. Raman Bragg solitons can also be created through this mechanism. We have simulated the process of stimulated Raman scattering in a nonlinear fiber Bragg grating by solving the time-dependent coupled mode equations.