The formation of ultrashort pulses using a spectral filtration technique in the presence of stimulated combination scattering in fiber light guides

The generation of ultrashort (60 ps) light pulses due to stimulated combination scattering in quartz-fiber light guides has been investigated, experimentally. The laser pumping source was a garnet neodymium laser emitting light at a wavelength of 1.064 microns. The nonlinear dynamics of the formation of the pulses were studied numerically and the results are discussed. The physical mechanism for the generation of the pulses is identified and consists in the combined effects of nonlinear combination frequency transformation; self-phase modulation; and dispersion of the group velocities of the channeled light guide pulses. The scanning dynamics of the pumping pulses frequency, upon excitation of the stimulated combination scattering in single-mode light guides, was also investigated. It is demonstrated that the mechanism for the generation of the intense light continuum is stimulated combination scattering is universal, i.e., it arises irrespective of the initial amplitude-phase structure of the pulses.