Towards coherent supercontinuum generation in the long pulse regime

In this paper, we use physical arguments and numerical simulations to examine in detail the degree to which stability of the output SC spectra can be modified through a suitable input pulse modulation. Our major result is that by imposing a suitable modulation it is possible to generate a near-octave spanning frequency comb with high stability and coherence using pulses with tens of picosecond duration. Under these conditions, the SC broadening is dominated by the dynamics of these ultrashort sub-pulses, with only a minor contribution from the background envelope and therefore we consider only the central sub-pulse with corresponding soliton order that can be readily estimated form the input pulse parameters and applied modulation characteristics. Although these results are based on the central sub-pulse parameters, of course neighboring sub-pulses would be expected to themselves induce similar coherent SC generation, with their presence manifested in the overall output spectrum in the form of spectral channeling at the frequency.