Influence of phase coherence on seeded supercontinuum generation

The noise properties of supercontinuum (SC) generation have attracted a lot of attention due to a large application demand for low noise SC sources and in the more fundamental context of clarifying links with instabilities in other systems. In typical commercial SC sources the pulse break-up is initiated by noise-driven modulational instability (MI). The resulting large spectral shot-to-shot fluctuations can be significantly reduced by modulating the pump with a phase coherent seed, which leads to a coherent pulse break-up through the amplification of a cascade of four-wave mixing (FWM) side-bands. The paper demonstrates that the noise properties of the generated SC are highly sensitive to the degree of phase noise of the seed and that a nearly coherent seed pulse is needed to achieve a coherent pulse break-up and low noise SC. This limits the mechanisms that can be used to generate the seed, which is important in designing next-generation low-noise SC sources.