3. Physics of supercontinuum formation

The physical mechanisms responsible for the spectral broadening observed in supercontinua depend on the duration of the pump lasers used. Indeed, we shall see that we can distinguish two main pumping regimes: supercontinua generated with pulses of a few tens of femtoseconds and those generated from pulses of at least a few hundreds of femtoseconds. These are referred to as short pulses and quasi-continuous pulses respectively. In both cases, the result is a train of solitonic pulses that will shift towards longer wavelengths via stimulated Raman scattering, and emit energy towards shorter wavelengths by generating so-called trapped dispersive waves.

In the first section, we'll focus on the mechanisms responsible for the formation of a train of solitonic pulses from quasi-continuous pump pulses, then from short pump pulses. The mechanisms responsible for broadening...