Localized frequency comb and formation of embedded solitons in silicon-based slot waveguides

We explore the possibility to excite the so-called embedded solitons in specially designed slot waveguides based on silicon and silica or silicon nanocrystals. This requires the excitation of the structure with quasi-TM polarized pulses -- for which Raman effect is absent -- and at a specific infrared wavelength for which only the second- and fourth-order group velocity coefficients are non-vanishing. Pulses launched in these conditions will generate a spectrally localized continuum, associated to a frequency comb coming from the spectral interference of many embedded solitons.