Fig. 4: Stimulated FWM comb upconversion.
From: Ultrabroadband milliwatt-level resonant frequency doubling on a chip
A Schematic of the stimulated FWM comb generation. The south loop is fed with a bichromatic pump created by mixing and amplifying two tunable sources spaced at a multiple of the FSR. The resonantly enhanced χ(3) interaction in the south resonator produces an incoherent comb through cascaded FWM. The comb is then frequency doubled in the interaction region, where it participates to AOP and related SHG and SFG, and finally output from the north resonator coupler. B Generated comb (spacing: 2 FSR) for varying resonance detuning configurations. When red-detuning the north ring resonances from the optimal condition, the entire SHG comb power is gradually decreased. The shaded area in the top graphs represents the squared FH comb envelope (shaded trace in the bottom graphs) rescaled to the maximum of the generated SH, for comparison.
