Broadband Resonance-Enhanced Frequency Generation by Four-Wave Mixing in a Silicon Floquet Topological Photonic Insulator

Floquet topological photonic insulators, whose light transport properties are dictated by the periodic drive sequence of the lattice, provide more flexibility for controlling and trapping light than undriven topological insulators, which can enable novel nonlinear optics applications in topological photonics. Here, we employ a novel resonance effect called Floquet Defect Mode Resonance in a 2D silicon Floquet microring lattice to demonstrate resonance-enhanced frequency generation by four-wave mixing of Floquet bulk modes in the presence of Kerr nonlinearity. The compact, cavity-less resonance mode, induced through a periodic perturbation of the lattice drive sequence, has the largest reported Q-factor for a topological resonator of ~10^5 with low group velocity dispersion, which enables efficient broadband frequency generation over several Floquet-Brillouin zones of the Floquet topological insulator. We achieved wavelength conversion over 10.1 nm spectral range with an average enhancement of 12.5 dB in the conversion efficiency due to the Floquet Defect Mode Resonance. Our work could lead to robust light sources generated directly on a topologically-protected photonic platform.