Frequency up-conversion of photonic moiré lattices via second-harmonic generation

We theoretically and numerically investigate the second harmonic generation (SHG) process of two-dimensional photonic moiré lattices. Using a type-II phase-matched nonlinear interaction, we experimentally demonstrate that the spatial modulation characteristic of the moiré lattice remains robustly preserved through the SHG process, yielding second-harmonic fields at 532 nm that faithfully reproduce the lattice structures formed at the fundamental wavelength of 1064 nm. Experimentally, we realize second-harmonic generation of photonic moiré lattices that reach moiré periods of ∼50 μm, while the image fidelity between the fundamental and SHG patterns remains in the range 0.86-0.93. Our findings highlight the capability of photonic moiré lattices to serve as a tunable and robust platform for nonlinear optical processes, offering stable and controllable structured light sources with significant implications for high-capacity optical communication, adaptive photonics, and reconfigurable optical systems.