Localization-to-delocalization transition of light in frequency-tuned photonic moire lattices

We demonstrate in a numerical manner the intriguing localization-to-delocalization transition of light in frequency-tuned photonic moire lattices, both in the zero-order and the higher-order regimes of light waves. We present a different technique to realize the composite photonic lattices, by means of two relatively twisted sublattices with different modulated lattice constants. Even though various kinds of photonic patterns including the commensurable and the incommensurable lattices can be well constructed, the observed transition between the localization and the delocalization of light field is moire angle-independent. This angle-insensitive property was not reported before, and cannot be achieved by those photonic moire lattices that are all moire angle-dependent. We reveal that the obtained phase transition of light is robust to the changes of refractive index modulation of the photonic lattices. Moreover, we reveal that the effect of moire angle-independent transition of light can be extended to the higher-order vortex light field, hence allowing prediction, for the first time to our knowledge, of both the localization and the delocalization of the vortex light field in the photonic lattices. (C) 2021 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

Automated summary

We demonstrate the localization-to-delocalization transition of light in frequency-tuned photonic moire lattices, achieved by realizing composite photonic lattices with two twisted sublattices. The observed transition between localization and delocalization of light field is moire angle-independent. This angle-insensitive property can be extended to higher-order vortex light field in photonic lattices, allowing prediction of both localization and delocalization.