Nonlinear Moire Superlattice for Super-Resolution Nondestructive Detection of Nonlinear Photonic Crystals

The moire effect is a universal phenomenon originating from the interference of waves, and it is widely applied in metrology as well as superconductor phenomena in graphene. The present study demonstrates a nonlinear moire effect originating from the moire superlattices of two nonlinear photonic crystals (NPCs). It is experimentally shown that these nonlinear moire superlattices facilitate the nondestructive detection of nonlinear photonic crystals. Two identical periodically poled lithium niobates (PPLNs) are used to observe the nonlinear moire effect originating from the nonlinear moire superlattices. This is followed by a demonstration of the detection capability of the nonlinear optical method for dissimilar PPLNs and calculation of the period detection range. The theoretically and experimentally obtained periods of the target PPLN are consistent, and the resolution of the nonlinear moire effect surpasses to that of presently used optical systems. Furthermore, the detection range of the nonlinear moire effect enables the sub-micrometer- and nanometer-scale detection of the nonlinear photonic crystal structure using only an optical microscope. The present study conceptually extends the conventional moire lattice to nonlinear optics, and it can also be extended to other fields where nonlinear effects cannot be avoided, such as polaritons and Bose-Einstein condensates.

Automated summary

This study demonstrates a nonlinear moire effect originating from the moire superlattices of two nonlinear photonic crystals, enabling nondestructive detection with high resolution and period detection range. The detection range of the nonlinear moire effect allows sub-micrometer- and nanometer-scale detection of the nonlinear photonic crystal structure using only an optical microscope. The concept of extending the conventional moire lattice to nonlinear optics can be applied to other fields where nonlinear effects are present.