Surface photosensitization enabled by embedded plasmonic nanoparticles in ferroelectric crystals for laser-induced periodic surface structures

Dielectric crystals, despite their rich optical properties and great potential in integrated optoelectronics, had generally fallen behind the competing photonic platforms, mainly due to the significant difficulties of material processing. By combining the unique capabilities of ion implantation in photosensitization and femtosecond laser direct writing (FsLDW) in nanostructuring, in this study, we propose an innovative methodology harnessing the high energy of focused femtosecond laser and the localized surface plasmon resonance (LSPR) of embedded metal nanoparticles (NPs). Such a combination leverages the ion-implantation-induced lattice damage as well as the LSPR-induced enhanced near-field enhancement and photothermal effects to relax the parameter threshold for laser-induced periodic surface structure formation in LiTaO3. To investigate the origin of such a "threshold lowering" phenomenon, ion-implantation-induced softened phonon modes and lattice distortion as well as FsLDW-induced self-assembly of NPs and ferroelectric domain inversion are both analyzed, and the synergistic action of these effects is found to be the key factor. Since both ion implantation and FsLDW feature a wide range material applicability and parameter flexibility, our work is an approach of surface multifunctionalization and nanostructuring of dielectric crystal families.