Laser‐Induced Plasmonic Nanostructures for Optical Storage and Encryption in Disordered Crystals

Abstract Heterostructured nanointerfaces composed of ordered nanoparticles integrated with non‐plasmonic functional materials offer broad application potential but remain limited by the lack of flexible and scalable fabrication techniques. This study presents a two‐step top‐down approach for constructing plasmonic architectures in neodymium‐doped disordered crystals, enabling optical data inscription and encryption. Ion implantation is used to introduce nanoparticle precursors into the subsurface region of the crystal. Then, femtosecond laser‐induced nonlinear near‐field optical forces drive the redistribution of nanoparticles along the laser propagation path, facilitating the formation of ordered 3D nanoshell structures. By precisely tuning the laser irradiation power, the resonance modes of the hybrid system are modulated, allowing for controlled upconversion luminescence in rare‐earth‐ion‐based plasmonic structures. The proposed method supports multifunctional optical applications, including data storage, encryption, and fluorescence/photoluminescence readout. This work establishes a general strategy for tailoring plasmon‐enhanced optical responses in rare‐earth‐doped crystalline materials and can be used for opto‐electronic and passive/active optical control.