Thermo‐Optical Sub‐Micrometer Ultrahigh Luminescence Emission Tuning in Hybrid Organic–Inorganic Upconversion Nanocomposites for Data Storage and Anticounterfeiting

Abstract Nanophotonics techniques, driven by optical microscopy, enable high‐capacity data recording and readout, yet ensuring data security demands versatile, multi‐stimuli activatable media. Lanthanide ion‐doped upconversion nanoparticles hold promise for these applications by fine‐tuning upconversion luminescence emission. While chemical methods customize this emission with meticulous adjustments, optical methods face challenges such as high laser beam intensities, setup complexity, and wavelength limitations. Efficiently modulating upconversion luminescence emission requires multi‐stimuli methods or integrating upconversion nanoparticles with responsive materials. Here, dual‐stimulus thermo‐optical activation and optical microscopy are used to achieve sub‐micrometer ultrahigh upconversion luminescence emission tuning in newly developed hybrid organic–inorganic upconversion nanocomposites for high‐capacity and secure data storage and anticounterfeiting. Thermal stimulus (activation I) facilitates a 102‐fold increase in absorption, promoting the formation of an inorganic network and complex. Optical stimulus via focused 460‐nm femtosecond laser beam irradiation (activation II) enhances absorption by fivefold through sub‐micrometer photo‐polymerization bit recording. The method achieves a 92% decrease of 450‐nm upconversion luminescence emission intensity after activation I and over 90% quenching of this emission after activation II, enabling sub‐micrometer bit readout under 980‐nm continuous‐wave excitation laser beam irradiation. This work demonstrates the potential for high‐capacity and secure data storage, anticounterfeiting, high‐security encryption, and high‐resolution display.