Femtosecond laser melting upconversion nanoparticles for sub-micrometer optical patterning

This study introduces a method for precise modulation of upconversion luminescence (UCL) in UCNP thin films via laser-induced melting, enabling high-resolution, sub-micrometer optical patterning. By employing a 460-nm femtosecond (fs) laser, localized melting disrupts the UCNP crystalline lattice, facilitating tunable UCL quenching with efficiencies exceeding 90%. This approach relies solely on the intrinsic properties of UCNPs, avoiding the need for composite materials or complex multi-stimulus systems. The technique provides precise control of UCL modulation, making it suitable for sub-micrometer-scale optical patterning.