An Optical Multiplexing Method Using Upconversion Nanoparticles with Tunable P–I Relationship

Abstract Optical multiplexing is of great value in information acquisition due to its excellent signal encoding ability. However, the number of encoding channels is often limited by instruments or luminescent materials used as information carriers in practical applications. To provide a new option, an optical multiplexing method based on the tunable relationship between excitation power density and emission intensity of upconversion nanoparticles (UCNPs; P–I relationship), which can be regulated by the co‐doping ratio of sensitizer ions and activator ions, is developed. This method can be implemented on commonly used optical imaging equipment. Since the P–I relationship is only related to the energy transfer process of lanthanide ions in UCNPs, it has the potential to be combined with other dimensions of optical multiplexing such as wavelength and intensity to provide more robust encoding ability.