The Regulation of Spectrum Profile for UCNP by Dual‐Beam Excitation

ABSTRACT The regulation of luminescence ratios in rare‐earth‐doped fluoride nanocrystals holds significant importance in fields such as optoelectronic devices and bioimaging. This study investigates the upconversion luminescence and evolution of the red‐to‐green emission intensity ratio (R/G) in NaYbF 4 :2%Er nanocrystals under dual‐wavelength co‐excitation at 980 nm and 1530 nm. When power modulation is applied using single‐wavelength excitation, it can regulate the red‐to‐green ratio of the nanocrystals to a limited extent. However, this range is extremely narrow and cannot achieve a reversal between red and green emission. Specifically, we achieved precise control over the emission spectrum profile of the nanocrystals within a remarkably wide range (R/G = 0.11–4.37) by adjusting the power ratio of the dual excitation wavelengths.