Enhanced infrared-to-visible upconversion imaging via metasurface-lanthanide nanoparticle hybrid screens

Accessing the rich information carried by infrared light typically relies on bulky, complex optoelectronic systems. Lanthanide-based upconverting nanoparticles (UCNPs) offer a compelling alternative by converting infrared light into visible photons through nonlinear anti-Stokes processes. However, achieving strong upconversion under the low excitation intensities relevant to infrared vision remains challenging, motivating strategies to enhance light-matter interaction. Here, we demonstrate enhanced infrared-to-visible upconversion imaging enabled by integrating alloyed Yb/Er UCNPs with a resonant dielectric metasurface. The metasurface supports an optical resonance aligned with the UCNP excitation band, leading to over three orders of magnitude enhancement in upconversion emission. Crucially, flat-band angular dispersion of this resonance enables uniform enhancement across incident angles relevant to imaging, thereby preserving spatial frequency content and yielding sharp, high-contrast images. In light of ongoing advances in lanthanide-based materials, this metasurface-UCNP hybrid screen provides a promising platform for compact, detector-free, and scalable infrared imaging technologies based on optical upconversion.