Enhancing the upconversion efficiency of NaYF4:Yb,Er microparticles for infrared vision applications

Abstract

In this study, (NaYF4:Yb,Er) microparticles dispersed in water and ethanol, were used to generate 540 nm visible light from 980 nm infrared light by means of a nonlinear stepwise two-photon process. IR-reflecting mirrors placed on four sides of the cuvette that contained the microparticles increased the intensity of the upconverted 540 nm light by a factor of three. We also designed and constructed microparticle-coated lenses that can be used as eyeglasses, making it possible to see rather intense infrared light images that are converted to visible.