Upconversion luminescence occurs via a multiphoton absorption process where a material absorbs several lower-energy photons, and subsequently higherenergy photons are emitted from the material. Upconversion can occur efficiently in glasses doped with rare-earth trivalent ions such as Er3+, Nd3+, Ho3+, and Yb3+. Rare-earth-doped upconversion phosphors find use in photonics because of their low cost, high stability, low toxicity, and size-independent optical properties. Applications of these phosphors may be found in fields such as solid-state lasers, fiber-optic amplifiers, medical imaging, security, and solar cells.1,2