Development of NIR-Rechargeable Phosphor Embedded in Active Glasses

The concept of laser glasses relates to the doping of a glass with rare-earth (RE) ions. These materials have been developed since 1961, when neodymium (Nd³⁺) ions were first considered for laser applications. TeO2-based glasses are known for their excellent chemical and mechanical stability, they exhibit a broad transparency range extending from visible to mid-infrared wavelengths, along with elevated values of both linear and nonlinear refractive indexes [1], [2]. Through the incorporation of luminescent particles, for instance PeL phosphors, with varied sizes and physical characteristics into the glass matrix, a spectrum of optical attributes can be attained, including afterglow, that is a consequence of energy storage in the material during excitation, when the absorption of the excitation light leads to charge trapping at a defect site which is then followed by the spontaneous release of the trapped charge and the emission of a photon, provided that sufficient thermal energy is available [3]. However, the afterglow is mainly obtained using UV-visible light.