Near-infrared-laser-driven robust glass-ceramic-based upconverted solid-state-lighting

Abstract

Laser lighting, generally consisting of a blue laser and downconversion phosphors, is considered to be the next promising form of illumination to replace traditional LED lighting. However, irradiation with a high-powered blue laser will inevitably cause significant thermal attack, which places a high demand on phosphor converters as well as on device architecture. In this work, a proof-of-concept prototype of near-infrared laser-driven upconversion solid-state-lighting is proposed. Robust lanthanide doped α/β-NaYF₄ embedded glass ceramics are developed as upconverted color converters and a routine 980 nm laser is used as the pumping source for its relatively low thermal effect and perfect resonance with Yb³⁺ sensitizers. Stable and bright upconversion white light is indeed produced by coupling a Yb/Tm/Er doped α-NaYF₄ glass ceramic with a 980 nm laser, but the luminous efficiency and energy efficiency are only 0.3 lm W⁻¹ and 0.12%, respectively, owing to low Er doping concentration. As an alternative, a stacking structure of Yb/Tm doped and Yb/Er doped glass ceramics is designed as a color converter to improve the luminous efficiency up to 1.0 lm W⁻¹ and energy efficiency up to 0.5% under a laser power density of 275 W cm⁻². It is believed that this research will provide a new idea for laser lighting and open up the application field of glass ceramics.