Thermally stable and tunable broadband near-infrared emission from NIR-I to NIR-II in Bi-doped germanate glass for smart light sources

Abstract

The rapid development of near-infrared (NIR) spectroscopic techniques has greatly facilitated the exploration of novel broadband NIR-emitting materials as advanced smart NIR light sources. However, the pursuit of high-efficiency and excellent thermal stability photonic materials with broadband NIR emission, especially in the NIR-II region, is still unsatisfactory. Herein, we report the design of a thermally stable Bi-doped germanate glass with tunable broadband NIR emission varying from the NIR-I (850–1050 nm) to NIR-II (850–1500 nm) region upon blue light excitation. The NIR emission peaks varied from 946 to 1142 nm due to conversion in the highly environmentally sensitive Bi NIR active centers, and their emission intensity and lifetimes were >84% at 150 °C due to high structural rigidity and the weak electron–phonon coupling effect. The NIR glass-converted-LEDs generated an output power of 53.2 mW (NIR-LED-I) and 179.5 mW (NIR-LED-II), respectively (at a current of 320 mA). The night vision, bio-imaging, and food quality analysis were also demonstrated, suggesting that Bi-doped glass has great application potential in novel smart compact NIR light sources.