Ultra‐Efficient GAGG:Cr3+ Ceramic Phosphor‐Converted Laser Diode: A Promising High‐Power Compact Near‐Infrared Light Source Enabling Clear Imaging

Abstract Near‐infrared (NIR) light is widely used in fields such as organic components detection and biological imaging, due to its strong tissue penetration and non‐destructive characteristics. To improve the detection sensitivity and spatial resolution of bioimaging, it is important to obtain a new NIR light source with good thermal stability, high efficiency, and ultra‐high optical output power, which currently remains a great challenge. In view of this, a Gd 3 Al 2 Ga 3 O 12 :Cr 3+ (GAGG:Cr 3+ ) NIR ceramic phosphor is proposed in this study. By optimizing the preparation process of GAGG:Cr 3+ ceramic phosphor and the concentration of Cr 3+ ions, high external quantum efficiency (EQE = 70.1%) and excellent thermal stability (96.8%@150 °C) are achieved. After coupling the GAGG:Cr 3+ ceramic phosphor with a blue light‐emitting diode (LED), the electro‐optical conversion efficiency of the NIR ceramic phosphor converted LED (NIR‐cpc‐LED) reaches 31%@20 mA, which is higher than the previously reported values. Moreover, when coupled with a blue laser diode (LD), the optical output power of the NIR‐cpc‐LD reaches as high as 1652.6 mW@5.5 W. Therefore, GAGG:Cr 3+ NIR‐cpc‐LD not only shows a great prospect in practical applications, but also provides a new solution for high‐power compact NIR light sources.