Octave-spanning broad luminescence of Cr 3+ , Cr 4+ -codoped Mg 2 SiO 4 phosphor for ultra-wideband near-infrared LEDs

We synthesized Cr 3+ , Cr 4+ -codoped Mg 2 SiO 4 phosphors and studied their optical properties for application as a novel wideband near-infrared (NIR) light-source. The phosphors have an ultra-wideband NIR luminescence spectrum of 650–1400 nm. The origin should be the 4 T 2 → 4 A 2 transition of Cr 3+ and the 3 T 2 → 3 A 2 transition of Cr 4+ . The luminescence spectrum spans over one octave range and covers the “optical window in biological tissues”. We successfully achieved an ultra-wideband luminescence of 650–1400 nm with a maximum output power of 367.5 μ W by combining a blue LED with Cr 3+ and Cr 4+ -codoped Mg 2 SiO 4 phosphors in a single package.