Octave-spanning broad luminescence of Cr3+, Cr4+-codoped Mg2SiO4 phosphor for ultra-wideband near-infrared LEDs

We synthesized Cr3+, Cr4+-codoped Mg2SiO4 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 T-4(2) -> (4)A(2) transition of Cr3+ and the T-3(2) -> (3)A(2) transition of Cr4+. 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 mu W by combining a blue LED with Cr(3+ )and Cr4+-codoped Mg2SiO4 phosphors in a single package. (C) 2019 The Japan Society of Applied Physics