Infrared (1.2–1.6 μm) luminescence in Yb, Cr:YAG with 940 nm diode pumping

Infrared (1.2–1.6 μm) luminescence in a yttrium aluminium garnet (YAG) crystal, co-doped with Yb (10 at.%) and Cr (0.05 at.%) ions, was investigated under CW laser diode pumping (λ = 940 nm). The Cr4+ emission band was observed with its peak at 1.35 μm and measured to be about 6% with respect to Yb3+ IR luminescence (λ = 1.03 μm). Analysis of the crystal absorption and luminescence spectra allows one to conclude that Yb3+–Cr4+ energy transfer is a mechanism responsible for the 3B2(3T2)–3B1(3A2) emission of Cr4+ ions. This crystal is promising as an efficient source of the near infrared emission.