Upconversion processes in Nd3+-doped fluoroarsenate glasses

In this work we have studied the infrared to visible upconversion luminesce nce of Nd3+-doped fluoroarsenate glasses with different neodymium concentra tions (0.1, 0.5, 2, 3, 4, and 5 mol% under continuous wave and pulsed laser excitation. Green, orange, and red emissions are observed with excitation at 802 and 874 nm within the F-4(5/2) and F-4(5/2) levels. In addition, a w eak blue emission appears under continuous wave (cw) laser excitation which under pulsed laser excitation only occurs for the most concentrated sample at 77 K. The green, orange, and red emissions can be attributed to transit ions from the (4)G(7/2) excited state. The pump power dependencies of these upconverted emissions together with the shape of the upconverted excitatio n spectra which are similar to the one-photon absorption spectrum and the t emporal behavior of the decays, indicate that an ETU process seems to be re sponsible for the observed visible luminescence, though other possible mech anisms cannot be disregarded. (C) 2001 Elsevier Science B.V. Ail rights res erved.