Efficient and thermally enhanced frequency upconversion in Yb3+-sensitizedTm3+-doped silica-on-silicon buried waveguides excited at 1.064 mu m

Efficient and thermally enhanced frequency upconversion of cw infrared radi ation at 1.064 mum into blue (480 nm), red (660 nm) and near-infrared (800 nm) light in integrated Tm3+/Nb3+-codoped phosphosilicate silica-on-silicon buried waveguides is reported. Thermally induced frequency upconversion en hancement is observed for the first time in Tm3+/Yb3+-codoped systems excit ed off-resonance at 1.064 mum. A times seven thermally induced upconversion efficiency enhancement was obtained when the waveguide's temperature was v aried in the 20-120 degreesC range. The thermal effect is believed to be as sociated with a temperature dependent effective absorption cross-section fo r the Yb3+-sensitizer, which depends upon the phonon occupation number in t he host matrix. (C) 2001 Elsevier Science B.V. All rights reserved.