Efficient and thermal-enhanced 480-nm upconversion emission in Tm3+/Yb3+-codoped silica-on-silicon channel waveguides pumped at 1064 nm

Efficient and thermally enhanced frequency upconversion of cw IR radiation at 1.064 micrometers into blue, red and near-IR light in integrated Tm3+/Yb3+-codoped phosphosilicate silica-on-silicon buried waveguides is reported. Thermally induced frequency upconversion enhancement is observed for the first time in a Tm3+/Yb3+-codoped system excited off-resonance at 1.064 micrometers . A sevenfold thermally induced upconversion efficiency enhancement was obtained when the waveguide's temperature was varied in the 20 degrees C-120 degrees C range. The thermal effect is believed to be associated with a temperature dependent effective absorption cross-section for the Yb3+-sensitizer, which depends upon the phonon occupation number in the host matrix.