Thermal effects on light emission in Yb3+-sensitized rare-earth doped optical glasses

The temperature effect upon infrared-to-visible frequency upconversion fluo rescence emission in off-resonance infrared excited Yb3+-sensitized rare-ea rth doped optical glasses is theoretically and experimentally investigated. We have examined samples of Er3+/Yb3+-codoped Ga2S3La2O3 chalcogenide glas ses and germanosilicate optical fibers, and Ga2O3:La2O3 chalcogenide and fl uoroindate glasses codoped with Pr3+/Yb3+, excited off-resonance at 1.064 m um. The experimental results revealed thermal induced enhancement in the vi sible upconversion emission intensity as the samples temperatures were incr eased within the range of 20 degreesC to 260 degreesC. The fluorescence emi ssion enhancement is attributed to the temperature dependent multiphonon-as sisted anti-Stokes excitation process of the ytterbium-sensitizer. A theore tical approach that takes into account a sensitizer temperature dependent e ffective absorption cross- section, which depends upon the phonon occupatio n number in the host matrices, has proven to agree very well with the exper imental data. As beneficial applications of the thermal enhancement, a temp erature tunable amplifier and a fiber laser with improved power performance are presented.