CHARACTERIZATION AND MODELING OF THULIUM-ZBLAN BLUE UP-CONVERSION FIBER LASERS

We have investigated the performance of blue upconversion fiber lasers based on thulium-doped ZBLAN fiber, operating at 480 nm with a 1140-n m pump. Extensive fluorescence measurements have provided the necessar y spectroscopic data to present a computer model that describes the pe rformance of such lasers with good accuracy despite the complicated th ree-step upconversion mechanism and the influence of ion-ion energy tr ansfer processes. We have identified the mechanisms that populate the levels above the (1)G(4) level and are able to specify the correspondi ng spectroscopic parameters. We discuss the relevance of these process es to the 480-nm laser performance. Furthermore, we have calculated op timized parameters for such lasers. (C) 1997 Optical Society of Americ a.