Temperature-dependent fluorescence and site-selective excitation studies of ytterbium doped silica

This contribution presents temperature-dependent and site-selective spectroscopy measurements of Yb, Al, F co-doped silica. White light absorption and fluorescence measurements using a multimode 915 nm diode for excitation were both made over the range 77K to 420 K. Low temperature measurements allow determination of the Stark levels. The high temperature measurements allow quantification of how the laser cross-sections vary with temperature over intervals applicable to high power laser operation. Between room temperature and 420 K, the cross-sections for some spectral regions change by more than 10%, whereas other regions are essentially unchanged over the same temperature range.