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 77 K 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.