Red-shift in Er:ZBLALiP Whispering Gallery Mode Laser
Résumé
Microspheres were fabricated using a new kind of Erbium doped heavy fluoride glass Er:ZBLALiP. Whispering gallery mode spectra around 1550 nm were recorded for different sphere diameters and Erbium concentrations under pumping by a fiber taper at 1480 nm. Red-shift effect on the wavelengths of both fluorescence and laser spectra is experimentally observed when the pump power is increased, originating from thermal effects. A spectroscopic technique based on the green upconversion fluorescence is used to compute a loading effective temperature for the Er:ZBLALiP microsphere. This method allows us to calibrate the glass properties in terms of the thermal expansion as well as the variation of the refractive index.