Red-shift Due to Pump Intensity in Er:ZBLALiP Whispering Gallery Mode Lasers

conference 4944 " Integrated Optical Devices: Fabrication and Testing ", session 1 " Microcavities and Photonic Crystals [4944-4]; International audience; A new kind of Erbium doped heavy fluoride glass Er:ZBLALiP has been studied. Microspheres were fabricated with this fluoride glass. Whispering Gallery Mode laser spectra around 1550 nm were analyzed for different sphere diameters and Erbium concentrations (from 0.01% to 0.2% by mole) under pumping by a fiber taper at 1480 nm. Red-shift effect on the frequencies 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 and this further allows us to calibrate the properties of the microsphere laser in terms of the thermal expansion as well as the variation of the refractive index.