New ytterbium-phosphate glass for diode-pumped lasers

A new ytterbium laser glass based on an alumoborophosphate composition is developed. It is shown that the chemical and thermal stabilities of this glass are record-high for phosphate glasses and that its spectral and luminescent characteristics compare well with popular laser glasses. A mould of laser-quality glass doped with ytterbium with a concentration of 5×10²⁰ cm^-3 is synthesised. Active laser elements 5×5×2 mm in size are prepared from this glass for longitudinal diode pumping. These elements were used to fabricate a laser, whose output power in the cw regime reached 783 mW and maximum slope efficiency was 28.9%. Pulses with a duration of ~150 fs and a peak power of about 5 kW are obtained in the passive mode-locking regime.