Patent ID: 6853659

Claim:
A laser system comprising an optical resonance cavity comprising a first totally reflective mirror, a second partially transmissive mirror, disposed within said optical resonance cavity, a phosphate glass laser medium and an optical pumping means operatively associated with said optical resonance cavity for exciting said glass laser medium to emit laser radiation, the composition of said glass comprising P 2 O 5 , Al 2 O 3 , one or more of Na 2 O, K 2 O, Li 2 O, Rb 2 O or Cs 2 O, erbium and/or ytterbium dopant in an amount exceeding 8.5 mole % on an oxide basis, a maximum of 4 weight percent of one or more of SiO 2 , As 2 O 3 , Sb 2 O, or Nb 2 O 5 , and optionally one or more of MgO, CaO, SrO or BaO, and/or ZnO, and wherein optionally up to 90% of the oxygen is replaced by fluorine in the glass.