Multiwavelength diode-cladding-pumped Nd3+-doped germano-aluminosilicate fiber laser

Simultaneous multiwavelength oscillation at 1060 and 1090 nm has been produced from a free-running Nd³⁺-doped multicomponent silica fiber laser. As a result of co-doping with both Al₂O₃ and GeO₂, the Nd³⁺ ions are situated at separate sites relating to either Al³⁺-rich or Ge⁴⁺-rich regions of the germano-aluminosilicate glass. The slope efficiency of the combined ∼1-μm output was ∼52% (56%) with respect to the launched (absorbed) pump power. The 1060-nm emission reaches threshold first because of the greater number of Nd³⁺ ions that are located at Al³⁺-rich sites. On chopping the pump light the relaxation oscillations relating to the 1090-nm emission are antiphase with the oscillations observed with the 1060-nm emission. A degree of spectral overlap exists between the fluorescence emitted from Nd³⁺ ions located at each site. Power equalization (to ∼1 W each) of the 1060- and 1090-nm emissions was carried out by way of Raman amplification that occurred either internally or externally to the Nd³⁺-doped silica fiber laser.