A novel design for high brightness fibre lasers pumped by high-power diodes

摘要

Lasing action is reported in a new type of fibre design. The fibre consists of an undoped core and a doped glass cladding surrounded by a plastic coating. The refractive indices obey the relation nclad > ncore ncoat . The refractive index-doping profile of the fibre suggests the designation M-profile fibre (MPF). The brightness and the output power of the MPF laser may be at least as high as that of a cladding pump design. A comparison of the MPF, the cladding pump design and a monomode fibre has been performed. The fluorescence power and pump power distributions along the fibre have been measured. From the measured gain and loss the output power and various efficiencies have been estimated. For one of the first properly working MPF lasers the near- and far-field intensity distributions are reported together with measurements of the pump light distribution in the fibre, the output power and the self-pulsing behaviour.