Lasing action is reported in a new type of fiber design. The fiber consists of an undoped core and a doped glass cladding surrounded by a plastic coating. The refractive indices obey the relation ndad > ncore ≫ ncore. The refractive index/doping profile of the fiber recommends to the designation M-profile fiber (MPF). The brightness and the output power of the MPF laser may at least be as high as that of a cladding pump design being based on a comparison of the M-profile fiber and the cladding pump design. The fluorescence power and pump power distributions along the fiber 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 along with measurements concerning the pump light distribution in the fiber, the output power and the polarization behaviour.
© 1996 Optical Society of AmericaPDF Article