Phosphosilicate fiber: simple high-power cw 1.24- and 1.48-/spl mu/m Raman lasers

Summary form only given. The cascaded Raman fiber lasers pumped by Nd or Yb fiber lasers are effective tools for generating high-power cw radiation at wavelengths 1.24 and 1.48 /spl mu/m. However, germanosilicate fibers have a small Stokes frequency shift of 440 cm/sup -10/. This leads to the necessity of using the third and sixth Stokes orders to obtain the radiation with the wavelengths of 1.24 and 1.48 /spl mu/m correspondingly. Because of this, the structure of a cascaded Raman fiber laser consists of three and six pairs of Bragg gratings for 1.24 and 1.48 /spl mu/m. Besides the complexity and high cost of such cascaded Raman fiber lasers, the conversion efficiency is reduced with the growth of the Stokes order. The best option is a fiber with a large enough Stokes frequency shift to obtain 1.24 and 1.48 /spl mu/m radiation corresponding to Stokes lines of low order. A phosphosilicate fiber satisfies this requirement.