Thulium-doped optical fibers for fiber lasers

We present preparation and characterization of thulium-doped silica-based optical fibers for fiber lasers. The fibers were prepared by modified chemical vapor deposition process and doped with alumina and thulium ions. Alumina co-doping was achieved through two different methods - solution doping and nanoparticle doping method. Prepared preforms were characterized in terms of refractive index profiles and dopants distribution. For the drawn fibers, their spectral attenuation, fluorescence lifetime and laser performance were measured. In the case of nanoparticle doping, better laser characteristics were observed. Discussion and explanation of the trends for laser efficiency improvement is given.