New Generation High Power Rare-Earth-Doped Phosphate Glass Fiber and Fiber Laser

High power, high brightness fiber lasers have numerous potential commercial and military applications. These lasers offer unique flexibility as they may be coherently combined to provide a potential multi-kilowatt laser source and integrated delivery system. Fiber lasers with cladding pump designs represent a new generation of diode pumped configurations that are extremely efficient, have single mode output and may be operated with or without active cooling. They have a number of novel or unusual attributes, stemming from the fact that they represent the extreme case of a long gain length thin laser cavity. Reports indicate that over 100 watts of TEMoo CW output power are readily demonstrated from current cladding pumped fiber laser designs. [1,2] Kigre has invented a new family of Er/Yb/Nd phosphate laser glass materials (designated QX) that promise to facilitate a rapid advancement in fiber laser technology. Phosphate glass Rare-Earth doped fibers exhibit many advantages over Silica or Fluoride base fiber with regard to fiber laser designs. [3,4] A comparison of phosphate glasses with other glasses is presented in Table 1. Host Material Rare-Earth Solubility Up-Conversion Dopant Level Gain Length Silica Low High <1000ppm Lower Long Fluoride Middle High Middle Low Long Phosphate High Lowest High High Short Table 1. Performance comparison of phosphate laser glass with other glasses. Phosphate glass offers a great advantage in gain. Table 2. Shows Erbium doped fiber gain measurements comparisons, with pumping at 980nm and 1480nm, made by Harris, Photon-X, NTT Photonics Laboratories, British Telecom and Lucent. [5,6,7,8,9] 980nm pump_____________ ___ 1480nm pump____ Silica QX/Er Telurite Flouride QX/Er 1dB/meter 2dB/cm 3.5dB/meter 0.13dB/cm 3 dB/cm