High power diode-pumped triply doped fibre laser

A triply doped fibre laser is demonstrated for the first time. Using the 805 nm and 975 nm output from two diode laser sources to simultaneously pump a 2.1 m Yb³⁺, Tm³⁺, Ho³⁺-doped silica fibre laser, a maximum output power of 4.3 W was generated at slope efficiencies of 21% and 11% with respect to the launched 805 nm and 975 nm pump light, respectively. Whilst a number of energy transfer upconversion processes at the current dopant concentration levels appear to have impacted on the overall efficiency of the laser, the use of two separately pumped sensitiser ions to excite a single lasant ion has been shown to be a successful approach. PACS 42.55.Wd; 42.55.Xi; 42.60.Lh; 42.60.Pk