Femtosecond Yb3+-doped Y3(Sc0.5Al0.5)2O12 ceramic laser

A passively mode-locked femtosecond Yb3+-doped Y3(Sc0.5Al0.5)2O12 (Yb:YSAG) ceramic laser has been studied. The new material, fabricated by sintering method, exhibited relatively low minimum pump intensity (Imin) and broad emission bandwidth even in the yttrium aluminum garnet systems. The value of Imin in the Yb:YSAG ceramics was found to be 2/3 compared with the Yb:YAG single crystal under 970-nm direct pumping. Efficient continuous-wave laser oscillation of 72% slope efficiency for incident pump power and wide tuning range of 53 nm (λ = 1012.9 nm ∼1065.5 nm) were obtained. By using a semiconductor saturable-absorber mirror (SESAM) for mode-locking operation, pulses as short as 280 fs having an average output power of 62 mW at 1035.8 nm were achieved. This is the shortest femtosecond pulse oscillation based on rare-earth-doped ceramic gain medium. The possibility of sub 100 fs pulse generation in a Yb:YSAG is discussed.