Watt-level femtosecond Tm-doped "mixed" sesquioxide ceramic laser in-band pumped by a Raman fiber laser at 1627 nm

We report on a semiconductor saturable absorber mirror mode-locked Tm:(Lu,Sc)(2)O-3 ceramic laser in-band pumped by a Raman fiber laser at 1627 nm. The nonlinear refractive index (n(2)) of the Tm:(Lu,Sc)(2)O-3 ceramic has been measured to be 4.66 x 10-20 m(2)/W at 2000 nm. An average output power up to 1.02 W at 2060 nm is achieved for transform-limited 280-fs pulses at a repetition rate of 86.5 MHz, giving an optical efficiency with respect to the absorbed pump power of 36.4%. Pulses as short as 66 fs at 2076 nm are produced at the expense of output power (0.3 W), corresponding to a spectral bandwidth of 69 nm. The present work reveals the potential of Tm3+-doped sesquioxide transparent ceramics for power scaling of femtosecond mode-locked bulk lasers emitting in the 2-mu m spectral range. (C) 2022 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement