Improved saturation fluence for peta-watt CPA system in low temperature Yb-doped materials

Summary form only given. Yb-doped materials is one of the most promising materials in the next generation of a compact table-top peta-watt laser using a chirped pulse amplification system (CPA). Yb:YLF and Yb:glass are suitable for ultra-short pulse generation due to a wide emission spectral width more than 50 nm. We demonstrated a LD-pumped oscillator performance with a Yb:YLF for the first time. In the hard pumping with more than 50 kW/cm/sup 2/, laser gain was not around emission peak wavelength due to large reabsorption of a lower lasing level. Effective saturation fluence at laser wavelength, therefore, was much higher than a bulk damage threshold for a chirped pulse. The reduction of saturation fluence is an inevitable difficulty in realizing a compact LD-pumped table-top CPA system.