Ultrafast (UF) mode-locked (ML) lasers are extremely powerful tools in scientific research and industrial applications including material processing, nonlinear optics, attosecond science, metrology, etc. The most popular UF Ti: sapphire laser applications are limited by its high ownership cost, system complexity and low power transfer efficiency. Yb3+: CaF2 has been recognized as a promising candidate for a high efficient and high power femtosecond laser, for its simple energy-level scheme, high quantum efficiency ( 1), very small quantum defect (70 nm), high thermal conductivity and...