Direct Amplification of Femtosecond Pulses in Ytterbium-Doped Fiber Amplifiers
Abstract
We review three experiments of direct femtosecond pulse amplification in ytterbium-doped fiber amplifiers under increasingly nonlinear propagation conditions, starting from the parabolic regime. The temporal quality of generated compressed pulses is analyzed using frequency-resolved optical gating measurements. Linear or nonlinear compensation of third-order spectral phase allows the generation of clean sub-70 fs pulses with energies in the range of 100 nJ-1 μJ, at repetition rates above 10 MHz.