Ultrashort-Pulse High-Power ${\hbox {Yb}}^{3+}$-Doped Fiber Amplifiers

Ultrashort optical pulse propagation in high-power Yb
³⁺
-doped fiber amplifiers (YDFA) is studied using a spectrally resolved nonlinear power equation for the coupled pulse components. The Yb
³⁺
ions transitions are modeled using a rate equation. Examples for high-power YDFAs with normal dispersion show good qualitative agreement with experimental results. We analyze the effects of the incident pulse wavelength, pulse peak power, Yb
³⁺
concentration, pump filling factor, fiber length, pumping configuration, pump power and nonlinear index, on the intensity distribution of short amplified pulses. We also demonstrate the spectral compression of an initially negative-chirped pulse.