We demonstrate a nonlinearity optimization method by altering distribution of passive fibers in a dissipative-soliton mode-locked fiber laser to level up output parameters. In the numerical simulation, we found that the passive fiber segment after gain fiber characterizes the highest average B-integral among fiber segments. By reducing the length of this fiber section and keeping the total passive fiber length as constant, the output pulse energy can be effectively scaled up while maintaining a short dechirped pulse duration, resulting in boosting peak power. With this method, 37-nJ pulses are generated from a dissipative-soliton mode-locked cladding pumped ytterbium-doped single-mode fiber laser in the experiment. The pulse can be dechirped to 66 fs with 350 kW peak power. Moreover, the pulse pedestal is suppressed by a vector-dispersion compressor.

Recent results in the development of diode-driven high energy, high repetition rate, picosecond lasers, including the demonstration of a cryogenic Yb:YAG active mirror amplifier that produces 1.5 J pulses at 500 Hz repetition rate (0.75 kW average power) are reviewed. These pulses are compressed resulting in the generation of ${\sim}5~\text{ps}$ duration, 1 J pulses with 0.5 kW average power. A full characterization of this high power cryogenic amplifier, including at-wavelength interferometry of the active region under ${>}1~\text{kW}$ average power pump conditions, is presented. An initial demonstration of operation at 1 kW average power (1 J, 1 kHz) is reported.