Femtosecond-Pulse Fiber Based Amplification Techniques and Their Applications

Three kinds of pulse amplification techniques including chirped-pulse amplification (CPA), parabolic pulse amplification, and divided-pulse amplification (DPA) based on rare-earth doped fiber gain medium are reviewed. Large core area fiber and cladding-pumping technique compose the foundation of high average power, high pulse energy fiber CPA technology. Femtosecond pulses have been demonstrated at average powers of up to 830 W, pulse energies of up to 2.2 mJ and compressed pulse duration of 23 fs from different fiber CPA systems. The state-of-the-art performance of fiber CPA system to date is the simultaneous generation of 530 W, 1.3 mJ compressed femtosecond pulses at 400 kHz repetition rate. The balance between fiber gain, dispersion and nonlinearity is required for the self-similar propagation and thus the formation of pulses with parabolic intensity profile. Sub-33 fs pulses were demonstrated from a gain-cascaded parabolic amplification system. A newly emerging DPA technique is also reviewed. In addition, the applications of pulsed fiber amplifiers in the areas of supercontinuum generation and material micromachining system are also introduced.