Generation of diffraction-limited femtosecond beams using spatially-multimode nanosecond pump sources in parametric chirped pulse amplification systems

Summary form only given.We have shown that spatially multimode output from a large core fiber amplifier can be efficiently converted into a diffraction-limited amplified signal beam by using optical parametric amplification. This allowed us to demonstrate a compact system for generating high-energy ultrashort pulses based on large-core cladding-pumped Yb fibers. Such approach eliminates limitations on the usable fiber core-size and, therefore, is expected to provide further significant increase in pulse energies and powers from fiber-based ultrafast laser systems.