Ultrafast pulse sources based on multi-mode optical fibers

Ultrafast pulse sources based on multi-mode optical fibers are discussed. H igh-power passively mode-locked fiber lasers based on multi-mode rare-earth -doped optical fibers greatly exceed the power limitations of single-mode o scillators. Ultrafast multi-mode fiber amplifiers operating in conjunction with multi-mode oscillators provide even higher power levels, where nonline ar propagation effects enable pulse compression to below 100 fs. Multi-mode fiber oscillators can be combined with single-mode Raman-shifting fibers t o produce widely wavelength-tunable sources of femtosecond pulses. Further amplification in Yb fibers allows for the generation of sub-100-fs pulses w ith W-level average powers.