Generation of 8-fs and 13-nJ pulse from a Yb-fiber system with nonlinear-pulse-compression.

In this study, we demonstrated a few-cycle pulse generation system delivering an 8-fs and 13-nJ pulse. The oscillator of this system is a mode-locked fiber laser based on a nonlinear amplifying loop mirror (NALM), which is injected into the gain management nonlinear (GMN) amplifier after pre-chirp management by a chirped fiber Bragg grating (CFBG) and a passive fiber. Subsequently, a hollow-core photonic bandgap (HC-PBG) fiber is employed to compensate for the dispersion, achieving a pulse duration of 49.8 fs with a pulse energy of 51.8 nJ. Finally, we integrate an ultra-high numerical aperture (UHNA) fiber at the end of the HC-PBG fiber for nonlinear spectral broadening. The resulting spectral range spans from 800 to 1400 nm. Dispersion compensation is achieved using the prism-pair, resulting in a further compression of the pulse duration to 8.2 fs, with a pulse energy of 13.1 nJ and a peak power of 1.59 MW. With an overall system footprint of <0.1 m and a total volume of <0.005 m, this few-cycle pulse generation system delivers ultra-short pulses with high peak power while maintaining compactness and stability, making it attractive for many applications.