Comparative study of spectral broadening and few-cycle compression of Yb:KGW laser pulses in gas-filled hollow-core fibers

TL;DR

This study compares different gases for spectral broadening of Yb:KGW laser pulses in hollow-core fibers, achieving few-cycle pulses with high efficiency and analyzing optimal conditions for pulse compression.

Contribution

It provides a comprehensive comparison of atomic and molecular gases for spectral broadening in hollow-core fibers, optimizing parameters for few-cycle pulse generation.

Findings

Achieved ~15 fs, few-cycle pulses with >70% energy transmission

Identified optimal gas pressures and fiber conditions for spectral broadening

Demonstrated scalability of parameters for different pulse energies

Abstract

While industrial-grade Yb-based amplifiers have become very prevalent, their limited gain bandwidth has created a large demand for robust spectral broadening techniques that allow for few-cycle pulse compression. In this work, we perform a comparative study between several atomic and molecular gases as media for spectral broadening in a hollow-core fiber geometry. Exploiting nonlinearities such as self-phase modulation, self-steepening, and stimulated Raman scattering, we explore the extent of spectral broadening and its dependence on gas pressure, the critical power for self-focusing, and the optimal regime for few-cycle pulse compression. Using a 3-mJ, 200-fs input laser pulses, we achieve ~ 15 fs, few-cycle pulses with >70% overall energy transmission efficiency. The optimal parameters can be scaled for higher or lower input pulse energies with appropriate gas parameters and fiber geometry.