Temporal compression of Yb-doped laser pulses in cascaded gas-filled hollow fibers

Femtosecond laser technology has been pivotal across scientific applications, including chemical reaction dynamics and strong-field physics, as well as in areas such as precision micromachining, eye surgery, and advanced materials processing. Ultrashort near-infrared (NIR) pulses, particularly those lasting only a few optical cycles, have enabled high harmonic generation (HHG), attosecond pulse generation, and time-resolved spectroscopy. Traditional Ti:Sapphire chirped pulse amplification (CPA) systems achieve sub-5 fs pulses through hollow-core fiber (HCF) compression of pulses initially around 20−50 fs in duration. However, newer compact laser sources, such as Yb-doped and other high-repetition-rate lasers, are known for their reliability and compactness but typically produce longer pulses (≥ 150 fs), making compression more challenging. This paper presents detailed simulations of pulse compression for a 1030 nm, 280 fs Yb laser using a cascaded fiber approach. The simulations, performed with the open-source Luna.jl package, compare a single 2-m HCF with a cascaded system of two 1-m HCFs. The results demonstrate that the cascaded fiber system achieves 3.3 times shorter pulses and 2.3 times higher peak powers. A novel cascaded configuration is proposed and simulated, in which a single fiber is double-passed using polarization switching.