Divided-pulse compression with gas-filled hollow-core fiber for generation of high-energy few-cycle pulses

We study theoretically a pulse compression method with gas-filled hollow-core fiber (HCF) based on pulse division. The input pulse is first divided temporally into a sequence of almost identical subpulses by birefringent optical elements that are designed to have nearly zero group delay dispersion. Then, these subpulses are coupled into gas-filled HCF for spectrum broadening independently. Last, the subpulses are recombined into one pulse by the birefringent elements and compressed temporally. This method is demonstrated to be suitable for compressing ultrafast pulses with energies far above the millijoule to few-cycle level. Several key issues on successfully implementing this method are analyzed quantitatively, and the limitations are also discussed.