title: Compressing μJ-level pulses from 250  fs to sub-10  fs at 38-MHz repetition rate using two gas-filled hollow-core photonic crystal fiber stages.
abstract: Compression of 250-fs, 1-μJ pulses from a KLM Yb:YAG thin-disk oscillator down to 9.1 fs is demonstrated. A kagomé-PCF with a 36-μm core-diameter is used with a pressure gradient from 0 to 40 bar of krypton. Compression to 22 fs is achieved by 1200  fs2group-delay-dispersion provided by chirped mirrors. By coupling the output into a second kagomé-PCF with a pressure gradient from 0 to 25 bar of argon, octave spanning spectral broadening via the soliton-effect is observed at 18-W average output power. Self-compression to 9.1 fs is measured, with compressibility to 5 fs predicted. Also observed is strong emission in the visible via dispersive wave generation, amounting to 4% of the total output power.
authors.forename: K F
authors.initials: KF
authors.lastname: Mak
authors.forename: M
authors.initials: M
authors.lastname: Seidel
authors.forename: O
authors.initials: O
authors.lastname: Pronin
authors.forename: M H
authors.initials: MH
authors.lastname: Frosz
authors.forename: A
authors.initials: A
authors.lastname: Abdolvand
authors.forename: V
authors.initials: V
authors.lastname: Pervak
authors.forename: A
authors.initials: A
authors.lastname: Apolonski
authors.forename: F
authors.initials: F
authors.lastname: Krausz
authors.forename: J C
authors.initials: JC
authors.lastname: Travers
authors.forename: P St J
authors.initials: PS
authors.lastname: Russell