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 fs² group-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.

Phase-stable, multi-µJ femtosecond pulses from a repetition-rate tunable Ti:Sa-oscillator-seeded Yb-fiber amplifier

“…The repetition rate of the 0.7-µJ, ~32-fs output pulses can be reduced from 74 MHz (fundamental repetition rate of the oscillator) by an integer factor of up to 4 without affecting the pulse parameters. In principle, the repetition rate can be further reduced at the same average power by stronger pulse stretching in the CPA [31] and the pulse duration can be further compressed with alternative, pulse-energy-scalable schemes [9][10][11][12][13][14]. For all repetition rates, an integrated phase noise of 60-mrad in-loop and 225-mrad out-of-loop was measured in a bandwidth from 2 mHz to 4 kHz.…”

“…The superior thermal properties of Yb-doped active media enable an improvement of several orders of magnitude in terms of average power [7][8][9][10][11]. To overcome the disadvantage of a significantly narrower gain bandwidth, several post-amplification nonlinear pulse compression techniques have been developed [9][10][11][12][13][14]. Recently, from an Yb:YAG thin-disk oscillator followed by two nonlinear compression stages, pulses of 2.2 cycles with 6 W of average power at a repetition rate of 38 MHz and with a phase jitter of 270 mrad (out-of-loop phase noise integrated in the band between 1 Hz and 500 kHz) were demonstrated [10].…”

Generation of microjoule pulses in the deep ultraviolet at megahertz repetition rates

“…DW emission in the deep and vacuum UV has been demonstrated in gas-filled HC-PCFs [19][20][21], and deep UV pulses with 72 nJ energy have been generated at 9.6 MHz repetition rate [22]. High-repetition rate (38 MHz) dispersive wave emission in the visible, with 13 nJ pulse energy, has also been reported [14].Here we report the use of DW emission from self-compressed solitons in gas-filled HC-PCF to generate µJ pulses in the deep UV at close to 2 MHz repetition rate. The pump source is a compact commercial ytterbium fiber laser (Active Fiber Systems GmbH) that delivers ~300-fs-long pulses at 1030 nm with pulse energies up to tens of µJ.…”

“…DW emission in the deep and vacuum UV has been demonstrated in gas-filled HC-PCFs [19][20][21], and deep UV pulses with 72 nJ energy have been generated at 9.6 MHz repetition rate [22]. High-repetition rate (38 MHz) dispersive wave emission in the visible, with 13 nJ pulse energy, has also been reported [14].…”

“…To this end, pulse compression schemes are commonly employed, based for example on spectral broadening in bulk material [12] or gas-filled capillary and hollow-core photonic crystal fibers (HC-PCFs). This has allowed pulse compression from hundreds of fs to the few-cycle regime in set-ups involving two fiber stages [13,14]. In capillary fibers, spectral broadening normally occurs via self-phase modulation (SPM) in the normal dispersion regime, which requires the use of negatively chirped mirrors after the fiber and compresses the pulses in time by compensating for the induced chirp.…”