Carrier-envelope-phase-stable soliton-based pulse compression to 4.4 fs and ultraviolet generation at the 800 kHz repetition rate

Generation and characterization of frequency tunable sub-15-fs pulses in a gas-filled hollow-core fiber pumped by a Yb:KGW laser

We investigate soliton self-compression and photoionization effects in an argon-filled antiresonant hollow-core photonic crystal fiber pumped with a commercial Yb:KGW laser. Before the onset of photoionization, we demonstrate self-compression of our 220 fs pump laser to 13 fs in a single and compact stage. By using the plasma driven soliton self-frequency blueshift, we also demonstrate a tunable source from 1030 to ∼700 nm. We fully characterize the compressed pulses using sum-frequency generation time-domain ptychography, experimentally revealing the full time-frequency plasma-soliton dynamics in hollow-core fiber for the first time.

Timing and energy stability of resonant dispersive wave emission in gas-filled hollow-core waveguides

We numerically investigate the energy and arrival-time noise of ultrashort laser pulses produced via resonant dispersive wave (RDW) emission in gas-filled hollow-core waveguides under the influence of pump-laser instability. We find that for low pump energy, fluctuations in the pump energy are strongly amplified. However, when the generation process is saturated, the energy of the RDW can be significantly less noisy than that of the pump pulse. This holds for a variety of generation conditions and while still producing few-femtosecond pulses. We further find that the arrival-time jitter of the generated pulse remains well below one femtosecond even for a conservative estimate of the pump pulse energy noise, and that photoionisation and plasma dynamics can lead to exceptional stability for some generation conditions. By applying our analysis to a scaled-down system, we demonstrate that our results hold for frequency conversion schemes based on both small-core microstructured fibre and large-core hollow capillary fibre.

Efficient single-cycle pulse compression of an ytterbium fiber laser at 10 MHz repetition rate

Over the past years, ultrafast lasers with average powers in the 100 W range have become a mature technology, with a multitude of applications in science and technology. Nonlinear temporal compression of these lasers to few- or even single-cycle duration is often essential, yet still hard to achieve, in particular at high repetition rates. Here we report a two-stage system for compressing pulses from a 1030 nm ytterbium fiber laser to single-cycle durations with 5 µJ output pulse energy at 9.6 MHz repetition rate. In the first stage, the laser pulses are compressed from 340 to 25 fs by spectral broadening in a krypton-filled single-ring photonic crystal fiber (SR-PCF), subsequent phase compensation being achieved with chirped mirrors. In the second stage, the pulses are further compressed to single-cycle duration by soliton-effect self-compression in a neon-filled SR-PCF. We estimate a pulse duration of ∼3.4 fs at the fiber output by numerically back-propagating the measured pulses. Finally, we directly measured a pulse duration of 3.8 fs (1.25 optical cycles) after compensating (using chirped mirrors) the dispersion introduced by the optical elements after the fiber, more than 50% of the total pulse energy being in the main peak. The system can produce compressed pulses with peak powers >0.6 GW and a total transmission exceeding 66%.