Vincent Cardin

10 mJ 5-cycle pulses at 1.8 μm through optical parametric amplification

We report the generation of 10 mJ, 5-cycle pulses at 1.8 μm (30 fs) at 100 Hz repetition rate using an optical parametric amplifier pumped by a high energy Titanium-Sapphire laser system (total energy of 23 mJ for Signal and Idler). This is the highest reported peak power (0.33 TW) in the infrared spectral range. This high-energy long wavelength laser source is well suited for driving various nonlinear optical phenomena such as high harmonic generation for high flux ultrafast soft X-ray pulses.

0.42 TW 2-cycle pulses at 1.8 μm via hollow-core fiber compression

By employing pulse compression with a stretched hollow-core fiber, we generated 2-cycle pulses at 1.8 μm (12 fs) carrying 5 mJ of pulse energy at 100 Hz repetition rate. This energy scaling in the mid-infrared spectral range was achieved by lowering the intensity in a loose focusing condition, thus suppressing the ionization induced losses. The correspondingly large focus was coupled into a hollow-core fiber of 1 mm inner diameter, operated with a pressure gradient to further reduce detrimental nonlinear effects. The required amount of self-phase modulation for spectral broadening was obtained over 3 m of propagation distance.

Direct compression of 170-fs 50-cycle pulses down to 1.5 cycles with 70% transmission

We present a straightforward route for extreme pulse compression, which relies on moderately driving self-phase modulation (SPM) over an extended propagation distance. This avoids that other detrimental nonlinear mechanisms take over and deteriorate the SPM process. The long propagation is obtained by means of a hollow-core fiber (HCF), up to 6 m in length. This concept is potentially scalable to TW pulse peak powers at kW average power level. As a proof of concept, we demonstrate 33-fold pulse compression of a 1 mJ, 6 kHz, 170 fs Yb laser down to 5.1 fs (1.5 cycles at 1030 nm), by employing a single HCF and subsequent chirped mirrors with an overall transmission of 70%.

Efficient 170 eV source directly driven by an Yb laser amplifier

High brightness XUV sources in the 140–170 eV spectral range are of great demand as this spectral range covers important magnetic and molecular materials, such as the N-edge of Gadolinium and Terbium (145 and 155 eV) and L2,3 edge of sulphur [1]. High-order harmonic generation (HHG) allows performing ultrafast dynamics measurements with high temporal resolution in this spectral range because of extremely short, potentially sub-fs, temporal envelopes that are intrinsically synchronized to the near-IR driving laser pulses. We present HHG in the 170 eV range using 8.5 mJ post-compressed 20 fs 1.03 μm pulses from a 14 mJ Yb:CaF2 laser chirped pulse amplifier operating at 0.5 kHz repetition rate.

Single shot absorption measurements in the water window XUV region via HHG

Using 6-cycle, 7mJ pulses at 1.8µm we exploited limit intensities and drove HHG from 50eV up to the oxygen edge (550eV) with sufficient flux for single shot absorption measurements at the carbon k-edge (280eV).

High peak-power (0.42TW) mid-IR pulses achieved through hollow-core fiber compression

A novel scheme of flexible hollow-core fiber compression is used to achieve 2-cycles pulses at 1.8µm with 5mJ pulse energy. This source is shown to greatly enhance the efficiency of the high harmonic generation process.

Mid-IR 0.4TW pulses achieved through hollow-core fiber compression

By employing hollow-core fiber compression using a stretched flexible fiber, we achieved 2-cycles pulses centered on 1.8μm with more than 5mJ energy per pulse.