43  W, 155  μm and 125  W, 31  μm dual-beam, sub-10 cycle, 100  kHz optical parametric chirped pulse amplifier

Abstract

Received XX Month XXXX; revised XX Month, XXXX; accepted XX Month XXXX; posted XX Month XXXX (Doc. ID XXXXX); published XX Month XXXX We present a 100 kHz optical parametric chirped pulse amplifier (OPCPA) developed for strong-field attosecond physics and soft-X-ray transient absorption experiments. The system relies on noncollinear potassium titanyl arsenate (KTA) booster OPCPAs and is pumped by a 240 W, 1.1 ps Yb:YAG Innoslab chirped pulse laser amplifier. Two optically synchronized infrared output beams are simultaneously available: a 430 µJ, 51 fs, carrierenvelope phase (CEP) stable beam at 1.55 µm and an angular-dispersion-compensated, 125 µJ, 73 fs beam at 3.1 µm.High-repetition-rate (i.e., >> 10 kHz) ultrafast laser sources operating in the near-infrared (NIR, 0.8-3 µm) and the midinfrared (MIR, 3-30 µm) combined with state-of-the-art chargedparticle detection systems enable the investigation of strong-field physics in hitherto unexplored regimes [1]. Long-wavelength drivers can also be exploited to push the cutoff photon energy in high-harmonic generation (HHG) towards, and into the soft-X-ray regime (SXR, > 120 eV) [2]. For the study of biomolecules in their natural aqueous environment, the so-called water window (284-543 eV) constitutes a particularly interesting spectral range [2]. However, the unfavorable scaling of the single-atom response in HHG,  -(5-6) , can only partly be overcome by phase-matching schemes [3]. Therefore, for high single-shot SXR photon numbers, optical driver pulse energies at the multi-100 µJ level are required even at center wavelengths below 2 µm, which has so-far limited table-top water-window SXR sources to repetition rates of ≤ 1 kHz [2].Diode-pumped, Tm-doped fiber chirped pulse laser amplification near 2 µm is a promising, scalable technology for pumping water-window SXR sources. Recently, 252 µJ, sub-50 fs

Progress in ultrafast, mid-infrared optical parametric chirped pulse amplifiers pumped at 1 µm

“…The system was developed for laser-driven electron rescattering and soft X-ray transient absorption experiments, and therefore, required average powers above 10 W at multi-GW peak powers both at 1.55 and 3.1 µm. 3 The seed pulses were obtained from a commercial two-branch Yb-fiber laser. The first branch was fiber-coupled and delivered stretched, 900 ps-long pulses at an energy of a few 10 nJ to seed a commercial Yb:YAG amplifier system.…”

“…In the 1.4-4 µm wavelength region, where a number of wide-bandgap oxide nonlinear optical crystals are commercially available, multi-GW peak powers at average powers well above 10 W have already been demonstrated with pulses lasting only a few optical cycles. Most of the demonstrated high-power OPA systems relied on bulk, critically phase-matched crystals for power scaling, [1][2][3][4] such as KNbO3, LiNbO3, and KTiOAsO4 (KTA), while only one utilized periodically poled LiNbO3 (PPLN) for this purpose. 5 Due to the lack of suitable nonlinear crystals, ultrafast optical parametric devices operating beyond 5 µm were based almost exclusively on an OPA followed by difference frequency generation (DFG) at an overall pump-to-MIR energy conversion efficiency below 1% at 8 µm.…”

Laser-induced damage of nonlinear crystals in ultrafast, high-repetition-rate, mid-infrared optical parametric amplifiers pumped at 1 µm

“…Figure 8 displays the architecture of our dual-beam, high-average-power OPA delivering a total average power of 55 W at 1.55 and 3.1 µm at a repetition rate of 100 kHz. 18 The second and third booster OPA's are based on a 4 and a 2-mm-long KTA crystal, both pumped at a peak intensity of 70 GW/cm 2 . The OPA design took into account the nonlinear refractive index of KTA and thermal lensing supplied by our z-scan studies.…”

“…The choice of pump peak intensities and wavefront curvatures ensures stable long-term operation with high beam quality of both infrared output beams. 18…”

High-repetition-rate and high-power picosecond regenerative amplifier based on a single bulk Nd:GdVO4 crystal

“…Compact, stable and high-power diode-pumped shortpulse laser amplifier systems with excellent spatial quality are ideal sources for high-power optical parametric chirped pulse amplification (OPCPA) and efficient laser processing [1][2][3][4][5] . Among various configurations, regenerative amplifiers (RAs) are routinely used to enhance the output of mode-locked oscillators because of their ability to provide gains of several orders of magnitude and a resonator structure that maintains the spatial quality of the seed [6][7][8][9] .…”