Optimization and phase matching of fiber-laser-driven high-order harmonic generation at high repetition rate

Cabasse, A.; Machinet, Guillaume; Dubrouil, A.; Cormier, Éric; Constant, Éric

doi:10.1364/ol.37.004618

Cited by 37 publications

(37 citation statements)

References 16 publications

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“…Note that a rectangular gas jet with the longer dimension oriented parallel (perpendicular) to the propagation direction of the driving laser can be utilized for reducing the gas load in case of loose (tight) focusing, respectively. Hence, our investigations, in contrast to the current opinion found in many publications [11,19], show that the phase matching pressure for HHG can be achieved with gas jets even in the tight focusing regime, at least for beam radii between 10 and 100 μm. For much smaller focal spots, not only do many of our approximations break down, but other physical limitations might also arise, such as clustering effects [27].…”

Section: High-density Target For Tight Focusing Hhgcontrasting

confidence: 96%

“…Tight focusing leads to HHG in a smaller, but equally denser medium and should theoretically result in the same conversion efficiency, provided that the high phase matching pressure (high target density) can be achieved. It has been claimed previously that technical constraints, in particular the throughput of the vacuum pumping system, hinder this experimentally [11,19]. Starting from the experimental setup used by Constant et al [3] (laser beam radius w 0 = 125 μm, jet diameter d = 800 μm and phase matching pressure p pm ∼ 100 mbar) we investigate how the gas load to the vacuum system scales with the laser beam radius by employing the abovepresented scaling laws.…”

Section: High-density Target For Tight Focusing Hhgmentioning

confidence: 99%

“…A numerical optimization recently revealed conditions for phase-matched HHGs in this tight focusing regime [19] and a conversion efficiency as high as 5 × 10 −7 has been achieved for H11 to H19 employing a 1.03 μm driving laser and a xenon gas cell target. More generally, Heyl et al investigated the scaling of phase matching with the focal diameter [11].…”

Section: Introductionmentioning

confidence: 99%

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Absorption-limited and phase-matched high harmonic generation in the tight focusing regime

Rothhardt¹,

Krebs²,

Hädrich³

et al. 2014

New J. Phys.

111

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High harmonic generation (HHG) at a high repetition rate requires tight focusing of the moderate peak power driving pulses. So far the conversion efficiencies that have been achieved in this regime are orders of magnitude behind the values that have been demonstrated with loose focusing of high energy (high peak power) lasers. In this contribution, we discuss the scaling laws for the main physical quantities of HHG and in particular analyze the limiting effects: dephasing, absorption and plasma defocusing. It turns out that phase-matched and absorption-limited HHG can be achieved even for very small focal spot sizes using a target gas provided with an adequately high density. Experimentally, we investigate HHG in a gas jet of argon, krypton and xenon. By analyzing the pressure dependence we are able to disentangle the dephasing and absorption effects and prove that the generated high order harmonics are phase-matched and absorption-limited. The obtained conversion efficiency is as high as 8 × 10 −6 for the 17th harmonic generated in xenon and 1.4 × 10 −6 for the 27th harmonic generated in argon. Our findings pave the way for highly efficient harmonic generation at megahertz repetition rates. New J. Phys. 16 (2014) 033022 J Rothhardt et al New J. Phys. 16 (2014) 033022 J Rothhardt et al 3 New J. Phys. 16 (2014) 033022 J Rothhardt et al New J. Phys. 16 (2014) 033022 J Rothhardt et al 5

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Section: High-density Target For Tight Focusing Hhgcontrasting

confidence: 96%

Section: High-density Target For Tight Focusing Hhgmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Absorption-limited and phase-matched high harmonic generation in the tight focusing regime

Rothhardt¹,

Krebs²,

Hädrich³

et al. 2014

New J. Phys.

111

View full text Add to dashboard Cite

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“…All of these architectures are based on ytterbium-doped laser materials that limit the attainable pulse duration to a few hundred femtoseconds. Nevertheless, early experiments on HHG with fiber lasers have already indicated the great potential of these sources 16,17 , which has also been validated by the recently measured photon flux of 4.5 3 10 12 photons s -1 over several harmonics at 100 kHz repetition rate 18 . However, as noted above, the rather long pulse duration hinders efficient HHG, suggesting the need for post-compression techniques, such as nonlinear compression in noble gas-filled glass capillaries 19 .…”

Section: Introductionmentioning

confidence: 80%

Exploring new avenues in high repetition rate table-top coherent extreme ultraviolet sources

et al. 2015

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The process of high harmonic generation (HHG) enables the development of table-top sources of coherent extreme ultraviolet (XUV) light. Although these are now matured sources, they still mostly rely on bulk laser technology that limits the attainable repetition rate to the low kilohertz regime. Moreover, many of the emerging applications of such light sources (e.g., photoelectron spectroscopy and microscopy, coherent diffractive imaging, or frequency metrology in the XUV spectral region) require an increase in the repetition rate. Ideally, these sources are operated with a multi-MHz repetition rate and deliver a high photon flux simultaneously. So far, this regime has been solely addressed using passive enhancement cavities together with low energy and high repetition rate lasers. Here, a novel route with significantly reduced complexity (omitting the requirement of an external actively stabilized resonator) is demonstrated that achieves the previously mentioned demanding parameters. A krypton-filled Kagome photonic crystal fiber is used for efficient nonlinear compression of 9 mJ, 250 fs pulses leading to ,7 mJ, 31 fs pulses at 10.7 MHz repetition rate. The compressed pulses are used for HHG in a gas jet. Particular attention is devoted to achieving phase-matched (transiently) generation yielding .10 13 photons s -1 (.50 mW) at 27.7 eV. This new spatially coherent XUV source improved the photon flux by four orders of magnitude for direct multi-MHZ experiments, thus demonstrating the considerable potential of this source.

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“…The amplified pulses can be strong enough to be non-linearly converted up to 108 eV at 78 MHz 81 . The fiber lasers thus foresee the high-repetition-rate ultrafast spectroscopy in the deep-to-extreme ultraviolet region [77][78][79][80][81][82][83][84] ; already, they have been nourishing the ultrafast spectroscopy in the low-photon-energy regions such as THz 85 and multi-photon-photoemission methods 86 . Besides, fiber lasers are compact because of the flexibility, stable due to the all-solid nature, and cost effective owing to the economics scale of the telecommunications industry.…”

Section: Introductionmentioning

confidence: 99%

High repetition pump-and-probe photoemission spectroscopy based on a compact fiber laser system

Ishida

Otsu

Ozawa

et al. 2016

Review of Scientific Instruments

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The paper describes a time-resolved photoemission (TRPES) apparatus equipped with a Yb-doped fiber laser system delivering 1.2-eV pump and 5.9-eV probe pulses at the repetition rate of 95 MHz. Time and energy resolutions are 11.3 meV and ∼310 fs, respectively; the latter is estimated by performing TRPES on a highly oriented pyrolytic graphite (HOPG). The high repetition rate is suited for achieving high signal-to-noise ratio in TRPES spectra, thereby facilitating investigations of ultrafast electronic dynamics in the low pump fluence (p) region. TRPES of polycrystalline bismuth (Bi) at p as low as 30 nJ/mm 2 is demonstrated. The laser source is compact and is docked to an existing TRPES apparatus based on a 250-kHz Ti:sapphire laser system. The 95-MHz system is less prone to space-charge broadening effects compared to the 250-kHz system, which we explicitly show in a systematic probe-power dependency of the Fermi cutoff of polycrystalline gold. We also describe that the TRPES response of an oriented Bi(111)/HOPG sample is useful for fine-tuning the spatial overlap of the pump and probe beams even when p is as low as 30 nJ/mm 2 .

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Optimization and phase matching of fiber-laser-driven high-order harmonic generation at high repetition rate

Cited by 37 publications

References 16 publications

Absorption-limited and phase-matched high harmonic generation in the tight focusing regime

Absorption-limited and phase-matched high harmonic generation in the tight focusing regime

Exploring new avenues in high repetition rate table-top coherent extreme ultraviolet sources

High repetition pump-and-probe photoemission spectroscopy based on a compact fiber laser system

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