Ultrafast spectroscopy in the extreme ultraviolet demands for ever-higher pulse repetition rates and photon energies. Here, we drive cavity-enhanced high-order harmonic generation (HHG) at a rate of 250 MHz, with 30 fs pulses an average power 10 kW. Employing optimized cavity geometry high-pressure gas target, couple out nanowatt-level harmonics energies around 100 eV. This constitutes improvement more than two orders magnitude over previous megahertz-repetition-rate HHG experiments paves...

Abstract Laser-dressed photoelectron spectroscopy, employing extreme-ultraviolet attosecond pulses obtained by femtosecond-laser-driven high-order harmonic generation, grants access to atomic-scale electron dynamics. Limited space charge effects determining the admissible number of photoelectrons ejected during each laser pulse, multidimensional (i.e. spatially or angle-resolved) spectroscopy solids and nanostructures requires high-photon-energy, broadband high sources operating at...

Three-dimensional photoelectron angular distributions (PADs) are measured from an atomic target ionized by ultrafast, elliptical fields of opposite handedness. Comparing these PADs to one another and numeric simulations, a difficult avoid systematic error in their orientation is identified subsequently corrected imposing the dichroic symmetry which they necessarily related. We show that this correction can be directly applied molecular targets same fields. This paves way for measurement...

We report on the pulse compression of an 18.5 MHz repetition rate train from 230 fs to sub-40 by nonlinear spectral broadening in a multi-pass cell and subsequent chirp removal. The compressed energy is <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$4.5~\mu \text{J}$ </tex-math></inline-formula> , which corresponds 84 W average power, with efficiency 88%. This recently introduced scheme suitable for large...

We introduce and experimentally validate a pulse picking technique based on travelling-wave-type acousto-optic modulator (AOM) having the AOM carrier frequency synchronized to repetition rate of original train.As consequence, phase noise characteristic train is largely preserved, rendering this suitable for applications requiring carrier-envelope stabilization.In proof-ofprinciple experiment, 1030-nm spectral part an 74-MHz, carrierenvelope stable Ti:sapphire oscillator amplified reduced in...

We combine high-finesse optical resonators and spatial-spectral interferometry to a highly phase-sensitive investigation technique for nonlinear light-matter interactions. experimentally validate an ab initio model the response of resonator housing gas target, permitting global optimization intracavity conversion processes like high-order harmonic generation. predict feasibility driving generation far beyond intensity limitations observed in state-of-the-art systems by exploiting...

Since their inception, velocity map imaging (VMI) techniques have received continued interest in expansion from 2D to 3D momentum measurements through either reconstructive or direct methods. Recently, much work has been devoted the latter of these by relating electron time-of-flight (TOF) third component. The challenge is having a timing resolution sufficient resolve structure narrow (<10 ns) TOF spread. Here, we build upon VMI lens design and measurement using plano-convex thick-lens...

We present a high-power, MHz-repetition-rate, phase-stable femtosecond laser system based on phase-stabilized Ti:Sa oscillator and multi-stage Yb-fiber chirped-pulse power amplifier. A 10-nm band around 1030 nm is split from the 7-fs output serves as seed for subsequent amplification by 54 dB to 80 W of average power. The µJ-level spectrally broadened in solid-core fiber compressed ~30 fs with chirped mirrors. pulse picker prior allows decreasing repetition rate 74 MHz factor up 4 without...

Abstract Time-resolved photoelectron spectroscopy with attosecond precision provides new insights into the photoelectric effect and gives information about timing of photoemission from different electronic states within band structure solids. Electron transport, scattering phenomena electron-electron correlation effects can be observed on time scales by valence against that core states. However, accessing intraband was so far particularly challenging due to simultaneous requirements energy,...

Modern ultrafast laser architectures enable high-order harmonic generation (HHG) in gases at (multi-) MHz repetition rates, where each atom interacts with multiple pulses before leaving the HHG volume. This raises question of cumulative plasma effects on nonlinear conversion. Utilizing a femtosecond enhancement cavity argon and on-axis geometric extreme-ultraviolet (XUV) output coupling, we experimentally compare single-pulse case double-pulse regime which gas is hit by two while traversing...

We present a simple approach to characterize the spatial variation of gain in microchannel plate (MCP) coupled phosphor detectors using single electron or photon hits. The technique is easy implement and general enough be extended other kinds detectors. demonstrate efficacy on both laboratory Monte Carlo generated datasets. Furthermore, we use measure over time as MCP exposed an increasing number electrons.

We demonstrate how the depleted pump of an optical parametric amplifier can be recycled for impulsive alignment a molecular gas inside hollow-core fiber and use such broadening frequency shift signal pulse at center wavelength ∼1300 nm. Our results combine non-adiabatic alignment, self-phase modulation, Raman non-linearities. spectral shifts up to 204 nm more than one octave. also report on time delays which occurs, do not coincide with any rotational constants. Further, we encounter that...

Enhancement cavities (ECs) seeded with femtosecond pulses have developed into the most powerful technique for high-order harmonic generation (HHG) at repetition rates in tens of MHz. Here, we demonstrate feasibility controlling phase front excited transverse eigenmode a ring EC by using mirrors stepped surface profiles, while maintaining high finesse required to reach peak intensities necessary HHG. The two lobes mode 3.93 m long EC, single-frequency laser, are delayed 15.6 fs respect each...

Femtosecond enhancement cavities have enabled multi-10-MHz-repetition-rate coherent extreme ultraviolet (XUV) sources with photon energies exceeding 100 eV -albeit rather severe limitations of the net conversion efficiency and duration XUV emission.Here, we explore possibility circumventing both these by harnessing spatiotemporal couplings in driving field, similar to "attosecond lighthouse," theory experiment.Our results predict dramatically improved output coupling efficiencies efficient...

Abstract The study of nanomaterials is an active area research for technological applications as well fundamental science. A common method studying properties isolated nanoparticles by in-vacuum particle beam produced via aerodynamic lens. Despite being practice, characterization such beams has proven difficult light scattering detection techniques fail particles with sizes beyond the diffraction limit. Here we present a new technique characterizing nanoparticle using strong field...

Cavity-enhanced high-order harmonic generation (HHG) affords broadband, coherent extreme-ultraviolet (XUV) pulse trains with repetition rates of several tens MHz. Geometrically coupling out the intracavity generated XUV beam through a small on-axis hole in cavity mirror following HHG focus has enabled scaling photon energies attainable this technology to 100 eV and more, promising new applications frequency-comb spectroscopy attosecond-temporal-resolution, multidimensional photoelectron...

A promising alternative to Gaussian beams for use in strong field science is Bessel-Gauss (BG or Bessel-like) laser as they are easily produced with readily available optics and provide more flexibility of the spot size working distances. Here we BG a lens-axicon optical system higher order harmonic generation (HHG) thin gas jet. The finite interaction region allows scans HHG yield along propagation axis. Further, by measuring ionization unison extreme ultraviolet (XUV) able distinguish...

Experiments requiring ultrafast laser pulses require a full characterization of the electric field to glean meaning from experimental data. Such typically requires separate parametric optical process. As central wavelength range new sources continues increase so too does need for nonlinear crystals suited characterizing these wavelengths. Here we report on use poly-crystalline zinc selenide as universal crystal in frequency resolved gating technique near long-wavelength infrared. Due its...

Scaling spectral broadening to higher pulse energies and average powers, respectively, is a critical step in ultrafast science, especially for narrowband Yb-based solid state lasers which become the new state-of-the-art. Despite their high nonlinearity, molecular gases as medium inside hollow-core fibers have been limited 25 W, at best. We demonstrate nitrogen ten-fold powers up 250W with repetition rates from 200kHz. The observed stronger compared more expensive krypton gas enables...

Scaling spectral broadening to higher pulse energies and average powers, respectively, is a critical step in ultrafast science, especially for narrowband Yb-based solid state lasers which become the new state-of-the-art. Despite their high nonlinearity, molecular gases as medium inside hollow-core fibers have been limited 25 W, at best. We demonstrate nitrogen ten-fold powers up 250W with repetition rates from 200kHz. The observed stronger compared more expensive krypton gas enables...

Scaling spectral broadening to higher pulse energies and average powers, respectively, is a critical step in ultrafast science, especially for narrowband Yb based solid state lasers which become the new of art. Despite their high nonlinearity, molecular gases as medium inside hollow core fibers have been limited 25 W, at best. We demonstrate nitrogen ten-fold powers up 250W with repetition rates from 200kHz. The observed stronger compared more expensive krypton gas enables compression 1.3ps...

3D photoelectron angular distributions (PADs) are measured from an atomic target ionized by ultrafast, elliptical fields of opposite handedness. Comparing these PADs to one another and numeric simulations, a difficult avoid systematic error in their orientation is identified subsequently corrected imposing the dichroic symmetry which they necessarily related. We show that this correction can be directly applied molecular targets same fields. This paves way for measurement enantiosensitive...

Scaling spectral broadening to higher pulse energies and average powers is a critical step in ultrafast science, especially for narrowband Yb-based solid state lasers, which have become the new state-of-the-art. Despite their high nonlinearity, molecular gases as medium inside hollow-core fibers been limited 25 W, at best. We demonstrate nitrogen ten-fold up 250 W with repetition rates from 200 kHz. The observed stronger compared more expensive krypton gas enables compression 1.3 ps 120 fs....