340 research outputs found
Table-Top Milliwatt-Class Extreme Ultraviolet High Harmonic Light Source
Extreme ultraviolet (XUV) lasers are essential for the investigation of
fundamental physics. Especially high repetition rate, high photon flux sources
are of major interest for reducing acquisition times and improving signal to
noise ratios in a plethora of applications. Here, an XUV source based on
cascaded frequency conversion is presented, which delivers due to the drastic
better single atom response for short wavelength drivers, an average output
power of (832 +- 204) {\mu}W at 21.7 eV. This is the highest average power
produced by any HHG source in this spectral range surpassing precious
demonstrations by more than a factor of four. Furthermore, a narrow-band
harmonic at 26.6 eV with a relative energy bandwidth of only {\Delta}E/E= 1.8 x
10E-3 has been generated, which is of high interest for high precision
spectroscopy experiments.Comment: 4 Pages, 4 Picture
High photon flux table-top coherent extreme ultraviolet source
High harmonic generation (HHG) enables extreme ultraviolet radiation with
table-top setups. Its exceptional properties, such as coherence and
(sub)-femtosecond pulse durations, have led to a diversity of applications.
Some of these require a high photon flux and megahertz repetition rates, e.g.
to avoid space charge effects in photoelectron spectroscopy. To date this has
only been achieved with enhancement cavities. Here, we establish a novel route
towards powerful HHG sources. By achieving phase-matched HHG of a megahertz
fibre laser we generate a broad plateau (25 eV - 40 eV) of strong harmonics,
each containing more than photons/s, which constitutes an increase by
more than one order of magnitude in that wavelength range. The strongest
harmonic (H25, 30 eV) has an average power of 143 W (
photons/s). This concept will greatly advance and facilitate applications in
photoelectron or coincidence spectroscopy, coherent diffractive imaging or
(multidimensional) surface science
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Hybrid soliton dynamics in liquid-core fibres
The discovery of optical solitons being understood as temporally and spectrally stationary optical states has enabled numerous innovations among which, most notably, supercontinuum light sources have become widely used in both fundamental and applied sciences. Here, we report on experimental evidence for dynamics of hybrid solitons—a new type of solitary wave, which emerges as a result of a strong non-instantaneous nonlinear response in CS2-filled liquid-core optical fibres. Octave-spanning supercontinua in the mid-infrared region are observed when pumping the hybrid waveguide with a 460 fs laser (1.95 μm) in the anomalous dispersion regime at nanojoule-level pulse energies. A detailed numerical analysis well correlated with the experiment uncovers clear indicators of emerging hybrid solitons, revealing their impact on the bandwidth, onset energy and noise characteristics of the supercontinua. Our study highlights liquid-core fibres as a promising platform for fundamental optics and applications towards novel coherent and reconfigurable light sources
Broadband ptychography using curved wavefront illumination
We examine the interplay between spectral bandwidth and illumination
curvature in ptychography. By tailoring the divergence of the illumination,
broader spectral bandwidths can be tolerated without requiring algorithmic
modifications to the forward model. In particular, a strong wavefront curvature
transitions a far-field diffreaction geometry to an effectively near-field one,
which is lees affected by temporal coherence effects. The relaxed temporal
coherence requirements allow for leveraging wider spectral bandwidths and
larger illumination spots. Our findings open up new avenues towards utilizing
pink and broadband beams for increased flux and throughput at both synchrotron
facilities and lab-scale beamlines
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Carbon chloride-core fibers for soliton mediated supercontinuum generation
We report on soliton-fission mediated infrared supercontinuum generation in liquid-core step-index fibers using highly transparent carbon chlorides (CCl4, C2Cl4). By developing models for the refractive index dispersions and nonlinear response functions, dispersion engineering and pumping with an ultrafast thulium fiber laser (300 fs) at 1.92 μm, distinct soliton fission and dispersive wave generation was observed, particularly in the case of tetrachloroethylene (C2Cl4). The measured results match simulations of both the generalized and a hybrid nonlinear Schrödinger equation, with the latter resembling the characteristics of non-instantaneous medium via a static potential term and representing a simulation tool with substantially reduced complexity. We show that C2Cl4 has the potential for observing non-instantaneous soliton dynamics along meters of liquid-core fiber opening a feasible route for directly observing hybrid soliton dynamics
3.5  kW coherently combined ultrafast fiber laser
An ultrafast laser based on the coherent beam combination of four ytterbium-doped step-index fiber amplifiers is presented. The system delivers an average power of 3.5 kW and a pulse duration of 430 fs at an 80 MHz repetition rate. The beam quality is excellent (M2<1.24·1.10), and the relative intensity noise is as low as 1% in the frequency span from 1 Hz to 1 MHz. The system is turn-key operable, as it features an automated spatial and temporal alignment of the interferometric amplification channels
10.4  kW coherently combined ultrafast fiber laser
An ultrafast laser delivering 10.4 kW average output power based on a coherent combination of 12 step-index fiber amplifiers is presented. The system emits close-to-transform-limited 254 fs pulses at an 80 MHz repetition rate, and has a high beam quality (M2≤1.2) and a low relative intensity noise of 0.56% in the frequency range of 1 Hz to 1 MHz. Automated spatiotemporal alignment allows for hands-off operation
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