Pulse-front tilt for short-wavelength lasing by means of traveling-wave plasma-excitation

Bleiner, Davide; Feurer, Thomas

doi:10.1364/ao.51.008848

Cited by 7 publications

(3 citation statements)

References 10 publications

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“…Considering the high photon energies of 103 eV or λ = 12 nm, the interaction with any material can efficiently lead to secondary electrons and photoemission. The source and its working principle are described in detail elsewhere [6][7][8][9][10][11][12].…”

Section: Extreme Ultraviolet Sourcementioning

confidence: 99%

Actinic damage of Y/Mo multilayer Bragg optics in a tabletop extreme ultraviolet laser

Bleiner¹

2019

Optics Damage and Materials Processing by EUV/X-ray Radiation VII

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Actinic irradiation (i.e. using ionizing light) of EUV pulses on a multilayer Bragg optics was investigated for characterizing the chemical effects. Photothermal effects are ruled out by the low repetition rate and low absolute energy of the EUV pulses. This would exclude the formation of melt-related particles, which have been however observed. Alternative explanations are discussed. The analysis concentrate on the structure and composition of the multilayer stack, with the aim of quantifying the kinetics.

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Section: Extreme Ultraviolet Sourcementioning

confidence: 99%

Actinic damage of Y/Mo multilayer Bragg optics in a tabletop extreme ultraviolet laser

Bleiner¹

2019

Optics Damage and Materials Processing by EUV/X-ray Radiation VII

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“…A partial turnaround to such trade-off was introduced with transient collisional excitation (TCE 3 ), i.e. using two drive pulses, and carrying out traveling-wave excitation (TWE), as explained in detail previously 4 . TWE aims to achieve the speed matching condition.…”

Section: Introductionmentioning

confidence: 99%

Quantitative compressor-easing for efficient coherent x-ray pulses

Bleiner¹

2019

Laser Beam Shaping XIX

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Tabletop plasma-driven X-ray lasers hold the promise to overcome beamtime limitation of accelerator facilities. Such unlimited access is essential for training purposes, industrial processes as well as for going beyond the "proof-of-principle" research. Tabletop X-ray lasers are demonstrated by single-pass amplified spontaneous emission (ASE) across a plasma medium by means of transient collisional excitation. The latter is either a discharge or a laser-produced plasma obtained by target material irradiation. The homogeneity of the plasma medium is crucial to minimize refraction or self-absorption. Generation of ASE across a plasma column is dramatically improved under traveling-wave excitation (TWE). This means that a pump laser pulse irradiates a target with a certain angle of attack, instead of classical normal incidence. In the latter case hot spots and cold spots are formed. In the case of TWE a single sweep of plasma is formed in the same direction of pump pulse. The latter is optimized when the sweep propagation is close to the speed of light (i.e the ASE speed), which implies small-angle of attack. Yet, short-wavelength plasma lasing needs large-angle target irradiation, in order to increase the pump penetration into the denser plasma core. High electron density is needed for high collisional pumping rates. The apparent tradeoff large angle (for short wavelength) vs small angle (for efficient gain) was solved by pulse shaping, i.e. pulse-front back-tilt. In fact, the TWE speed depends on the pulse-front slope (envelope of propagation front), whereas the optical penetration depth depends on the wavefront slope (envelope of phase). Pulse-front tilt was accomplished by means of pulse compressor misalignment ("easing"). The latter is the final stage of a chirped-pulse amplification (CPA) system that recompresses the stretched pulse. In this study it was found effective to use the easing of the compressor, only if coupled with a high-magnification frontend imaging/focusing component, and that higher order terms are marginal. It is concluded that sweep speed matching should be accomplished with minimal compressor misalignment of a few degrees and maximal imaging magnification. A complete computational study by means of Fourier Optics was performed and validated experimentally.

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“…Nilsen et al 8 have done a detailed gain length study of Mo plasma-laser with the traveling-wave excitation (TWE) 18 , and showed that without the traveling wave color-2 showed a weak gain. The use of the traveling-wave setup does increase the output of the color-2 in Mo by two orders of magnitude and is essential for observing strong lasing on this line.…”

Section: Introductionmentioning

confidence: 99%

Table-top two-color soft x-ray laser from Ni-like Mo plasma

Bleiner

2017

X-Ray Lasers and Coherent X-Ray Sources: Development and Applications

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Two-color laser pulses in a laboratory setup are interesting for enabling a number of advanced spectroscopy techniques. The generation by means of Ni-like laser-produced plasmas is promising for scaling down the wavelength towards the soft X-ray. The occurrence of a two-color signal has been documented in the 1990s and a detailed atomic physics study interpreted the pulse as due to concomitant collisional pumping (color-1) and self-photoexcitation (color-2). If this framework is on the atomic physics basis valid, its kinetic and hydrodynamic quantitative aspects need to be better understood. In particular, experimental observations leave room for a number of open points. Here we propose am amplified Raman scattering (ARS) scheme, to explain the growth of color-2 and its sensitivity to the plasma irradiation scheme.

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Pulse-front tilt for short-wavelength lasing by means of traveling-wave plasma-excitation

Cited by 7 publications

References 10 publications

Actinic damage of Y/Mo multilayer Bragg optics in a tabletop extreme ultraviolet laser

Actinic damage of Y/Mo multilayer Bragg optics in a tabletop extreme ultraviolet laser

Quantitative compressor-easing for efficient coherent x-ray pulses

Table-top two-color soft x-ray laser from Ni-like Mo plasma

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