Ar Capillary Discharge Research Articles

Spectral linewidth of a Ne-like Ar capillary discharge soft-x-ray laser and its dependence on amplification beyond gain saturation

Spectral linewidth of a Ne-like Ar capillary discharge soft-x-ray laser and its dependence on amplification beyond gain saturation

Demonstration of Nanomachining With Focused Extreme Ultraviolet Laser Beams

A major challenge in laser machining of microstructures is that of extending the spatial domain to the smaller dimensions of interest in nanotechnology. We demonstrate the feasibility of directly machining nanoscale structures with a focused extreme ultraviolet (EUV) laser beam. Clean sub-200-nm-wide trenches (130-nm full width at half maximum) were ablated on polymethyl methacrylate photoresist by focusing the 46.9-nm wavelength beam from a Ne-like Ar capillary discharge tabletop laser with a Fresnel zone plate lens. Considering that clean 82-nm holes were also ablated using the same laser, it can be expected that focused EUV laser light will enable the machining of significantly smaller features.

Large area interference lithography using a table-top extreme ultraviolet laser: a systematicstudy of the degree of mutual coherence

A prototype low cost table-top Ar capillary discharge laser source (1.5 ns pulse duration,λ = 46.9 nm) wassuccessfully used to produce, by means of interference lithography (with a simple Lloyd mirror setup), largearea (0.1 mm2) regular patterns from 400 nm down to 22.5 nm (half-pitch) on PMMA/Si (PMMA:polymethylmethacrylate) substrates. The experiments allowed a systematical investigationof the degree of mutual coherence of the source, giving a clear indication that theinterference lithography can be pushed down to the ultimate resolution limit ofλ/4.

Nanopatterning with interferometric lithography using a compact /spl lambda/=46.9-nm laser

We report the imprinting of nanometer-scale gratings by interferometric lithography at /spl lambda/=46.9 nm using an Ne-like Ar capillary discharge laser. Gratings with periods as small as 55 nm were imprinted on poly-methyl methacrylate using a Lloyd's mirror interferometer. This first demonstration of nanopatterning using an extreme ultraviolet (EUV) laser illustrates the potential of compact EUV lasers in nanotechnology applications.

Focusing of Soft X-ray using a Grazing Incidence Mirror

Attempts have been made to focus the light beam of soft X-rays generated from an Ar capillary discharge, using a grazing incidence Wolter-type mirror. A soft X-ray beam with an image of approximately 10 mm in diameter is focused to a spot less than a 1 mm. The result proves that the Wolter-type mirror is technically applicable for the focusing of the soft X-rays generated from a capillary discharge.

Application of extremely compact capillary discharge soft x-ray lasers to dense plasma diagnostics

Table-top capillary discharge soft x-ray lasers combine the advantages of a small size and a high repetition rate with an extremely high brightness similar to that of their laboratory-size predecessors. When utilized to probe high density plasmas their short wavelength results in a higher critical density, reduced refraction, decreased free-electron absorption, and higher resolution as compared to optical probes. These characteristics allow the design of experiments capable of measuring the evolution of plasmas with density–scale length products that are outside the reach of optical lasers. This paper reviews the use of a 46.9 nm wavelength Ne-like Ar capillary discharge table-top laser in dense plasma diagnostics, and reports soft x-ray laser interferometry results of spot-focus Nd:YAG laser plasmas created at moderate irradiation intensity (∼7×1012 W cm−2) with ∼13 ns pulse width duration laser pulses. The measurements produced electron density maps with densities up to 0.9×1021 cm−3 that show the development of a concave electron density profile that differ significantly from those of a classical expansion. This two-dimensional behavior, that was recently also observed in line-focus plasmas, is analyzed here for the case of spot-focus plasmas with the assistance of hydrodynamic model simulations. The results demonstrate the use of a table-top soft x-ray laser interferometer as a new high resolution tool for the study of high density plasma phenomena and the validation of hydrodynamic codes.

Generation of millijoule-level soft-x-ray laser pulses at a 4-Hz repetition rate in a highly saturated tabletop capillary discharge amplifier

Laser pulses with energies of as much as 1 mJ were generated at a wavelength of 46.9 nm by single-pass amplification in a 34.5 cm-long Ne-like Ar capillary discharge plasma. The large gain-length product of this plasma column allows for soft-x-ray amplification in a highly saturated regime, resulting in efficient energy extraction. Average laser output pulse energy of 0.88 mJ and peak power of 0.6 MW were obtained at a repetition rate of 4 Hz. With an estimated peak spectral brightness of approximately 1x10(23)photons /(s mm(2)mrad> (2)0.01% bandwidth) this tabletop laser is one of the brightest soft-x-ray sources to date.

Two-dimensional Near-field and Far-field Imaging of a Ne-like Ar Capillary Discharge Table-top Soft X-ray Laser

Get PDF Email Share Share with Facebook Tweet This Post on reddit Share with LinkedIn Add to CiteULike Add to Mendeley Add to BibSonomy Get Citation Copy Citation Text C. H. Moreno, M. C. Marconi, V. N. Shlyaptsev, B. R. Benware, C. D. Macchietto, J. L. A. Chilla, J. J. Rocca, and A. L. Osterheld, "Two-dimensional Near-field and Far-field Imaging of a Ne-like Ar Capillary Discharge Table-top Soft X-ray Laser," Optics & Photonics News 9(12), 55-55 (1998) Export Citation BibTex Endnote (RIS) HTML Plain Text Citation alert Save article

Two-dimensional near-field and far-field imaging of a Ne-like Ar capillary discharge table-top soft-x-ray laser

We have performed systematic measurements and numerical modeling of the divergence and exit beam size of a 46.9 nm Ne-like Ar capillary discharge pumped soft-x-ray amplifier. Two-dimensional near-field and far-field measurements were obtained over a wide range of discharge parameters. The spot size and divergence of the laser beam were observed to increase significantly with decreasing discharge pressure. Simultaneously, the beam intensity distribution changed from a single peak pattern to an annular profile. These effects are shown to be the result of increased refraction of the soft-x-ray beam, caused by larger density gradients in the plasma columns of the lower pressure discharges. The spatial images are nearly cylindrically symmetric, and have less structure than those reported in the literature for laser-driven soft-x-ray lasers. Beam profiles synthesized by model calculations are found to be in good agreement with the recorded images. The obtained images in combination with the model computations clarify the origin of the different beam patterns that are observed in capillary discharge soft-x-ray laser experiments.

Measurement of the Spatial Coherence Buildup in a Discharge Pumped Table-Top Soft X-Ray Laser

We have measured the variation of the spatial coherence with plasma column length in a saturated table-top 46.9-nm Ne-like Ar capillary discharge soft x-ray amplifier for lengths up to 16.4 cm. The measurements, which are in good agreement with time dependent wave-optics model computations, provide the first experimental evidence of a monotonic increase of the coherence with length in a soft x-ray amplifier. The variation of the coherence across the beam profile was also studied. Off axis, the coherence is larger in the tangential than in the radial direction. [S0031-9007(97)04235-X]