| 1. |
- Alessi, D., et al.
(författare)
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Efficient Excitation of Gain-Saturated Sub-9-nm-Wavelength Tabletop Soft-X-Ray Lasers and Lasing Down to 7.36 nm
- 2011
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Ingår i: Physical Review X. - : American Physical Society. - 2160-3308. ; 1:2
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Tidskriftsartikel (refereegranskat)abstract
- We have demonstrated the efficient generation of sub-9-nm-wavelength picosecond laser pulses of microjoule energy at 1-Hz repetition rate with a tabletop laser. Gain-saturated lasing was obtained at λ=8.85 nm in nickel-like lanthanum ions excited by collisional electron-impact excitation in a precreated plasma column heated by a picosecond optical laser pulse of 4-J energy. Furthermore, isoelectronic scaling along the lanthanide series resulted in lasing at wavelengths as short as λ=7.36 nm. Simulations show that the collisionally broadened atomic transitions in these dense plasmas can support the amplification of subpicosecond soft-x-ray laser pulses.
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| 2. |
- Alessi, D., et al.
(författare)
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Spectral Linewidth Measurement of an Injection-Seeded Transient 18.9 nm Soft X-Ray Laser
- 2011
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Ingår i: 2011 CONFERENCE ON LASERS AND ELECTRO-OPTICS (CLEO). - 9781557529107
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Konferensbidrag (refereegranskat)abstract
- The linewidth of an injection-seeded 18.9nm molybdenum soft x-ray laser (SXRL) was measured to be significantly wider than seeded optical field ionization SXRLs that use gaseous targets, an advantage for the development of sub-picosecond SXRLs.
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| 3. |
- Meng, L. M., et al.
(författare)
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Temporal coherence and spectral linewidth of an injection-seeded transient collisional soft x-ray laser
- 2011
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Ingår i: Optics Express. - : Optical Society of America. - 1094-4087. ; 19:13, s. 12087-12092
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Tidskriftsartikel (refereegranskat)abstract
- The temporal coherence of an injection-seeded transient 18.9 nm molybdenum soft x-ray laser was measured using a wavefront division interferometer and compared to model simulations. The seeded laser is found to have a coherence time similar to that of the unseeded amplifier, ~1 ps, but a significantly larger degree of temporal coherence. The measured coherence time for the unseeded amplifier is only a small fraction of the pulsewidth, while in the case of the seeded laser it approaches full temporal coherence. The measurements confirm that the bandwidth of the solid target amplifiers is significantly wider than that of soft x-ray lasers that use gaseous targets, an advantage for the development of sub-picosecond soft x-ray lasers.
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| 4. |
- Rocca, J. J., et al.
(författare)
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Advances in high repetition rate table-top soft X-ray lasers
- 2011
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Ingår i: X-RAY LASERS AND COHERENT X-RAY SOURCES. - : SPIE.
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Konferensbidrag (refereegranskat)abstract
- We discuss recent advances in the development of high repetition rate table-soft soft x-ray lasers resulting from research conducted at Colorado State University. Advancing saturated table-top lasers to shorter wavelengths we report the operation of gain-saturated sub-10 nm table-top lasers at 1 Hz repetition rate. We also present experimental results that show that injection-seeding of solid-target soft x-ray plasma amplifiers reduces the far field divergence by an order of magnitude and to allow for control of the far-field beam characteristics by tailoring the divergence of the seed. We finally discuss progress towards the development of high repetition rate compact all-diode-pumped soft x-ray lasers. We have operated the front end of the diode-pumped soft-ray laser driver at 100Hz repetition rate, obtaining sub-5 ps optical laser pulses of 100 mJ energy.
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| 5. |
- Rocca, J. J., et al.
(författare)
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Compact Soft X-ray Lasers for Imaging, Material Processing, and Characterization at the Nanoscale
- 2007
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Ingår i: 32nd IEEE/CPMT International Electronic Manufacturing Technology Symposium. - 9781424413355 ; , s. 72-73
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Konferensbidrag (refereegranskat)abstract
- As manufacturing of devices advances into the nanoscale, critical feature sizes have rapidly shrunk to below the wavelength of visible light. These advances in nanotechnology have created a need to develop better ways of accessing the nanoworld. The extreme ultraviolet (EUV)/ soft x-ray (SXR) region of the spectrum provides an opportunity to use coherent light at wavelengths that are 10- to 100-times shorter than visible light, at 1 to 100 nm. Given the diffraction limit in imaging resolution, these wavelengths allow us to "see" smaller features and "write" smaller patterns than would be possible with visible light. We have developed compact laser-pumped and discharge-pumped lasers operating at wavelengths of λ=13.2 nm [1] and λ=46.9 nm [2] respectively, and have used them in the demonstration of nanoscale full field imaging [3,4], nanopatterning [5], and nanoscale laser ablation [6]. The high brightness and short wavelength output from these lasers when combined with specialized EUV/SXR optics, offer unique opportunities for the implementation of table-top imaging, patterning and metrology tools with superior spatial resolution for applications in nanoscience and nanotechnology. Using these new compact short wavelength lasers we have built two microscopes, using λ=46.9 nm or λ=l 3.2 nm laser illumination. The compact λ=46.9 nm microscope (Fig. 1a and lb) condenses the light using a multilayer coated Schwarzschild mirror, and images the test object using a diffractive zone plate lens. The spatial resolution of this microscopes was assessed by imaging test samples consisting of dense line gratings of half-periods ranging from 200 down to 35 nm. Figure 2(a) and (b) show images of a 100 nm and 70 nm half-period gratings obtained with the λ =46.9 nm microscope. The lineout in the image of the 70 nm lines shows a modulation of ∼30% indicating that the features are fully resolved according to the Rayleigh criterion. By rearranging the optics, the λ=46.9 nm microscope can also image surfaces. An image of fully resolved dense metal lines, with half-period of 170 nm, patterned on the silicon wafer is shown in Figure 2 (c). The shorter wavelength λ= 3.2 nm microscope uses all zone plate optics to render images of transmissive test patterns with increased spatial resolution . An image of fully resolved 50 nm half-period dense lines acquired with a 20 seconds exposure is shown in Figure 2(d). From images like this one, the spatial resolution of the λ=13.2 nm table-top microscope was determined to be better than 38 nm [3]. The high coherence of these short wavelength lasers also allows for the printing of arrays of nanoscale features using interferometric lithography. We have demonstrated combined a λ=46.9 nm capillary discharge laser and a Lloyd's mirror to print arrays of cone-shaped nano-dots with ∼ 58 nm FWHM diameter (Fig 3a) [5]. The same arrangement was used to print arrays of nano-holes 120 nm FWHM and 100 nm in depth over areas in excess of 500 × 500 μm2 in different photoresists using exposure times as short as 80 s. Larger area patterns can be readily printed using precision translation stages and multiple exposures by overlay superposition. The ability to focus SXL laser light into near diffraction-limited spots also opens the possibility to develop new types of nanoprobes. We have demonstrated ablation of sub-100 nm diameter holes by directly focusing the output of a λ=46.9 nm laser onto a sample with a zone plate lens. Figure 3(b) shows an AFM image of a 82 nm diameter crater obtained ablating a 500 nm thick PMMA layer with a single laser shot. The holes were observed to have very clean walls and high reproducibility. We have recently added the capability to spectroscopically analyze the light emitted from the plasma created during the ablation, opening the possibility to develop analytic nanoprobles. All of these results illustrate the capabilities of compact short wavelength lasers for nanotechnology applications.
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| 6. |
- Rocca, J. J., et al.
(författare)
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High brightness table-top soft x-ray lasers at high repetition rate : injection-seeding of solid target plasma amplifiers and other developments - art. no. 670202
- 2007
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Ingår i: SOFT X-RAY LASERS AND APPLICATIONS VII. - : SPIE. ; , s. 70202-70202
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Konferensbidrag (refereegranskat)abstract
- We have recently demonstrated high repetition rate tabletop lasers operating at wavelengths as short as 10.9 rim based on collisional transient excitation of ions in plasmas created by laser heating of solid targets. As a further step in the development of these lasers into very high brightness and fully coherent soft x-ray sources, we have demonstrated injection seeding of the amplifiers with high harmonic seed pulses. We report results of an experiment in which a 32.6 rim Ne-like Ti amplifier was used to amplify a seed pulse from the 25(th) harmonic of Ti:Sapphire into the gain saturation regime. Simultaneous amplification of the 27(th) harmonic at 30.1 nm was also observed. The seeded soft x-ray laser beam was measured to approach full spatial coherence. We have demonstrated that this scheme is scalable to shorter wavelengths and that is capable of producing extremely bright soft x-ray laser pulse with essentially full coherence.
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| 7. |
- Alessi, D., et al.
(författare)
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Beam Characteristics of an Injection-Seeded Solid-Target Plasma Soft X-Ray Laser
- 2010
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Ingår i: 2010 23RD ANNUAL MEETING OF THE IEEE PHOTONICS SOCIETY. ; , s. 341-342
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Konferensbidrag (refereegranskat)abstract
- We have measured the near-field and far-field profiles (for lambda=13.9 nm) as well as temporal coherence (for lambda=18.9 nm) of injection-seeded and self-seeded solid-target amplifiers. The measurements were compared with model simulations.
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| 8. |
- Alessi, D, et al.
(författare)
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Gain-saturated 10.9 nm tabletop laser operating at 1 Hz repetition rate
- 2010
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Ingår i: Optics Letters. - : Optical Society of America. - 0146-9592 .- 1539-4794. ; 35:3, s. 414-6
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Tidskriftsartikel (refereegranskat)abstract
- We report the demonstration of a gain-saturated 10.9 nm tabletop soft x-ray laser operating at 1 Hz repetition rate. Lasing occurs by collisional electron impact excitation in the 4dS01-->4pP11 transition of nickel-like Te in a line-focus plasma heated by a chirped-pulse-amplification Ti:sapphire laser. With an average power of 1muW and pulse energy up to approximately 2microJ, this laser extends the ability to conduct tabletop laser experiments to a shorter wavelength.
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| 9. |
- Martz, Dale, et al.
(författare)
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High-energy 13.9 nm table-top soft-x-ray laser at 2.5 Hz repetition rate excited by a slab-pumped Ti:sapphire laser
- 2010
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Ingår i: Optics Letters. - : Optical Society of America. - 0146-9592 .- 1539-4794. ; 35:10, s. 1632-1634
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Tidskriftsartikel (refereegranskat)abstract
- We have demonstrated repetitive operation of a table-top lambda=13.9 nm Ni-like Ag soft-x-ray laser that generates laser pulses with 10 microJ energy. The soft-x-ray laser is enabled by a Ti:sapphire laser pumped by high-repetition-rate frequency-doubled high-energy Nd:glass slab amplifiers. Soft-x-ray laser operation at 2.5 Hz repetition rate resulted in 20 microwatt average power.
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| 10. |
- Menoni, C. S., et al.
(författare)
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Nanometer-scale imaging and ablation with Extreme Ultraviolet lasers
- 2007
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Ingår i: 2007 CONFERENCE ON LASERS & ELECTRO-OPTICS/QUANTUM ELECTRONICS AND LASER SCIENCE CONFERENCE (CLEO/QELS 2007), VOLS 1-5. - 9781424435906 ; , s. 1401-1402
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Konferensbidrag (refereegranskat)abstract
- The short wavelength and high brightness of compact extreme ultraviolet lasers is shown to enable the development of microscopes with spatial resolution of tens of nanometers and new types of nanoprobes.
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