[show abstract][hide abstract] ABSTRACT: We have demonstrated broad bandwidth large area (229 mm x 114 mm) multilayer dielectric diffraction gratings for the efficient compression of high energy 800 nm laser pulses at high average power. The gratings are etched in the top layers of an aperiodic (Nb0.5Ta0.5)2O5-SiO2 multilayer coating deposited by ion beam sputtering. The mean efficiency of the grating across the area is better than 97% at the center wavelength and remains above 96% at wavelengths between 820 nm and 780 nm. The gratings were used to compress 5.5 J pulses from a Ti:sapphire laser with an efficiency above 80 percent.
[show abstract][hide abstract] ABSTRACT: Phase-coherent soft x-ray laser pulses of 1.13 plusmn 0.47 ps duration were generated by injection-seeding a solid-target Ne-like Ti plasma amplifier with high harmonic pulses. This is the shortest pulse duration reported to date from a table-top soft x-ray laser amplifier.
[show abstract][hide abstract] ABSTRACT: We report on a pulsewidth measurement of phase-coherent soft x-ray laser pulses generated by injection seeding a solid-target plasma amplifier with high harmonic pulses. A pulse duration of 1.13±0.47 ps was measured for a seeded Ne-like Ti plasma amplifier operating at 32.6 nm using an ultrafast streak camera. This is the shortest pulse duration reported to date from a table-top soft x-ray laser amplifier. The result agrees with model simulations which suggest that intense femtosecond soft x-ray laser pulses could be obtained by injection seeding a tailored plasma amplifier in which the gain is confined to a high density region.
Physical Review A 02/2009; 79(2). · 3.04 Impact Factor
[show abstract][hide abstract] ABSTRACT: We have recently demonstrated high repetition rate tabletop lasers operating at wavelengths as short as 10.9 nm 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 nm Ne-like Ti amplifier was used to amplify a seed pulse from the 25th harmonic of Ti:Sapphire into the gain saturation regime. Simultaneous amplification of the 27th 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.
[show abstract][hide abstract] ABSTRACT: The output energy dependence of high repetition rate grazing incidence pumped Ni-like Mo, Ni-like Ag, and Ne-like Ti transient collisional soft x-ray lasers on the duration of the pump pulse was studied combining experiments and model simulations. Lasing is observed to occur for a wide range of pump pulse widths (e.g., 2 to 18 ps for Ni-like Ag), with maximum output occurring for pump pulses of 4–6 ps FWHM, corresponding to pump intensities of 1.4–2.0×1014 W∕cm2. Moderately short pump pulses are observed to be optimum for lasers that make use of preplasmas in which the mean degree of ionization approaches the charge of the lasing ion, while long pump pulses produce over-ionization and weaker lasing. However, long pump pulses are capable of producing gain and lasing in low Z ions even when the preplasma has a very low degree of ionization after expanding for 5 ns. As the duration of the pump pulse shortens the optimum delay respect to the prepulse is observed to decrease. The physics that determines these and other measured trends is discussed.
Physical Review A 06/2007; 75(6). · 3.04 Impact Factor
[show abstract][hide abstract] ABSTRACT: We demonstrated the generation of an extremely bright Â¿=32.6nm laser beam with high spatial coherence by saturated amplification of high harmonic seed pulses in a soft x-ray laser plasma amplifier created heating a titanium target.
Quantum Electronics and Laser Science Conference, 2007. QELS '07; 06/2007
[show abstract][hide abstract] ABSTRACT: The spatial coherence of a 13.2 nm transient collisional Ni-like Cd soft X-ray laser pumped at 23 degrees grazing incidence was measured in a series of Young's double-slit experiments. We observed pronounced fringe visibility variations associated with microstructures in the beam's intensity profile. The transverse coherence length was measured to be about 1/20 of the beam diameter and did not significantly improve with longer plasma columns. The equivalent incoherent source size is determined to be 10 mum and the laser's peak spectral brightness ~ 3 x 10(23) photons/sec/mm(2)/mrad(2) within less than 0.01% spectral bandwidth.
[show abstract][hide abstract] ABSTRACT: We have developed two compact full-field extreme ultraviolet (EUV) microscopes that combine short-wavelength light from high-brightness tabletop lasers with zone plate and multilayer-coated reflective optics. One of these systems uses 47 nm wavelength light from a desktop-sized capillary discharge laser with resolution down to 70nm. This microscope can image in both transmission and reflection mode, allowing for imaging of surfaces. The other microscope uses 13 nm wavelength light from a table-top optically pumped EUV laser to acquire images with spatial resolution better than 38 nm. Both of these systems have the ability to render images with typical acquisition times of 10- 30 seconds These results open a path to the development of compact and widely available extreme-ultraviolet imaging tools capable of inspecting samples in a variety of environments with a 15-20 nm spatial resolution and a picosecond time resolution.
[show abstract][hide abstract] ABSTRACT: We have demonstrated saturated tabletop lasers operating at 5 Hz repetition rate with microwatt average powers at wavelengths
between 18.9 nm and 13.2 nm in the 4d 1P1-4p 1S0 transitions of Ni-like ions. Lasing was also observed on transitions of the same isolectronic sequence for wavelengths
as low as 10.9 nm in Ni-like Te, and on transitions near 30 nm in Ne-like ions. The results were obtained using picosecond
laser heating pulses with an energy of only 1J by optimizing the grazing incidence angle of the pump beam for maximum energy
deposition. As a further step in the development of these lasers we also realized the first demonstration of saturated amplification
of a high harmonic seed in a transient collisional soft x-ray laser amplifier created by heating a solid target. A 32.6 nm
Ne-like Ti amplifier was used to amplify a seed pulse from the 25th harmonic of Ti:Sa into the gain saturation regime. The amplified beam was measured to approach full spatial coherence. The
peak spectral brightness is estimated to be ~ 2x1026 photons/(s.mm2.mrad2 0.01% bandwidth). The scheme is scalable to produce extremely bright lasers at very short wavelength.
[show abstract][hide abstract] ABSTRACT: We report the demonstration of soft x-ray microscopes with resolution down to sub-38 nm using tabletop soft x-ray laser illumination.
One of the compact microscopes combines the 46.9 nm wavelength output from a capillary discharge Ne-like Ar laser with a reflective
condenser and a free standing zone plate objective. High quality images were acquired with this microscope in transmission
mode and reflection mode. The latter includes images of an integrated circuit pattern containing polysilicon features on silicon.
The spatial resolution for this microscope is between 120-150 nm. Increased resolution was demonstrated in another microscope
using 13.2/13.9 nm wavelength illumination from Ni-like Cd/Ag transient soft x-ray lasers in combination with diffractive
zone plate optics for both the condenser and objective. Using an objective zone plate with a 50 nm outer zone width, this
optical system achieved a record sub-38 nm spatial resolution. These results demonstrate the feasibility of using compact
high repetition rate soft-x-ray laser sources in nanometer-scale microscopy.
[show abstract][hide abstract] ABSTRACT: In this paper, we have demonstrated nanoscale resolution microscopy in transmission and reflection modes using the lambda=46.9 nm and lambda=13 nm wavelength output from table-top EUV lasers. This compact microscope acquires high quality images in transmission and reflection modes in tens of seconds. Its spatial resolution has been determined to be 120-150 nm
Lasers and Electro-Optics Society, 2006. LEOS 2006. 19th Annual Meeting of the IEEE; 11/2006
[show abstract][hide abstract] ABSTRACT: We have measured the pulse duration of gain-saturated 13.9 nm Ni-like Ag and 13.2 nm Ni-like Cd transient collisional lasers excited by grazing-incidence-pumping for several pumping conditions. High-resolution streak-camera measurements yielded FWHM pulse durations close to 5 ps for both lasers under optimum pumping conditions. The very high brightness and short pulse duration of these new high repetition tabletop soft x-ray lasers make them an attractive source for dynamic applications.
[show abstract][hide abstract] ABSTRACT: Images with sub-38nm spatial resolution were obtained with a tabletop microscope based on a high repetition rate tabletop 13nm wavelength laser and zone-plate optics.
[show abstract][hide abstract] ABSTRACT: New high repetition rate table-top soft X-ray lasers allow the generation of intense coherent soft X-ray beams. The high peak spectral brightness of these lasers in the 25-100 eV photon energy region enable new applications
[show abstract][hide abstract] ABSTRACT: We demonstrate the generation of an intense soft-x-ray-laser beam by saturated amplification of high harmonic seed pulses in a dense transient collisional soft-x-ray-laser plasma amplifier created by heating a titanium target. Amplification in the 32.6 nm line of Ne-like Ti generates laser pulses of subpicosecond duration that are measured to approach full spatial coherence. The peak spectral brightness is estimated to be approximately 2 x 10(26) photons/(s mm(2) mrad(2) 0.01% bandwidth). The scheme is scalable to produce extremely bright lasers at very short wavelengths with full temporal and spatial coherence.
[show abstract][hide abstract] ABSTRACT: We have generated a laser average output power of 2 microW at a wavelength of 13.9 nm by operating a tabletop laser-pumped Ni-like Ag laser at a 5 Hz repetition rate, using a solid helicoidal target that is continuously rotated and advanced to renew the target surface between shots. More than 2 x 10(4) soft-x-ray laser shots were obtained by using a single target. Similar results were obtained at 13.2 nm in Ni-like Cd with a Cd-coated target. This scheme will allow uninterrupted operation of laser-pumped tabletop collisional soft-x-ray lasers at a repetition rate of 10 Hz for a period of hours, enabling the generation of continuous high average soft-x-ray powers for applications.
[show abstract][hide abstract] ABSTRACT: We have acquired images with a spatial resolution better than 38 nm by using a tabletop microscope that combines 13 nm wavelength light from a high-brightness tabletop laser and Fresnel zone plate optics. These results open a gateway to the development of compact and widely available extreme-ultraviolet imaging tools capable of inspecting samples in a variety of environments with a 15-20 nm spatial resolution and a picosecond time resolution.
[show abstract][hide abstract] ABSTRACT: A table-top lambda = 13.2 nm soft X-ray laser operating at 5 Hertz repetition rate with 1 muW average power was demonstrated in Ni-like Cd. Lasing down to 10.9 nm was also obtained in transitions of other Ni-like ions.
[show abstract][hide abstract] ABSTRACT: There is significant interest in the development of compact high-average-power soft-x-ray lasers for a variety of applications in imaging, spectroscopy, plasma diagnostics, and metrology. In particular, there is a need for the development of compact sources of coherent light at wavelengths within the bandwidth of the Mo--Si mirrors centered at 13.5 nm for at-wavelength metrology related to extreme ultraviolet lithography. Soft x-ray laser operation at this wavelength have been limited to one shot every several minutes due to inefficient plasma heating. In this work we report the first demonstration of high repetition rate operation of saturated lasers emitting in this spectral region. Operation at 5 Hz repetition rate generated an average power of 1-2 muW at 13.9 and 13.2 nm in the 4d1S0--4p1P1 transitions of Ni-like Ag and Ni-like Cd ions respectively. The results were obtained by efficiently heating a plasma an with 8 ps pulse of only 1 J energy impinging at grazing incidence. Laser amplification at wavelengths as short as 10.9 nm was also observed by isoelectronic scaling these results along the Ni-like ion sequence. These table-top lasers can be expected to enable numerous new applications of intense coherent soft x-ray light. Work supported by the NSF EUV ERC, Award EEC-0310717 and by the US Department of Energy.