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We describe a platform to measure the material properties, specifically the equation of state and electron temperature, at pressures of 100 Mbar to a Gbar at the National Ignition Facility (NIF). In these experiments we launch spherically convergent shock waves into solid CH, CD, or diamond samples using a hohlraum radiation drive, in an indirect drive laser geometry. X-ray radiography is applied to measure the shock speed and infer the mass density profile, enabling determination of the material pressure and Hugoniot equation of state. X-ray scattering is applied to measure the electron temperature through probing of the electron velocity distribution via Doppler broadening.

We report a recent experiment where the first hard x-ray beam line, X-ray Pump Probe (XPP) instrument using the SLAC National Accelerator Laboratory's Linac Coherent Light Source (LCLS) free electron laser, was used to heat thin foils to high energy densities ∼ 107 J/cm 3. An intense 9 keV, 60 fs (FWHM) duration beam with energy of 2 - 4 mJ at the XPP beam line was focused using beryllium lenses to an irradiance approaching 1016 Wcm -2. Targets of 0.5 - 3.5 μm thick foils of Ag and Cu were studied using a suite of diagnostics including Fourier Domain Interferometry, energy calorimetry and grating and crystal spectrometers. The experimental details and spectroscopic results from the campaign will be described. Preliminary results indicate that the target is heated relatively uniformly to a temperature lower than 20 eV. © 2011 SPIE.

We report on soft X-ray scattering experiments on cryogenic hydrogen and simple metal samples. As a source of intense, ultrashort soft X-ray pulses we have used free-electron laser radiation at 92 eV photon energy from FLASH at DESY, Hamburg. X-ray pulses with energies up to 150 μJ and durations 15-50 fs provide interaction with the sample leading simultaneously to plasma formation and scattering. Experiments exploiting both of these interactions have been carried out, using the same experimental setup. Firstly, recording of soft X-ray inelastic scattering from near-solid density hydrogen plasmas at few electron volt temperatures confirms the feasibility of this diagnostics technique. Secondly, the soft X-ray excitation of few electron volt solid-density plasmas in bulk metal samples could be studied by recording soft X-ray line and continuum emission integrated over emission times from fs to ns. © 2009 Elsevier B.V.

We report on the x-ray absorption of Warm Dense Matter experiment at the FLASH Free Electron Laser (FEL) facility at DESY. The FEL beam is used to produce Warm Dense Matter with soft x-ray absorption as the probe of electronic structure. A multilayer-coated parabolic mirror focuses the FEL radiation, to spot sizes as small as 0.3μm in a ∼15fs pulse of containing >10 12 photons at 13.5 nm wavelength, onto a thin sample. Silicon photodiodes measure the transmitted and reflected beams, while spectroscopy provides detailed measurement of the temperature of the sample. The goal is to measure over a range of intensities approaching 10 18 W/cm 2. Experimental results will be presented along with theoretical calculations. A brief report on future FEL efforts will be given. © 2009 SPIE.

We have developed accurate x-ray scattering techniques to measure the physical properties of dense plasmas. Temperature and density are inferred from inelastic x-ray scattering data whose interpretation is model-independent for low to moderately coupled systems. Specifically, the spectral shape of the non-collective Compton scattering spectrum directly reflects the electron velocity distribution. In partially Fermi-degenerate systems that have been investigated experimentally in laser shock-compressed beryllium, the Compton scattering spectrum provides the Fermi energy and hence the electron density. We show that forward scattering spectra that observe collective plasmon oscillations yield densities in agreement with non-collective Compton scattering. In addition, electron temperatures inferred from the dispersion of the plasmon feature are consistent with the ion temperature sensitive elastic scattering feature. Hence, theoretical models of the static ion–ion structure factor and consequently the equation of state of dense matter can be directly tested.

We present measurements of the chlorine K-alpha emission from reduced mass targets, irradiated with ultra-high intensity laser pulses. Chlorinated plastic targets with diameters down to 50 μm and mass of a few 10−8 g were irradiated with up to 7 J of laser energy focused to intensities of several 1019 W/cm2. The conversion of laser energy to K-alpha radiation is measured, and high-resolution spectra that allow observation of line shifts are observed, indicating isochoric heating of the target up to 18 eV. A zero-dimensional 2-temperature equilibration model, combined with electron impact K-shell ionization and post processed spectra from collisional radiative calculations reproduces the observed K-alpha yields and line shifts, and shows the importance of target expansion due to the hot electron pressure.

The plasma conditions in isochorically heated beryllium are measured by collective x-ray Thomson scattering. The collectively scattered Cl Ly-α x-ray line at 2.96 keV shows up- and down-shifted plasmon signals. From the detailed balance relation, i.e., the ratio of the up-shifted to the down-shifted plasmon intensities, the plasma temperature can be determined independent of model assumptions. Results are shown for an experiment in which a temperature of 18 eV was measured. Using detailed balance for temperature measurement will be important to validate models that calculate the static ion–ion structure factor Sii(k).

A plasmonic interference pattern can be formed when multiple surface plasmon waves overlap coherently. Utilizing a sharp edge coupling mechanism, we experimentally demonstrate plasmonic interference patterns that can be designed at will by shaping the edges in a metallic film. The patterns can also be dynamically tailored by adjusting the wavelength, the polarization, and the incident angle of the excitation light beam. Possessing the subdiffraction limited feature resolution, this dynamical manipulation method of surface plasmon patterns will have profound potentials in nanolithography, particle manipulation, and other related fields.

The fabrication process as well as the optical characterization of a Far-field Superlens (FSL) is presented in detail. A FSL is capable of optically imaging well below the diffraction limit and works by enhancing and scattering evanescent waves to the far field which is then used to numerically reconstruct the object image [S. Durant, J. Opt. Soc. Am. B. 23(2006) 2383; Z. Liu, S. Durant, H. Lee, Y. Pikus, N. Fang, Y. Xiong, C. Sun, X. Zhang, Nano Lett. 7 (2007) 403]. We demonstrate the resolution of 70 nm gap distance of a three-line object in the far field. Also, a full optical imaging scheme, without the need for numerical processing, for a direct real-time subdiffraction-limited imaging is presented. Such remarkable imaging capability of FSL will revolutionize the optical imaging technique in the field of bio-imaging and nanolithography.

Far-field optical lens resolution is fundamentally limited by diffraction, which typically is about half of the wavelength. This is due to the evanescent waves carrying small scale information from an object that fades away in the far field. A recently proposed superlens theory offers a new approach by surface excitation at the negative index medium. We introduce a far-field optical superlens (FSL) that is capable of imaging beyond the diffraction limit. The FSL significantly enhances the evanescent waves of an object and converts them into propagating waves that are measured in the far field. We show that a FSL can image a subwavelength object consisting of two 50 nm wide lines separated by 70 nm working at 377 nm wavelength. The optical FSL promises new potential for nanoscale imaging and lithography.

We numerically investigate the effect of the pixel boundary on the angular emission characteristics of top-emitting organic light-emitting diodes (OLEDs) using the finite element method. A three-dimensional OLED structure has the square pixel boundary, which is surrounded by the pixel definition layer. The angular emission characteristics based on the Poynting vectors are calculated in various positions of a Hertz dipole emitter within the pixel boundary. When the dipole emitter is located near the center of the square pixel, the angular emission characteristics have a symmetric forward-directed pattern, which is similar to the angular emission pattern calculated by the thin-film-based optical model. When the position of the dipole emitter is close to the pixel boundary, the angular emission pattern becomes asymmetric because the optical reflections from the pixel boundary in the horizontal direction affect the emission pattern of the dipole emitter. The total angular emission characteristics of the top-emitting OLED are obtained by summing the individual angular emission pattern of the whole dipole emitters, which are assumed to be uniformly distributed in the two-dimensional emission plane. The asymmetrical angular emission characteristics of the dipole emitters near the pixel boundary contribute to narrowing the total angular emission pattern. (C) 2015 Optical Society of America.

Recent theory has predicted a superlens that is capable of producing sub–diffraction-limited images. This superlens would allow the recovery of evanescent waves in an image via the excitation of surface plasmons. Using silver as a natural optical superlens, we demonstrated sub–diffraction-limited imaging with 60-nanometer half-pitch resolution, or one-sixth of the illumination wavelength. By proper design of the working wavelength and the thickness of silver that allows access to a broad spectrum of subwavelength features, we also showed that arbitrary nanostructures can be imaged with good fidelity. The optical superlens promises exciting avenues to nanoscale optical imaging and ultrasmall optoelectronic devices.

By utilizing the band-selective nature of optically resonant nanoparticles, Tanner Research is developing a room temperature multi-spectral IR detection technology termed Nanobolometer. Because the device physics is not based on photodiode/photoconductive (cooled IR detectors) operation, it does not require cooling. It is also not a heat sensing (Microbolometers) scheme and is capable of multi-spectral detection from NIR to LWIR. A nanobolometer is built on a Si substrate for the entire detection bands (NIR-LWIR), which enables low material and fabrication costs, with an added advantage of being able to integrate UV/Vis detector pixels in the same platform. We present the theory and working principle of Tanner's Nanobolomter technology and report a proof-of-concept demonstration that achieved IR detection at 1.5 μm. Tanner's on-going R&D effort aims to extend the detection bands to MWIR/LWIR.

Collective x-ray Thomson scattering allows measuring plasmons, i.e electron plasma oscillations (Langmuir waves). This is manifest in the appearance of spectrally up- and down-shifted spectral features in addition to the Rayleigh signal. The ratio of the up- and down-shifted signals is directly related to detailed balance, allowing to determine the plasma temperature from first principles. The spectral shift of the plasmon signals is sensitive to temperature and electron density. We discuss the experimental considerations that have to be fulfilled to observe plasmon signals with x-ray Thomson scattering. As an example, we describe an experiment that used the Cl Ly-{alpha} x-ray line at 2.96 keV to measure collective Thomson scattering from solid beryllium, isochorically heated to 18 eV. Since temperature measurement based on detailed balance is based on first principles, this method is important to validate models that, for example, calculate the static ion-ion structure factor S{sub ii}(k).

Electric field-controlled ferromagnetism of (Zn,Co)O is demonstrated via anomalous Hall effect measurements. The electron carrier concentration in this material is 1.65× 1020 cm-3 as measured via ordinary Hall effect at 4 K, and an anomalous Hall effect is observed up to 6 K, but with no hysteresis at any temperature. With positive electric gate field, the carrier concentration is increased by approximately 2%, resulting in a clear magnetic hysteresis at 4 K. The ability to reversibly induce/eliminate ferromagnetism by applied gate field alone, measured via the effect on the carriers, is a clear sign of carrier-induced ferromagnetism in this system. © 2009 American Institute of Physics.

We experimentally demonstrate a new optical imaging technique based on an optical hyperlens made by metal/dielectric metamaterial. The hyperlens can magnify sub-diffraction -limited objects into far field thus opens up new possibilities for optical nano-imaging.

We present the attempt to diagnose electron temperature and density of a plasma via Thomson Scattering in the Warm Dense Matter Regimew using soft x-ray Free Electron Laser radiation. A preliminary Self Thomson Scattering experiment has already been conducted. In a current pump-probe experiment, together with an optical heating laser, we will record the temporal evolution of the plasma achieving a resolution of approximately 250fs.

We present collective Thomson scattering with soft x-ray free electron laser radiation as a method to track the evolution of warm dense matter plasmas with ∼200 fs time resolution. In a pump-probe scheme an 800 nm laser heats a 20 ∼m hydrogen droplet to the plasma state. After a variable time delay in the order of ps the plasma is probed by an x-ray ultra violet (XUV) pulse which scatters from the target and is recorded spectrally. Alternatively, in a self-Thomson scattering experiment, a single XUV pulse heats the target while a portion of its photons are being scattered probing the target. From such inelastic x-ray scattering spectra free electron temperature and density can be inferred giving insight on relaxation time scales in plasmas as well as the equation of state. We prove the feasibility of this method in the XUV range utilizing the free electron laser facility in Hamburg, FLASH. We recorded Thomson scattering spectra for hydrogen plasma, both in the self-scattering and in the pump-probe mode using optical laser heating. © 2009 SPIE-.

Saturable absorption is a phenomenon readily seen in the optical and infrared wavelengths. It has never been observed in core-electron transitions owing to the short lifetime of the excited states involved and the high intensities of the soft X-rays needed. We report saturable absorption of an L-shell transition in aluminium using record intensities over 10 16 W cm 2 at a photon energy of 92 eV. From a consideration of the relevant timescales, we infer that immediately after the X-rays have passed, the sample is in an exotic state where all of the aluminium atoms have an L-shell hole, and the valence band has approximately a 9 eV temperature, whereas the atoms are still on their crystallographic positions. Subsequently, Auger decay heats the material to the warm dense matter regime, at around 25 eV temperatures. The method is an ideal candidate to study homogeneous warm dense matter, highly relevant to planetary science, astrophysics and inertial confinement fusion. © 2009 Macmillan Publishers Limited. All rights reserved.

Compton scattering techniques have been developed for accurate measurements of densities and temperatures in dense plasmas. One future challenge is the application of this technique to characterize compressed matter on the National Ignition Facility where hydrogen and beryllium will approach extremely dense states of matter of up to 1000 g/cc. In this regime, the density, compressibility, and capsule fuel adiabat may be directly measured from the Compton scattered spectrum of a high-energy x-ray line source. Specifically, the scattered spectra directly reflect the electron velocity distribution. In non-degenerate plasmas, the width provides an accurate measure of the electron temperatures, while in partially Fermi degenerate systems that occur in laser-compressed matter it provides the Fermi energy and hence the electron density. Both of these regimes have been accessed in experiments at the Omega laser by employing isochorically heated solid-density beryllium and moderately compressed beryllium foil targets. In the latter experiment, compressions by a factor of 3 at pressures of 40 Mbar have been measured in excellent agreement with radiation hydrodynamic modeling.

We have demonstrated a surface plasmon polariton mediated optical Moire effect by inserting a silver slab between two subwavelength gratings. Enhancement of the evanescent fields by the surface plasmon excitations on the silver slab leads to a remarkable contrast improvement in the Moire fringes from two subwavelength gratings. Numerical calculations, which agree very well with the experimental observation of evanescent-wave Moire fringes, elucidate the crucial role of the surface plasmon polaritons. The near-field Moire effect has potential applications to extend the existing Moire techniques to subwavelength characterization of nanostructures.

A beamline optimized for the bunch slicing technique has been construction at the Advanced Light Source (ALS). This beamline includes an in‐vacuum undulator, soft and hard x‐ray beamlines and a femtosecond laser system. The soft x‐ray beamline may operate in spectrometer mode, where an entire absorption spectrum is accumulated at one time, or in monochromator mode. The femtosecond laser system has a high repetition rate of 20 kHz to improve the average slicing flux. The performance of the soft x‐ray branch of the ALS slicing undulator beamline will be presented.

We experimentally demonstrate the first optical hyperlens made by metal/dielectric metamaterial which is able to magnify sub-diffraction-limited objects. Hyperlens opens up new possibilities for optical nano-imaging in the far-field.

Summary form only given. It is necessary to generate an ultrahigh intensity subpicosecond laser pulse for application to the laser wakefield accelerator (LWFA) or inertial confinement fusion (ICF). For the achievement of above petawatt (10/sup 15/ W) laser power, both conventional amplifiers and the chirp pulse amplification (CPA) technique are not adequate because they have limitation of laser intensity to GW/cm/sup 2/ and TW/cm/sup 2/, respectively. For more powerful amplification, it has been shown that three wave interaction between the counterpropagating electromagnetic waves and a plasma wave can generate superradiant amplification of a short laser pulse. In this study, we simulate the amplification of a short laser pulse by a counterpropagating pump in a plasma. We use the one dimensional version of XOOPIC, an object-oriented particle-in-cell code. Two plane waves are launched from opposite sides of the plasma. For appropriately chosen parameters the energy of the pump probe can be transferred to the ultra-short pulse. Energy gain, compression of the short pulse, and pump depletion are studied with the simulation for a wide variety of system parameters such as intensity of pump wave, frequency, plasma density, and pulse shape. The simulation results are compared with theoretical predictions.

Summary form only given. It has been suggested that colliding a short laser pulse with a long laser pulse in a plasma can, under appropriate circumstances, greatly amplify the short pulse by drawing energy from the long pulse. The coupling between laser pulses occurs through a three-wave interaction with a resonant plasma wave, and is sensitive to the shape of the laser pulse. Previous studies of this concept have been based primarily on 1D theory and fluid simulations. Here, we report on 2D PIC studies using the XOOPIC code. Energy transfer between pulses is studied for a range of system parameters and comparisons are made with theory and 1D simulations.

Summary form only given, as follows. Direct current microhollow cathode discharges (MHCDs), operated in XeCl, ArF, Xe, Ar, Ne and He, are sources of excimer radiation with efficiencies between 1% and 10%. The radiant power of the excimer emission was found to increase linearly with current. For DC operation in xenon the current was kept below 8 mA, at a discharge voltage of 220 V, in order to avoid thermal damage of the electrodes. Reducing the average power by operating the discharge in a pulsed mode with on-times of 700 /spl mu/s and a duty cycle of 0.007 allowed us to increase the current to 70 mA, limited by the onset of instabilities. Whereas for this case the radiant power increased, as expected, by an order of magnitude over the dc values, the radiant emittance of the excimer source was found to stay constant due to the linear increase in the emitting plasma area with current For xenon, at a pressure of 760 Torr, it was measured as 2 W/cm/sup 2/. One possibility to increase the radiant emittance beyond this value, is to place MHCDs in series, as demonstrated with a XeCl tandem discharge. A second method of discharge operation, which provides not only an increase in radiant emittance, but also in radiant power is based on MHCD operation in a transient, nonequilibrium mode. By applying short voltage pulses, excimer emission pulses of 700 ns duration (FWHM) were generated with peak radiant power levels of six times the steady state levels. Using high speed VUV imaging system in combination with a calibrated radiometer, the peak radiant power density was measured as approximately 400 W/cm/sup 2/, more than two orders of magnitude above the dc value. Results of measurements on the recovery time of these pulsed excimer sources, indicate the possibility to generate repetitively pulsed, MHCD excimer emitters.

Summary form only given, as follows. We developed a 1-d small/large signal Kirchhoff-PIC hybrid code for modeling coupled-cavity traveling-wave tube (CCTWT). The objective is to determine the interaction between the electron beam and cavities both in the linear and nonlinear regimes. A, small signal multi-frequency TWT code can provide a description of the power spectrum produced by a low frequency modulated beam. A large signal multi-frequency TWT code is required to study the nonlinear mechanism responsible for mixing the low frequency modulation with the high frequency carrier signal. Each cavity is modeled as a three-port equivalent Curnow circuit with R, L, C elements. The input/output ports of each Curnow element connects to the corresponding output/input port of the following element, while the third port, called the beam port, models the interaction between the cavity gaps and the beam. The voltage across the beam port and the current through it are solved self-consistently, and the beam space charge forces for all discrete modes are included via the standard PIC method.

Summary form only given, as follows. Resonance trapping and radiation transport in fluorescent lamp discharges are critical for the calculation of efficiency, but many models do not include the effects in evolving the steady state. In this study, we coupled radiation transport into a self-consistent kinetic particle-in-cell simulation. We established a basic model to include radiation transport and nonuniformity of background neutral gas in a one dimensional particle-in-cell code, XPDC1, for the case of single species neutral gas. We treat, electrons and ions with the conventional particle-in-cell method, and the ground state and excited neutral atoms with a fluid model. We include radiation transport in the fluid equations with a simplification, as well as the collisions between neutral and excited atoms, and the nonuniformity of the background gas. The results are compared for the case calculated by the modified code and that calculated by using only the steady state excited atom profile for parameters relevant to a lamp-like discharge in pure argon.

We describe the theory and report the first experimental demonstration of Cavity Resonance Lithography (CRL); a double pattering (DP) technique that can generate patterns on a photoresist 1) with twice the spatial frequency of that of the diffraction limited lithography mask, and 2) at an offset distance that is in the far field of the mask. CRL requires only a single exposure and development step and does not require any additional processes. With commercially available photoresists (PR) and developers, we have recorded a 32.5 nm half-pitch pattern (which is well below the diffraction limit) at an offset distance of 180 nm (which is well beyond the evanescent decay length scales) using 193 nm illumination. We also discuss strategies to improve the minimum feature size and potential implementation schemes.

An ultrafast x-ray streak camera has been realized using a grazing incidence reflection photocathode. X-rays are incident on a gold photocathode at a grazing angle of 20 degree and photoemitted electrons are focused by a large aperture magnetic solenoid lens. The streak camera has high quantum efficiency, 600fs temporal resolution, and 6mm imaging length in the spectral direction. Its single shot capability eliminates temporal smearing due to sweep jitter, and allows recording of the ultrafast dynamics of samples that undergo non-reversible changes.

The diffraction limit of light, which is causd by the loss of evanescent waves in the far field that carry high spatial frequency information, limits the resolution of optical lenses to the order of the wavelength of light. We report experimental demonstration of the optical hyperlens for sub-diffraction-limited imaging in the far field. The device magnifies subwavelength objects by transforming the scattered evanescent waves into propagating waves in an anisotropic medium and projects the high-resolution image at far field. The optical hyperlens opens up possibilities in applications such as real-time biomolecular imaging and nanolithography.

We report here the design, fabrication and characterization of optical hyperlens that can image sub-diffraction-limited objects in the far field. The hyperlens is based on an artificial anisotropic metamaterial with carefully designed hyperbolic dispersion. We successfully designed and fabricated such a metamaterial hyperlens composed of curved silver/alumina multilayers. Experimental results demonstrate far-field imaging with resolution down to 125nm at 365nm working wavelength which is below the diffraction limit.

A far-field optical superlens, which is able to form sub-diffraction- limited images in the far field at UV wavelength, was recently demonstrated. In current work we present two methods to tune the working wavelength from UV to visible by tuning either the permittivity of the surrounding medium or that of the metal. A practical design is provided for each method. The tunable far-field superlens enables possible applications of the far-field superlens in sub-diffraction-limited imaging and sensing over a wide range of wavelength.

Contrary to the conventional near-field superlensing, subwavelength superlens imaging is experimentally demonstrated in the far-field. The key element is termed as a Far-field SuperLens (FSL) which consists of a conventional superlens and a nanoscale coupler. The evanescent fields from the object are enhanced and then converted into propagating fields by the FSL. By only measuring the propagating field in the far-field, the object image can be reconstructed with subwavelength resolution. As an example of this concept, we design and fabricate a silver structured one dimensional FSL. Experimental results show that feature resolution of better than 50nm is possible using current FSL design.

We report the experimental realization of tuning the focus position of a plasmonic lens by adjusting the angle of the incident light similar to conventional lenses. A circular slit in silver film acts as both a surface plasmon polariton coupler and a plasmonic focusing lens. At small incident angles, the plasmonic lens has a very good focus with the position depending only on the angle of the incident beam. Numerical simulations of the focusing properties, including polarization dependence, agree well with experimental observations. This tunable plasmonic lens can be used in nanoscale photonics, biological sensing, and manipulation.

Recently, the concept of superlensing has received considerable attention for its unique ability to produce images below the diffraction limit. The theoretical study has predicted a 'superlens' made of materials with negative permittivity and/or permeability, is capable of resolving features much smaller than the working wavelength and a near-perfect image can be obtained through the restoration of lost evanescent waves (Pendry 2000 Phys. Rev. Lett. 85 3966–9). We have already demonstrated that a 60 nm half-pitch object can indeed be resolved with λ0/6 resolution with the implementation of a silver superlens with λ0 = 365 nm illumination wavelength, which is well below the diffraction limit (Fang et al 2005 Science 308 534–7). In order to further support the imaging ability of our silver superlens, a two-dimensional arbitrary object with 40 nm line width was also imaged (Fang et al 2005 Science 308 534–7). In this paper, we present experimental and theoretical investigations of optical superlensing through a thin silver slab. Experimental design and procedures as well as theoretical studies are presented in detail. In addition, a new superlens imaging result is presented which shows the image of a 50 nm half-pitch object at λ0/7 resolution.