Probing ultra-fast processes with high dynamic range at 4th-generation light sources: Arrival time and intensity binning at unprecedented repetition rates.

PubMed

Kovalev, S; Green, B; Golz, T; Maehrlein, S; Stojanovic, N; Fisher, A S; Kampfrath, T; Gensch, M

2017-03-01

Understanding dynamics on ultrafast timescales enables unique and new insights into important processes in the materials and life sciences. In this respect, the fundamental pump-probe approach based on ultra-short photon pulses aims at the creation of stroboscopic movies. Performing such experiments at one of the many recently established accelerator-based 4th-generation light sources such as free-electron lasers or superradiant THz sources allows an enormous widening of the accessible parameter space for the excitation and/or probing light pulses. Compared to table-top devices, critical issues of this type of experiment are fluctuations of the timing between the accelerator and external laser systems and intensity instabilities of the accelerator-based photon sources. Existing solutions have so far been only demonstrated at low repetition rates and/or achieved a limited dynamic range in comparison to table-top experiments, while the 4th generation of accelerator-based light sources is based on superconducting radio-frequency technology, which enables operation at MHz or even GHz repetition rates. In this article, we present the successful demonstration of ultra-fast accelerator-laser pump-probe experiments performed at an unprecedentedly high repetition rate in the few-hundred-kHz regime and with a currently achievable optimal time resolution of 13 fs (rms). Our scheme, based on the pulse-resolved detection of multiple beam parameters relevant for the experiment, allows us to achieve an excellent sensitivity in real-world ultra-fast experiments, as demonstrated for the example of THz-field-driven coherent spin precession.

Probing Photoinduced Structural Phase Transitions by Fast or Ultra-Fast Time-Resolved X-Ray Diffraction

NASA Astrophysics Data System (ADS)

Cailleau, Hervé Collet, Eric; Buron-Le Cointe, Marylise; Lemée-Cailleau, Marie-Hélène Koshihara, Shin-Ya

A new frontier in the field of structural science is the emergence of the fast and ultra-fast X-ray science. Recent developments in time-resolved X-ray diffraction promise direct access to the dynamics of electronic, atomic and molecular motions in condensed matter triggered by a pulsed laser irradiation, i.e. to record "molecular movies" during the transformation of matter initiated by light pulse. These laser pump and X-ray probe techniques now provide an outstanding opportunity for the direct observation of a photoinduced structural phase transition as it takes place. The use of X-ray short-pulse of about 100ps around third-generation synchrotron sources allows structural investigations of fast photoinduced processes. Other new X-ray sources, such as laser-produced plasma ones, generate ultra-short pulses down to 100 fs. This opens the way to femtosecond X-ray crystallography, but with rather low X-ray intensities and more limited experimental possibilities at present. However this new ultra-fast science rapidly progresses around these sources and new large-scale projects exist. It is the aim of this contribution to overview the state of art and the perspectives of fast and ultra-fast X-ray scattering techniques to study photoinduced phase transitions (here, the word ultra-fast is used for sub-picosecond time resolution). In particular we would like to largely present the contribution of crystallographic methods in comparison with optical methods, such as pump-probe reflectivity measurements, the reader being not necessary familiar with X-ray scattering. Thus we want to present which type of physical information can be obtained from the positions of the Bragg peaks, their intensity and their shape, as well as from the diffuse scattering beyond Bragg peaks. An important physical feature is to take into consideration the difference in nature between a photoinduced phase transition and conventional homogeneous photoinduced chemical or biochemical processes where molecules transform in an independent way each other. Actually the photoinduced phase transition with the establishment of the new electronic and structural oscopic order is preceded by precursor co-operative phenomena due to the formation of nano-scale correlated objects. These are the counterpart of pre-transitional fluctuations at thermal equilibrium which take place above the transition temperature (short range order preceding long range one). Moreover ultra-fast X-ray scattering will play a central role within the fascinating field of manipulating coherence, for instance to directly observe coherent atomic motions induced by a light pulse, such as optical phonons. In the first part of this contribution we present what experimental features are accessible by X-ray scattering to describe the physical picture for a photoinduced structural phase transition. The second part shows how a time-resolved X-ray scattering experiment can be performed with regards to the different pulsed X-ray sources. The first time-resolved X-ray diffraction experiments on photoinduced phase transitions are described and discussed in the third part. Finally some challenges for future are briefly indicated in the conclusion.

Femtosecond pulsed laser processing of electronic materials: Fundamentals and micro/nano-scale applications

NASA Astrophysics Data System (ADS)

Choi, Tae-Youl

Ultra-short pulsed laser radiation has been shown to be effective for precision materials processing and surface micro-modification. One of advantages is the substantial reduction of the heat penetration depth, which leads to minimal lateral damage. Other advantages include non-thermal nature of ablation process, controlled ablation and ideal characteristics for precision micro-structuring. Yet, fundamental questions remain unsolved regarding the nature of melting and ablation mechanisms in femtosecond laser processing of materials. In addition to micro engineering problems, nano-structuring and nano-fabrication are emerging fields that are of particular interest in conjunction with femtosecond laser processing. A comprehensive experimental study as well as theoretical development is presented to address these issues. Ultra-short pulsed laser irradiation was used to crystallize 100 nm amorphous silicon (a-Si) films. The crystallization process was observed by time-resolved pump-and-probe reflection imaging in the range of 0.2 ps to 100 ns. The in-situ images in conjunction with post-processed SEM and AFM mapping of the crystallized structure provide evidence for non-thermal ultra-fast phase transition and subsequent surface-initiated crystallization. Mechanisms of ultra-fast laser-induced ablation on crystalline silicon and copper are investigated by time-resolved pump-and-probe microscopy in normal imaging and shadowgraph arrangements. A one-dimensional model of the energy transport is utilized to predict the carrier temperature and lattice temperature as well as the electron and vapor flux emitted from the surface. The temporal delay between the pump and probe pulses was set by a precision translation stage up to about 500 ps and then extended to the nanosecond regime by an optical fiber assembly. The ejection of material was observed at several picoseconds to tens of nanoseconds after the main (pump) pulse by high-resolution, ultra-fast shadowgraphs. The ultrashort laser pulse accompanied by the pre-pulse induces air breakdown that can be detrimental to materials processing. A time-resolved pump-and-probe experiment provides distinct evidence for the occurrence of an air plasma and air breakdown. This highly nonlinear phenomenon takes place before the commencement of the ablation process, which is traced beyond elapsed time of the order of 10 ps with respect to the ablating pulse. The nonlinear refractive index of the generated air plasma is calculated as a function of electron density. The self-focusing of the main pulse is identified by the third order nonlinear susceptibility. A crystalline silicon sample is subjected to two optically separated ultra-fast laser pulses of full-width-half-maximum (FWHM) duration of about 80 femtoseconds. These pulses are delivered at wavelength, lambda = 800 nm. Femtosecond-resolved imaging pump-and-probe experiments in reflective and Schlieren configurations have been performed to investigate plasma dynamics and shock wave propagation during the sample ablation process. By using a diffractive optical element (DOE) for beam shaping, microchannels were fabricated. A super-long working distance objective lens was used to machine silicon materials in the sub-micrometer scale. As an extension of micro-machining, the finite difference time domain (FDTD) method is used to assess the feasibility of using near-field distribution of laser light. Gold coated films were machined with nano-scale dimensions and characterized with atomic force microscopy (AFM).

Probing ultra-fast processes with high dynamic range at 4th-generation light sources: Arrival time and intensity binning at unprecedented repetition rates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kovalev, S.; Green, B.; Golz, T.

Here, understanding dynamics on ultrafast timescales enables unique and new insights into important processes in the materials and life sciences. In this respect, the fundamental pump-probe approach based on ultra-short photon pulses aims at the creation of stroboscopic movies. Performing such experiments at one of the many recently established accelerator-based 4th-generation light sources such as free-electron lasers or superradiant THz sources allows an enormous widening of the accessible parameter space for the excitation and/or probing light pulses. Compared to table-top devices, critical issues of this type of experiment are fluctuations of the timing between the accelerator and external laser systemsmore » and intensity instabilities of the accelerator-based photon sources. Existing solutions have so far been only demonstrated at low repetition rates and/or achieved a limited dynamic range in comparison to table-top experiments, while the 4th generation of accelerator-based light sources is based on superconducting radio-frequency technology, which enables operation at MHz or even GHz repetition rates. In this article, we present the successful demonstration of ultra-fast accelerator-laser pump-probe experiments performed at an unprecedentedly high repetition rate in the few-hundred-kHz regime and with a currently achievable optimal time resolution of 13 fs (rms). Our scheme, based on the pulse-resolved detection of multiple beam parameters relevant for the experiment, allows us to achieve an excellent sensitivity in real-world ultra-fast experiments, as demonstrated for the example of THz-field-driven coherent spin precession.« less

Probing ultra-fast processes with high dynamic range at 4th-generation light sources: Arrival time and intensity binning at unprecedented repetition rates

DOE PAGES

Kovalev, S.; Green, B.; Golz, T.; ...

2017-03-06

Here, understanding dynamics on ultrafast timescales enables unique and new insights into important processes in the materials and life sciences. In this respect, the fundamental pump-probe approach based on ultra-short photon pulses aims at the creation of stroboscopic movies. Performing such experiments at one of the many recently established accelerator-based 4th-generation light sources such as free-electron lasers or superradiant THz sources allows an enormous widening of the accessible parameter space for the excitation and/or probing light pulses. Compared to table-top devices, critical issues of this type of experiment are fluctuations of the timing between the accelerator and external laser systemsmore » and intensity instabilities of the accelerator-based photon sources. Existing solutions have so far been only demonstrated at low repetition rates and/or achieved a limited dynamic range in comparison to table-top experiments, while the 4th generation of accelerator-based light sources is based on superconducting radio-frequency technology, which enables operation at MHz or even GHz repetition rates. In this article, we present the successful demonstration of ultra-fast accelerator-laser pump-probe experiments performed at an unprecedentedly high repetition rate in the few-hundred-kHz regime and with a currently achievable optimal time resolution of 13 fs (rms). Our scheme, based on the pulse-resolved detection of multiple beam parameters relevant for the experiment, allows us to achieve an excellent sensitivity in real-world ultra-fast experiments, as demonstrated for the example of THz-field-driven coherent spin precession.« less

Ultra-fast Movies Resolve Ultra-short Pulse Laser Ablation and Bump Formation on Thin Molybdenum Films

NASA Astrophysics Data System (ADS)

Domke, Matthias; Rapp, Stephan; Huber, Heinz

For the monolithic serial interconnection of CIS thin film solar cells, 470 nm molybdenum films on glass substrates must be separated galvanically. The single pulse ablation with a 660 fs laser at a wavelength of 1053 nm is investigated in a fluence regime from 0.5 to 5.0 J/cm2. At fluences above 2.0 J/cm2 bump and jet formation can be observed that could be used for creating microstructures. For the investigation of the underlying mechanisms of the laser ablation process itself as well as of the bump or jet formation, pump probe microscopy is utilized to resolve the transient ablation behavior.

Expansion of Non-Quasi-Neutral Limited Plasmas Driven by Two-Temperature Electron Clouds

NASA Astrophysics Data System (ADS)

Murakami, Masakatsu; Honrubia, Javier

2017-10-01

Fast heating of an isolated solid mass, under irradiation of ultra-intense ultra-short laser pulse, to averaged temperatures of order of keV is theoretically studied. Achievable maximum ion temperatures are determined as a consequence of the interplay of the electron-to-ion energy deposition and nonrelativistic plasma expansion, where fast ion emission plays an important role in the energy balance. To describe the plasma expansion, we develop a self-similar solution, in which the plasma is composed of three fluids, i.e., ions and two-temperature electrons. Under the condition of isothermal electron expansion in cylindrical geometry, such a fluid system, self-consistently incorporated with the Poisson equation, is fully solved. The charge separation and resultant accelerated ion population due to the induced electrostatic field are quantitatively presented. The analytical model is compared with two-dimensional hydrodynamic simulations to provide practical working windows for the target and laser parameters for the fast heating.

Joining of thin glass with semiconductors by ultra-fast high-repetition laser welding

NASA Astrophysics Data System (ADS)

Horn, Alexander; Mingaeev, Ilja; Werth, Alexander; Kachel, Martin

2008-02-01

Lighting applications like OLED or on silicon for electro-optical applications need a reproducible sealing process. The joining has to be strong, the permeability for gasses and humidity very low and the process itself has to be very localized not affecting any organic or electronic parts inside the sealed region. The actual sealing process using glue does not fulfil these industrial needs. A new joining process using ultra-fast laser radiation offers a very precise joining with geometry dimensions smaller than 50 μm. Ultra-fast laser radiation is absorbed by multi-photon absorption in the glass. Due to the very definite threshold for melting and ablation the process of localized heating can be controlled without cracking. Repeating the irradiation at times smaller than the heat diffusion time the temperature in the focus is increased by heat accumulation reaching melting of the glass. Mowing the substrate relatively to the laser beam generates a seal of re-solidified glass. Joining of glass is achieved by positioning the laser focus at the interface. A similar approach is used for glass-silicon joining. The investigations presented will demonstrate the joining geometry by microscopy of cross-sections achieved by welding two glass plates (Schott D263 and AF45) with focused IR femtosecond laser radiation (wavelength λ = 1045nm, repetition rate f = 1 MHz, pulse duration t p = 500 fs, focus diameter w 0 = 4 μm, feeding velocity v= 1-10 mm/s). The strength of the welding seam is measured by tensile stress measurements and the gas and humidity is detected. A new diagnostic method for the on-line detection of the welding seam properties will be presented. Using a non-interferometric technique by quantitative phase microscopy the refractive index is measured during welding of glass in the time regime 0-2 μs. By calibration of the measured refractive index with a relation between refractive index and temperature a online-temperature detection can be achieved.

Ultra-fast dynamics in the nonlinear optical response of silver nanoprism ordered arrays.

PubMed

Sánchez-Esquivel, Héctor; Raygoza-Sanchez, Karen Y; Rangel-Rojo, Raúl; Kalinic, Boris; Michieli, Niccolò; Cesca, Tiziana; Mattei, Giovanni

2018-03-15

In this work we present the study of the ultra-fast dynamics of the nonlinear optical response of a honeycomb array of silver triangular nanoprisms, performed using a femtosecond pulsed laser tuned with the dipolar surface plasmon resonance of the nanoarray. Nonlinear absorption and refraction, and their time-dependence, were explored using the z-scan and time-resolved excite-probe techniques. Nonlinear absorption is shown to change sign with the input irradiance and the behavior was explained on the basis of a three-level model. The response time was determined to be in the picosecond regime. A technique based on a variable frequency chopper was also used in order to discriminate the thermal and electronic contributions to the nonlinearity, which were found to have opposite signs. All these findings propel the investigated nanoprism arrays as good candidates for applications in advanced ultra-fast nonlinear nanophotonic devices.

Target Surface Area Effects on Hot Electron Dynamics from High Intensity Laser-Plasma Interactions

DTIC Science & Technology

2016-08-19

New J. Phys. 18 (2016) 063020 doi:10.1088/1367-2630/18/6/063020 PAPER Target surface area effects on hot electron dynamics from high intensity laser ...Science, University ofMichigan, AnnArbor,MI 48109-2099, USA E-mail: czulick@umich.edu Keywords: laser -plasma,mass-limited, fast electrons, sheath...field Abstract Reduced surface area targets were studied using an ultra-high intensity femtosecond laser in order to determine the effect of electron

External control of semiconductor nanostructure lasers

NASA Astrophysics Data System (ADS)

Naderi, Nader A.

2011-12-01

Novel semiconductor nanostructure laser diodes such as quantum-dot and quantum-dash are key optoelectronic candidates for many applications such as data transmitters in ultra fast optical communications. This is mainly due to their unique carrier dynamics compared to conventional quantum-well lasers that enables their potential for high differential gain and modified linewidth enhancement factor. However, there are known intrinsic limitations associated with semiconductor laser dynamics that can hinder the performance including the mode stability, spectral linewidth, and direct modulation capabilities. One possible method to overcome these limitations is through the use of external control techniques. The electrical and/or optical external perturbations can be implemented to improve the parameters associated with the intrinsic laser's dynamics, such as threshold gain, damping rate, spectral linewidth, and mode selectivity. In this dissertation, studies on the impact of external control techniques through optical injection-locking, optical feedback and asymmetric current bias control on the overall performance of the nanostructure lasers were conducted in order to understand the associated intrinsic device limitations and to develop strategies for controlling the underlying dynamics to improve laser performance. In turn, the findings of this work can act as a guideline for making high performance nanostructure lasers for future ultra fast data transmitters in long-haul optical communication systems, and some can provide an insight into making a compact and low-cost terahertz optical source for future implementation in monolithic millimeter-wave integrated circuits.

Dependence of core heating properties on heating pulse duration and intensity

NASA Astrophysics Data System (ADS)

Johzaki, Tomoyuki; Nagatomo, Hideo; Sunahara, Atsushi; Cai, Hongbo; Sakagami, Hitoshi; Mima, Kunioki

2009-11-01

In the cone-guiding fast ignition, an imploded core is heated by the energy transport of fast electrons generated by the ultra-intense short-pulse laser at the cone inner surface. The fast core heating (˜800eV) has been demonstrated at integrated experiments with GEKKO-XII+ PW laser systems. As the next step, experiments using more powerful heating laser, FIREX, have been started at ILE, Osaka university. In FIREX-I (phase-I of FIREX), our goal is the demonstration of efficient core heating (Ti ˜ 5keV) using a newly developed 10kJ LFEX laser. In the first integrated experiments, the LFEX laser is operated with low energy mode (˜0.5kJ/4ps) to validate the previous GEKKO+PW experiments. Between the two experiments, though the laser energy is similar (˜0.5kJ), the duration is different; ˜0.5ps in the PW laser and ˜ 4ps in the LFEX laser. In this paper, we evaluate the dependence of core heating properties on the heating pulse duration on the basis of integrated simulations with FI^3 (Fast Ignition Integrated Interconnecting) code system.

A 10Gbps optical burst switching network incorporating ultra-fast (5ns) wavelength switched tunable laser sources

NASA Astrophysics Data System (ADS)

Ryan, Neil; Todd, Michael; Farrell, Tom; Lavin, Adrian; Rigole, Pierre-Jean; Corbett, Brian; Roycroft, Brendan; Engelstaedter, Jan-Peter

2017-11-01

This paper outlines the development of a prototype optical burst mode switching network based upon a star topology, the ultimate application of which could be as a transparent payload processor onboard satellite repeaters. The network architecture incorporates multiple tunable laser sources, burst mode receivers and a passive optical router (Arrayed Waveguide Grating). Each tunable optical signal should carry >=10Gbps and be capable of wavelength switching in c. 5ns timescales. Two monolithic tunable laser types, based upon different technologies, will be utilised: a Slotted Fabry Perot laser (a Fabry Perot laser with slots added in order to introduce controlled cavity perturbations); and a Modulated Grating Y-Branch Laser (MGY: a widely tunable, multi-section device similar to the DBR laser). While the Slotted Fabry Perot laser is expected to achieve the required switching times, it is an immature technology not yet capable of achieving tunability over 80 ITU channels from a single chip. The MGY device is a more mature technology and has full C-band ITU channel coverage, but is not capable of the required short switching times. Hence, in order to facilitate the integration of this more mature technology into the prototype breadboard with the requisite switching time capabilities, a system of `dual laser' transmitters is being developed to enable data transmission from one MGY laser while the other switches and vice-versa. This work is being performed under ESA contract AO 1-5025/06/NL/PM, Optical Technologies for Ultra - fast Processing.

Thermo-optic locking of a semiconductor laser to a microcavity resonance.

PubMed

McRae, T G; Lee, Kwan H; McGovern, M; Gwyther, D; Bowen, W P

2009-11-23

We experimentally demonstrate thermo-optic locking of a semiconductor laser to an integrated toroidal optical microcavity. The lock is maintained for time periods exceeding twelve hours, without requiring any electronic control systems. Fast control is achieved by optical feedback induced by scattering centers within the microcavity, with thermal locking due to optical heating maintaining constructive interference between the cavity and the laser. Furthermore, the optical feedback acts to narrow the laser linewidth, with ultra high quality microtoroid resonances offering the potential for ultralow linewidth on-chip lasers.

Laser-assisted heating of a plasmonic nanofluid in a microchannel

NASA Astrophysics Data System (ADS)

Walsh, Timothy

The work presented in this study analyses the theoretical modeling and experimentation of laser-assisted heating of plasmonic nanofluids (PNFs) in a microchannel for accurate, efficient, and ultra-fast heating of a microdroplet. Suspended plasmonic nanoparticles exhibit strong light absorption and scattering upon the excitation of localized surface plasmons (LSPs), resulting in intense and rapid photothermal heating. Several multi-stepped computational models were utilized to theoretically characterize and verify the laser-assisted heating behavior of gold nanoshells (GNS) and gold nanorod (GNR) plasmonic nanofluid droplets in a microchannel. From the experimental investigation, a full range of controllable steady-state temperatures, room temperature to 100°C, are confirmed to be achievable for the 780-nm-tuned plasmonic nanofluid. Droplet fluid heating is verified to occur as a result of LSP excitation, in time scales of milliseconds, and to be repeatable over many cycles. Additionally, the significance and effects of parameters in the process, such as nanoparticle structure, volumetric concentration, microchannel depth, and laser power density are established. The obtained results in this research may be integrated into other existing microfluidic technologies and biological techniques, such as the polymerase chain reaction, where accurate and ultra-fast heating of microdroplets in a microchannel can greatly improve efficiency.

Guiding and focusing of fast electron beams produced by ultra-intense laser pulse using a double cone funnel target

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Wen-shuai; Cai, Hong-bo, E-mail: Cai-hongbo@iapcm.ac.cn; HEDPS, Center for Applied Physics and Technology, Peking University, Beijing 100871

A novel double cone funnel target design aiming at efficiently guiding and focusing fast electron beams produced in high intensity (>10{sup 19 }W/cm{sup 2}) laser-solid interactions is investigated via two-dimensional particle-in-cell simulations. The forward-going fast electron beams are shown to be directed and focused to a smaller size in comparison with the incident laser spot size. This plasma funnel attached on the cone target guides and focuses electrons in a manner akin to the control of liquid by a plastic funnel. Such device has the potential to add substantial design flexibility and prevent inefficiencies for important applications such as fast ignition.more » Two reasons account for the collimation of fast electron beams. First, the sheath electric fields and quasistatic magnetic fields inside the vacuum gap of the double cone provide confinement of the fast electrons in the laser-plasma interaction region. Second, the interface magnetic fields inside the beam collimator further guide and focus the fast electrons during the transport. The application of this technique to cone-guided fast ignition is considered, and it is shown that it can enhance the laser energy deposition in the compressed fuel plasma by a factor of 2 in comparison with the single cone target case.« less

Ion acceleration in electrostatic field of charged cavity created by ultra-short laser pulses of 1020-1021 W/cm2

NASA Astrophysics Data System (ADS)

Bychenkov, V. Yu.; Singh, P. K.; Ahmed, H.; Kakolee, K. F.; Scullion, C.; Jeong, T. W.; Hadjisolomou, P.; Alejo, A.; Kar, S.; Borghesi, M.; Ter-Avetisyan, S.

2017-01-01

Ion acceleration resulting from the interaction of ultra-high intensity and ultra-high contrast (˜10-10) laser pulses with thin A l foil targets at 30° angle of laser incidence is studied. Proton maximum energies of 30 and 18 MeV are measured along the target normal rear and front sides, respectively, showing intensity scaling as Ib . For the target front bf r o n t= 0.5-0.6 and for the target rear br e a r= 0.7-0.8 is observed in the intensity range 1020-1021 W/cm2. The fast scaling from the target rear ˜I0.75 can be attributed enhancement of laser energy absorption as already observed at relatively low intensities. The backward acceleration of the front side protons with intensity scaling as ˜I0.5 can be attributed to the to the formation of a positively charged cavity at the target front via ponderomotive displacement of the target electrons at the interaction of relativistic intense laser pulses with a solid target. The experimental results are in a good agreement with theoretical predictions.

Observation of extremely strong shock waves in solids launched by petawatt laser heating

DOE PAGES

Lancaster, K. L.; Robinson, A. P. L.; Pasley, J.; ...

2017-08-25

Understanding hydrodynamic phenomena driven by fast electron heating is important for a range of applications including fast electron collimation schemes for fast ignition and the production and study of hot, dense matter. In this work, detailed numerical simulations modelling the heating, hydrodynamic evolution, and extreme ultra-violet (XUV) emission in combination with experimental XUV images indicate shock waves of exceptional strength (200 Mbar) launched due to rapid heating of materials via a petawatt laser. In conclusion, we discuss in detail the production of synthetic XUV images and how they assist us in interpreting experimental XUV images captured at 256 eV usingmore » a multi-layer spherical mirror.« less

Cavity mode-width spectroscopy with widely tunable ultra narrow laser.

PubMed

Cygan, Agata; Lisak, Daniel; Morzyński, Piotr; Bober, Marcin; Zawada, Michał; Pazderski, Eugeniusz; Ciuryło, Roman

2013-12-02

We explore a cavity-enhanced spectroscopic technique based on determination of the absorbtion coefficient from direct measurement of spectral width of the mode of the optical cavity filled with absorbing medium. This technique called here the cavity mode-width spectroscopy (CMWS) is complementary to the cavity ring-down spectroscopy (CRDS). While both these techniques use information on interaction time of the light with the cavity to determine absorption coefficient, the CMWS does not require to measure very fast signals at high absorption conditions. Instead the CMWS method require a very narrow line width laser with precise frequency control. As an example a spectral line shape of P7 Q6 O₂ line from the B-band was measured with use of an ultra narrow laser system based on two phase-locked external cavity diode lasers (ECDL) having tunability of ± 20 GHz at wavelength range of 687 to 693 nm.

Efficient monoenergetic proton beam from ultra-fast laser interaction with nanostructured targets

NASA Astrophysics Data System (ADS)

Fazeli, R.

2018-03-01

The broad energy spectrum of laser-accelerated proton beams is the most important difficulty associated with such particle sources on the way to future applications such as medical therapy, proton imaging, inertial fusion, and high-energy physics. The generation of proton beams with enhanced monoenergetic features through an ultra-intense laser interaction with optimized nanostructured targets is reported. Targets were irradiated by 40 fs laser pulses of intensity 5.5 ×1020 W c m -2 and wavelength 1 μm. The results of multi-parametric Particle-in-Cell calculations showed that proton beams with considerably reduced energy spread can be obtained by using the proposed nanostructured target. At optimized target dimensions, the proton spectrum was found to exhibit a narrow peak at about 63 MeV with a relative energy spread of ΔE /Epeak˜ 5 % which is efficiently lower than what is expected for unstructured double layer targets (˜70%).

A novel femtosecond-gated, high-resolution, frequency-shifted shearing interferometry technique for probing pre-plasma expansion in ultra-intense laser experiments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Feister, S., E-mail: feister.7@osu.edu; Orban, C.; Innovative Scientific Solutions, Inc., Dayton, Ohio 45459

Ultra-intense laser-matter interaction experiments (>10{sup 18} W/cm{sup 2}) with dense targets are highly sensitive to the effect of laser “noise” (in the form of pre-pulses) preceding the main ultra-intense pulse. These system-dependent pre-pulses in the nanosecond and/or picosecond regimes are often intense enough to modify the target significantly by ionizing and forming a plasma layer in front of the target before the arrival of the main pulse. Time resolved interferometry offers a robust way to characterize the expanding plasma during this period. We have developed a novel pump-probe interferometry system for an ultra-intense laser experiment that uses two short-pulse amplifiersmore » synchronized by one ultra-fast seed oscillator to achieve 40-fs time resolution over hundreds of nanoseconds, using a variable delay line and other techniques. The first of these amplifiers acts as the pump and delivers maximal energy to the interaction region. The second amplifier is frequency shifted and then frequency doubled to generate the femtosecond probe pulse. After passing through the laser-target interaction region, the probe pulse is split and recombined in a laterally sheared Michelson interferometer. Importantly, the frequency shift in the probe allows strong plasma self-emission at the second harmonic of the pump to be filtered out, allowing plasma expansion near the critical surface and elsewhere to be clearly visible in the interferograms. To aid in the reconstruction of phase dependent imagery from fringe shifts, three separate 120° phase-shifted (temporally sheared) interferograms are acquired for each probe delay. Three-phase reconstructions of the electron densities are then inferred by Abel inversion. This interferometric system delivers precise measurements of pre-plasma expansion that can identify the condition of the target at the moment that the ultra-intense pulse arrives. Such measurements are indispensable for correlating laser pre-pulse measurements with instantaneous plasma profiles and for enabling realistic Particle-in-Cell simulations of the ultra-intense laser-matter interaction.« less

Ultra-low noise optical phase-locked loop

NASA Astrophysics Data System (ADS)

Ayotte, Simon; Babin, André; Costin, François

2014-03-01

The relative phase between two fiber lasers is controlled via a high performance optical phase-locked loop (OPLL). Two parameters are of particular importance for the design: the intrinsic phase noise of the laser (i.e. its linewidth) and a high-gain, low-noise electronic locking loop. In this work, one of the lowest phase noise fiber lasers commercially available was selected (i.e. NP Photonics Rock fiber laser module), with sub-kHz linewidth at 1550.12 nm. However, the fast tuning mechanism of such lasers is through stretching its cavity length with a piezoelectric transducer which has a few 10s kHz bandwidth. To further increase the locking loop bandwidth to several MHz, a second tuning mechanism is used by adding a Lithium Niobate phase modulator in the laser signal path. The OPLL is thus divided into two locking loops, a slow loop acting on the laser piezoelectric transducer and a fast loop acting on the phase modulator. The beat signal between the two phase-locked lasers yields a highly pure sine wave with an integrated phase error of 0.0012 rad. This is orders of magnitude lower than similar existing systems such as the Laser Synthesizer used for distribution of photonic local oscillator (LO) for the Atacama Large Millimeter Array radio telescope in Chile. Other applications for ultra-low noise OPLL include coherent power combining, Brillouin sensing, light detection and ranging (LIDAR), fiber optic gyroscopes, phased array antenna and beam steering, generation of LOs for next generation coherent communication systems, coherent analog optical links, terahertz generation and coherent spectroscopy.

Physical mechanisms of SiN{sub x} layer structuring with ultrafast lasers by direct and confined laser ablation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rapp, S., E-mail: rapp@hm.edu; Erlangen Graduate School in Advanced Optical Technologies; Heinrich, G.

2015-03-14

In the production process of silicon microelectronic devices and high efficiency silicon solar cells, local contact openings in thin dielectric layers are required. Instead of photolithography, these openings can be selectively structured with ultra-short laser pulses by confined laser ablation in a fast and efficient lift off production step. Thereby, the ultrafast laser pulse is transmitted by the dielectric layer and absorbed at the substrate surface leading to a selective layer removal in the nanosecond time domain. Thermal damage in the substrate due to absorption is an unwanted side effect. The aim of this work is to obtain a deepermore » understanding of the physical laser-material interaction with the goal of finding a damage-free ablation mechanism. For this, thin silicon nitride (SiN{sub x}) layers on planar silicon (Si) wafers are processed with infrared fs-laser pulses. Two ablation types can be distinguished: The known confined ablation at fluences below 300 mJ/cm{sup 2} and a combined partial confined and partial direct ablation at higher fluences. The partial direct ablation process is caused by nonlinear absorption in the SiN{sub x} layer in the center of the applied Gaussian shaped laser pulses. Pump-probe investigations of the central area show ultra-fast reflectivity changes typical for direct laser ablation. Transmission electron microscopy results demonstrate that the Si surface under the remaining SiN{sub x} island is not damaged by the laser ablation process. At optimized process parameters, the method of direct laser ablation could be a good candidate for damage-free selective structuring of dielectric layers on absorbing substrates.« less

Strong-field physics with mid-infrared lasers

NASA Astrophysics Data System (ADS)

Pogorelsky, I. V.

2002-04-01

Mid-infrared gas laser technology promises to become a unique tool for research in strong-field relativistic physics. The degree to which physics is relativistic is determined by a ponderomotive potential. At a given intensity, a 10 μm wavelength CO2 laser reaches a 100 times higher ponderomotive potential than the 1 μm wavelength solid state lasers. Thus, we can expect a proportional increase in the throughput of such processes as laser acceleration, x-ray production, etc. These arguments have been confirmed in proof-of-principle Thomson scattering and laser acceleration experiments conducted at BNL and UCLA where the first terawatt-class CO2 lasers are in operation. Further more, proposals for the 100 TW, 100 fs CO2 lasers based on frequency-chirped pulse amplification have been conceived. Such lasers can produce physical effects equivalent to a hypothetical multi-petawatt solid state laser. Ultra-fast mid-infrared lasers will open new routes to the next generation electron and ion accelerators, ultra-bright monochromatic femtosecond x-ray and gamma sources, allow to attempt the study of Hawking-Unruh radiation, and explore relativistic aspects of laser-matter interactions. We review the present status and experiments with terawatt-class CO2 lasers, sub-petawatt projects, and prospective applications in strong-field science. .

STRONG FIELD PHYSICS WITH MID INFRARED LASERS.

DOE Office of Scientific and Technical Information (OSTI.GOV)

POGORELSKY,I.V.

2001-08-27

Mid-infrared gas laser technology promises to become a unique tool for research in strong-field relativistic physics. The degree to which physics is relativistic is determined by a ponderomotive potential. At a given intensity, a 10 {micro}m wavelength CO{sub 2} laser reaches a 100 times higher ponderomotive potential than the 1 {micro}m wavelength solid state lasers. Thus, we can expect a proportional increase in the throughput of such processes as laser acceleration, x-ray production, etc. These arguments have been confirmed in proof-of-principle Thomson scattering and laser acceleration experiments conducted at BNL and UCLA where the first terawatt-class CO{sub 2} lasers aremore » in operation. Further more, proposals for the 100 TW, 100 fs CO{sub 2} lasers based on frequency-chirped pulse amplification have been conceived. Such lasers can produce physical effects equivalent to a hypothetical multi-petawatt solid state laser. Ultra-fast mid-infrared lasers will open new routes to the next generation electron and ion accelerators, ultra-bright monochromatic femtosecond x-ray and gamma sources, allow to attempt the study of Hawking-Unruh radiation, and explore relativistic aspects of laser-matter interactions. We review the present status and experiments with terawatt-class CO{sub 2} lasers, sub-petawatt projects, and prospective applications in strong-field science.« less

The picosecond structure of ultra-fast rogue waves

NASA Astrophysics Data System (ADS)

Klein, Avi; Shahal, Shir; Masri, Gilad; Duadi, Hamootal; Sulimani, Kfir; Lib, Ohad; Steinberg, Hadar; Kolpakov, Stanislav A.; Fridman, Moti

2018-02-01

We investigated ultrafast rogue waves in fiber lasers and found three different patterns of rogue waves: single- peaks, twin-peaks, and triple-peaks. The statistics of the different patterns as a function of the pump power of the laser reveals that the probability for all rogue waves patterns increase close to the laser threshold. We developed a numerical model which prove that the ultrafast rogue waves patterns result from both the polarization mode dispersion in the fiber and the non-instantaneous nature of the saturable absorber. This discovery reveals that there are three different types of rogue waves in fiber lasers: slow, fast, and ultrafast, which relate to three different time-scales and are governed by three different sets of equations: the laser rate equations, the nonlinear Schrodinger equation, and the saturable absorber equations, accordingly. This discovery is highly important for analyzing rogue waves and other extreme events in fiber lasers and can lead to realizing types of rogue waves which were not possible so far such as triangular rogue waves.

Nail-like targets for laser plasma interaction experiments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pasley, J; Wei, M; Shipton, E

2007-12-18

The interaction of ultra-high power picosecond laser pulses with solid targets is of interest both for benchmarking the results of hybrid particle in cell (PIC) codes and also for applications to re-entrant cone guided fast ignition. We describe the construction of novel targets in which copper/titanium wires are formed into 'nail-like' objects by a process of melting and micromachining, so that energy can be reliably coupled to a 24 {micro}m diameter wire. An extreme-ultraviolet image of the interaction of the Titan laser with such a target is shown.

Picosecond laser ablation of poly-L-lactide: Effect of crystallinity on the material response

NASA Astrophysics Data System (ADS)

Ortiz, Rocío; Quintana, Iban; Etxarri, Jon; Lejardi, Ainhoa; Sarasua, Jose-Ramon

2011-11-01

The picosecond laser ablation of poly-L-lactide (PLLA) as a function of laser fluence and degree of crystallinity was examined. The ablation parameters and the surface modifications were analyzed under various irradiation conditions using laser wavelengths ranging from the ultraviolet through the visible. When processing the amorphous PLLA, both energy threshold and topography varied considerably depending on laser wavelength. Laser irradiation showed a reduction in the energy ablation threshold as the degree of crystallinity increased, probably related to photomechanical effects involved in laser ablation with ultra-short pulses and the lower stress accommodation behavior of semicrystalline polymers. In particular, cooperative chain motions are impeded by the higher degree of crystallinity, showing fragile mechanical behavior and lower energy dissipation. The experimental results on ablation rate versus laser energy showed that UV laser ablation on semicrystalline PLLA was more efficient than the visible ablation, i.e., it exhibits higher etch rates over a wide range of pulse energy conditions. These results were interpreted in terms of photo-thermal and photo-chemical response of polymers as a function of material micro-structure and incident laser wavelength. High quality micro-grooves were produced in amorphous PLLA, reveling the potential of ultra-fast laser processing technique in the field of micro-structuring biocompatible and biodegradable polymers for biomedical applications.

Characterization of FBG sensor interrogation based on a FDML wavelength swept laser

PubMed Central

Jung, Eun Joo; Kim, Chang-Seok; Jeong, Myung Yung; Kim, Moon Ki; Jeon, Min Yong; Jung, Woonggyu; Chen, Zhongping

2012-01-01

In this study, we develop an ultra-fast fiber Bragg grating sensor system that is based on the Fourier domain mode-locked (FDML) swept laser. A FDML wavelength swept laser has many advantages compared to the conventional wavelength swept laser source, such as high-speed interrogation, narrow spectral sensitivity, and high phase stability. The newly developed FDML wavelength swept laser shows a superior performance of a high scan rate of 31.3 kHz and a broad scan range of over 70 nm simultaneously. The performance of the grating sensor interrogating system using a FDML wavelength swept laser is characterized in both static and dynamic strain responses. PMID:18852764

Beam engineering for zero conicity cutting and drilling with ultra fast laser (Conference Presentation)

NASA Astrophysics Data System (ADS)

Letan, Amelie; Mishchik, Konstantin; Audouard, Eric; Hoenninger, Clemens; Mottay, Eric P.

2017-03-01

With the development of high average power, high repetition rate, industrial ultrafast lasers, it is now possible to achieve a high throughput with femtosecond laser processing, providing that the operating parameters are finely tuned to the application. Femtosecond lasers play a key role in these processes, due to their ability to high quality micro processing. They are able to drill high thickness holes (up to 1 mm) with arbitrary shapes, such as zero-conicity or even inversed taper, but can also perform zero-taper cutting. A clear understanding of all the processing steps necessary to optimize the processing speed is a main challenge for industrial developments. Indeed, the laser parameters are not independent of the beam steering devices. Pulses energy and repetition rate have to be precisely adjusted to the beam angle with the sample, and to the temporal and spatial sequences of pulses superposition. The purpose of the present work is to identify the role of these parameters for high aspect ratio drilling and cutting not only with experimental trials, but also with numerical estimations, using a simple engineering model based on the two temperature description of ultra-fast ablation. Assuming a nonlinear logarithmic response of the materials to ultrafast pulses, each material can be described by only two adjustable parameters. Simple assumptions allow to predict the effect of beam velocity and non-normal incident beams to estimate profile shapes and processing time.

Thin liquid sheet target capabilities for ultra-intense laser acceleration of ions at a kHz repetition rate

NASA Astrophysics Data System (ADS)

Klim, Adam; Morrison, J. T.; Orban, C.; Feister, S.; Ngirmang, G. K.; Smith, J.; Frische, K.; Peterson, A. C.; Chowdhury, E. A.; Freeman, R. R.; Roquemore, W. M.

2016-10-01

The success of laser-accelerated ion experiments depends crucially on a number of factors including how thin the targets can be created. We present experimental results demonstrating extremely thin (under 200 nm) water sheet targets that can be used for ultra-intense laser-accelerated ion experiments conducted at the Air Force Research Laboratory at Wright-Patterson Air Force Base. Importantly, these experiments operate at a kHz repetition rate and the recovery time of the liquid targets is fast enough to allow the laser to interact with a refreshed, thin target on every shot. We present results from liquid water targets which are useful for proton acceleration experiments via the mechanism of Target Normal Sheath Acceleration (TNSA). In future work, we will create thin sheets from deuterated water in order to perform laser-accelerated deuteron experiments. This research was sponsored by the Quantum and Non-Equilibrium Processes Division of the AFOSR, under the management of Dr. Enrique Parra, and support from the DOD HPCMP Internship Program.

Fast heating of ultrahigh-density plasma as a step towards laser fusion ignition.

PubMed

Kodama, R; Norreys, P A; Mima, K; Dangor, A E; Evans, R G; Fujita, H; Kitagawa, Y; Krushelnick, K; Miyakoshi, T; Miyanaga, N; Norimatsu, T; Rose, S J; Shozaki, T; Shigemori, K; Sunahara, A; Tampo, M; Tanaka, K A; Toyama, Y; Yamanaka, T; Zepf, M

2001-08-23

Modern high-power lasers can generate extreme states of matter that are relevant to astrophysics, equation-of-state studies and fusion energy research. Laser-driven implosions of spherical polymer shells have, for example, achieved an increase in density of 1,000 times relative to the solid state. These densities are large enough to enable controlled fusion, but to achieve energy gain a small volume of compressed fuel (known as the 'spark') must be heated to temperatures of about 108 K (corresponding to thermal energies in excess of 10 keV). In the conventional approach to controlled fusion, the spark is both produced and heated by accurately timed shock waves, but this process requires both precise implosion symmetry and a very large drive energy. In principle, these requirements can be significantly relaxed by performing the compression and fast heating separately; however, this 'fast ignitor' approach also suffers drawbacks, such as propagation losses and deflection of the ultra-intense laser pulse by the plasma surrounding the compressed fuel. Here we employ a new compression geometry that eliminates these problems; we combine production of compressed matter in a laser-driven implosion with picosecond-fast heating by a laser pulse timed to coincide with the peak compression. Our approach therefore permits efficient compression and heating to be carried out simultaneously, providing a route to efficient fusion energy production.

Hollow screw-like drill in plasma using an intense Laguerre-Gaussian laser

NASA Astrophysics Data System (ADS)

Wang, Wenpeng; Shen, Baifei; Zhang, Xiaomei; Zhang, Lingang; Shi, Yin; Xu, Zhizhan

2015-02-01

With the development of ultra-intense laser technology, MeV ions can be obtained from laser-foil interactions in the laboratory. These energetic ion beams can be applied in fast ignition for inertial confinement fusion, medical therapy, and proton imaging. However, these ions are mainly accelerated in the laser propagation direction. Ion acceleration in an azimuthal orientation was scarcely studied. In this research, a doughnut Laguerre-Gaussian (LG) laser is used for the first time to examine laser-plasma interaction in the relativistic intensity regime in three-dimensional particle-in-cell simulations. Studies have shown that a novel rotation of the plasma is produced from the hollow screw-like drill of an mode laser. The angular momentum of particles in the longitudinal direction produced by the LG laser is enhanced compared with that produced by the usual laser pulses, such as linearly and circularly polarized Gaussian pulses. Moreover, the particles (including electrons and ions) can be trapped and uniformly compressed in the dark central minimum of the doughnut LG pulse. The hollow-structured LG laser has potential applications in the generation of x-rays with orbital angular momentum, plasma accelerators, fast ignition for inertial confinement fusion, and pulsars in the astrophysical environment.

Hollow screw-like drill in plasma using an intense Laguerre-Gaussian laser.

PubMed

Wang, Wenpeng; Shen, Baifei; Zhang, Xiaomei; Zhang, Lingang; Shi, Yin; Xu, Zhizhan

2015-02-05

With the development of ultra-intense laser technology, MeV ions can be obtained from laser-foil interactions in the laboratory. These energetic ion beams can be applied in fast ignition for inertial confinement fusion, medical therapy, and proton imaging. However, these ions are mainly accelerated in the laser propagation direction. Ion acceleration in an azimuthal orientation was scarcely studied. In this research, a doughnut Laguerre-Gaussian (LG) laser is used for the first time to examine laser-plasma interaction in the relativistic intensity regime in three-dimensional particle-in-cell simulations. Studies have shown that a novel rotation of the plasma is produced from the hollow screw-like drill of an mode laser. The angular momentum of particles in the longitudinal direction produced by the LG laser is enhanced compared with that produced by the usual laser pulses, such as linearly and circularly polarized Gaussian pulses. Moreover, the particles (including electrons and ions) can be trapped and uniformly compressed in the dark central minimum of the doughnut LG pulse. The hollow-structured LG laser has potential applications in the generation of x-rays with orbital angular momentum, plasma accelerators, fast ignition for inertial confinement fusion, and pulsars in the astrophysical environment.

Efficient energy absorption of intense ps-laser pulse into nanowire target

NASA Astrophysics Data System (ADS)

Habara, H.; Honda, S.; Katayama, M.; Sakagami, H.; Nagai, K.; Tanaka, K. A.

2016-06-01

The interaction between ultra-intense laser light and vertically aligned carbon nanotubes is investigated to demonstrate efficient laser-energy absorption in the ps laser-pulse regime. Results indicate a clear enhancement of the energy conversion from laser to energetic electrons and a simultaneously small plasma expansion on the surface of the target. A two-dimensional plasma particle calculation exhibits a high absorption through laser propagation deep into the nanotube array, even for a dense array whose structure is much smaller than the laser wavelength. The propagation leads to the radial expansion of plasma perpendicular to the nanotubes rather than to the front side. These features may contribute to fast ignition in inertial confinement fusion and laser particle acceleration, both of which require high current and small surface plasma simultaneously.

Ultra-High-Contrast Laser Acceleration of Relativistic Electrons in Solid Targets

NASA Astrophysics Data System (ADS)

Higginson, Drew Pitney

The cone-guided fast ignition approach to Inertial Confinement Fusion requires laser-accelerated relativistic electrons to deposit kilojoules of energy within an imploded fuel core to initiate fusion burn. One obstacle to coupling electron energy into the core is the ablation of material, known as preplasma, by laser energy proceeding nanoseconds prior to the main pulse. This causes the laser-absorption surface to be pushed back hundreds of microns from the initial target surface; thus increasing the distance that electrons must travel to reach the imploded core. Previous experiments have shown an order of magnitude decrease in coupling into surrogate targets when intentionally increasing the amount of preplasma. Additionally, for electrons to deposit energy within the core, they should have kinetic energies on the order of a few MeV, as less energetic electrons will be stopped prior to the core and more energetic electrons will pass through the core without depositing much energy. Thus a quantitative understanding of the electron energy spectrum and how it responds to varied laser parameters is paramount for fast ignition. For the first time, this dissertation quantitatively investigates the acceleration of electrons using an ultra-high-contrast laser. Ultra-high-contrast lasers reduce the laser energy that reaches the target prior to the main pulse; drastically reducing the amount of preplasma. Experiments were performed in a cone-wire geometry relevant to fast ignition. These experiments irradiated the inner-tip of a Au cone with the laser and observed electrons that passed through a Cu wire attached to the outer-tip of the cone. The total emission of Kalpha x-rays is used as a diagnostic to infer the electron energy coupled into the wire. Imaging the x-ray emission allowed an effective path-length of electrons within the wire to be determined, which constrained the electron energy spectrum. Experiments were carried out on the ultra-high-contrast Trident laser at Los Alamos National Laboratory and at the low-contrast Titan laser at Lawrence Livermore National Laboratory. The targets were irradiated using these 1.054 microm wavelength lasers at intensities from 1019 to 10 20 W/cm2. The coupling of energy into the Cu wire was found to be 2.7x higher when the preplasma was reduced using high-contrast. Additionally, higher laser intensity elongated the effective path-length of electrons within the wire, indicating that their kinetic energy was higher. To understand the physics behind laser-acceleration of electrons and to examine how this mechanism is affected by the presence of preplasma, simulations were performed to model the laser interaction. This simulations modeled the interaction using a 0.1 to 3 microm exponential preplasma scale length for the high-contrast cases and hydronamically simulated longer scale preplasma (˜25 microm) for the low-contrast case. The simulations show that absorption of laser light increases from only 20% with a 0.1 microm scale length to nearly 90% with a long low-contrast-type preplasma. However, as observed in experiments, a smaller fraction of this absorbed energy is transported to the diagnostic wire, which is due to an increased distance that the electrons must travel to reach the wire and increase angular divergence of the electrons. The simulations show that increasing the preplasma scale length from 0.1 to 3 microm increases the average energy by a factor of 2.5x. This is consistent with an increased interaction length over which the electrons can gain energy from the laser. The simulated electrons are compared with experimental data by injecting them into another simulation modeling the transport of electrons through the cone-wire target. This method quantitatively reproduced the experimentally measured the Kalpha x-ray emission profiles in the high-contrast cases, which gives confidence in the simulations and the generated electron distributions. By showing that the reduction of preplasma increases coupling into surrogate targets this work shows a significant advantage for the fast ignition scheme. Such work gives confidence to facilities that increasing the contrast of their laser systems will increase electron coupling. Additionally, detailed investigation of these high-contrast systems will aid researchers in understanding the effect that preplasma has on the acceleration of electrons.

Dynamic conductivity and plasmon profile of aluminum in the ultra-fast-matter regime

NASA Astrophysics Data System (ADS)

Dharma-wardana, M. W. C.

2016-06-01

We use an explicitly isochoric two-temperature theory to analyze recent x-ray laser scattering data for aluminum in the ultra-fast-matter (UFM) regime up to 6 eV. The observed surprisingly low conductivities are explained by including strong electron-ion scattering effects using the phase shifts calculated via the neutral-pseudo-atom model. The difference between the static conductivity for UFM-Al and equilibrium aluminum in the warm-dense matter state is clearly brought out by comparisons with available density-fucntional+molecular-dynamics simulations. Thus the applicability of the Mermin model to UFM is questioned. The static and dynamic conductivity, collision frequency, and the plasmon line shape, evaluated within the simplest Born approximation for UFM aluminum, are in good agreement with experiment.

Generation of High Brightness X-rays with the PLEIADES Thomson X-ray Source

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brown, W J; Anderson, S G; Barty, C P J

2003-05-28

The use of short laser pulses to generate high peak intensity, ultra-short x-ray pulses enables exciting new experimental capabilities, such as femtosecond pump-probe experiments used to temporally resolve material structural dynamics on atomic time scales. PLEIADES (Picosecond Laser Electron InterAction for Dynamic Evaluation of Structures) is a next generation Thomson scattering x-ray source being developed at Lawrence Livermore National Laboratory (LLNL). Ultra-fast picosecond x-rays (10-200 keV) are generated by colliding an energetic electron beam (20-100 MeV) with a high intensity, sub-ps, 800 nm laser pulse. The peak brightness of the source is expected to exceed 10{sup 20} photons/s/0.1% bandwidth/mm2/mrad2. Simulationsmore » of the electron beam production, transport, and final focus are presented. Electron beam measurements, including emittance and final focus spot size are also presented and compared to simulation results. Measurements of x-ray production are also reported and compared to theoretical calculations.« less

Efficient energy absorption of intense ps-laser pulse into nanowire target

DOE Office of Scientific and Technical Information (OSTI.GOV)

Habara, H.; Honda, S.; Katayama, M.

The interaction between ultra-intense laser light and vertically aligned carbon nanotubes is investigated to demonstrate efficient laser-energy absorption in the ps laser-pulse regime. Results indicate a clear enhancement of the energy conversion from laser to energetic electrons and a simultaneously small plasma expansion on the surface of the target. A two-dimensional plasma particle calculation exhibits a high absorption through laser propagation deep into the nanotube array, even for a dense array whose structure is much smaller than the laser wavelength. The propagation leads to the radial expansion of plasma perpendicular to the nanotubes rather than to the front side. Thesemore » features may contribute to fast ignition in inertial confinement fusion and laser particle acceleration, both of which require high current and small surface plasma simultaneously.« less

Thin liquid sheet target capabilities for ultra-intense laser acceleration of ions at a kHz repetition rate

NASA Astrophysics Data System (ADS)

Klim, Adam; Morrison, J.; Orban, C.; Chowdhury, E.; Frische, K.; Feister, S.; Roquemore, M.

2017-10-01

The success of laser-accelerated ion experiments depends crucially on a number of factors including how thin the targets can be created. We present experimental results demonstrating extremely thin (under 200 nm) glycol sheet targets that can be used for ultra-intense laser-accelerated ion experiments conducted at the Air Force Research Laboratory at Wright-Patterson Air Force Base. Importantly, these experiments operate at a kHz repetition rate and the recovery time of the liquid targets is fast enough to allow the laser to interact with a refreshed, thin target on every shot. These thin targets can be used to produce energetic electrons, light ions, and neutrons as well as x-rays, we present results from liquid glycol targets which are useful for proton acceleration experiments via the mechanism of Target Normal Sheath Acceleration (TNSA). In future work, we will create thin sheets from deuterated water in order to perform laser-accelerated deuteron experiments. This research was sponsored by the Quantum and Non-Equilibrium Processes Division of the AFOSR, under the management of Dr. Enrique Parra, and support from the DOD HPCMP Internship Program.

Time-Space Position of Warm Dense Matter in Laser Plasma Interaction Process

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cao, L F; Uschmann, I; Forster, E

2006-09-25

Laser plasma interaction experiments have been perform performed using an fs Titanium Sapphire laser. Plasmas have been generated from planar PMMA targets using single laser pulses with 3.3 mJ pulse energy, 50 fs pulse duration at 800 nm wavelength. Electron density distributions of the plasmas in different delay times have been characterized by means of Nomarski Interferometry. Experimental data were cautiously compared with relevant 1D numerical simulation. Finally these results provide a first experience of searching for the time-space position of the so-called warm dense plasma in an ultra fast laser target interaction process. These experiments aim to prepare nearmore » solid-density plasmas for Thomson scattering experiments using the short wavelength free-electron laser FLASH, DESY Hamburg.« less

A Novel Femtosecond-gated, High-resolution, Frequency-shifted Shearing Interferometry Technique for Probing Pre-plasma Expansion in Ultra-intense Laser Experiments

DTIC Science & Technology

2014-07-17

frequency-shifted shearing interferometry technique for probing pre-plasma expansion in ultra-intense laser experimentsa) Ultra-intense laser -matter...interaction experiments (>1018 W/cm2) with dense targets are highly sensitive to the effect of laser “noise” (in the form of pre-pulses) preceding the...interferometry technique for probing pre- plasma expansion in ultra-intense laser experimentsa) Report Title Ultra-intense laser -matter interaction

Study of QCL Laser Sources for the Realization of Advanced Sensors.

PubMed

de Risi, Giuseppe; Columbo, Lorenzo Luigi; Brambilla, Massimo

2015-08-05

We study the nonlinear dynamics of a quantum cascade laser (QCL) with a strong reinjection provided by the feedback from two external targets in a double cavity configuration. The nonlinear coupling of interferometric signals from the two targets allows us to propose a displacement sensor with nanometric resolution. The system exploits the ultra-stability of QCLs in self-mixing configuration to access the intrinsic nonlinearity of the laser, described by the Lang-Kobayashi model, and it relies on a stroboscopic-like effect in the voltage signal registered at the QCL terminals that relates the "slow" target motion to the "fast" target one.

Ultra-Fast Laser Desorption/Laser Ionization Mass Spectrometry for the Organic Analysis of Stardust Sample Return

NASA Technical Reports Server (NTRS)

Clemett, Simon J.; McKay, David S.

2005-01-01

The STARDUST sample return capsule is anticipated to provide 500-1000 cometary particles 15 m in size. These were collected during the 340 km flyby of Comet P/Wild-2 and impacted the aerogel collection medium at a relative velocity of approx. 6.1 /kms. Hypervelocity impact studies suggest that some fraction of the original organic inventory of collected particles ought to remain intact, although there is likely to be a significant amount of devolatilization and disassociation of the lower mass organic fraction.

Ultrafast electronic relaxation in superheated bismuth

NASA Astrophysics Data System (ADS)

Gamaly, E. G.; Rode, A. V.

2013-01-01

Interaction of moving electrons with vibrating ions in the lattice forms the basis for many physical properties from electrical resistivity and electronic heat capacity to superconductivity. In ultrafast laser interaction with matter the electrons are heated much faster than the electron-ion energy equilibration, leading to a two-temperature state with electron temperature far above that of the lattice. The rate of temperature equilibration is governed by the strength of electron-phonon energy coupling, which is conventionally described by a coupling constant, neglecting the dependence on the electron and lattice temperature. The application of this constant to the observations of fast relaxation rate led to a controversial notion of ‘ultra-fast non-thermal melting’ under extreme electronic excitation. Here we provide theoretical grounds for a strong dependence of the electron-phonon relaxation time on the lattice temperature. We show, by taking proper account of temperature dependence, that the heating and restructuring of the lattice occurs much faster than were predicted on the assumption of a constant, temperature independent energy coupling. We applied the temperature-dependent momentum and energy transfer time to experiments on fs-laser excited bismuth to demonstrate that all the observed ultra-fast transformations of the transient state of bismuth are purely thermal in nature. The developed theory, when applied to ultrafast experiments on bismuth, provides interpretation of the whole variety of transient phase relaxation without the non-thermal melting conjecture.

Steering optical comb frequencies by rotating the polarization state

NASA Astrophysics Data System (ADS)

Zhang, Yanyan; Zhang, Xiaofei; Yan, Lulu; Zhang, Pan; Rao, Bingjie; Han, Wei; Guo, Wenge; Zhang, Shougang; Jiang, Haifeng

2017-12-01

Optical frequency combs, with precise control of repetition rate and carrier-envelope-offset frequency, have revolutionized many fields, such as fine optical spectroscopy, optical frequency standards, ultra-fast science research, ultra-stable microwave generation and precise ranging measurement. However, existing high bandwidth frequency control methods have small dynamic range, requiring complex hybrid control techniques. To overcome this limitation, we develop a new approach, where a home-made intra-cavity electro-optic modulator tunes polarization state of laser signal rather than only optical length of the cavity, to steer frequencies of a nonlinear-polarization-rotation mode-locked laser. By taking advantage of birefringence of the whole cavity, this approach results in not only broadband but also relative large-dynamic frequency control. Experimental results show that frequency control dynamic range increase at least one order in comparison with the traditional intra-cavity electro-optic modulator technique. In additional, this technique exhibits less side-effect than traditional frequency control methods.

Propagation of an ultra-short, intense laser in a relativistic fluid

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ritchie, A.B.; Decker, C.D.

1997-12-31

A Maxwell-relativistic fluid model is developed to describe the propagation of an ultrashort, intense laser pulse through an underdense plasma. The model makes use of numerically stabilizing fast Fourier transform (FFT) computational methods for both the Maxwell and fluid equations, and it is benchmarked against particle-in-cell (PIC) simulations. Strong fields generated in the wake of the laser are calculated, and the authors observe coherent wake-field radiation generated at harmonics of the plasma frequency due to nonlinearities in the laser-plasma interaction. For a plasma whose density is 10% of critical, the highest members of the plasma harmonic series begin to overlapmore » with the first laser harmonic, suggesting that widely used multiple-scales-theory, by which the laser and plasma frequencies are assumed to be separable, ceases to be a useful approximation.« less

Direct acceleration in intense laser fields used for bunch amplification of relativistic electrons

NASA Astrophysics Data System (ADS)

Braenzel, J.; Andreev, A. A.; Ehrentraut, L.; Schnürer, M.

2017-05-01

A method, how electrons can be directly accelerated in intense laser fields, is investigated experimentally and discussed with numerical and analytical simulation. When ultrathin foil targets are exposed with peak laser intensities of 1x1020 W/cm2 , slow electrons ( keV kinetic energy), that are emitted from the ultrathin foil target along laser propagation direction, are post-accelerated in the transmitted laser field. They received significant higher kinetic energies (MeV), when this interaction was limited in duration and an enhanced number of fast electrons were detected. The decoupling of the light field from the electron interaction we realized with a second separator foil, blocking the transmitted laser light at a particular distance and allowing the fast electrons to pass. Variation of the propagation distance in the laser field results in different energy gains for the electrons. This finding is explained with electron acceleration in the electromagnetic field of a light pulse and confirms a concept being discussed for some time. In the experiments the effect manifests in an electron number amplification of about 3 times around a peak at 1 MeV electron energy. Measurements confirmed that the overall number in the whole bunch is enhanced to about 109 electrons covering kinetic energies between 0.5 to 5 MeV. The method holds promise for ultrashort electron bunch generation at MeV energies for direct application, e.g. ultra-fast electron diffraction, or for injection into post accelerator stages for different purposes.

Hollow screw-like drill in plasma using an intense Laguerre–Gaussian laser

PubMed Central

Wang, Wenpeng; Shen, Baifei; Zhang, Xiaomei; Zhang, Lingang; Shi, Yin; Xu, Zhizhan

2015-01-01

With the development of ultra-intense laser technology, MeV ions can be obtained from laser–foil interactions in the laboratory. These energetic ion beams can be applied in fast ignition for inertial confinement fusion, medical therapy, and proton imaging. However, these ions are mainly accelerated in the laser propagation direction. Ion acceleration in an azimuthal orientation was scarcely studied. In this research, a doughnut Laguerre–Gaussian (LG) laser is used for the first time to examine laser–plasma interaction in the relativistic intensity regime in three-dimensional particle-in-cell simulations. Studies have shown that a novel rotation of the plasma is produced from the hollow screw-like drill of an mode laser. The angular momentum of particles in the longitudinal direction produced by the LG laser is enhanced compared with that produced by the usual laser pulses, such as linearly and circularly polarized Gaussian pulses. Moreover, the particles (including electrons and ions) can be trapped and uniformly compressed in the dark central minimum of the doughnut LG pulse. The hollow-structured LG laser has potential applications in the generation of x-rays with orbital angular momentum, plasma accelerators, fast ignition for inertial confinement fusion, and pulsars in the astrophysical environment. PMID:25651780

QUANTUM CONTROL OF LIGHT: From Slow Light and FAST CARS to Nuclear γ-ray Spectroscopy

NASA Astrophysics Data System (ADS)

Scully, Marlan

2007-06-01

In recent work we have demonstrated strong coherent backward wave oscillation using forward propagating fields only. This surprising result is achieved by applying laser fields to an ultra-dispersive medium with proper chosen detunings to excite a molecular vibrational coherence that corresponds to a backward propagating wave [PRL, 97, 113001 (2006)]. The physics then has much in common with propagation of ultra-slow light. Applications of coherent scattering and remote sensing to the detection of bio and chemical pathogens (e.g., anthrax) via Coherent Anti-Raman Scattering together with Femtosecond Adaptive Spectroscopic Techniques (FAST CARS [Opt. Comm., 244, 423 (2005)]) will be discussed. Furthermore, the interplay between quantum optics (Dicke super and sub-radiant states) and nuclear physics (forward scattering of γ radiation) provides interesting problems and insights into the quantum control of scattered light [PRL, 96, 010501 (2005)].

Looking for Speed!! Go Optical Ultra-Fast Photonic Logic Gates for the Future Optical Communication and Computing

NASA Technical Reports Server (NTRS)

Abdeldayem, Hossin; Frazier, Donald O.; Penn, Benjamin; Paley, Mark S.

2003-01-01

Recently, we developed two ultra-fast all-optical switches in the nanosecond and picosecond regimes. The picosecond switch is made of a polydiacetylene thin film coated on the interior wall of a hollow capillary of approximately 50 micron diameter by a photo-polymerization process. In the setup a picosecond Nd:YAG laser at 10 Hz and at 532 nm with a pulse duration of approximately 40 ps was sent collinearly along a cw He-Ne laser beam and both were waveguided through the hollow capillary. The setup functioned as an Exclusive OR gate. On the other hand, the material used in the nanosecond switch is a phthalocyanine thin film, deposited on a glass substrate by a vapor deposition technique. In the setup a nanosecond, 10 Hz, Nd:YAG laser of 8 ns pulse duration was sent collinearly along a cw He-Ne laser beam and both were wave-guided through the phthalocyanine thin film. The setup in this case functioned as an all-optical AND logic gate. The characteristic table of the ExOR gate in polydiacetylene film was attributed to an excited state absorption process, while that of the AND gate was attributed to a saturation process of the first excited state. Both mechanisms were thoroughly investigated theoretically and found to agree remarkably well with the experimental results. An all-optical inverter gate has been designed but has not yet been demonstrated. The combination of all these three gates form the foundation for building all the necessary gates needed to build a prototype of an all-optical system.

Laser ablation for the synthesis of carbon nanotubes

DOEpatents

Holloway, Brian C; Eklund, Peter C; Smith, Michael W; Jordan, Kevin C; Shinn, Michelle

2012-11-27

Single walled carbon nanotubes are produced in a novel apparatus by the laser-induced ablation of moving carbon target. The laser used is of high average power and ultra-fast pulsing. According to various preferred embodiments, the laser produces and output above about 50 watts/cm.sup.2 at a repetition rate above about 15 MHz and exhibits a pulse duration below about 10 picoseconds. The carbon, carbon/catalyst target and the laser beam are moved relative to one another and a focused flow of "side pumped", preheated inert gas is introduced near the point of ablation to minimize or eliminate interference by the ablated plume by removal of the plume and introduction of new target area for incidence with the laser beam. When the target is moved relative to the laser beam, rotational or translational movement may be imparted thereto, but rotation of the target is preferred.

Laser ablation for the synthesis of carbon nanotubes

DOEpatents

Holloway, Brian C.; Eklund, Peter C.; Smith, Michael W.; Jordan, Kevin C.; Shinn, Michelle

2010-04-06

Single walled carbon nanotubes are produced in a novel apparatus by the laser-induced ablation of moving carbon target. The laser used is of high average power and ultra-fast pulsing. According to various preferred embodiments, the laser produces an output above about 50 watts/cm.sup.2 at a repetition rate above about 15 MHz and exhibits a pulse duration below about 10 picoseconds. The carbon, carbon/catalyst target and the laser beam are moved relative to one another and a focused flow of "side pumped", preheated inert gas is introduced near the point of ablation to minimize or eliminate interference by the ablated plume by removal of the plume and introduction of new target area for incidence with the laser beam. When the target is moved relative to the laser beam, rotational or translational movement may be imparted thereto, but rotation of the target is preferred.

Laser ablation for the synthesis of carbon nanotubes

NASA Technical Reports Server (NTRS)

Holloway, Brian C. (Inventor); Eklund, Peter C. (Inventor); Smith, Michael W. (Inventor); Jordan, Kevin C. (Inventor); Shinn, Michelle (Inventor)

2010-01-01

Single walled carbon nanotubes are produced in a novel apparatus by the laser-induced ablation of moving carbon target. The laser used is of high average power and ultra-fast pulsing. According to various preferred embodiments, the laser produces an output above about 50 watts/cm.sup.2 at a repetition rate above about 15 MHz and exhibits a pulse duration below about 10 picoseconds. The carbon, carbon/catalyst target and the laser beam are moved relative to one another and a focused flow of side pumped, preheated inert gas is introduced near the point of ablation to minimize or eliminate interference by the ablated plume by removal of the plume and introduction of new target area for incidence with the laser beam. When the target is moved relative to the laser beam, rotational or translational movement may be imparted thereto, but rotation of the target is preferred.

Laser ablation for the synthesis of carbon nanotubes

NASA Technical Reports Server (NTRS)

Holloway, Brian C. (Inventor); Eklund, Peter C. (Inventor); Smith, Michael W. (Inventor); Jordan, Kevin C. (Inventor); Shinn, Michelle (Inventor)

2012-01-01

Single walled carbon nanotubes are produced in a novel apparatus by the laser-induced ablation of moving carbon target. The laser used is of high average power and ultra-fast pulsing. According to various preferred embodiments, the laser produces and output above about 50 watts/cm.sup.2 at a repetition rate above about 15 MHz and exhibits a pulse duration below about 10 picoseconds. The carbon, carbon/catalyst target and the laser beam are moved relative to one another and a focused flow of "side pumped", preheated inert gas is introduced near the point of ablation to minimize or eliminate interference by the ablated plume by removal of the plume and introduction of new target area for incidence with the laser beam. When the target is moved relative to the laser beam, rotational or translational movement may be imparted thereto, but rotation of the target is preferred.

Ablation dynamics - from absorption to heat accumulation/ultra-fast laser matter interaction

NASA Astrophysics Data System (ADS)

Kramer, Thorsten; Remund, Stefan; Jäggi, Beat; Schmid, Marc; Neuenschwander, Beat

2018-05-01

Ultra-short laser radiation is used in manifold industrial applications today. Although state-of-the-art laser sources are providing an average power of 10-100 W with repetition rates of up to several megahertz, most applications do not benefit from it. On the one hand, the processing speed is limited to some hundred millimeters per second by the dynamics of mechanical axes or galvanometric scanners. On the other hand, high repetition rates require consideration of new physical effects such as heat accumulation and shielding that might reduce the process efficiency. For ablation processes, process efficiency can be expressed by the specific removal rate, ablated volume per time, and average power. The analysis of the specific removal rate for different laser parameters, like average power, repetition rate or pulse duration, and process parameters, like scanning speed or material, can be used to find the best operation point for microprocessing applications. Analytical models and molecular dynamics simulations based on the so-called two-temperature model reveal the causes for the appearance of limiting physical effects. The findings of models and simulations can be used to take advantage and optimize processing strategies.

Graphene saturable absorber mirror for ultra-fast-pulse solid-state laser.

PubMed

Xu, Jin-Long; Li, Xian-Lei; Wu, Yong-Zhong; Hao, Xiao-Peng; He, Jing-Liang; Yang, Ke-Jian

2011-05-15

High-quality graphene sheets with lateral size over 20 μm have been obtained by bath sonicating after subjecting the wormlike graphite marginally to mixed oxidizer. To date, to our knowledge, they are the largest graphene sheets prepared by exfoliation in the liquid phase. A saturable absorber mirror was fabricated based on these sheets. We exploited it to realize mode-locking operation in a diode-pumped Nd:GdVO(4) laser. A pulse duration of 16 ps was produced with an average power of 360 mW and a highest pulse energy of 8.4 nJ for a graphene mode-locked laser. © 2011 Optical Society of America

The Interaction of Intense Laser Pulses with Preformed Plasmas for Fast Ignitor Studies

NASA Astrophysics Data System (ADS)

MacKinnon, A. J.

1998-11-01

The understanding of the interaction of intense picosecond laser pulses with preformed plasmas is essential for the fast ignitor concept. One of the major issues for this scheme concerns the propagation of ultra intense laser pulses through near critical density plasmas. Measurements of self-channelling of picosecond pulses due to relativistic and ponderomotive expulsion effects have recently been obtained in preformed plasmas at laser irradiances between 5-9x10^18 Wcm-2 footnote M. Borghesi et al, Phys. Rev Lett 78, 879 (1997).. The channel expansion after the laser pulse has been measured and an expansion velocity up to 1x10^9cms-1. was observed, implying ion energies around 1MeV. In addition, it was observed via Faraday rotation of an optical probe that the self focused channel is surrounded by a multi-megagauss magnetic field as predicted by 3D PIC simulations footnote A. Pukhov and J. Meyer-ter-Vehn, Phys. Rev Lett 76, 3975 (1996); M. Borghesi et al, Phys. Rev. Lett. 80, 5137 (1998).. The existence of this magnetic field is important for magnetic self-channelling of the relativistic electrons to high plasma densities. Good agreement was observed between the measurements and the 3D PIC simulations. The experimental results and PIC simulations will be presented and their relevance to the fast ignitor concept will be discussed.

Gain dynamics in a soft X-ray laser ampli er perturbed by a strong injected X-ray eld

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Yong; Wang, Shoujun; Oliva, E

2014-01-01

Seeding soft X-ray plasma ampli ers with high harmonics has been demonstrated to generate high-brightness soft X-ray laser pulses with full spatial and temporal coherence. The interaction between the injected coherent eld and the swept-gain medium has been modelled. However, no exper- iment has been conducted to probe the gain dynamics when perturbed by a strong external seed eld. Here, we report the rst X-ray pump X-ray probe measurement of the nonlinear response of a plasma ampli er perturbed by a strong soft X-ray ultra-short pulse. We injected a sequence of two time-delayed high-harmonic pulses (l518.9 nm) into a collisionallymore » excited nickel-like molybdenum plasma to measure with femto-second resolution the gain depletion induced by the saturated ampli cation of the high-harmonic pump and its subsequent recovery. The measured fast gain recovery in 1.5 1.75 ps con rms the possibility to generate ultra-intense, fully phase-coherent soft X-ray lasers by chirped pulse ampli cation in plasma ampli ers.« less

Semitransparent organic photovoltaic modules with Ag nanowire top electrodes

NASA Astrophysics Data System (ADS)

Guo, Fei; Kubis, Peter; Przybilla, Thomas; Spiecker, Erdmann; Forberich, Karen; Brabec, Christoph J.

2014-10-01

Semitransparent organic photovoltaic (OPV) cells are promising for applications in transparent architectures where their opaque counterparts are not suitable. Manufacturing of large-area modules without performance losses compared to their lab-scale devices is a key step towards practical applications of this PV technology. In this paper, we report the use of solution-processed silver nanowires as top electrodes and fabricate semitransparent OPV modules based on ultra-fast laser scribing. Through a rational choice of device architecture in combination with high-precision laser patterning, we demonstrate efficient semitransparent modules with comparable performance as compared to the reference devices.

THREE-DIMENSIONAL RANDOM ACCESS MULTIPHOTON MICROSCOPY FOR FAST FUNCTIONAL IMAGING OF NEURONAL ACTIVITY

PubMed Central

Reddy, Gaddum Duemani; Kelleher, Keith; Fink, Rudy; Saggau, Peter

2009-01-01

The dynamic ability of neuronal dendrites to shape and integrate synaptic responses is the hallmark of information processing in the brain. Effectively studying this phenomenon requires concurrent measurements at multiple sites on live neurons. Significant progress has been made by optical imaging systems which combine confocal and multiphoton microscopy with inertia-free laser scanning. However, all systems developed to date restrict fast imaging to two dimensions. This severely limits the extent to which neurons can be studied, since they represent complex three-dimensional (3D) structures. Here we present a novel imaging system that utilizes a unique arrangement of acousto-optic deflectors to steer a focused ultra-fast laser beam to arbitrary locations in 3D space without moving the objective lens. As we demonstrate, this highly versatile random-access multiphoton microscope supports functional imaging of complex 3D cellular structures such as neuronal dendrites or neural populations at acquisition rates on the order of tens of kilohertz. PMID:18432198

Ultra-fast laser microprocessing of medical polymers for cell engineering applications.

PubMed

Ortiz, R; Moreno-Flores, S; Quintana, I; Vivanco, MdM; Sarasua, J R; Toca-Herrera, J L

2014-04-01

Picosecond laser micromachining technology (PLM) has been employed as a tool for the fabrication of 3D structured substrates. These substrates have been used as supports in the in vitro study of the effect of substrate topography on cell behavior. Different micropatterns were PLM-generated on polystyrene (PS) and poly-L-lactide (PLLA) and employed to study cellular proliferation and morphology of breast cancer cells. The laser-induced microstructures included parallel lines of comparable width to that of a single cell (which in this case is roughly 20μm), and the fabrication of square-like compartments of a much larger area than a single cell (250,000μm(2)). The results obtained from this in vitro study showed that though the laser treatment altered substrate roughness, it did not noticeably affect the adhesion and proliferation of the breast cancer cells. However, pattern direction directly affected cell proliferation, leading to a guided growth of cell clusters along the pattern direction. When cultured in square-like compartments, cells remained confined inside these for eleven incubation days. According to these results, laser micromachining with ultra-short laser pulses is a suitable method to directly modify the cell microenvironment in order to induce a predefined cellular behavior and to study the effect of the physical microenvironment on cell proliferation. Copyright © 2013 Elsevier B.V. All rights reserved.

Fast spatial beam shaping by acousto-optic diffraction for 3D non-linear microscopy.

PubMed

Akemann, Walther; Léger, Jean-François; Ventalon, Cathie; Mathieu, Benjamin; Dieudonné, Stéphane; Bourdieu, Laurent

2015-11-02

Acousto-optic deflection (AOD) devices offer unprecedented fast control of the entire spatial structure of light beams, most notably their phase. AOD light modulation of ultra-short laser pulses, however, is not straightforward to implement because of intrinsic chromatic dispersion and non-stationarity of acousto-optic diffraction. While schemes exist to compensate chromatic dispersion, non-stationarity remains an obstacle. In this work we demonstrate an efficient AOD light modulator for stable phase modulation using time-locked generation of frequency-modulated acoustic waves at the full repetition rate of a high power laser pulse amplifier of 80 kHz. We establish the non-local relationship between the optical phase and the generating acoustic frequency function and verify the system for temporal stability, phase accuracy and generation of non-linear two-dimensional phase functions.

640-Gbit/s fast physical random number generation using a broadband chaotic semiconductor laser

NASA Astrophysics Data System (ADS)

Zhang, Limeng; Pan, Biwei; Chen, Guangcan; Guo, Lu; Lu, Dan; Zhao, Lingjuan; Wang, Wei

2017-04-01

An ultra-fast physical random number generator is demonstrated utilizing a photonic integrated device based broadband chaotic source with a simple post data processing method. The compact chaotic source is implemented by using a monolithic integrated dual-mode amplified feedback laser (AFL) with self-injection, where a robust chaotic signal with RF frequency coverage of above 50 GHz and flatness of ±3.6 dB is generated. By using 4-least significant bits (LSBs) retaining from the 8-bit digitization of the chaotic waveform, random sequences with a bit-rate up to 640 Gbit/s (160 GS/s × 4 bits) are realized. The generated random bits have passed each of the fifteen NIST statistics tests (NIST SP800-22), indicating its randomness for practical applications.

Space-Time Characterization of Laser Plasma Interactions in the Warm Dense Matter Regime

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cao, L F; Uschmann, I; Forster, E

2008-04-30

Laser plasma interaction experiments have been performed using a fs Titanium Sapphire laser. Plasmas have been generated from planar PMMA targets using single laser pulses with 3.3 mJ pulse energy, 50 fs pulse duration at 800 nm wavelength. The electron density distributions of the plasmas in different delay times have been characterized by means of Nomarski Interferometry. Experimental data were compared with hydrodynamic simulation. First results to characterize the plasma density and temperature as a function of space and time are obtained. This work aims to generate plasmas in the warm dense matter (WDM) regime at near solid-density in anmore » ultra-fast laser target interaction process. Plasmas under these conditions can serve as targets to develop x-ray Thomson scattering as a plasma diagnostic tool, e.g., using the VUV free-electron laser (FLASH) at DESY Hamburg.« less

Ab initio description of the first stages of laser-induced ultra-fast nonthermal melting of InSb

NASA Astrophysics Data System (ADS)

Zijlstra, E. S.; Walkenhorst, J.; Gilfert, C.; Sippel, C.; Töws, W.; Garcia, M. E.

2008-12-01

Using first principles, all-electron calculations and dynamical simulations we study the behavior of solid InSb immediately after intense femtosecond excitation. First, we determine the laser-excited potential energy surfaces with high accuracy for different electronic temperatures (corresponding to different laser fluences). Then, we demonstrate that, although most phonon modes become only slightly softened even for high electron temperatures, the transverse acoustic modes at the boundary of the Brillouin zone undergo dramatic changes and become unstable. This is the origin of nonthermal melting. Based on these results, the dynamics during the first hundreds of femtoseconds after laser excitation can be unambiguously elucidated. Our results are in agreement with recent experiments and support the predictions made by Stampfli and Bennemann for silicon.

Fast-Ion Spectrometry of ICF Implosions and Laser-Foil Experiments at the Omega and MTW Laser Facilities

NASA Astrophysics Data System (ADS)

Sinenian, Nareg

Fast ions generated from laser-plasma interactions (LPI) have been used to study inertial confinement fusion (ICF) implosions and laser-foil interactions. LPI, which vary in nature depending on the wavelength and intensity of the driver, generate hot electrons with temperatures ranging from tens to thousands of kilo-electron-volts. These electrons, which accelerate the ions measured in this work, can be either detrimental or essential to implosion performance depending on the ICF scheme employed. In direct-drive hot-spot ignition, hot electrons can preheat the fuel and raise the adiabat, potentially degrading compression in the implosion. The amount of preheat depends on the hot-electron source characteristics and the time duration over which electrons can deposit energy into the fuel. This time duration is prescribed by the evolution of a sheath that surrounds the implosion and traps electrons. Fast-ion measurements have been used to develop a circuit model that describes the time decay of the sheath voltage for typical OMEGA implosions. In the context of electron fast ignition, the produced fast ions are considered a loss channel that has been characterized for the first time. These ions have also been used as a diagnostic tool to infer the temperature of the hot electrons in fast-ignition experiments. It has also been shown that the hot-electron temperature scales with laser intensity as expected, but is enhanced by a factor of 2-3. This enhancement is possibly due to relativistic effects and leads to poor implosion performance. Finally, fast-ion generation by ultra-intense lasers has also been studied using planar targets. The mean and maximum energies of protons and heavy ions has been measured, and it has been shown that a two-temperature hot-electron distribution affects the energies of heavy ions and protons. This work is important for advanced fusion concepts that utilize ion beams and also has applications in medicine. (Copies available exclusively from MIT Libraries, libraries.mit.edu/docs - docs@mit.edu)

Photonic crystal Fano resonances for realizing optical switches, lasers, and non-reciprocal elements

NASA Astrophysics Data System (ADS)

Bekele, Dagmawi A.; Yu, Yi; Hu, Hao; Ding, Yunhong; Sakanas, Aurimas; Ottaviano, Luisa; Semenova, Elizaveta; Oxenløwe, Leif K.; Yvind, Kresten; Mork, Jesper

2017-08-01

We present our work on photonic crystal membrane devices exploiting Fano resonance between a line-defect waveguide and a side coupled nanocavity. Experimental demonstration of fast and compact all-optical switches for wavelength-conversion is reported. It is shown how the use of an asymmetric structure in combination with cavity-enhanced nonlinearity can be used to realize non-reciprocal transmission at ultra-low power and with large bandwidth. A novel type of laser structure, denoted a Fano laser, is discussed in which one of the mirrors is based on a Fano resonance. Finally, the design, fabrication and characterization of grating couplers for efficient light coupling in and out of the indium phosphide photonic crystal platform is discussed.

Coupled Optoelectronic Oscillators:. Application to Low-Jitter Pulse Generation

NASA Astrophysics Data System (ADS)

Yu, N.; Tu, M.; Maleki, L.

2002-04-01

Actively mode-locked Erbium-doped fiber lasers (EDFL) have been studied for generating stable ultra-fast pulses (< 2 ps) at high repetition rates (> 5 GHz) [1,2]. These devices can be compact and environmentally stable, quite suitable for fiber-based high-data-rate communications and optical ultra-fast analog-to-digital conversions (ADC) [3]. The pulse-to-pulse jitter of an EDFL-based pulse generator will be ultimately limited by the phase noise of the mode-locking microwave source (typically electronic frequency synthesizers). On the other hand, opto-electronic oscillators (OEO) using fibers have been demonstrated to generate ultra-low phase noise microwaves at 10 GHz and higher [4]. The overall phase noise of an OEO can be much lower than commercially available synthesizers at the offset-frequency range above 100 Hz. Clearly, ultra-low jitter pulses can be generated by taking advantage of the low phase noise of OEOs. In this paper, we report the progress in developing a new low-jitter pulse generator by combing the two technologies. In our approach, the optical oscillator (mode-locked EDFL) and the microwave oscillator (OEO) are coupled through a common Mach-Zehnder (MZ) modulator, thus named coupled opto-electronic oscillator (COEO) [5]. Based on the results of previous OEO study, we can expect a 10 GHz pulse train with jitters less than 10 fs.

Feasibility of UltraFast Doppler in Post-operative Evaluation of Hepatic Artery in Recipients following Liver Transplantation.

PubMed

Kim, Se-Young; Kim, Kyoung Won; Choi, Sang Hyun; Kwon, Jae Hyun; Song, Gi-Won; Kwon, Heon-Ju; Yun, Young Ju; Lee, Jeongjin; Lee, Sung-Gyu

2017-11-01

To determine the feasibility of using UltraFast Doppler in post-operative evaluation of the hepatic artery (HA) after liver transplantation (LT), we evaluated 283 simultaneous conventional and UltraFast Doppler sessions in 126 recipients over a 2-mo period after LT, using an Aixplorer scanner The Doppler indexes of the HA (peak systolic velocity [PSV], end-diastolic velocity [EDV], resistive index [RI] and systolic acceleration time [SAT]) by retrospective analysis of retrieved waves from UltraFast Doppler clips were compared with those obtained by conventional spectral Doppler. Correlation, performance in diagnosing the pathologic wave, examination time and reproducibility were evaluated. The PSV, EDV, RI and SAT of spectral and UltraFast Doppler measurements exhibited excellent correlation with favorable diagnostic performance. During the bedside examination, the mean time spent for UltraFast clip storing was significantly shorter than that for conventional Doppler US measurements. Both conventional and UltraFast Doppler exhibited good to excellent inter-analysis consistency. In conclusion, compared with conventional spectral Doppler, UltraFast Doppler values correlated excellently and yielded acceptable pathologic wave diagnostic performance with reduced examination time at the bedside and excellent reproducibility. Copyright © 2017 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.

Spectra of laser generated relativistic electrons using cone-wire targets

NASA Astrophysics Data System (ADS)

Sawada, Hiroshi

2012-10-01

We report on the characterization of the in situ energy spectrum of fast electrons generated by ultra-intense (I˜10^19 W cm-2) short pulse (τ˜0.7 and 10 ps) laser-plasma interactions using the TITAN and OMEGA EP lasers. That in situ spectrum is a key component of ignition efficiency for the Fast Ignition (FI) Inertial Confinement Fusion (ICF) concept. It is challenging to model and, until now, has resisted direct experimental characterization; other techniques have very large error bars or measure the modified spectrum of escaped electrons. This technique also gives an indication of the forward coupling efficiency of the laser to fast electrons. This information is derived from the measurement of Cu Kα x-rays emitted from a 1.5 mm long Cu wire attached to the tip of Au or Al cone targets. Fast electrons, generated in the cone, transport through the cone tip with a fraction of coupling to the wire. Electrons in the wire excite fluorescence measured by a monochromatic imager and an absolutely calibrated HOPG spectrometer. An implicit hybrid-PIC code, LSP, is applied to deduce electron parameters from the Kα measurements. Experiments on the TITAN laser with Au cones attached to wires show an increase in pre-pulse energy from 17 to 1000 mJ, decreases the fast electron fraction entering the wire from 8.4% to 2.5%. On OMEGA EP with Al cones attached to wires, total Kα yield, normalized to laser energy, drops ˜30% for laser pulse length increasing from 1 to 10 ps, indicative of a saturation mechanism. For Au cones, Kα yields were 50% of that measured for Al cones indicating a strong material dependence. In all cases, the spatial distribution can only be fit with a two-temperature electron energy distribution, the relative fractions depending on prepulse level. These results are being used to develop an optimum cone design for integrated FI experiments. This work was performed under the auspices of the USDOE by LLNL under Contract DE-AC52-07NA27344 and DE-FG-02-05ER54834.

Implementation of an Ultra-Bright Thermographic Phosphor for Gas Turbine Engine Temperature Measurements

NASA Technical Reports Server (NTRS)

Eldridge, Jeffrey I.; Bencic, Timothy J.; Zhu, Dongming; Cuy, Michael D.; Wolfe, Douglas E.; Allison, Stephen W.; Beshears, David L.; Jenkins, Thomas P.; Heeg, Bauke; Howard, Robert P.;

Reaction-time-resolved measurements of laser-induced fluorescence in a shock tube with a single laser pulse

NASA Astrophysics Data System (ADS)

Zabeti, S.; Fikri, M.; Schulz, C.

2017-11-01

Shock tubes allow for the study of ultra-fast gas-phase reactions on the microsecond time scale. Because the repetition rate of the experiments is low, it is crucial to gain as much information as possible from each individual measurement. While reaction-time-resolved species concentration and temperature measurements with fast absorption methods are established, conventional laser-induced fluorescence (LIF) measurements with pulsed lasers provide data only at a single reaction time. Therefore, fluorescence methods have rarely been used in shock-tube diagnostics. In this paper, a novel experimental concept is presented that allows reaction-time-resolved LIF measurements with one single laser pulse using a test section that is equipped with several optical ports. After the passage of the shock wave, the reactive mixture is excited along the center of the tube with a 266-nm laser beam directed through a window in the end wall of the shock tube. The emitted LIF signal is collected through elongated sidewall windows and focused onto the entrance slit of an imaging spectrometer coupled to an intensified CCD camera. The one-dimensional spatial resolution of the measurement translates into a reaction-time-resolved measurement while the species information can be gained from the spectral axis of the detected two-dimensional image. Anisole pyrolysis was selected as the benchmark reaction to demonstrate the new apparatus.

Ultra-fast pulse propagation in nonlinear graphene/silicon ridge waveguide

NASA Astrophysics Data System (ADS)

Liu, Ken; Zhang, Jian Fa; Xu, Wei; Zhu, Zhi Hong; Guo, Chu Cai; Li, Xiu Jian; Qin, Shi Qiao

2015-11-01

We report the femtosecond laser propagation in a hybrid graphene/silicon ridge waveguide with demonstration of the ultra-large Kerr coefficient of graphene. We also fabricated a slot-like graphene/silicon ridge waveguide which can enhance its effective Kerr coefficient 1.5 times compared with the graphene/silicon ridge waveguide. Both transverse-electric-like (TE-like) mode and transverse-magnetic-like (TM-like) mode are experimentally measured and numerically analyzed. The results show nonlinearity dependence on mode polarization not in graphene/silicon ridge waveguide but in slot-like graphene/silicon ridge waveguide. Great spectral broadening was observed due to self-phase modulation (SPM) after propagation in the hybrid waveguide with length of 2 mm. Power dependence property of the slot-like hybrid waveguide is also measured and numerically analyzed. The results also confirm the effective Kerr coefficient estimation of the hybrid structures. Spectral blue shift of the output pulse was observed in the slot-like graphene/silicon ridge waveguide. One possible explanation is that the blue shift was caused by the ultra-fast free carrier effect with the optical absorption of the doped graphene. This interesting effect can be used for soliton compression in femtosecond region. We also discussed the broadband anomalous dispersion of the Kerr coefficient of graphene.

Laser-induced reversion of δ' precipitates in an Al-Li alloy: Study on temperature rise in pulsed laser atom probe.

PubMed

Khushaim, Muna; Gemma, Ryota; Al-Kassab, Talaat

2016-08-01

The influence of tuning the laser pulse energy during the analyses on the resulting microstructure in a specimen utilizing an ultra-fast laser assisted atom probe was demonstrated by a case study of a binary Al-Li alloy. The decomposition parameters, such as the size, number density, volume fraction, and composition of δ' precipitates, were carefully monitored after each analysis. A simple model was employed to estimate the corresponding specimen temperature for each value of the laser energy. The results indicated that the corresponding temperatures for the laser pulse energy in the range of 10 to 80 pJ are located inside the miscibility gap of the binary Al-Li phase diagram and fall into the metastable equilibrium field. In addition, the corresponding temperature for a laser pulse energy of 100 pJ was in fairly good agreement with reported range of  δ' solvus temperature, suggesting a result of reversion upon heating due to laser pulsing. Microsc. Res. Tech. 79:727-737, 2016. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chesnokov, E. N., E-mail: chesnok@kinetics.nsc.ru; Novosibirsk State University, Novosibirsk 630090; Kubarev, V. V.

Using the pulses of terahertz free electron laser and ultra-fast Schottky diode detectors, we observed the coherent transients within a free induction decay of gaseous nitrogen dioxide NO{sub 2}. The laser excited different sub-bands of rotation spectra of NO{sub 2} containing about 50–70 lines. The free induction signal continued more than 30 ns and consisted of many echo-like bursts duration about 0.2 ns. Unlike the similar effect observed previously for linear and symmetric top molecules, the sequence of echo bursts is not periodic. The values for delay of individual echo are stable, and the set of these delays can be considered asmore » a “molecular fingerprint” in the time domain.« less

mrsFAST-Ultra: a compact, SNP-aware mapper for high performance sequencing applications.

PubMed

Hach, Faraz; Sarrafi, Iman; Hormozdiari, Farhad; Alkan, Can; Eichler, Evan E; Sahinalp, S Cenk

2014-07-01

High throughput sequencing (HTS) platforms generate unprecedented amounts of data that introduce challenges for processing and downstream analysis. While tools that report the 'best' mapping location of each read provide a fast way to process HTS data, they are not suitable for many types of downstream analysis such as structural variation detection, where it is important to report multiple mapping loci for each read. For this purpose we introduce mrsFAST-Ultra, a fast, cache oblivious, SNP-aware aligner that can handle the multi-mapping of HTS reads very efficiently. mrsFAST-Ultra improves mrsFAST, our first cache oblivious read aligner capable of handling multi-mapping reads, through new and compact index structures that reduce not only the overall memory usage but also the number of CPU operations per alignment. In fact the size of the index generated by mrsFAST-Ultra is 10 times smaller than that of mrsFAST. As importantly, mrsFAST-Ultra introduces new features such as being able to (i) obtain the best mapping loci for each read, and (ii) return all reads that have at most n mapping loci (within an error threshold), together with these loci, for any user specified n. Furthermore, mrsFAST-Ultra is SNP-aware, i.e. it can map reads to reference genome while discounting the mismatches that occur at common SNP locations provided by db-SNP; this significantly increases the number of reads that can be mapped to the reference genome. Notice that all of the above features are implemented within the index structure and are not simple post-processing steps and thus are performed highly efficiently. Finally, mrsFAST-Ultra utilizes multiple available cores and processors and can be tuned for various memory settings. Our results show that mrsFAST-Ultra is roughly five times faster than its predecessor mrsFAST. In comparison to newly enhanced popular tools such as Bowtie2, it is more sensitive (it can report 10 times or more mappings per read) and much faster (six times or more) in the multi-mapping mode. Furthermore, mrsFAST-Ultra has an index size of 2GB for the entire human reference genome, which is roughly half of that of Bowtie2. mrsFAST-Ultra is open source and it can be accessed at http://mrsfast.sourceforge.net. © The Author(s) 2014. Published by Oxford University Press on behalf of Nucleic Acids Research.

Plasma-wall interaction in laser inertial fusion reactors: novel proposals for radiation tests of first wall materials

NASA Astrophysics Data System (ADS)

Alvarez Ruiz, J.; Rivera, A.; Mima, K.; Garoz, D.; Gonzalez-Arrabal, R.; Gordillo, N.; Fuchs, J.; Tanaka, K.; Fernández, I.; Briones, F.; Perlado, J.

2012-12-01

Dry-wall laser inertial fusion (LIF) chambers will have to withstand strong bursts of fast charged particles which will deposit tens of kJ m-2 and implant more than 1018 particles m-2 in a few microseconds at a repetition rate of some Hz. Large chamber dimensions and resistant plasma-facing materials must be combined to guarantee the chamber performance as long as possible under the expected threats: heating, fatigue, cracking, formation of defects, retention of light species, swelling and erosion. Current and novel radiation resistant materials for the first wall need to be validated under realistic conditions. However, at present there is a lack of facilities which can reproduce such ion environments. This contribution proposes the use of ultra-intense lasers and high-intense pulsed ion beams (HIPIB) to recreate the plasma conditions in LIF reactors. By target normal sheath acceleration, ultra-intense lasers can generate very short and energetic ion pulses with a spectral distribution similar to that of the inertial fusion ion bursts, suitable to validate fusion materials and to investigate the barely known propagation of those bursts through background plasmas/gases present in the reactor chamber. HIPIB technologies, initially developed for inertial fusion driver systems, provide huge intensity pulses which meet the irradiation conditions expected in the first wall of LIF chambers and thus can be used for the validation of materials too.

Overview of options for generating high-brightness attosecond x-ray pulses at free-electron lasers and applications at the European XFEL

NASA Astrophysics Data System (ADS)

Serkez, S.; Geloni, G.; Tomin, S.; Feng, G.; Gryzlova, E. V.; Grum-Grzhimailo, A. N.; Meyer, M.

2018-02-01

The generation of attosecond, highbrightness x-ray pulses is a matter of great interest given their applications in the study of ultra-fast processes. In recent years, the production of x-ray pulses of high brightness, both in the soft and in the hard x-ray range, has been enabled by x-ray free-electron lasers (XFELs). In contrast to conventional quantum lasers, XFELs are based on the use of an ultra-relativistic electron beam as gain medium. They often work in the self-amplified spontaneous emission (SASE) regime, which provides pulses of duration down to a few femtoseconds, composed of several longitudinal modes. In order to further decrease the duration of these pulses, special methods need to be implemented. In this paper we review available methods, with particular focus on the x-ray laser-enhanced attosecond pulse generation, which is one of the most promising techniques. We illustrate the method using the SASE3 soft x-ray undulator of the European XFEL facility as a case study, emphasizing the importance of high-repetition rate attosecond x-ray pulses. The expected attosecond-level radiation output is used for simulations of sequential ionization processes in atoms in the case of ionization in the soft x-ray regime, demonstrating the importance of this opportunity for the user community.

Laser cutting of ultra-thin glasses based on a nonlinear laser interaction effect

NASA Astrophysics Data System (ADS)

Chen, Jian; Wu, Zhouling

2013-07-01

Glass panel substrates have been widely used in consumer electronics such as in flat panel TVs, laptops, and cell phones. With the advancement in the industry, the glass substrates are becoming thinner and stronger for reduced weight and volume, which brings great challenges for traditional mechanical processes in terms of cut quality, yield, and throughput. Laser glass cutting provides a non-contact process with minimum impact and superior quality compared to the mechanical counterparts. In this paper, we presented recent progresses in advanced laser processing of ultra-thin glass substrates, especially laser-cutting of ultra-thin glasses by a high power laser through a nonlinear interaction effect. Our results indicate that this technique has great potential of application for mass production of ultra-thin glass substrates.

Extending laser plasma accelerators into the mid-IR spectral domain with a next-generation ultra-fast CO 2 laser

DOE PAGES

Pogorelsky, I. V.; Babzien, M.; Ben-Zvi, I.; ...

2016-01-20

Here we discuss how expanding the scope of relativistic plasma research to wavelengths longer than λ/≈0.8₋1.1μm covered by conventional mode-locked solid-state lasers would offer attractive opportunities due to the quadratic scaling of the ponderomotive electron energy and critical plasma density with λ. Answering this quest, a next-generation mid-IR laser project is being advanced at the BNL ATF as a part of the user facility upgrade. We discuss the technical approach to this conceptually new 100 TW, 100 fs, λ=9₋11 μm CO 2 laser BESTIA (Brookhaven Experimental Supra-Terawatt Infrared at ATF) that encompasses several innovations applied for the first time tomore » molecular gas lasers. BESTIA will enable new regimes of laser plasma accelerators. One for example is shock-wave ion acceleration from gas jets. We review ongoing efforts to achieve stable, monoenergetic proton acceleration by dynamically shaping the plasma density profile from a hydrogen gas target with laser-produced blast waves. At its full power, 100 TW BESTIA promises to achieve proton beams at energy exceeding 200 MeV. In addition to ion acceleration in over-critical plasma, the ultra-intense mid-IR laser BESTIA will open new opportunities in driving wakefields in tenuous plasmas, expanding the landscape of Laser Wake Field Accelerator (LWFA) studies into unexplored long-wavelength spectral domain. Simple wavelength scaling suggests that a 100-TW CO2 laser beam will be capable to efficiently generate plasma “bubbles” thousand times bigger in volume compared to a near-IR solid state laser of an equivalent power. Combined with a femtosecond electron linac available at the ATF, this wavelength scaling will facilitate study of external seeding and staging of LWFA.« less

The Improved Locating Algorithm of Particle Filter Based on ROS Robot

NASA Astrophysics Data System (ADS)

Fang, Xun; Fu, Xiaoyang; Sun, Ming

2018-03-01

This paperanalyzes basic theory and primary algorithm of the real-time locating system and SLAM technology based on ROS system Robot. It proposes improved locating algorithm of particle filter effectively reduces the matching time of laser radar and map, additional ultra-wideband technology directly accelerates the global efficiency of FastSLAM algorithm, which no longer needs searching on the global map. Meanwhile, the re-sampling has been largely reduced about 5/6 that directly cancels the matching behavior on Roboticsalgorithm.

Elaboration and Characterization of Nano-Sized AlxMoyOz/Al Thermites

DTIC Science & Technology

2006-07-01

corresponding micrographs are not the experiments of time resolved shown here). In the Th. 1 material, the cinematography . micron-sized MoO 3...necessary to know cinelnalogra/)hy andspec’troscot)y- the effective power (P) delivered by the laser The time resolved cinematography (TRC) is source as...necessary to initiate the film paper ((D P 1.4 amm). The combustion rate 8 PU 614/2006 (Vr) is measured by ultra fast cinematography the lower are the

Durable silver thin film coating for diffraction gratings

DOEpatents

Wolfe, Jesse D [Discovery Bay, CA; Britten, Jerald A [Oakley, CA; Komashko, Aleksey M [San Diego, CA

2006-05-30

A durable silver film thin film coated non-planar optical element has been developed to replace Gold as a material for fabricating such devices. Such a coating and resultant optical element has an increased efficiency and is resistant to tarnishing, can be easily stripped and re-deposited without modifying underlying grating structure, improves the throughput and power loading of short pulse compressor designs for ultra-fast laser systems, and can be utilized in variety of optical and spectrophotometric systems, particularly high-end spectrometers that require maximized efficiency.

Investigations of ultrafast charge dynamics in laser-irradiated targets by a self probing technique employing laser driven protons

NASA Astrophysics Data System (ADS)

Ahmed, H.; Kar, S.; Cantono, G.; Nersisyan, G.; Brauckmann, S.; Doria, D.; Gwynne, D.; Macchi, A.; Naughton, K.; Willi, O.; Lewis, C. L. S.; Borghesi, M.

2016-09-01

The divergent and broadband proton beams produced by the target normal sheath acceleration mechanism provide the unique opportunity to probe, in a point-projection imaging scheme, the dynamics of the transient electric and magnetic fields produced during laser-plasma interactions. Commonly such experimental setup entails two intense laser beams, where the interaction produced by one beam is probed with the protons produced by the second. We present here experimental studies of the ultra-fast charge dynamics along a wire connected to laser irradiated target carried out by employing a 'self' proton probing arrangement - i.e. by connecting the wire to the target generating the probe protons. The experimental data shows that an electromagnetic pulse carrying a significant amount of charge is launched along the wire, which travels as a unified pulse of 10s of ps duration with a velocity close to speed of light. The experimental capabilities and the analysis procedure of this specific type of proton probing technique are discussed.

Ultra-fast quantum randomness generation by accelerated phase diffusion in a pulsed laser diode.

PubMed

Abellán, C; Amaya, W; Jofre, M; Curty, M; Acín, A; Capmany, J; Pruneri, V; Mitchell, M W

2014-01-27

We demonstrate a high bit-rate quantum random number generator by interferometric detection of phase diffusion in a gain-switched DFB laser diode. Gain switching at few-GHz frequencies produces a train of bright pulses with nearly equal amplitudes and random phases. An unbalanced Mach-Zehnder interferometer is used to interfere subsequent pulses and thereby generate strong random-amplitude pulses, which are detected and digitized to produce a high-rate random bit string. Using established models of semiconductor laser field dynamics, we predict a regime of high visibility interference and nearly complete vacuum-fluctuation-induced phase diffusion between pulses. These are confirmed by measurement of pulse power statistics at the output of the interferometer. Using a 5.825 GHz excitation rate and 14-bit digitization, we observe 43 Gbps quantum randomness generation.

Temporally and Spatially Resolved Plasma Spectroscopy in Pulsed Laser Deposition of Ultra-Thin Boron Nitride Films (Postprint)

DTIC Science & Technology

2015-04-24

AFRL-RX-WP-JA-2016-0196 TEMPORALLY AND SPATIALLY RESOLVED PLASMA SPECTROSCOPY IN PULSED LASER DEPOSITION OF ULTRA-THIN BORON NITRIDE...AND SPATIALLY RESOLVED PLASMA SPECTROSCOPY IN PULSED LASER DEPOSITION OF ULTRA-THIN BORON NITRIDE FILMS (POSTPRINT) 5a. CONTRACT NUMBER FA8650...distributions within a PVD plasma plume ablated from a boron nitride (BN) target by a KrF laser at different pressures of nitrogen gas were investigated

Development of a Low cost Ultra tiny Line Laser Range Sensor

DTIC Science & Technology

2016-12-01

Development of a Low-cost Ultra-tiny Line Laser Range Sensor Xiangyu Chen∗, Moju Zhao∗, Lingzhu Xiang†, Fumihito Sugai∗, Hiroaki Yaguchi∗, Kei Okada...and Masayuki Inaba∗ Abstract— To enable robotic sensing for tasks with require- ments on weight, size, and cost, we develop an ultra-tiny line laser ...view customizable using different laser lenses. The optimal measurement range of the sensor is 0.05[m] ∼ 2[m]. Higher sampling rates can be achieved

Time-resolved study of femtosecond laser induced micro-modifications inside transparent brittle materials

NASA Astrophysics Data System (ADS)

Hendricks, F.; Matylitsky, V. V.; Domke, M.; Huber, Heinz P.

2016-03-01

Laser processing of optically transparent or semi-transparent, brittle materials is finding wide use in various manufacturing sectors. For example, in consumer electronic devices such as smartphones or tablets, cover glass needs to be cut precisely in various shapes. The unique advantage of material processing with femtosecond lasers is efficient, fast and localized energy deposition in nearly all types of solid materials. When an ultra-short laser pulse is focused inside glass, only the localized region in the neighborhood of the focal volume absorbs laser energy by nonlinear optical absorption. Therefore, the processing volume is strongly defined, while the rest of the target stays unaffected. Thus ultra-short pulse lasers allow cutting of the chemically strengthened glasses such as Corning Gorilla glass without cracking. Non-ablative cutting of transparent, brittle materials, using the newly developed femtosecond process ClearShapeTM from Spectra-Physics, is based on producing a micron-sized material modification track with well-defined geometry inside. The key point for development of the process is to understand the induced modification by a single femtosecond laser shot. In this paper, pump-probe microscopy techniques have been applied to study the defect formation inside of transparent materials, namely soda-lime glass samples, on a time scale between one nanosecond to several tens of microseconds. The observed effects include acoustic wave propagation as well as mechanical stress formation in the bulk of the glass. Besides better understanding of underlying physical mechanisms, our experimental observations have enabled us to find optimal process parameters for the glass cutting application and lead to better quality and speed for the ClearShapeTM process.

Novel, ultra-compact, high-performance, eye-safe laser rangefinder for demanding applications

NASA Astrophysics Data System (ADS)

Silver, M.; Lee, S. T.; Borthwick, A.; Morton, G.; McNeill, C.; McSporran, D.; McRae, I.; McKinlay, G.; Jackson, D.; Alexander, W.

2016-05-01

Compact eye-safe laser rangefinders (LRFs) are a key technology for future sensors. In addition to reduced size, weight and power (SWaP), compact LRFs are increasingly being required to deliver a higher repetition rate, burst mode capability. Burst mode allows acquisition of telemetry data from fast moving targets or while sensing-on-the-move. We will describe a new, ultra-compact, long-range, eye-safe laser rangefinder that incorporates a novel transmitter that can deliver a burst capability. The transmitter is a diode-pumped, erbium:glass, passively Q-switched, solid-state laser which uses design and packaging techniques adopted from the telecom components sector. The key advantage of this approach is that the transmitter can be engineered to match the physical dimensions of the active laser components and the submillimetre sized laser spot. This makes the transmitter significantly smaller than existing designs, leading to big improvements in thermal management, and allowing higher repetition rates. In addition, the design approach leads to devices that have higher reliability, lower cost, and smaller form-factor, than previously possible. We present results from the laser rangefinder that incorporates the new transmitter. The LRF has dimensions (L x W x H) of 100 x 55 x 34 mm and achieves ranges of up to 15km from a single shot, and over a temperature range of -32°C to +60°C. Due to the transmitter's superior thermal performance, the unit is capable of repetition rates of 1Hz continuous operation and short bursts of up to 4Hz. Short bursts of 10Hz have also been demonstrated from the transmitter in the laboratory.

Fast quantification of bovine milk proteins employing external cavity-quantum cascade laser spectroscopy.

PubMed

Schwaighofer, Andreas; Kuligowski, Julia; Quintás, Guillermo; Mayer, Helmut K; Lendl, Bernhard

2018-06-30

Analysis of proteins in bovine milk is usually tackled by time-consuming analytical approaches involving wet-chemical, multi-step sample clean-up procedures. The use of external cavity-quantum cascade laser (EC-QCL) based IR spectroscopy was evaluated as an alternative screening tool for direct and simultaneous quantification of individual proteins (i.e. casein and β-lactoglobulin) and total protein content in commercial bovine milk samples. Mid-IR spectra of protein standard mixtures were used for building partial least squares (PLS) regression models. A sample set comprising different milk types (pasteurized; differently processed extended shelf life, ESL; ultra-high temperature, UHT) was analysed and results were compared to reference methods. Concentration values of the QCL-IR spectroscopy approach obtained within several minutes are in good agreement with reference methods involving multiple sample preparation steps. The potential application as a fast screening method for estimating the heat load applied to liquid milk is demonstrated. Copyright © 2018 Elsevier Ltd. All rights reserved.

TDM interrogation of intensity-modulated USFBGs network based on multichannel lasers.

PubMed

Rohollahnejad, Jalal; Xia, Li; Cheng, Rui; Ran, Yanli; Rahubadde, Udaya; Zhou, Jiaao; Zhu, Lin

2017-01-23

We report a large-scale multi-channel fiber sensing network, where ultra-short FBGs (USFBGs) instead of conventional narrow-band ultra-weak FBGs are used as the sensors. In the time division multiplexing scheme of the network, each grating response is resolved as three adjacent discrete peaks. The central wavelengths of USFBGs are tracked with the differential detection, which is achieved by calculating the peak-to-peak ratio of two maximum peaks. Compared with previous large-scale hybrid multiplexing sensing networks (e.g., WDM/TDM) which typically have relatively low interrogation speed and very high complexity, the proposed system can achieve interrogation of all channel sensors through very fast and simple intensity measurements with a broad dynamic range. A proof-of-concept experiment with twenty USFBGs, at two wavelength channels, was performed and a fast static strain measurements were demonstrated, with a high average sensitivity of ~0.54dB/µƐ and wide dynamic range of over ~3000µƐ. The channel to channel switching time was 10ms and total network interrogation time was 50ms.

Photon-in photon-out hard X-ray spectroscopy at the Linac Coherent Light Source

DOE PAGES

Alonso-Mori, Roberto; Sokaras, Dimosthenis; Zhu, Diling; ...

2015-04-15

X-ray free-electron lasers (FELs) have opened unprecedented possibilities to study the structure and dynamics of matter at an atomic level and ultra-fast timescale. Many of the techniques routinely used at storage ring facilities are being adapted for experiments conducted at FELs. In order to take full advantage of these new sources several challenges have to be overcome. They are related to the very different source characteristics and its resulting impact on sample delivery, X-ray optics, X-ray detection and data acquisition. Here it is described how photon-in photon-out hard X-ray spectroscopy techniques can be applied to study the electronic structure andmore » its dynamics of transition metal systems with ultra-bright and ultra-short FEL X-ray pulses. In particular, some of the experimental details that are different compared with synchrotron-based setups are discussed and illustrated by recent measurements performed at the Linac Coherent Light Source.« less

Computational study of hot electron generation and energy transport in intense laser produced hot dense matter

NASA Astrophysics Data System (ADS)

Mishra, Rohini

Present ultra high power lasers are capable of producing high energy density (HED) plasmas, in controlled way, with a density greater than solid density and at a high temperature of keV (1 keV ˜ 11,000,000° K). Matter in such extreme states is particularly interesting for (HED) physics such as laboratory studies of planetary and stellar astrophysics, laser fusion research, pulsed neutron source etc. To date however, the physics in HED plasma, especially, the energy transport, which is crucial to realize applications, has not been understood well. Intense laser produced plasmas are complex systems involving two widely distinct temperature distributions and are difficult to model by a single approach. Both kinetic and collisional process are equally important to understand an entire process of laser-solid interaction. By implementing atomic physics models, such as collision, ionization, and radiation damping, self consistently, in state-of-the-art particle-in-cell code (PICLS) has enabled to explore the physics involved in the HED plasmas. Laser absorption, hot electron transport, and isochoric heating physics in laser produced hot dense plasmas are studied with a help of PICLS simulations. In particular, a novel mode of electron acceleration, namely DC-ponderomotive acceleration, is identified in the super intense laser regime which plays an important role in the coupling of laser energy to a dense plasma. Geometric effects on hot electron transport and target heating processes are examined in the reduced mass target experiments. Further, pertinent to fast ignition, laser accelerated fast electron divergence and transport in the experiments using warm dense matter (low temperature plasma) is characterized and explained.

Laser Sources for Generation of Ultrasound

NASA Technical Reports Server (NTRS)

Wagner, James W.

1996-01-01

Two laser systems have been built and used to demonstrate enhancements beyond current technology used for laser-based generation and detection of ultrasound. The first system consisted of ten Nd:YAG laser cavities coupled electronically and optically to permit sequential bursts of up to ten laser pulses directed either at a single point or configured into a phased array of sources. Significant enhancements in overall signal-to-noise ratio for laser ultrasound incorporating this new source system was demonstrated, using it first as a source of narrowband ultrasound and secondly as a phased array source producing large enhanced signal displacements. A second laser system was implemented using ultra fast optical pulses from a Ti:Sapphire laser to study a new method for making laser generated ultrasonic measurements of thin films with thicknesses on the order of hundreds of angstroms. Work by prior investigators showed that such measurements could be made based upon fluctuations in the reflectivity of thin films when they are stressed by an arriving elastic pulse. Research performed using equipment purchased under this program showed that a pulsed interferometric system could be used as well as a piezoreflective detection system to measure pulse arrivals even in thin films with very low piezoreflective coefficients.

ICPP: Relativistic Plasma Physics with Ultra-Short High-Intensity Laser Pulses

NASA Astrophysics Data System (ADS)

Meyer-Ter-Vehn, Juergen

2000-10-01

Recent progress in generating ultra-short high-intensity laser pulses has opened a new branch of relativistic plasma physics, which is discussed in this talk in terms of particle-in-cell (PIC) simulations. These pulses create small plasma volumes of high-density plasma with plasma fields above 10^12 V/m and 10^8 Gauss. At intensities beyond 10^18 W/cm^2, now available from table-top systems, they drive relativistic electron currents in self-focussing plasma channels. These currents are close to the Alfven limit and allow to study relativistic current filamentation. A most remarkable feature is the generation of well collimated relativistic electron beams emerging from the channels with energies up to GeV. In dense matter they trigger cascades of gamma-rays, e^+e^- pairs, and a host of nuclear and particle processes. One of the applications may be fast ignition of compressed inertial fusion targets. Above 10^23 W/cm^2, expected to be achieved in the future, solid-density matter becomes relativistically transparent for optical light, and the acceleration of protons to multi-GeV energies is predicted in plasma layers less than 1 mm thick. These results open completely new perspectives for plasma-based accelerator schemes. Three-dimensional PIC simulations turn out to be the superior tool to explore the relativistic plasma kinetics at such intensities. Results obtained with the VLPL code [1] are presented. Different mechanisms of particle acceleration are discussed. Both laser wakefield and direct laser acceleration in plasma channels (by a mechanism similar to inverse free electron lasers) have been identified. The latter describes recent MPQ experimental results. [1] A. Pukhov, J. Plasma Physics 61, 425 - 433 (1999): Three-dimensional electromagnetic relativistic particle-in-cell code VLPL (Virtual Laser Plasma Laboratory).

Method for laser welding ultra-thin metal foils

DOEpatents

Pernicka, J.C.; Benson, D.K.; Tracy, C.E.

1996-03-26

A method for simultaneously cutting and welding ultra-thin foils having a thickness of less than 0.002 inches wherein two ultra-thin films are stacked and clamped together. A pulsed laser such as of the Neodymium: YAG type is provided and the beam of the laser is directed onto the stacked films to cut a channel through the films. The laser is moved relative to the stacked foils to cut the stacked foils at successive locations and to form a plurality of connected weld beads to form a continuous weld. 5 figs.

Method for laser welding ultra-thin metal foils

DOEpatents

Pernicka, John C.; Benson, David K.; Tracy, C. Edwin

1996-01-01

A method for simultaneously cutting and welding ultra-thin foils having a thickness of less than 0.002 inches wherein two ultra-thin films are stacked and clamped together. A pulsed laser such as of the Neodymium: YAG type is provided and the beam of the laser is directed onto the stacked films to cut a channel through the films. The laser is moved relative to the stacked foils to cut the stacked foils at successive locations and to form a plurality of connected weld beads to form a continuous weld.

Towards simultaneous measurements of electronic and structural properties in ultra-fast x-ray free electron laser absorption spectroscopy experiments

NASA Astrophysics Data System (ADS)

Gaudin, J.; Fourment, C.; Cho, B. I.; Engelhorn, K.; Galtier, E.; Harmand, M.; Leguay, P. M.; Lee, H. J.; Nagler, B.; Nakatsutsumi, M.; Ozkan, C.; Störmer, M.; Toleikis, S.; Tschentscher, Th; Heimann, P. A.; Dorchies, F.

2014-04-01

The rapidly growing ultrafast science with X-ray lasers unveils atomic scale processes with unprecedented time resolution bringing the so called ``molecular movie'' within reach. X-ray absorption spectroscopy is one of the most powerful x-ray techniques providing both local atomic order and electronic structure when coupled with ad-hoc theory. Collecting absorption spectra within few x-ray pulses is possible only in a dispersive setup. We demonstrate ultrafast time-resolved measurements of the LIII-edge x-ray absorption near-edge spectra of irreversibly laser excited Molybdenum using an average of only few x-ray pulses with a signal to noise ratio limited only by the saturation level of the detector. The simplicity of the experimental set-up makes this technique versatile and applicable for a wide range of pump-probe experiments, particularly in the case of non-reversible processes.

Towards simultaneous measurements of electronic and structural properties in ultra-fast x-ray free electron laser absorption spectroscopy experiments

PubMed Central

Gaudin, J.; Fourment, C.; Cho, B. I.; Engelhorn, K.; Galtier, E.; Harmand, M.; Leguay, P. M.; Lee, H. J.; Nagler, B.; Nakatsutsumi, M.; Ozkan, C.; Störmer, M.; Toleikis, S.; Tschentscher, Th; Heimann, P. A.; Dorchies, F.

2014-01-01

The rapidly growing ultrafast science with X-ray lasers unveils atomic scale processes with unprecedented time resolution bringing the so called “molecular movie” within reach. X-ray absorption spectroscopy is one of the most powerful x-ray techniques providing both local atomic order and electronic structure when coupled with ad-hoc theory. Collecting absorption spectra within few x-ray pulses is possible only in a dispersive setup. We demonstrate ultrafast time-resolved measurements of the LIII-edge x-ray absorption near-edge spectra of irreversibly laser excited Molybdenum using an average of only few x-ray pulses with a signal to noise ratio limited only by the saturation level of the detector. The simplicity of the experimental set-up makes this technique versatile and applicable for a wide range of pump-probe experiments, particularly in the case of non-reversible processes. PMID:24740172

Towards simultaneous measurements of electronic and structural properties in ultra-fast x-ray free electron laser absorption spectroscopy experiments

DOE PAGES

Gaudin, J.; Fourment, C.; Cho, B. I.; ...

2014-04-17

The rapidly growing ultrafast science with X-ray lasers unveils atomic scale processes with unprecedented time resolution bringing the so called “molecular movie” within reach. X-ray absorption spectroscopy is one of the most powerful x-ray techniques providing both local atomic order and electronic structure when coupled with ad-hoc theory. Collecting absorption spectra within few x-ray pulses is possible only in a dispersive setup. We demonstrate ultrafast time-resolved measurements of the LIII-edge x-ray absorption near-edge spectra of irreversibly laser excited Molybdenum using an average of only few x-ray pulses with a signal to noise ratio limited only by the saturation level ofmore » the detector. The simplicity of the experimental set-up makes this technique versatile and applicable for a wide range of pump-probe experiments, particularly in the case of non-reversible processes.« less

High harmonic generation in underdense plasmas by intense laser pulses with orbital angular momentum

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mendonça, J. T., E-mail: josetitomend@gmail.com; Vieira, J., E-mail: jorge.vieira@ist.utl.pt

We study high harmonic generation produced by twisted laser pulses, with orbital angular momentum in the relativistic regime, for pulse propagation in underdense plasma. We consider fast time scale processes associated with an ultra-short pulse, where the ion motion can be neglected. We use both analytical models and numerical simulations using a relativistic particle-in-cell code. The present description is valid for relativistic laser intensities, when the normalized field amplitude is much larger than one, a ≫ 1. We also discuss two distinct processes associated with linear and circular polarization. Using both analytical solutions and particle-in-cell simulations, we are able tomore » show that, for laser pulses in a well defined Laguerre-Gauss mode, angular momentum conservation is observed during the process of harmonic generation. Intensity modulation of the harmonic spectrum is also verified, as imposed by the nonlinear time-scale for energy transfer between different harmonics.« less

Fast neutron production from lithium converters and laser driven protons

DOE Office of Scientific and Technical Information (OSTI.GOV)

Storm, M.; Jiang, S.; Wertepny, D.

2013-05-15

Experiments to generate neutrons from the {sup 7}Li(p,n){sup 7}Be reaction with 60 J, 180 fs laser pulses have been performed at the Texas Petawatt Laser Facility at the University of Texas at Austin. The protons were accelerated from the rear surface of a thin target membrane using the target-normal-sheath-acceleration mechanism. The neutrons were generated in nuclear reactions caused by the subsequent proton bombardment of a pure lithium foil of natural isotopic abundance. The neutron energy ranged up to 2.9 MeV. The total yield was estimated to be 1.6 × 10{sup 7} neutrons per steradian. An extreme ultra-violet light camera, usedmore » to image the target rear surface, correlated variations in the proton yield and peak energy to target rear surface ablation. Calculations using the hydrodynamics code FLASH indicated that the ablation resulted from a laser pre-pulse of prolonged intensity. The ablation severely limited the proton acceleration and neutron yield.« less

Graphene field-effect transistors as room-temperature terahertz detectors.

PubMed

Vicarelli, L; Vitiello, M S; Coquillat, D; Lombardo, A; Ferrari, A C; Knap, W; Polini, M; Pellegrini, V; Tredicucci, A

2012-10-01

The unique optoelectronic properties of graphene make it an ideal platform for a variety of photonic applications, including fast photodetectors, transparent electrodes in displays and photovoltaic modules, optical modulators, plasmonic devices, microcavities, and ultra-fast lasers. Owing to its high carrier mobility, gapless spectrum and frequency-independent absorption, graphene is a very promising material for the development of detectors and modulators operating in the terahertz region of the electromagnetic spectrum (wavelengths in the hundreds of micrometres), still severely lacking in terms of solid-state devices. Here we demonstrate terahertz detectors based on antenna-coupled graphene field-effect transistors. These exploit the nonlinear response to the oscillating radiation field at the gate electrode, with contributions of thermoelectric and photoconductive origin. We demonstrate room temperature operation at 0.3 THz, showing that our devices can already be used in realistic settings, enabling large-area, fast imaging of macroscopic samples.

High-power all-fiber ultra-low noise laser

NASA Astrophysics Data System (ADS)

Zhao, Jian; Guiraud, Germain; Pierre, Christophe; Floissat, Florian; Casanova, Alexis; Hreibi, Ali; Chaibi, Walid; Traynor, Nicholas; Boullet, Johan; Santarelli, Giorgio

2018-06-01

High-power ultra-low noise single-mode single-frequency lasers are in great demand for interferometric metrology. Robust, compact all-fiber lasers represent one of the most promising technologies to replace the current laser sources in use based on injection-locked ring resonators or multi-stage solid-state amplifiers. Here, a linearly polarized high-power ultra-low noise all-fiber laser is demonstrated at a power level of 100 W. Special care has been taken in the study of relative intensity noise (RIN) and its reduction. Using an optimized servo actuator to directly control the driving current of the pump laser diode, we obtain a large feedback bandwidth of up to 1.3 MHz. The RIN reaches - 160 dBc/Hz between 3 and 20 kHz.

Novel applications of lasers in biology, chemistry, and paleontology

NASA Astrophysics Data System (ADS)

Johnston, Roger G.

1994-06-01

Los Alamos National Laboratory has a long history of exploring unconventional applications for lasers. Three novel applications currently under investigation include using lasers for the analysis of dinosaur gastroliths, for detecting Salmonella contamination in chicken eggs, and for ultra- sensitive, ultra-stable interferometry.

Latest developments for low-power infrared laser-based trace gas sensors for sensor networks

NASA Astrophysics Data System (ADS)

So, Stephen; Thomazy, David; Wang, Wen; Marchat, Oscar; Wysocki, Gerard

2011-09-01

Academic and industrial researchers require ultra-low power, compact laser based trace-gas sensor systems for the most demanding environmental and space-borne applications. Here the latest results from research projects addressing these applications will be discussed: 1) an ultra-compact CO2 sensor based on a continuous wave quantum cascade laser, 2) an ultra-sensitive Faraday rotation spectrometer for O2 detection, 3) a fully ruggedized compact and low-power laser spectrometer, and 4) a novel non-paraxial nonthin multipass cell. Preliminary tests and projection for performance of future sensors based on this technology is presented.

Picosecond laser micro/nano surface texturing of nickel for superhydrophobicity

NASA Astrophysics Data System (ADS)

Wang, X. C.; Wang, B.; Xie, H.; Zheng, H. Y.; Lam, Y. C.

2018-03-01

A single step direct picosecond laser texturing process was demonstrated to be able to obtain a superhydrophobic surface on a nickel substrate, a key material for mold fabrication in the manufacture of various devices, including polymeric microfluidic devices. A two-scale hierarchical surface structure of regular 2D array micro-bumps with nano-ripples was produced on a nickel surface. The laser textured surface initially showed superhydrophilicity with almost complete wetting of the structured surface just after laser treatment, then quickly changed to nearly superhydrophobic with a water contact angle (WCA) of 140° in less than 1 d, and finally became superhydrophobic with a WCA of more than 150° and a contact angle hysteresis (CAH) of less than 5°. The mechanism involved in the process is discussed in terms of surface morphology and surface chemistry. The ultra-fast laser induced NiO catalytic effect was thought to play a key role in modifying the surface chemistry so as to lower the surface energy. The developed process has the potential to improve the performance of nickel mold in the fabrication of microfluidic devices.

Wavefront control with a spatial light modulator containing dual-frequency liquid crystal

NASA Astrophysics Data System (ADS)

Gu, Dong-Feng; Winker, Bruce; Wen, Bing; Taber, Don; Brackley, Andrew; Wirth, Allan; Albanese, Marc; Landers, Frank

2004-10-01

A versatile, scalable wavefront control approach based upon proven liquid crystal (LC) spatial light modulator (SLM) technology was extended for potential use in high-energy near-infrared laser applications. The reflective LC SLM module demonstrated has a two-inch diameter active aperture with 812 pixels. Using an ultra-low absorption transparent conductor in the LC SLM, a high laser damage threshold was demonstrated. Novel dual frequency liquid crystal materials and addressing schemes were implemented to achieve fast switching speed (<1ms at 1.31 microns). Combining this LCSLM with a novel wavefront sensing method, a closed loop wavefront controller is being demonstrated. Compared to conventional deformable mirrors, this non-mechanical wavefront control approach offers substantial improvements in speed (bandwidth), resolution, power consumption and system weight/volume.

Device for wavefront correction in an ultra high power laser

DOEpatents

Ault, Earl R.; Comaskey, Brian J.; Kuklo, Thomas C.

2002-01-01

A system for wavefront correction in an ultra high power laser. As the laser medium flows past the optical excitation source and the fluid warms its index of refraction changes creating an optical wedge. A system is provided for correcting the thermally induced optical phase errors.

Spatiotemporal distributions of pair production and cascade in solid targets irradiated by ultra-relativistic lasers with different polarizations

NASA Astrophysics Data System (ADS)

Yuan, T.; Yu, J. Y.; Liu, W. Y.; Weng, S. M.; Yuan, X. H.; Luo, W.; Chen, M.; Sheng, Z. M.; Zhang, J.

2018-06-01

Two-dimensional particle-in-cell simulations have been performed to study electron-positron pair production and cascade development in single ultra-relativistic laser interaction with solid targets. The spatiotemporal distributions of particles produced via QED processes are illustrated and their dependence on laser polarizations is investigated. The evolution of particle generation displays clear QED cascade characters. Studies show that although a circularly polarized laser delays the QED process due to the effective ion acceleration, it can reduce the target heating and confine high-energy charged particles, which leads to deeper QED cascade order and denser pair plasma production than linearly polarized lasers. These findings may benefit the understanding of the coming experimental studies of ultra-relativistic laser target interaction in the QED dominated regime.

A 75-ps Gated CMOS Image Sensor with Low Parasitic Light Sensitivity

PubMed Central

Zhang, Fan; Niu, Hanben

2016-01-01

In this study, a 40 × 48 pixel global shutter complementary metal-oxide-semiconductor (CMOS) image sensor with an adjustable shutter time as low as 75 ps was implemented using a 0.5-μm mixed-signal CMOS process. The implementation consisted of a continuous contact ring around each p+/n-well photodiode in the pixel array in order to apply sufficient light shielding. The parasitic light sensitivity of the in-pixel storage node was measured to be 1/8.5 × 107 when illuminated by a 405-nm diode laser and 1/1.4 × 104 when illuminated by a 650-nm diode laser. The pixel pitch was 24 μm, the size of the square p+/n-well photodiode in each pixel was 7 μm per side, the measured random readout noise was 217 e− rms, and the measured dynamic range of the pixel of the designed chip was 5500:1. The type of gated CMOS image sensor (CIS) that is proposed here can be used in ultra-fast framing cameras to observe non-repeatable fast-evolving phenomena. PMID:27367699

A 75-ps Gated CMOS Image Sensor with Low Parasitic Light Sensitivity.

PubMed

Zhang, Fan; Niu, Hanben

2016-06-29

In this study, a 40 × 48 pixel global shutter complementary metal-oxide-semiconductor (CMOS) image sensor with an adjustable shutter time as low as 75 ps was implemented using a 0.5-μm mixed-signal CMOS process. The implementation consisted of a continuous contact ring around each p+/n-well photodiode in the pixel array in order to apply sufficient light shielding. The parasitic light sensitivity of the in-pixel storage node was measured to be 1/8.5 × 10⁷ when illuminated by a 405-nm diode laser and 1/1.4 × 10⁴ when illuminated by a 650-nm diode laser. The pixel pitch was 24 μm, the size of the square p+/n-well photodiode in each pixel was 7 μm per side, the measured random readout noise was 217 e(-) rms, and the measured dynamic range of the pixel of the designed chip was 5500:1. The type of gated CMOS image sensor (CIS) that is proposed here can be used in ultra-fast framing cameras to observe non-repeatable fast-evolving phenomena.

Generation and acceleration of neutral atoms in intense laser plasma experiments

NASA Astrophysics Data System (ADS)

Tata, Sheroy; Mondal, Angana; Sarkar, Shobhik; Ved, Yash; Lad, Amit D.; Pasley, John; Colgan, James; Krishnamurthy, M.

2017-10-01

The interaction of a high intensity (>=1018 W/cm2), high contrast (>=109), ultra-short (30fs) laser with solid targets generates a highly dense hot plasma. The quasi-static electric fields in such plasmas are well known for ion acceleration via the target normal sheath acceleration process. Under such conditions charge reduction to generate fast neutral atoms is almost inhibited. Improvised Thomson parabola spectrometry with improved signal to noise ratio has enabled us to measure the signals of fast neutral atoms and negative ions having energies in excess of tens of keV. A study on the neutralization of accelerated protons in plasma shows that the neutral atom to all particle ratio rises sharply from a few percent at the highest detectable energy to 50 % at 15 keV. Using usual charge transfer reactions the generation of neutral atoms can not be explained, thus we conjecture that the neutralization of the accelerated ions is not from the hot dense region of the plasma but neutral atom formation takes place by co-propagating ions with low energy electrons enhancing the effective neutral ratio.

Ultra-flat and ultra-broadband supercontinuum generation in photonic crystal fiber pumped by noise-like pulses

NASA Astrophysics Data System (ADS)

Chen, Yewang; Ruan, Shuangchen; Wu, Xu; Guo, Chunyu; Liu, Weiqi; Yu, Jun; Luo, Ruoheng; Ren, Xikui; Zhu, Yihuai

2017-02-01

An ultra-flat and ultra-broadband supercontinuum (SC) is demonstrated in a 4-m photonic crystal fiber (PCF) pumped by an Yb-doped all-fiber noise-like pulses (NLP) laser. The Yb-doped fiber laser is seeded by a SESAM mode-locked fiber laser, and amplified by cascaded fiber amplifiers, with its center wavelength, repetition frequency and the average noise-like bunch duration of 1064.52 nm, 50.18 MHz, 9.14 ps, respectively. Pumped by this NLP laser, the SC source has a 3 dB bandwidth and a 7 dB bandwidth (ignore the pump residue) of 1440 nm and 1790 nm at the maximum average output power of 6.94 W. To the best of our knowledge, this flatness is significantly prominent for the performance of PCF-based SC sources.

Measurement and compensation schemes for the pulse front distortion of ultra-intensity ultra-short laser pulses

NASA Astrophysics Data System (ADS)

Wu, Fenxiang; Xu, Yi; Yu, Linpeng; Yang, Xiaojun; Li, Wenkai; Lu, Jun; Leng, Yuxin

2016-11-01

Pulse front distortion (PFD) is mainly induced by the chromatic aberration in femtosecond high-peak power laser systems, and it can temporally distort the pulse in the focus and therefore decrease the peak intensity. A novel measurement scheme is proposed to directly measure the PFD of ultra-intensity ultra-short laser pulses, which can work not only without any extra struggle for the desired reference pulse, but also largely reduce the size of the required optical elements in measurement. The measured PFD in an experimental 200TW/27fs laser system is in good agreement with the calculated result, which demonstrates the validity and feasibility of this method effectively. In addition, a simple compensation scheme based on the combination of concave lens and parabolic lens is also designed and proposed to correct the PFD. Based on the theoretical calculation, the PFD of above experimental laser system can almost be completely corrected by using this compensator with proper parameters.

Characterization of electrical noise limits in ultra-stable laser systems.

PubMed

Zhang, J; Shi, X H; Zeng, X Y; Lü, X L; Deng, K; Lu, Z H

2016-12-01

We demonstrate thermal noise limited and shot noise limited performance of ultra-stable diode laser systems. The measured heterodyne beat linewidth between such two independent diode lasers reaches 0.74 Hz. The frequency instability of one single laser approaches 1.0 × 10 -15 for averaging time between 0.3 s and 10 s, which is close to the thermal noise limit of the reference cavity. Taking advantage of these two ultra-stable laser systems, we systematically investigate the ultimate electrical noise contributions, and derive expressions for the closed-loop spectral density of laser frequency noise. The measured power spectral density of the beat frequency is compared with the theoretically calculated closed-loop spectral density of the laser frequency noise, and they agree very well. It illustrates the power and generality of the derived closed-loop spectral density formula of the laser frequency noise. Our result demonstrates that a 10 -17 level locking in a wide frequency range is feasible with careful design.

Controllable robust laser driven ion acceleration from near-critical density relativistic self-transparent plasma

NASA Astrophysics Data System (ADS)

Liu, Bin; Meyer-Ter-Vehn, Juergen; Ruhl, Hartmut

2017-10-01

We introduce an alternative approach for laser driven self-injected high quality ion acceleration. We call it ion wave breaking acceleration. It operates in relativistic self-transparent plasma for ultra-intense ultra-short laser pulses. Laser propagating in a transparent plasma excites an electron wave as well as an ion wave. When the ion wave breaks, a fraction of ions is self-injected into the positive part of the laser driven wake. This leads to a superior ion pulse with peaked energy spectra; in particular in realistic three-dimensional geometry, the injection occurs localized close to the laser axis producing highly directed bunches. A theory is developed to investigate the ion wave breaking dynamics. Three dimensional Particle-in-Cell simulations with pure-gaussian laser pulses and pre-expanded near-critical density plasma targets have been done to verify the theoretical results. It is shown that hundreds of MeV, easily controllable and manipulable, micron-scale size, highly collimated and quasi-mono-energetic ion beams can be produced by using ultra-intense ultra-short laser pulses with total laser energies less than 10 Joules. Such ion beams may find important applications in tumour therapy. B. Liu acknowledges support from the Alexander von Humboldt Foundation. B. Liu and H. Ruhl acknowledge supports from the Gauss Centre for Supercomputing (GCS), and the Cluster-of-Excellence Munich Centre for Advanced Photonics (MAP).

Experimental characterization of an ultra-fast Thomson scattering x-ray source with three-dimensional time and frequency-domain analysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kuba, J; Slaughter, D R; Fittinghoff, D N

We present a detailed comparison of the measured characteristics of Thomson backscattered x-rays produced at the PLEIADES (Picosecond Laser-Electron Interaction for the Dynamic Evaluation of Structures) facility at Lawrence Livermore National Laboratory to predicted results from a newly developed, fully three-dimensional time and frequency-domain code. Based on the relativistic differential cross section, this code has the capability to calculate time and space dependent spectra of the x-ray photons produced from linear Thomson scattering for both bandwidth-limited and chirped incident laser pulses. Spectral broadening of the scattered x-ray pulse resulting from the incident laser bandwidth, perpendicular wave vector components in themore » laser focus, and the transverse and longitudinal phase space of the electron beam are included. Electron beam energy, energy spread, and transverse phase space measurements of the electron beam at the interaction point are presented, and the corresponding predicted x-ray characteristics are determined. In addition, time-integrated measurements of the x-rays produced from the interaction are presented, and shown to agree well with the simulations.« less

Ultra-short wavelength operation in Thulium-doped silica fiber laser with bidirectional pumping

NASA Astrophysics Data System (ADS)

Xiao, Xusheng; Guo, Haitao; Yan, Zhijun; Wang, Hushan; Xu, Yantao; Lu, Min; Wang, Yishan; Peng, Bo

2017-02-01

An ultra-short wavelength operation of Tm-doped all fiber laser based on fiber Bragg gratings (FBGs) was developed. A bi-directional pump configuration for the ultra-short wavelength operation was designed and investigated for the first time. the laser yielded 3.15W of continuous-wave output at 1706.75nm with a narrow-linewidth of 50pm and a maximum slope efficiency of 42.1%. The dependencies of the slope efficiencies and pump threshold of the laser versus the length of active fiber and reflectivity of the output mirror (FBG) were investigated in detail. An experimental comparative study between two Thulium-doped fiber lasers (TDFLs) with two different pumping configuration(forward unidirectional pumping and bidirectional pumping) was presented. It is indisputable that the development of 1.7μm silicate fiber lasers with Watt-level output power open up a number of heart-stirring and tempting application windows.

Study of nonlinear absorption properties of reduced graphene oxide by Z-scan technique

NASA Astrophysics Data System (ADS)

Sreeja, V. G.; Vinitha, G.; Reshmi, R.; Anila, E. I.; Jayaraj, M. K.

2017-05-01

Graphene has generated enormous research interest during the last decade due to its significant unique properties and wide applications in the field of optoelectronics and photonics. This research studied the structural and nonlinear absorption properties of reduced graphene oxide (rGO) synthesized by Modified Hummer's method. Structural and physiochemical properties of the rGO were explored with the help of Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy (Raman). Nonlinear absorption property in rGO, was investigated by open aperture Z-scan technique by using a continuous wave (CW) laser. The Z-scan results demonstrate saturable absorption property of rGO with a nonlinear absorption coefficient, β, of -2.62 × 10-4 cm/W, making it suitable for applications in Q switching, generation of ultra-fast high energy pulses in laser cavity and mode lockers.

Towards ultrahigh resting-state functional connectivity in the mouse brain using photoacoustic microscopy

NASA Astrophysics Data System (ADS)

Hariri, Ali; Bely, Nicholas; Chen, Chen; Nasiriavanaki, Mohammadreza

2016-03-01

The increasing use of mouse models for human brain disease studies, coupled with the fact that existing high-resolution functional imaging modalities cannot be easily applied to mice, presents an emerging need for a new functional imaging modality. Utilizing both mechanical and optical scanning in the photoacoustic microscopy, we can image spontaneous cerebral hemodynamic fluctuations and their associated functional connections in the mouse brain. The images is going to be acquired noninvasively with a fast frame rate, a large field of view, and a high spatial resolution. We developed an optical resolution photoacoustic microscopy (OR-PAM) with diode laser. Laser light was raster scanned due to XY-stage movement. Images from ultra-high OR-PAM can then be used to study brain disorders such as stroke, Alzheimer's, schizophrenia, multiple sclerosis, autism, and epilepsy.

Nano- and picosecond 3 μm Er: YSGG lasers using InAs as passive Q-switchers and mode-lockers

NASA Astrophysics Data System (ADS)

Vodopyanov, K. L.; Lukashev, A. V.; Phillips, C. C.

1993-01-01

Recent results are reported using ultra-thin molecular beam epitaxy (MBE)-grown InAs epilayers on GaAs substrates as passive shutters for 3 μm Er: YSGG lasers ( λ = 2.8 μm). The laser photon energy is 27% higher than the InAs bandgap at 300 K and bleaching occurs due to a band filling effect with a fast recovery time of < 100 ps. Depending on the resonator geometry two modes of operation can be achieved: Q-switched with pulse duration of 35 ns and 5-6 mJ energy (TEM 00 mode) and a Q-switched/mode-locked regime with an output in the form of a train of 30 pulses separated by a 4.3 ns interval, 0.25 mJ energy per spike and 30-50 ps pulse duration in a TEM 00-mode. The latter are the shortest pulses obtained with this lasing medium to date.

Imaging single cells in a beam of live cyanobacteria with an X-ray laser.

PubMed

van der Schot, Gijs; Svenda, Martin; Maia, Filipe R N C; Hantke, Max; DePonte, Daniel P; Seibert, M Marvin; Aquila, Andrew; Schulz, Joachim; Kirian, Richard; Liang, Mengning; Stellato, Francesco; Iwan, Bianca; Andreasson, Jakob; Timneanu, Nicusor; Westphal, Daniel; Almeida, F Nunes; Odic, Dusko; Hasse, Dirk; Carlsson, Gunilla H; Larsson, Daniel S D; Barty, Anton; Martin, Andrew V; Schorb, Sebastian; Bostedt, Christoph; Bozek, John D; Rolles, Daniel; Rudenko, Artem; Epp, Sascha; Foucar, Lutz; Rudek, Benedikt; Hartmann, Robert; Kimmel, Nils; Holl, Peter; Englert, Lars; Duane Loh, Ne-Te; Chapman, Henry N; Andersson, Inger; Hajdu, Janos; Ekeberg, Tomas

2015-02-11

There exists a conspicuous gap of knowledge about the organization of life at mesoscopic levels. Ultra-fast coherent diffractive imaging with X-ray free-electron lasers can probe structures at the relevant length scales and may reach sub-nanometer resolution on micron-sized living cells. Here we show that we can introduce a beam of aerosolised cyanobacteria into the focus of the Linac Coherent Light Source and record diffraction patterns from individual living cells at very low noise levels and at high hit ratios. We obtain two-dimensional projection images directly from the diffraction patterns, and present the results as synthetic X-ray Nomarski images calculated from the complex-valued reconstructions. We further demonstrate that it is possible to record diffraction data to nanometer resolution on live cells with X-ray lasers. Extension to sub-nanometer resolution is within reach, although improvements in pulse parameters and X-ray area detectors will be necessary to unlock this potential.

Fast physical-random number generation using laser diode's frequency noise: influence of frequency discriminator

NASA Astrophysics Data System (ADS)

Matsumoto, Kouhei; Kasuya, Yuki; Yumoto, Mitsuki; Arai, Hideaki; Sato, Takashi; Sakamoto, Shuichi; Ohkawa, Masashi; Ohdaira, Yasuo

2018-02-01

Not so long ago, pseudo random numbers generated by numerical formulae were considered to be adequate for encrypting important data-files, because of the time needed to decode them. With today's ultra high-speed processors, however, this is no longer true. So, in order to thwart ever-more advanced attempts to breach our system's protections, cryptologists have devised a method that is considered to be virtually impossible to decode, and uses what is a limitless number of physical random numbers. This research describes a method, whereby laser diode's frequency noise generate a large quantities of physical random numbers. Using two types of photo detectors (APD and PIN-PD), we tested the abilities of two types of lasers (FP-LD and VCSEL) to generate random numbers. In all instances, an etalon served as frequency discriminator, the examination pass rates were determined using NIST FIPS140-2 test at each bit, and the Random Number Generation (RNG) speed was noted.

Sub-picosecond streak camera measurements at LLNL: From IR to x-rays

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kuba, J; Shepherd, R; Booth, R

An ultra fast, sub-picosecond resolution streak camera has been recently developed at the LLNL. The camera is a versatile instrument with a wide operating wavelength range. The temporal resolution of up to 300 fs can be achieved, with routine operation at 500 fs. The streak camera has been operated in a wide wavelength range from IR to x-rays up to 2 keV. In this paper we briefly review the main design features that result in the unique properties of the streak camera and present its several scientific applications: (1) Streak camera characterization using a Michelson interferometer in visible range, (2)more » temporally resolved study of a transient x-ray laser at 14.7 nm, which enabled us to vary the x-ray laser pulse duration from {approx}2-6 ps by changing the pump laser parameters, and (3) an example of a time-resolved spectroscopy experiment with the streak camera.« less

Quantum Entanglement Molecular Absorption Spectrum Simulator

NASA Technical Reports Server (NTRS)

Nguyen, Quang-Viet; Kojima, Jun

2006-01-01

Quantum Entanglement Molecular Absorption Spectrum Simulator (QE-MASS) is a computer program for simulating two photon molecular-absorption spectroscopy using quantum-entangled photons. More specifically, QE-MASS simulates the molecular absorption of two quantum-entangled photons generated by the spontaneous parametric down-conversion (SPDC) of a fixed-frequency photon from a laser. The two-photon absorption process is modeled via a combination of rovibrational and electronic single-photon transitions, using a wave-function formalism. A two-photon absorption cross section as a function of the entanglement delay time between the two photons is computed, then subjected to a fast Fourier transform to produce an energy spectrum. The program then detects peaks in the Fourier spectrum and displays the energy levels of very short-lived intermediate quantum states (or virtual states) of the molecule. Such virtual states were only previously accessible using ultra-fast (femtosecond) laser systems. However, with the use of a single-frequency continuous wave laser to produce SPDC photons, and QEMASS program, these short-lived molecular states can now be studied using much simpler laser systems. QE-MASS can also show the dependence of the Fourier spectrum on the tuning range of the entanglement time of any externally introduced optical-path delay time. QE-MASS can be extended to any molecule for which an appropriate spectroscopic database is available. It is a means of performing an a priori parametric analysis of entangled photon spectroscopy for development and implementation of emerging quantum-spectroscopic sensing techniques. QE-MASS is currently implemented using the Mathcad software package.

Ultra-fast consensus of discrete-time multi-agent systems with multi-step predictive output feedback

NASA Astrophysics Data System (ADS)

Zhang, Wenle; Liu, Jianchang

2016-04-01

This article addresses the ultra-fast consensus problem of high-order discrete-time multi-agent systems based on a unified consensus framework. A novel multi-step predictive output mechanism is proposed under a directed communication topology containing a spanning tree. By predicting the outputs of a network several steps ahead and adding this information into the consensus protocol, it is shown that the asymptotic convergence factor is improved by a power of q + 1 compared to the routine consensus. The difficult problem of selecting the optimal control gain is solved well by introducing a variable called convergence step. In addition, the ultra-fast formation achievement is studied on the basis of this new consensus protocol. Finally, the ultra-fast consensus with respect to a reference model and robust consensus is discussed. Some simulations are performed to illustrate the effectiveness of the theoretical results.

A Hybrid Ion/Electron Beam Fast Ignition Concept

NASA Astrophysics Data System (ADS)

Albright, B. J.

2009-11-01

Fast ignition (FI) inertial confinement fusion is an approach to high-gain inertial fusion, whereby a dense core of deuterium/tritium fuel is assembled via direct or indirect drive and then a hot spot within the core is heated rapidly (over a time scale of order 10 ps) to ignition conditions by beams of fast charged particles. These particle beams are generated outside the capsule by the interaction of ultra-intense laser pulses with solid density targets. Most study of FI to date has focused on the use of electron [Tabak et al., Phys. Plasmas 1, 1696 (1994)] or ion [Fern'andez et al., Nuclear Fusion 49, 065004 (2009)] beams, however a hybrid approach involving both may have advantages. This paper will describe recent work in this arena. Work performed under the auspices of the U. S. Dept. of Energy by the Los Alamos National Security, Los Alamos National Laboratory. This work was supported by LANL Laboratory Directed Research and Development (LDRD).

Comparative study of energy of particles ejected from coulomb explosion of rare gas and metallic clusters irradiated by intense femtosecond laser field

NASA Astrophysics Data System (ADS)

Boucerredj, N.; Beggas, K.

2016-10-01

We present our study of high intensity femtosecond laser field interaction with large cluster of Kr and Na (contained 2.103 to 2.107 atoms). When laser intensity is above a critical value, it blows off all of electrons from the cluster and forms a non neutral ion cloud. The irradiation of these clusters by the intense laser field leads to highly excitation energy which can be the source of energetic electrons, electronic emission, highly charge, energetic ions and fragmentation process. During the Coulomb explosion of the resulting highly ionized, high temperature nanoplasma, ions acquire again their energy. It is shown that ultra fast ions are produced. The goal of our study is to investigate in detail a comparative study of the expansion and explosion then the ion energy of metallic and rare gas clusters irradiated by an intense femtosecond laser field. We have found that ions have a kinetic energy up to 105 eV and the Coulomb pressure is little than the hydrodynamic pressure. The Coulomb explosion of a cluster may provide a new high energy ion source.

Ultra-fast ipsilateral DPOAE adaptation not modulated by attention?

NASA Astrophysics Data System (ADS)

Dalhoff, Ernst; Zelle, Dennis; Gummer, Anthony W.

2018-05-01

Efferent stimulation of outer hair cells is supposed to attenuate cochlear amplification of sound waves and is accompanied by reduced DPOAE amplitudes. Recently, a method using two subsequent f2 pulses during presentation of a longer f1 pulse was introduced to measure fast ipsilateral adaptation effects on separated DPOAE components. Compensating primary-tone onsets for their latencies at the f2-tonotopic place, the average adaptation measured in four normal-hearing subjects was 5.0 dB with a time constant below 5 ms. In the present study, two experiments were performed to determine the origin of this ultra-fast ipsilateral adaptation effect. The first experiment measured ultra-fast ipsilateral adaptation using a two-pulse paradigm at three frequencies in the four subjects, while controlling for visual attention of the subjects. The other experiment also controlled for visual attention, but utilized a sequence of f2 short pulses in the presence of a continuous f1 tone to sample ipsilateral adaptation effects with longer time constants in eight subjects. In the first experiment, no significant change in the ultra-fast adaptation between non-directed attention and visual attention could be detected. In contrast, the second experiment revealed significant changes in the magnitude of the slower ipsilateral adaptation in the visual-attention condition. In conclusion, the lack of an attentional influence indicates that the ultra-fast ipsilateral DPOAE adaptation is not solely mediated by the medial olivocochlear reflex.

The method for scanning reshaping the spectrum of chirped laser pulse based on the quadratic electro-optic effects

NASA Astrophysics Data System (ADS)

Ye, Rong; Yin, Ming; Wu, Xianyun; Tan, Hang

2017-10-01

T A new method for scanning reshaping the spectrum of chirped laser pulse based on quadratic electro-optic effects is proposed. The scanning reshaping scheme with a two-beam interference system is designed and the spectrum reshaping properties are analyzed theoretically. For the Gaussian chirped laser pulse with central wavelength λ0=800nm, nearly flat-topped spectral profiles with wider bandwidth is obtained with the proposed scanning reshaping method, which is beneficial to compensate for the gain narrowing effect in CPA and OPCPA. Further numerical simulations show that the reshaped spectrum is sensitive to the time-delay and deviation of the voltage applied to the crystal. In order to avoid narrowing or distorting the reshaped spectrum pointing to target, it is necessary to reduce the unfavorable deviations. With the rapid and wide applications of ultra-short laser pulse supported by some latter research results including photo-associative formation of ultra-cold molecules from ultra-cold atoms[1-3], laser-induced communications[4], capsule implosions on the National Ignition Facility(NIF)[5-6], the control of the temporal and spectral profiles of laser pulse is very important and urgently need to be addressed. Generally, the control of the pulse profiles depends on practical applications, ranging from femtosecond and picosecond to nanosecond. For instance, the basic shaping setup is a Fourier transform system for ultra-short laser pulse. The most important element is a spatially patterned mask which modulates the phase or amplitude, or sometimes the polarization after the pulse is decomposed into its constituent spectral components by usually a grating and a lens[7]. One of the generation techniques of ultra-short laser pulse is the chirped pulse amplifications(CPA), which brings a new era of development for high energy and high peak intensity ultra-short laser pulse, proposed by D. Strcik and G. Mourou from the chirping radar technology in microwave region since 1985[8]. The other generation technique of ultra-short pulse is the optical parametric chirped pulse amplification(OPCPA) invented by Dubietis et al. in 1992, which combined the respective superiorities of CPA and optical parametric amplification(OPA). However, there are disadvantages for the both technologies such as gain narrowing, gain saturation effects, and even spectrum shift. The first one among the three is the most significant which narrows the spectrum after amplification so that it limits the minimum durations of ultra-short laser pulse. This paper proposed a approach for scanning reshaping the spectrum of chirped laser pulse to compensate for the gain narrowing effect, according to the characteristics of the chirped laser pulse, i.e. the frequency varies with time linearly. The spectral characteristics of the scanning reshaping was analyzed quantitatively. Furthermore, the influence of the time-delay and deviation of the controlling voltage employed on the electro-optic crystal on the reshaped spectrum was also been discussed in detail.

Physicochemical characterization and failure analysis of military coating systems

NASA Astrophysics Data System (ADS)

Keene, Lionel Thomas

Modern military coating systems, as fielded by all branches of the U.S. military, generally consist of a diverse array of organic and inorganic components that can complicate their physicochemical analysis. These coating systems consist of VOC-solvent/waterborne automotive grade polyurethane matrix containing a variety of inorganic pigments and flattening agents. The research presented here was designed to overcome the practical difficulties regarding the study of such systems through the combined application of several cross-disciplinary techniques, including vibrational spectroscopy, electron microscopy, microtomy, ultra-fast laser ablation and optical interferometry. The goal of this research has been to determine the degree and spatial progression of weathering-induced alteration of military coating systems as a whole, as well as to determine the failure modes involved, and characterizing the impact of these failures on the physical barrier performance of the coatings. Transmission-mode Fourier Transform Infrared (FTIR) spectroscopy has been applied to cross-sections of both baseline and artificially weathered samples to elucidate weathering-induced spatial gradients to the baseline chemistry of the coatings. A large discrepancy in physical durability (as indicated by the spatial progression of these gradients) has been found between older and newer generation coatings. Data will be shown implicating silica fillers (previously considered inert) as the probable cause for this behavioral divergence. A case study is presented wherein the application of the aforementioned FTIR technique fails to predict the durability of the coating system as a whole. The exploitation of the ultra-fast optical phenomenon of femtosecond (10-15S) laser ablation is studied as a potential tool to facilitate spectroscopic depth profiling of composite materials. Finally, the interferometric technique of Phase Shifting was evaluated as a potential high-sensitivity technique applied to the problem of determining internal stress evolution in curing and aging coatings.

Multilayer Black Phosphorus Near-Infrared Photodetectors.

PubMed

Hou, Chaojian; Yang, Lijun; Li, Bo; Zhang, Qihan; Li, Yuefeng; Yue, Qiuyang; Wang, Yang; Yang, Zhan; Dong, Lixin

2018-05-23

Black phosphorus (BP), owing to its distinguished properties, has become one of the most competitive candidates for photodetectors. However, there has been little attention paid on photo-response performance of multilayer BP nanoflakes with large layer thickness. In fact, multilayer BP nanoflakes with large layer thickness have greater potential from the fabrication viewpoint as well as due to the physical properties than single or few layer ones. In this report, the thickness-dependence of the intrinsic property of BP photodetectors in the dark was initially investigated. Then the photo-response performance (including responsivity, photo-gain, photo-switching time, noise equivalent power, and specific detectivity) of BP photodetectors with relative thicker thickness was explored under a near-infrared laser beam ( λ IR = 830 nm). Our experimental results reveal the impact of BP's thickness on the current intensity of the channel and show degenerated p-type BP is beneficial for larger current intensity. More importantly, the photo-response of our thicker BP photodetectors exhibited a larger responsivity up to 2.42 A/W than the few-layer ones and a fast response photo-switching speed (response time is ~2.5 ms) comparable to thinner BP nanoflakes was obtained, indicating BP nanoflakes with larger layer thickness are also promising for application for ultra-fast and ultra-high near-infrared photodetectors.

High longitudinal relaxivity of ultra-small gadolinium oxide prepared by microsecond laser ablation in diethylene glycol

NASA Astrophysics Data System (ADS)

Luo, Ningqi; Tian, Xiumei; Xiao, Jun; Hu, Wenyong; Yang, Chuan; Li, Li; Chen, Dihu

2013-04-01

Ultra-small gadolinium oxide (Gd2O3) can be used as T1-weighted Magnetic Resonance Imaging (MRI) contrast agent own to its high longitudinal relaxivity (r1) and has attracted intensive attention in these years. In this paper, ultra-small Gd2O3 nanoparticles of 3.8 nm in diameter have been successfully synthesized by a microsecond laser ablating a gadolinium (Gd) target in diethylene glycol (DEG). The growth inhibition effect induced by the large viscosity of DEG makes it possible to synthesize ultra-small Gd2O3 by laser ablation in DEG. The r1 value and T1-weighted MR images are measured by a 3.0 T MRI spectroscope. The results show these nanoparticles with a high r1 value of 9.76 s-1 mM-1 to be good MRI contrast agents. We propose an explanation for the high r1 value of ultra-small Gd2O3 by considering the decreasing factor (surface to volume ratio of the nanoparticles, S/V) and the increasing factor (water hydration number of the Gd3+ on Gd2O3 surface, q), which offer a new look into the relaxivity studies of MRI contrast agents. Our research provides a new approach to preparing ultra-small Gd2O3 of high r1 value by laser ablation in DEG and develops the understanding of high relaxivity of ultra-small Gd2O3 MRI contrast agents.

Ultra-widefield imaging for the management of pediatric retinal diseases.

PubMed

Kang, Kai B; Wessel, Matthew M; Tong, Jianping; D'Amico, Donald J; Chan, R V Paul

2013-01-01

To describe the utility of using ultra-widefield digital fundus photography and ultra-widefield fluorescein angiography (UWFA) in the pediatric patient population to evaluate peripheral retinal pathology and to manage Coats' disease and familial exudative vitreoretinopathy (FEVR). Retrospective review of pediatric retinal patients with FEVR or Coats' disease who underwent ultra-widefield fundus photography and UWFA. Eight patients were included in this case series. Five patients had the clinical diagnosis of FEVR, and two eyes of two patients with FEVR received UWFA-guided laser photocoagulation. Three patients were diagnosed as having Coats' disease and received UWFA-guided laser photocoagulation. Ultra-widefield fundus photography and UWFA can be used successfully as an outpatient procedure in the pediatric patient population without the necessity of examination under anesthesia and can aid the physician in the documentation and evaluation of peripheral retinal pathology. UWFA can also assist in directing laser photocoagulation in the treatment of pediatric retinal diseases. Copyright 2013, SLACK Incorporated.

The Clinical Efficacy of Autologous Platelet-Rich Plasma Combined with Ultra-Pulsed Fractional CO2 Laser Therapy for Facial Rejuvenation

PubMed Central

Hui, Qiang; Chang, Peng; Guo, Bingyu; Zhang, Yu

2017-01-01

Abstract Ultra-pulsed fractional CO2 laser is an efficient, precise, and safe therapeutic intervention for skin refreshing, although accompanied with prolonged edema and erythema. In recent years, autologous platelet-rich plasma (PRP) has been proven to promote wound and soft tissue healing and collagen regeneration. To investigate whether the combination of PRP and ultra-pulsed fractional CO2 laser had a synergistic effect on therapy for facial rejuvenation. Totally, 13 facial aging females were treated with ultra-pulsed fractional CO2 laser. One side of the face was randomly selected as experimental group and injected with PRP, the other side acted as the control group and was injected with physiological saline at the same dose. Comprehensive assessment of clinical efficacy was performed by satisfaction scores, dermatologists' double-blind evaluation and the VISIA skin analysis system. After treatment for 3 months, subjective scores of facial wrinkles, skin texture, and skin elasticity were higher than that in the control group. Similarly, improvement of skin wrinkles, texture, and tightness in the experimental group was better compared with the control group. Additionally, the total duration of erythema, edema, and crusting was decreased, in the experimental group compared with the control group. PRP combined with ultra-pulsed fractional CO2 laser had a synergistic effect on facial rejuvenation, shortening duration of side effects, and promoting better therapeutic effect. PMID:27222038

Polymer enabled 100 Gbaud connectivity for datacom applications

NASA Astrophysics Data System (ADS)

Katopodis, V.; Groumas, P.; Zhang, Z.; Dinu, R.; Miller, E.; Konczykowska, A.; Dupuy, J.-Y.; Beretta, A.; Dede, A.; Choi, J. H.; Harati, P.; Jorge, F.; Nodjiadjim, V.; Riet, Muriel; Cangini, G.; Vannucci, A.; Keil, N.; Bach, H.-G.; Grote, N.; Avramopoulos, H.; Kouloumentas, Ch.

2016-03-01

Polymers hold the promise for ultra-fast modulation of optical signals due to their potential for ultra-fast electro-optic (EO) response and high EO coefficient. In this work, we present the basic structure and properties of an efficient EO material system, and we summarize the efforts made within the project ICT-POLYSYS for the development of high-speed transmitters based on this system. More specifically, we describe successful efforts for the monolithic integration of multi-mode interference (MMI) couplers and Bragg-gratings (BGs) along with Mach-Zehnder modulators (MZMs) on this platform, and for the hybrid integration of InP active elements in the form of laser diodes (LDs) and gain chips (GCs). Using these integration techniques and the combination of the hybrid optical chips with ultra-fast indium phosphide double heterojunction bipolar transistor (InP-DHBT) electronics, we develop and fully package a single 100 Gb/s transmitter and a 2×100 Gb/s transmitter that can support serial operation at this rate with conventional non-return-to-zero on-off-keying (NRZ-OOK) modulation format. We also present the experimental evaluation of the devices, validating the efficiency of the monolithic and hybrid integration concepts and confirming the potential of this technology for single-lane 100 Gb/s optical connectivity in data-center network environments. Results from transmission experiments to this end include the achievement of BER close to 6·10-9 in B2B configuration, the achievement of BER lower than 10-7 for propagation over standard single-mode fiber (SSMF) with total length up to 1000 m, and the achievement of BER at the level of 10-5 after 1625 m of SSMF. Finally, plans for the use of the EO polymer system in a more complex hybrid integration platform for high-flexibility/high-capacity transmitters are also outlined.

Ultra-high brightness wavelength-stabilized kW-class fiber coupled diode laser

NASA Astrophysics Data System (ADS)

Huang, Robin K.; Chann, Bien; Glenn, John D.

2011-03-01

TeraDiode has produced a fiber-coupled direct diode laser with a power level of 1,040 W from a 200 μm core diameter, 0.18 numerical aperture (NA) output fiber at a single center wavelength. This was achieved with a novel beam combining and shaping technique using COTS diode lasers. The fiber-coupled output corresponds to a Beam Parameter Product (BPP) of 18 mm-mrad and is the lowest BPP kW-class direct diode laser yet reported. The laser has been used to demonstrate laser cutting and welding of steel sheet metal up to 6.65 mm thick. Further advances of these ultra-bright lasers are also projected.

Potential clinical impact of laser-accelerated beams in cancer ion therapy

NASA Astrophysics Data System (ADS)

Obcemea, Ceferino

2016-09-01

In this article, I present three advantages of plasma-accelerated ion beams for cancer therapy. I discuss how: 1. low-emittance and well-collimated beams are advantageous in proximal normal tissue-sparing; 2. highly-peaked quasi-monoenergetic beams are ideal for fast energy selection and switching in Pencil Beam Scanning (PBS) as a treatment delivery; 3. high fluence and ultra-short pulse delivery produce collective excitations in the medium and enhance the stopping power. This in turn produces denser ionization track signatures (spurs, blobs, etc.) in target tumors, higher linear energy transfer, higher Bragg peak, and higher radiobiological effectiveness at the micro-level.

Note: Fully integrated 3.2 Gbps quantum random number generator with real-time extraction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Xiao-Guang; Nie, You-Qi; Liang, Hao

2016-07-15

We present a real-time and fully integrated quantum random number generator (QRNG) by measuring laser phase fluctuations. The QRNG scheme based on laser phase fluctuations is featured for its capability of generating ultra-high-speed random numbers. However, the speed bottleneck of a practical QRNG lies on the limited speed of randomness extraction. To close the gap between the fast randomness generation and the slow post-processing, we propose a pipeline extraction algorithm based on Toeplitz matrix hashing and implement it in a high-speed field-programmable gate array. Further, all the QRNG components are integrated into a module, including a compact and actively stabilizedmore » interferometer, high-speed data acquisition, and real-time data post-processing and transmission. The final generation rate of the QRNG module with real-time extraction can reach 3.2 Gbps.« less

Two-dimensional time-resolved ultra-high speed imaging of K-alpha emission from short-pulse-laser interactions to observe electron recirculation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nagel, S. R.; Chen, H.; Park, J.

Time resolved x-ray images with 7 ps resolution are recorded on relativistic short-pulse laser-plasma experiments using the dilation x-ray imager, a high-speed x-ray framing camera, sensitive to x-rays in the range of ≈1-17 keV. Furthermore, this capability enables a series of 2D x-ray images to be recorded at picosecond scales, which allows for the investigation of fast electron transport within the target with unprecedented temporal resolution. With an increase in the Kα-emission spot size over time we found that targets were thinner than the recirculation limit and is absent for thicker targets. Together with the observed polarization dependence of themore » spot size increase, this indicates that electron recirculation is relevant for the x-ray production in thin targets.« less

Control of a laser inertial confinement fusion-fission power plant

DOEpatents

Moses, Edward I.; Latkowski, Jeffery F.; Kramer, Kevin J.

2015-10-27

A laser inertial-confinement fusion-fission energy power plant is described. The fusion-fission hybrid system uses inertial confinement fusion to produce neutrons from a fusion reaction of deuterium and tritium. The fusion neutrons drive a sub-critical blanket of fissile or fertile fuel. A coolant circulated through the fuel extracts heat from the fuel that is used to generate electricity. The inertial confinement fusion reaction can be implemented using central hot spot or fast ignition fusion, and direct or indirect drive. The fusion neutrons result in ultra-deep burn-up of the fuel in the fission blanket, thus enabling the burning of nuclear waste. Fuels include depleted uranium, natural uranium, enriched uranium, spent nuclear fuel, thorium, and weapons grade plutonium. LIFE engines can meet worldwide electricity needs in a safe and sustainable manner, while drastically shrinking the highly undesirable stockpiles of depleted uranium, spent nuclear fuel and excess weapons materials.

Two-dimensional time-resolved ultra-high speed imaging of K-alpha emission from short-pulse-laser interactions to observe electron recirculation

DOE PAGES

Nagel, S. R.; Chen, H.; Park, J.; ...

2017-04-04

Time resolved x-ray images with 7 ps resolution are recorded on relativistic short-pulse laser-plasma experiments using the dilation x-ray imager, a high-speed x-ray framing camera, sensitive to x-rays in the range of ≈1-17 keV. Furthermore, this capability enables a series of 2D x-ray images to be recorded at picosecond scales, which allows for the investigation of fast electron transport within the target with unprecedented temporal resolution. With an increase in the Kα-emission spot size over time we found that targets were thinner than the recirculation limit and is absent for thicker targets. Together with the observed polarization dependence of themore » spot size increase, this indicates that electron recirculation is relevant for the x-ray production in thin targets.« less

Ultra high performance liquid chromatography with ion-trap TOF-MS for the fast characterization of flavonoids in Citrus bergamia juice.

PubMed

Sommella, Eduardo; Pepe, Giacomo; Pagano, Francesco; Tenore, Gian Carlo; Dugo, Paola; Manfra, Michele; Campiglia, Pietro

2013-10-01

We have developed a fast ultra HPLC with ion-trap TOF-MS method for the analysis of flavonoids in Citrus bergamia juice. With respect to the typical methods for the analysis of these matrices based on conventional HPLC techniques, a tenfold faster separation was attained. The use of a core-shell particle column ensured high resolution within the fast analysis time of only 5 min. Unambiguous determination of flavonoid identity was obtained by the employment of a hybrid ion-trap TOF mass spectrometer with high mass accuracy (average error 1.69 ppm). The system showed good retention time and peak area repeatability, with maximum RSD% values of 0.36 and 3.86, respectively, as well as good linearity (R(2) ≥ 0.99). Our results show that ultra HPLC can be a useful tool for ultra fast qualitative/quantitative analysis of flavonoid compounds in citrus fruit juices. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Wavelength-versatile graphene-gold film saturable absorber mirror for ultra-broadband mode-locking of bulk lasers.

PubMed

Ma, Jie; Xie, Guoqiang; Lv, Peng; Gao, Wenlan; Yuan, Peng; Qian, Liejia; Griebner, Uwe; Petrov, Valentin; Yu, Haohai; Zhang, Huaijin; Wang, Jiyang

2014-05-23

An ultra-broadband graphene-gold film saturable absorber mirror (GG-SAM) with a spectral coverage exceeding 1300 nm is experimentally demonstrated for mode-locking of bulk solid-state lasers. Owing to the p-type doping effect caused by graphene-gold film interaction, the graphene on gold-film substrate shows a remarkably lower light absorption relative to pristine graphene, which is very helpful to achieve continuous-wave mode-locking in low-gain bulk lasers. Using the GG-SAM sample, stable mode-locking is realized in a Yb:YCOB bulk laser near 1 μm, a Tm:CLNGG bulk laser near 2 μm and a Cr:ZnSe bulk laser near 2.4 μm. The saturable absorption is characterised at an intermediate wavelength of 1.56 μm by pump-probe measurements. The as-fabricated GG-SAM with ultra-broad bandwidth, ultrafast recovery time, low absorption, and low cost has great potential as a universal saturable absorber mirror for mode-locking of various bulk lasers with unprecedented spectral coverage.

Wavelength-Versatile Graphene-Gold Film Saturable Absorber Mirror for Ultra-Broadband Mode-Locking of Bulk Lasers

PubMed Central

Ma, Jie; Xie, Guoqiang; Lv, Peng; Gao, Wenlan; Yuan, Peng; Qian, Liejia; Griebner, Uwe; Petrov, Valentin; Yu, Haohai; Zhang, Huaijin; Wang, Jiyang

2014-01-01

An ultra-broadband graphene-gold film saturable absorber mirror (GG-SAM) with a spectral coverage exceeding 1300 nm is experimentally demonstrated for mode-locking of bulk solid-state lasers. Owing to the p-type doping effect caused by graphene-gold film interaction, the graphene on gold-film substrate shows a remarkably lower light absorption relative to pristine graphene, which is very helpful to achieve continuous-wave mode-locking in low-gain bulk lasers. Using the GG-SAM sample, stable mode-locking is realized in a Yb:YCOB bulk laser near 1 μm, a Tm:CLNGG bulk laser near 2 μm and a Cr:ZnSe bulk laser near 2.4 μm. The saturable absorption is characterised at an intermediate wavelength of 1.56 μm by pump-probe measurements. The as-fabricated GG-SAM with ultra-broad bandwidth, ultrafast recovery time, low absorption, and low cost has great potential as a universal saturable absorber mirror for mode-locking of various bulk lasers with unprecedented spectral coverage. PMID:24853072

Exploring ultrastability in nanostructured glassy polymer films by fast-scanning calorimetry.

NASA Astrophysics Data System (ADS)

Chowdhury, Mithun; Wang, Yucheng; Jeong, Hyuncheol; Cangialosi, Daniele; Priestley, Rodney

A decade ago ultra-stable small molecule glass formers were discovered. Since then a significant amount of research has been devoted to traverse down the energy landscape of such glass formers via physical vapor deposition (PVD). Matrix assisted pulsed laser evaporation (MAPLE) has the known ability to produce vapour deposited nanostructured polymer glass with exceptional kinetic stability. We explored the role of deposition temperature/ growth rate on thermodynamic and kinetic stabilities of poly (methyl methacrylate) (PMMA) films, deposited over a fast-scanning calorimetry sensor. We found in general any MAPLE deposited glass is kinetically more stable than bulk polymer and its spin-coated film. Moreover slow growth rate and optimum temperature during MAPLE deposition can additionally lead to thermodynamically stable (low-energy) glass. The role of interfaces formed through dramatic nanostructuring and packing of nanoglobules (removal of void space) may have additional role on such ultrastability. NSF-MRSEC through PCCM (Grant: DMR-1420541).

Ultra-fast all-optical plasmon induced transparency in a metal–insulator–metal waveguide containing two Kerr nonlinear ring resonators

NASA Astrophysics Data System (ADS)

Nurmohammadi, Tofiq; Abbasian, Karim; Yadipour, Reza

2018-05-01

In this work, an ultra-fast all-optical plasmon induced transparency based on a metal–insulator–metal nanoplasmonic waveguide with two Kerr nonlinear ring resonators is studied. Two-dimensional simulations utilizing the finite-difference time-domain method are used to show an obvious optical bistability and significant switching mechanisms of the signal light by varying the pump-light intensity. The proposed all-optical switching based on plasmon induced transparency demonstrates femtosecond-scale feedback time (90 fs), meaning ultra-fast switching can be achieved. The presented all-optical switch may have potential significant applications in integrated optical circuits.

Extreme ultra-violet movie camera for imaging microsecond time scale magnetic reconnection

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chai, Kil-Byoung; Bellan, Paul M.

2013-12-15

An ultra-fast extreme ultra-violet (EUV) movie camera has been developed for imaging magnetic reconnection in the Caltech spheromak/astrophysical jet experiment. The camera consists of a broadband Mo:Si multilayer mirror, a fast decaying YAG:Ce scintillator, a visible light block, and a high-speed visible light CCD camera. The camera can capture EUV images as fast as 3.3 × 10{sup 6} frames per second with 0.5 cm spatial resolution. The spectral range is from 20 eV to 60 eV. EUV images reveal strong, transient, highly localized bursts of EUV radiation when magnetic reconnection occurs.

Breaking the Attosecond, Angstrom and TV/M Field Barriers with Ultra-Fast Electron Beams

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rosenzweig, James; Andonian, Gerard; Fukasawa, Atsushi

2012-06-22

Recent initiatives at UCLA concerning ultra-short, GeV electron beam generation have been aimed at achieving sub-fs pulses capable of driving X-ray free-electron lasers (FELs) in single-spike mode. This use of very low Q beams may allow existing FEL injectors to produce few-100 attosecond pulses, with very high brightness. Towards this end, recent experiments at the LCLS have produced {approx}2 fs, 20 pC electron pulses. We discuss here extensions of this work, in which we seek to exploit the beam brightness in FELs, in tandem with new developments in cryogenic undulator technology, to create compact accelerator-undulator systems that can lase belowmore » 0.15 {angstrom}, or be used to permit 1.5 {angstrom} operation at 4.5 GeV. In addition, we are now developing experiments which use the present LCLS fs pulses to excite plasma wakefields exceeding 1 TV/m, permitting a table-top TeV accelerator for frontier high energy physics applications.« less

Ultra-bright γ-ray flashes and dense attosecond positron bunches from two counter-propagating laser pulses irradiating a micro-wire target.

PubMed

Li, Han-Zhen; Yu, Tong-Pu; Hu, Li-Xiang; Yin, Yan; Zou, De-Bin; Liu, Jian-Xun; Wang, Wei-Quan; Hu, Shun; Shao, Fu-Qiu

2017-09-04

We propose a novel scheme to generate ultra-bright ultra-short γ-ray flashes and high-energy-density attosecond positron bunches by using multi-dimensional particle-in-cell simulations with quantum electrodynamics effects incorporated. By irradiating a 10 PW laser pulse with an intensity of 10 23 W/cm 2 onto a micro-wire target, surface electrons are dragged-out of the micro-wire and are effectively accelerated to several GeV energies by the laser ponderomotive force, forming relativistic attosecond electron bunches. When these electrons interact with the probe pulse from the other side, ultra-short γ-ray flashes are emitted with an ultra-high peak brightness of 1.8 × 10 24 photons s -1 mm -2 mrad -2 per 0.1%BW at 24 MeV. These photons propagate with a low divergence and collide with the probe pulse, triggering the Breit-Wheeler process. Dense attosecond e - e + pair bunches are produced with the positron energy density as high as 10 17 J/m 3 and number of 10 9 . Such ultra-bright ultra-short γ-ray flashes and secondary positron beams may have potential applications in fundamental physics, high-energy-density physics, applied science and laboratory astrophysics.

Ultra-widefield retinal imaging through a black intraocular lens.

PubMed

Yusuf, Imran H; Fung, Timothy H M; Patel, Chetan K

2015-09-01

To evaluate the feasibility of ultra-widefield retinal imaging in patients with near infrared (IR)-transmitting black intraocular lenses (IOLs). Oxford Eye Hospital, Oxford, United Kingdom. Laboratory evaluation of a diagnostic technology with interventional case report. The field of retinal imaging through a Morcher poly(methyl methacrylate) (PMMA) black IOL was determined in a purpose-built adult schematic model eye with the HRA2 Spectralis confocal scanning laser ophthalmoscope using standard imaging, Staurenghi retina lens-assisted imaging, and ultra-widefield noncontact imaging. Retinal imaging using each modality was then performed on a patient implanted with another Morcher PMMA black IOL model. Ultra-widefield noncontact imaging and lens-assisted imaging captured up to 150 degrees of field (versus 40 degrees with a standard confocal scanning laser ophthalmoscope). Ultra-widefield retinal images were successfully acquired in a patient eye with a black IOL. This study has identified the first ultra-widefield retinal imaging modalities for patients with near IR-transmitting black IOLs. Should larger studies confirm this finding, noncontact ultra-widefield confocal scanning laser ophthalmoscopy might be considered the gold standard imaging technique for retinal surveillance in patients with near IR-transmitting black IOLs. No author has a financial or proprietary interest in any material or method mentioned. Copyright © 2015 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

Two-dimensional angular energy spectrum of electrons accelerated by the ultra-short relativistic laser pulse

DOE Office of Scientific and Technical Information (OSTI.GOV)

Borovskiy, A. V.; Galkin, A. L.; Department of Physics of MBF, Pirogov Russian National Research Medical University, 1 Ostrovitianov Street, Moscow 117997

The new method of calculating energy spectra of accelerated electrons, based on the parameterization by their initial coordinates, is proposed. The energy spectra of electrons accelerated by Gaussian ultra-short relativistic laser pulse at a selected angle to the axis of the optical system focusing the laser pulse in a low density gas are theoretically calculated. The two-peak structure of the electron energy spectrum is obtained. Discussed are the reasons for its appearance as well as an applicability of other models of the laser field.

Effective Analysis of NGS Metagenomic Data with Ultra-Fast Clustering Algorithms (MICW - Metagenomics Informatics Challenges Workshop: 10K Genomes at a Time)

ScienceCinema

Li, Weizhong

2018-02-12

San Diego Supercomputer Center's Weizhong Li on "Effective Analysis of NGS Metagenomic Data with Ultra-fast Clustering Algorithms" at the Metagenomics Informatics Challenges Workshop held at the DOE JGI on October 12-13, 2011.

Ultra-fast Object Recognition from Few Spikes

DTIC Science & Technology

2005-07-06

Computer Science and Artificial Intelligence Laboratory Ultra-fast Object Recognition from Few Spikes Chou Hung, Gabriel Kreiman , Tomaso Poggio...neural code for different kinds of object-related information. *The authors, Chou Hung and Gabriel Kreiman , contributed equally to this work...Supplementary Material is available at http://ramonycajal.mit.edu/ kreiman /resources/ultrafast

H.sub.2O doped WO.sub.3, ultra-fast, high-sensitivity hydrogen sensors

DOEpatents

Liu, Ping [Denver, CO; Tracy, C Edwin [Golden, CO; Pitts, J Roland [Lakewood, CO; Lee, Se-Hee [Lakewood, CO

2011-03-22

An ultra-fast response, high sensitivity structure for optical detection of low concentrations of hydrogen gas, comprising: a substrate; a water-doped WO.sub.3 layer coated on the substrate; and a palladium layer coated on the water-doped WO.sub.3 layer.

Interaction dynamics of fs-laser induced cavitation bubbles and their impact on the laser-tissue-interaction of modern ophthalmic laser systems

NASA Astrophysics Data System (ADS)

Tinne, N.; Ripken, T.; Lubatschowski, H.; Heisterkamp, A.

2011-07-01

A today well-known laser based treatment in ophthalmology is the LASIK procedure which nowadays includes cutting of the corneal tissue with ultra-short laser pulses. Instead of disposing a microkeratome for cutting a corneal flap, a focused ultra-short laser pulse is scanned below the surface of biological tissue causing the effect of an optical breakdown and hence obtaining a dissection. Inside the tissue, the energy of the laser pulses is absorbed by non-linear processes; as a result a cavitation bubble expands and ruptures the tissue. Hence, positioning of several optical breakdowns side by side generates an incision. Due to a reduction of the amount of laser energy, with a moderate duration of treatment at the same time, the current development of ultra-short pulse laser systems points to higher repetition rates in the range of even Megahertz instead of tens or hundreds of Kilohertz. In turn, this results in a pulse overlap and therefor a probable occurrence of interaction between different optical breakdowns and respectively cavitation bubbles of adjacent optical breakdowns. While the interaction of one single laser pulse with biological tissue is analyzed reasonably well experimentally and theoretically, the interaction of several spatial and temporal following pulses is scarcely determined yet. Thus, the aim of this study is to analyse the dynamic and interaction of two cavitation bubbles by using high speed photography. The applied laser pulse energy, the energy ratio and the spot distance between different cavitation bubbles were varied. Depending on a change of these parameters different kinds of interactions such as a flattening and deformation of bubble shape or jet formation are observed. The effects will be discussed regarding the medical ophthalmic application of fs-lasers. Based on these results a further research seems to be inevitable to comprehend and optimize the cutting effect of ultra-short pulse laser systems with high (> 500 kHz) repetition rates.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hora, H.; Korn, G.; Eliezer, S.

Measured highly elevated gains of proton–boron (HB11) fusion (Picciottoet al., Phys. Rev. X4, 031030 (2014)) confirmed the exceptional avalanche reaction process (Lalousiset al., Laser Part. Beams 32, 409 (2014); Horaet al., Laser Part. Beams33, 607 (2015)) for the combination of the non-thermal block ignition using ultrahigh intensity laser pulses of picoseconds duration. The ultrahigh accelerationabovemore » $$10^{20}~\\text{cm}~\\text{s}^{-2}$$ for plasma blocks was theoretically and numerically predicted since 1978 (Hora,Physics of Laser Driven Plasmas(Wiley, 1981), pp. 178 and 179) and measured (Sauerbrey, Phys. Plasmas3, 4712 (1996)) in exact agreement (Horaet al., Phys. Plasmas14, 072701 (2007)) when the dominating force was overcoming thermal processes. This is based on Maxwell’s stress tensor by the dielectric properties of plasma leading to the nonlinear (ponderomotive) force $$f_{\\text{NL}}$$ resulting in ultra-fast expanding plasma blocks by a dielectric explosion. Combining this with measured ultrahigh magnetic fields and the avalanche process opens an option for an environmentally absolute clean and economic boron fusion power reactor. Finally, this is supported also by other experiments with very high HB11 reactions under different conditions (Labauneet al., Nature Commun.4, 2506 (2013)).« less

Ultra-short laser interactions with nanoparticles in different media: from electromagnetic to thermal and electrostatic effects

NASA Astrophysics Data System (ADS)

Itina, Tatiana E.

2017-02-01

Key issues of the controlled synthesis of nanoparticles and nanostructures, as well as laser-particle interactions are considered in the context of the latest applications appearing in many fields such as photonics, medicine, 3D printing, etc. The results of a multi-physics numerical study of laser interaction with nanoparticles will be presented in the presence of several environments. In particular, attention will be paid to the numerical study of laser interactions with heterogeneous materials (eg. colloidal liquids and/or nanoparticles in a dielectric medium) and the aggregation/sintering/fragmentation processes induced by ultra-short laser pulses.

Femtosecond laser machining and lamination for large-area flexible organic microfluidic chips

NASA Astrophysics Data System (ADS)

Malek, C. Khan; Robert, L.; Salut, R.

2009-04-01

A hybrid process compatible with reel-to-reel manufacturing is developed for ultra low-cost large-scale manufacture of disposable microfluidic chips. It combines ultra-short laser microstructuring and lamination technology. Microchannels in polyester foils were formed using focused, high-intensity femtosecond laser pulses. Lamination using a commercial SU8-epoxy resist layer was used to seal the microchannel layer and cover foil. This hybrid process also enables heterogeneous material structuration and integration.

Avalanche boron fusion by laser picosecond block ignition with magnetic trapping for clean and economic reactor

DOE PAGES

Hora, H.; Korn, G.; Eliezer, S.; ...

2016-10-11

Measured highly elevated gains of proton–boron (HB11) fusion (Picciottoet al., Phys. Rev. X4, 031030 (2014)) confirmed the exceptional avalanche reaction process (Lalousiset al., Laser Part. Beams 32, 409 (2014); Horaet al., Laser Part. Beams33, 607 (2015)) for the combination of the non-thermal block ignition using ultrahigh intensity laser pulses of picoseconds duration. The ultrahigh accelerationabovemore » $$10^{20}~\\text{cm}~\\text{s}^{-2}$$ for plasma blocks was theoretically and numerically predicted since 1978 (Hora,Physics of Laser Driven Plasmas(Wiley, 1981), pp. 178 and 179) and measured (Sauerbrey, Phys. Plasmas3, 4712 (1996)) in exact agreement (Horaet al., Phys. Plasmas14, 072701 (2007)) when the dominating force was overcoming thermal processes. This is based on Maxwell’s stress tensor by the dielectric properties of plasma leading to the nonlinear (ponderomotive) force $$f_{\\text{NL}}$$ resulting in ultra-fast expanding plasma blocks by a dielectric explosion. Combining this with measured ultrahigh magnetic fields and the avalanche process opens an option for an environmentally absolute clean and economic boron fusion power reactor. Finally, this is supported also by other experiments with very high HB11 reactions under different conditions (Labauneet al., Nature Commun.4, 2506 (2013)).« less

Standard measurement procedures for the characterization of fs-laser optical components

NASA Astrophysics Data System (ADS)

Starke, Kai; Ristau, Detlev; Welling, Herbert

2003-05-01

Ultra-short pulse laser systems are considered as promising tools in the fields of precise micro-machining and medicine applications. In the course of the development of reliable table top laser systems, a rapid growth of ultra-short pulse applications could be observed during the recent years. The key for improving the performance of high power laser systems is the quality of the optical components concerning spectral characteristics, optical losses and the power handling capability. In the field of ultra-short pulses, standard measurement procedures in quality management have to be validated in respect to effects induced by the extremely high peak power densities. The present work, which is embedded in the EUREKA-project CHOCLAB II, is predominantly concentrated on measuring the multiple-pulse LIDT (ISO 11254-2) in the fs-regime. A measurement facility based on a Ti:Sapphire-CPA system was developed to investigate the damage behavior of optical components. The set-up was supplied with an improved pulse energy detector discriminating the influence of pulse-to-pulse energy fluctuations on the incidence of damage. Aditionally, a laser-calorimetric measurement facility determining the absorption (ISO 11551) utilizing a fs-Ti:Sapphire laser was accomplished. The investigation for different pulse durations between 130 fs and 1 ps revealed a drastic increase of absorption in titania coatings for ultra-short pulses.

Intravital autofluorescence 2-photon microscopy of murine intestinal mucosa with ultra-broadband femtosecond laser pulse excitation: image quality, photodamage, and inflammation

NASA Astrophysics Data System (ADS)

Klinger, Antje; Krapf, Lisa; Orzekowsky-Schroeder, Regina; Koop, Norbert; Vogel, Alfred; Hüttmann, Gereon

2015-11-01

Ultra-broadband excitation with ultrashort pulses may enable simultaneous excitation of multiple endogenous fluorophores in vital tissue. Imaging living gut mucosa by autofluorescence 2-photon microscopy with more than 150 nm broad excitation at an 800-nm central wavelength from a sub-10 fs titanium-sapphire (Ti:sapphire) laser with a dielectric mirror based prechirp was compared to the excitation with 220 fs pulses of a tunable Ti:sapphire laser at 730 and 800 nm wavelengths. Excitation efficiency, image quality, and photochemical damage were evaluated. At similar excitation fluxes, the same image brightness was achieved with both lasers. As expected, with ultra-broadband pulses, fluorescence from NAD(P)H, flavines, and lipoproteins was observed simultaneously. However, nonlinear photodamage apparent as hyperfluorescence with functional and structural alterations of the tissue occurred earlier when the laser power was adjusted to the same image brightness. After only a few minutes, the immigration of polymorphonuclear leucocytes into the epithelium and degranulation of these cells, a sign of inflammation, was observed. Photodamage is promoted by the higher peak irradiances and/or by nonoptimal excitation of autofluorescence at the longer wavelength. We conclude that excitation with a tunable narrow bandwidth laser is preferable to ultra-broadband excitation for autofluorescence-based 2-photon microscopy, unless the spectral phase can be controlled to optimize excitation conditions.

Determination of ultra-short laser induced damage threshold of KH{sub 2}PO{sub 4} crystal: Numerical calculation and experimental verification

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cheng, Jian; Department of Physics, The Ohio State University, 191 W. Woodruff Ave, Columbus, OH 43210; Chen, Mingjun, E-mail: chenmj@hit.edu.cn, E-mail: chowdhury.24@osu.edu

Rapid growth and ultra-precision machining of large-size KDP (KH{sub 2}PO{sub 4}) crystals with high laser damage resistance are tough challenges in the development of large laser systems. It is of high interest and practical significance to have theoretical models for scientists and manufacturers to determine the laser-induced damage threshold (LIDT) of actually prepared KDP optics. Here, we numerically and experimentally investigate the laser-induced damage on KDP crystals in ultra-short pulse laser regime. On basis of the rate equation for free electron generation, a model dedicated to predicting the LIDT is developed by considering the synergistic effect of photoionization, impact ionizationmore » and decay of electrons. Laser damage tests are performed to measure the single-pulse LIDT with several testing protocols. The testing results combined with previously reported experimental data agree well with those calculated by the model. By taking the light intensification into consideration, the model is successfully applied to quantitatively evaluate the effect of surface flaws inevitably introduced in the preparation processes on the laser damage resistance of KDP crystals. This work can not only contribute to further understanding of the laser damage mechanisms of optical materials, but also provide available models for evaluating the laser damage resistance of exquisitely prepared optical components used in high power laser systems.« less

Dynamic and interaction of fs-laser induced cavitation bubbles for analyzing the cutting effect

NASA Astrophysics Data System (ADS)

Tinne, N.; Schumacher, S.; Nuzzo, V.; Ripken, T.; Lubatschowski, H.

2009-07-01

A prominent laser based treatment in ophthalmology is the LASIK procedure which nowadays includes a cutting of the corneal tissue based on ultra short pulses. Focusing an ultra short laser pulse below the surface of biological tissue an optical breakdown is caused and hence a dissection is obtained. The laser energy of the laser pulses is absorbed by nonlinear processes. As a result a cavitation bubble expands and ruptures the tissue. Hence positioning of several optical breakdowns side by side generates an incision. Due to a reduction of the duration of the treatment the current development of ultra short laser systems points to higher repetition rates in the range of hundreds of KHz or even MHz instead of tens of kHz. This in turn results in a probable occurrence of interaction between different optical breakdowns and respectively cavitation bubbles of adjacent optical breakdowns. While the interaction of one single laser pulse with biological tissue is analyzed reasonably well experimentally and theoretically, the interaction of several spatial and temporal following pulses is scarcely determined yet. Thus the aim of this study is to analyse the dynamic and interaction of two cavitation bubbles by using high speed photography. The applied laser pulse energy, the energy ratio and the spot distance between different cavitation bubbles were varied. Depending on a change of these parameters different kinds of interactions such as a flattening and deformation of bubble shape or jet formation are observed. Based on these results a further research seems to be inevitable to comprehend and optimize the cutting effect of ultra short pulse laser systems with high (> 1 MHz) repetition rates.

Mesons from Laser-Induced Processes in Ultra-Dense Hydrogen H(0)

PubMed Central

2017-01-01

Large signals of charged light mesons are observed in the laser-induced particle flux from ultra-dense hydrogen H(0) layers. The mesons are formed in such layers on metal surfaces using < 200 mJ laser pulse-energy. The time variation of the signal to metal foil collectors and the magnetic deflection to a movable pin collector are now studied. Relativistic charged particles with velocity up to 500 MeV u-1 thus 0.75 c are observed. Characteristic decay time constants for meson decay are observed, for charged and neutral kaons and also for charged pions. Magnetic deflections agree with charged pions and kaons. Theoretical predictions of the decay chains from kaons to muons in the particle beam agree with the results. Muons are detected separately by standard scintillation detectors in laser-induced processes in ultra-dense hydrogen H(0) as published previously. The muons formed do not decay appreciably within the flight distances used here. Most of the laser-ejected particle flux with MeV energy is not deflected by the magnetic fields and is thus neutral, either being neutral kaons or the ultra-dense HN(0) precursor clusters. Photons give only a minor part of the detected signals. PACS: 67.63.Gh, 14.40.-n, 79.20.Ds, 52.57.-z. PMID:28081199

Selective laser melting of hypereutectic Al-Si40-powder using ultra-short laser pulses

NASA Astrophysics Data System (ADS)

Ullsperger, T.; Matthäus, G.; Kaden, L.; Engelhardt, H.; Rettenmayr, M.; Risse, S.; Tünnermann, A.; Nolte, S.

2017-12-01

We investigate the use of ultra-short laser pulses for the selective melting of Al-Si40-powder to fabricate complex light-weight structures with wall sizes below 100 μ {m} combined with higher tensile strength and lower thermal expansion coefficient in comparison to standard Al-Si alloys. During the cooling process using conventional techniques, large primary silicon particles are formed which impairs the mechanical and thermal properties. We demonstrate that these limitations can be overcome using ultra-short laser pulses enabling the rapid heating and cooling in a non-thermal equilibrium process. We analyze the morphology characteristics and micro-structures of single tracks and thin-walled structures depending on pulse energy, repetition rate and scanning velocity utilizing pulses with a duration of 500 {fs} at a wavelength of 1030 {nm}. The possibility to specifically change and optimize the microstructure is shown.

Bright and ultra-fast scintillation from a semiconductor?

PubMed Central

Derenzo, Stephen E.; Bourret-Courshesne, Edith; Bizarri, Gregory; Canning, Andrew

2015-01-01

Semiconductor scintillators are worth studying because they include both the highest luminosities and shortest decay times of all known scintillators. Moreover, many semiconductors have the heaviest stable elements (Tl, Hg, Pb, Bi) as a major constituent and a high ion pair yield that is proportional to the energy deposited. We review the scintillation properties of semiconductors activated by native defects, isoelectronic impurities, donors and acceptors with special emphasis on those that have exceptionally high luminosities (e.g. ZnO:Zn, ZnS:Ag,Cl, CdS:Ag,Cl) and those that have ultra-fast decay times (e.g. ZnO:Ga; CdS:In). We discuss underlying mechanisms that are consistent with these properties and the possibilities for achieving (1) 200,000 photons/MeV and 1% fwhm energy resolution for 662 keV gamma rays, (2) ultra-fast (ns) decay times and coincident resolving times of 30 ps fwhm for time-of-flight positron emission tomography, and (3) both a high luminosity and an ultra-fast decay time from the same scintillator at cryogenic temperatures. PMID:26855462

Dissemination of optical-comb-based ultra-broadband frequency reference through a fiber network.

PubMed

Nagano, Shigeo; Kumagai, Motohiro; Li, Ying; Ido, Tetsuya; Ishii, Shoken; Mizutani, Kohei; Aoki, Makoto; Otsuka, Ryohei; Hanado, Yuko

2016-08-22

We disseminated an ultra-broadband optical frequency reference based on a femtosecond (fs)-laser optical comb through a kilometer-scale fiber link. Its spectrum ranged from 1160 nm to 2180 nm without additional fs-laser combs at the end of the link. By employing a fiber-induced phase noise cancellation technique, the linewidth and fractional frequency instability attained for all disseminated comb modes were of order 1 Hz and 10^-18 in a 5000 s averaging time. The ultra-broad optical frequency reference, for which absolute frequency is traceable to Japan Standard Time, was applied in the frequency stabilization of an injection-seeded Q-switched 2051 nm pulse laser for a coherent light detection and ranging LIDAR system.

Photonic generation of ultra-wideband signals by direct current modulation on SOA section of an SOA-integrated SGDBR laser.

PubMed

Lv, Hui; Yu, Yonglin; Shu, Tan; Huang, Dexiu; Jiang, Shan; Barry, Liam P

2010-03-29

Photonic ultra-wideband (UWB) pulses are generated by direct current modulation of a semiconductor optical amplifier (SOA) section of an SOA-integrated sampled grating distributed Bragg reflector (SGDBR) laser. Modulation responses of the SOA section of the laser are first simulated with a microwave equivalent circuit model. Simulated results show a resonance behavior indicating the possibility to generate UWB signals with complex shapes in the time domain. The UWB pulse generation is then experimentally demonstrated for different selected wavelength channels with an SOA-integrated SGDBR laser.

Using the ultra-long pulse width pulsed dye laser and elliptical spot to treat resistant nasal telangiectasia.

PubMed

Madan, Vishal; Ferguson, Janice

2010-01-01

Thick linear telangiectasia on the ala nasi and nasolabial crease can be resistant to treatment with the potassium-titanyl-phosphate (KTP) laser and the traditional round spot on a pulsed dye laser (PDL). We evaluated the efficacy of a 3 mm x 10 mm elliptical spot using the ultra-long pulse width on a Candela Vbeam(R) PDL for treatment of PDL- and KTP laser-resistant nasal telangiectasia. Nasal telangiectasia resistant to PDL (12 patients) and KTP laser (12 patients) in 18 patients were treated with a 3 mm x 10 mm elliptical spot on the ultra-long pulse pulsed dye laser (ULPDL) utilising long pulse width [595 nm, 40 ms, double pulse, 30:20 dynamic cooling device (DCD)]. Six patients had previously received treatment with both PDL and KTP laser prior to ULPDL (40 treatments, range1-4, mean 2.2). Complete clearance was seen in ten patients, and eight patients displayed more than 80% improvement after ULPDL treatment. Self-limiting purpura occurred with round spot PDL and erythema with KTP laser and ULPDL. Subtle linear furrows along the treatment sites were seen in three patients treated with the KTP laser. ULPDL treatment delivered using a 3 mm x 10 mm elliptical spot was non-purpuric and highly effective in the treatment of nasal telangiectasia resistant to KTP laser and PDL.

The creation of radiation dominated plasmas using laboratory extreme ultra-violet lasers

NASA Astrophysics Data System (ADS)

Tallents, G. J.; Wilson, S.; West, A.; Aslanyan, V.; Lolley, J.; Rossall, A. K.

2017-06-01

Ionization in experiments where solid targets are irradiated by high irradiance extreme ultra-violet (EUV) lasers is examined. Free electron degeneracy effects on ionization in the presence of a high EUV flux of radiation is shown to be important. Overlap of the physics of such plasmas with plasma material under compression in indirect inertial fusion is explored. The design of the focusing optics needed to achieve high irradiance (up to 1014 Wcm-2) using an EUV capillary laser is presented.

Inhibited-coupling HC-PCF based beam-delivery-system for high power green industrial lasers

NASA Astrophysics Data System (ADS)

Chafer, M.; Gorse, A.; Beaudou, B.; Lekiefs, Q.; Maurel, M.; Debord, B.; Gérôme, F.; Benabid, F.

2018-02-01

We report on an ultra-low loss Hollow-Core Photonic Crystal Fiber (HC-PCF) beam delivery system (GLO-GreenBDS) for high power ultra-short pulse lasers operating in the green spectral range (including 515 nm and 532 nm). The GLOBDS- Green combines ease-of-use, high laser-coupling efficiency, robustness and industrial compatible cabling. It comprises a pre-aligned laser-injection head, a sheath-cable protected HC-PCF and a modular fiber-output head. It enables fiber-core gas loading and evacuation in a hermetic fashion. A 5 m long GLO-BDS were demonstrated for a green short pulse laser with a transmission coefficient larger than 80%, and a laser output profile close to single-mode (M2 <1.3).

Network Modeling for Functional Magnetic Resonance Imaging (fMRI) Signals during Ultra-Fast Speech Comprehension in Late-Blind Listeners

PubMed Central

Dietrich, Susanne; Hertrich, Ingo; Ackermann, Hermann

2015-01-01

In many functional magnetic resonance imaging (fMRI) studies blind humans were found to show cross-modal reorganization engaging the visual system in non-visual tasks. For example, blind people can manage to understand (synthetic) spoken language at very high speaking rates up to ca. 20 syllables/s (syl/s). FMRI data showed that hemodynamic activation within right-hemispheric primary visual cortex (V1), bilateral pulvinar (Pv), and left-hemispheric supplementary motor area (pre-SMA) covaried with their capability of ultra-fast speech (16 syllables/s) comprehension. It has been suggested that right V1 plays an important role with respect to the perception of ultra-fast speech features, particularly the detection of syllable onsets. Furthermore, left pre-SMA seems to be an interface between these syllabic representations and the frontal speech processing and working memory network. So far, little is known about the networks linking V1 to Pv, auditory cortex (A1), and (mesio-) frontal areas. Dynamic causal modeling (DCM) was applied to investigate (i) the input structure from A1 and Pv toward right V1 and (ii) output from right V1 and A1 to left pre-SMA. As concerns the input Pv was significantly connected to V1, in addition to A1, in blind participants, but not in sighted controls. Regarding the output V1 was significantly connected to pre-SMA in blind individuals, and the strength of V1-SMA connectivity correlated with the performance of ultra-fast speech comprehension. By contrast, in sighted controls, not understanding ultra-fast speech, pre-SMA did neither receive input from A1 nor V1. Taken together, right V1 might facilitate the “parsing” of the ultra-fast speech stream in blind subjects by receiving subcortical auditory input via the Pv (= secondary visual pathway) and transmitting this information toward contralateral pre-SMA. PMID:26148062

Network Modeling for Functional Magnetic Resonance Imaging (fMRI) Signals during Ultra-Fast Speech Comprehension in Late-Blind Listeners.

PubMed

Dietrich, Susanne; Hertrich, Ingo; Ackermann, Hermann

2015-01-01

In many functional magnetic resonance imaging (fMRI) studies blind humans were found to show cross-modal reorganization engaging the visual system in non-visual tasks. For example, blind people can manage to understand (synthetic) spoken language at very high speaking rates up to ca. 20 syllables/s (syl/s). FMRI data showed that hemodynamic activation within right-hemispheric primary visual cortex (V1), bilateral pulvinar (Pv), and left-hemispheric supplementary motor area (pre-SMA) covaried with their capability of ultra-fast speech (16 syllables/s) comprehension. It has been suggested that right V1 plays an important role with respect to the perception of ultra-fast speech features, particularly the detection of syllable onsets. Furthermore, left pre-SMA seems to be an interface between these syllabic representations and the frontal speech processing and working memory network. So far, little is known about the networks linking V1 to Pv, auditory cortex (A1), and (mesio-) frontal areas. Dynamic causal modeling (DCM) was applied to investigate (i) the input structure from A1 and Pv toward right V1 and (ii) output from right V1 and A1 to left pre-SMA. As concerns the input Pv was significantly connected to V1, in addition to A1, in blind participants, but not in sighted controls. Regarding the output V1 was significantly connected to pre-SMA in blind individuals, and the strength of V1-SMA connectivity correlated with the performance of ultra-fast speech comprehension. By contrast, in sighted controls, not understanding ultra-fast speech, pre-SMA did neither receive input from A1 nor V1. Taken together, right V1 might facilitate the "parsing" of the ultra-fast speech stream in blind subjects by receiving subcortical auditory input via the Pv (= secondary visual pathway) and transmitting this information toward contralateral pre-SMA.

Ultra-short pulse delivery at high average power with low-loss hollow core fibers coupled to TRUMPF's TruMicro laser platforms for industrial applications

NASA Astrophysics Data System (ADS)

Baumbach, S.; Pricking, S.; Overbuschmann, J.; Nutsch, S.; Kleinbauer, J.; Gebs, R.; Tan, C.; Scelle, R.; Kahmann, M.; Budnicki, A.; Sutter, D. H.; Killi, A.

2017-02-01

Multi-megawatt ultrafast laser systems at micrometer wavelength are commonly used for material processing applications, including ablation, cutting and drilling of various materials or cleaving of display glass with excellent quality. There is a need for flexible and efficient beam guidance, avoiding free space propagation of light between the laser head and the processing unit. Solid core step index fibers are only feasible for delivering laser pulses with peak powers in the kW-regime due to the optical damage threshold in bulk silica. In contrast, hollow core fibers are capable of guiding ultra-short laser pulses with orders of magnitude higher peak powers. This is possible since a micro-structured cladding confines the light within the hollow core and therefore minimizes the spatial overlap between silica and the electro-magnetic field. We report on recent results of single-mode ultra-short pulse delivery over several meters in a lowloss hollow core fiber packaged with industrial connectors. TRUMPF's ultrafast TruMicro laser platforms equipped with advanced temperature control and precisely engineered opto-mechanical components provide excellent position and pointing stability. They are thus perfectly suited for passive coupling of ultra-short laser pulses into hollow core fibers. Neither active beam launching components nor beam trackers are necessary for a reliable beam delivery in a space and cost saving packaging. Long term tests with weeks of stable operation, excellent beam quality and an overall transmission efficiency of above 85 percent even at high average power confirm the reliability for industrial applications.

A highly ordered mesostructured material containing regularly distributed phenols: preparation and characterization at a molecular level through ultra-fast magic angle spinning proton NMR spectroscopy.

PubMed

Roussey, Arthur; Gajan, David; Maishal, Tarun K; Mukerjee, Anhurada; Veyre, Laurent; Lesage, Anne; Emsley, Lyndon; Copéret, Christophe; Thieuleux, Chloé

2011-03-14

Highly ordered organic-inorganic mesostructured material containing regularly distributed phenols is synthesized by combining a direct synthesis of the functional material and a protection-deprotection strategy and characterized at a molecular level through ultra-fast magic angle spinning proton NMR spectroscopy.

Ultra-stable microwave generation with a diode-pumped solid-state laser in the 1.5-μm range

NASA Astrophysics Data System (ADS)

Dolgovskiy, Vladimir; Schilt, Stéphane; Bucalovic, Nikola; Di Domenico, Gianni; Grop, Serge; Dubois, Benoît; Giordano, Vincent; Südmeyer, Thomas

2014-09-01

We demonstrate the first ultra-stable microwave generation based on a 1.5-μm diode-pumped solid-state laser (DPSSL) frequency comb. Our system relies on optical-to-microwave frequency division from a planar-waveguide external cavity laser referenced to an ultra-stable Fabry-Perot cavity. The evaluation of the microwave signal at ~10 GHz uses the transportable ultra-low-instability signal source ULISS®, which employs a cryo-cooled sapphire oscillator. With the DPSSL comb, we measured -125 dBc/Hz phase noise at 1 kHz offset frequency, likely limited by the photo-detection shot-noise or by the noise floor of the reference cryo-cooled sapphire oscillator. For comparison, we also generated low-noise microwave using a commercial Er:fiber comb stabilized in similar conditions and observed >20 dB lower phase noise in the microwave generated from the DPSSL comb. Our results confirm the high potential of the DPSSL technology for low-noise comb applications.

Stimulated Brillouin scattering in ultra-long distributed feedback Bragg gratings in standard optical fiber.

PubMed

Loranger, Sébastien; Lambin-Iezzi, Victor; Wahbeh, Mamoun; Kashyap, Raman

2016-04-15

Distributed feedback (DFB) fiber Bragg gratings (FBG) are widely used as narrow-band filters and single-mode cavities for lasers. Recently, a nonlinear generation has been shown in 10-20 cm DFB gratings in a highly nonlinear fiber. First, we show in this Letter a novel fabrication technique of ultra-long DFBs in a standard fiber (SMF-28). Second, we demonstrate nonlinear generation in such gratings. A particular inscription technique was used to fabricate all-in-phase ultra-long FBG and to implement reproducible phase shift to form a DFB mode. We demonstrate stimulated Brillouin scattering (SBS) emission from this DFB mode and characterize the resulting laser. It seems that such a SBS based DFB laser stabilizes a pump's jittering and reduces its linewidth.

Femtosecond timing-jitter between photo-cathode laser and ultra-short electron bunches by means of hybrid compression

NASA Astrophysics Data System (ADS)

Pompili, R.; Anania, M. P.; Bellaveglia, M.; Biagioni, A.; Castorina, G.; Chiadroni, E.; Cianchi, A.; Croia, M.; Di Giovenale, D.; Ferrario, M.; Filippi, F.; Gallo, A.; Gatti, G.; Giorgianni, F.; Giribono, A.; Li, W.; Lupi, S.; Mostacci, A.; Petrarca, M.; Piersanti, L.; Di Pirro, G.; Romeo, S.; Scifo, J.; Shpakov, V.; Vaccarezza, C.; Villa, F.

2016-08-01

The generation of ultra-short electron bunches with ultra-low timing-jitter relative to the photo-cathode (PC) laser has been experimentally proved for the first time at the SPARC_LAB test-facility (INFN-LNF, Frascati) exploiting a two-stage hybrid compression scheme. The first stage employs RF-based compression (velocity-bunching), which shortens the bunch and imprints an energy chirp on it. The second stage is performed in a non-isochronous dogleg line, where the compression is completed resulting in a final bunch duration below 90 fs (rms). At the same time, the beam arrival timing-jitter with respect to the PC laser has been measured to be lower than 20 fs (rms). The reported results have been validated with numerical simulations.

Quantum cascade laser-based mid-IR frequency metrology system with ultra-narrow linewidth and 1  ×  10⁻¹³-level frequency instability.

PubMed

Hansen, Michael G; Magoulakis, Evangelos; Chen, Qun-Feng; Ernsting, Ingo; Schiller, Stephan

2015-05-15

We demonstrate a powerful tool for high-resolution mid-IR spectroscopy and frequency metrology with quantum cascade lasers (QCLs). We have implemented frequency stabilization of a QCL to an ultra-low expansion (ULE) reference cavity, via upconversion to the near-IR spectral range, at a level of 1×10(-13). The absolute frequency of the QCL is measured relative to a hydrogen maser, with instability <1×10(-13) and inaccuracy 5×10(-13), using a frequency comb phase stabilized to an independent ultra-stable laser. The QCL linewidth is determined to be 60 Hz, dominated by fiber noise. Active suppression of fiber noise could result in sub-10 Hz linewidth.

Ultra-high Temperature Emittance Measurements for Space and Missile Applications

NASA Technical Reports Server (NTRS)

Rogers, Jan; Crandall, David

2009-01-01

Advanced modeling and design efforts for many aerospace components require high temperature emittance data. Applications requiring emittance data include propulsion systems, radiators, aeroshells, heatshields/thermal protection systems, and leading edge surfaces. The objective of this work is to provide emittance data at ultra-high temperatures. MSFC has a new instrument for the measurement of emittance at ultra-high temperatures, the Ultra-High Temperature Emissometer System (Ultra-HITEMS). AZ Technology Inc. developed the instrument, designed to provide emittance measurements over the temperature range 700-3500K. The Ultra-HITEMS instrument measures the emittance of samples, heated by lasers, in vacuum, using a blackbody source and a Fourier Transform Spectrometer. Detectors in a Nicolet 6700 FT-IR spectrometer measure emittance over the spectral range of 0.4-25 microns. Emitted energy from the specimen and output from a Mikron M390S blackbody source at the same temperature with matched collection geometry are measured. Integrating emittance over the spectral range yields the total emittance. The ratio provides a direct measure of total hemispherical emittance. Samples are heated using lasers. Optical pyrometry provides temperature data. Optical filters prevent interference from the heating lasers. Data for Inconel 718 show excellent agreement with results from literature and ASTM 835. Measurements taken from levitated spherical specimens provide total hemispherical emittance data; measurements taken from flat specimens mounted in the chamber provide near-normal emittance data. Data from selected characterization studies will be presented. The Ultra-HITEMS technique could advance space and missile technologies by advancing the knowledge base and the technology readiness level for ultra-high temperature materials.

Mid-IR lasers based on transition metal and rare-earth ion doped crystals

NASA Astrophysics Data System (ADS)

Mirov, S.; Fedorov, V.; Martyshkin, D.; Moskalev, I.; Mirov, M.; Vasilyev, S.

2015-05-01

We report a novel design of CW Cr2+:ZnS/ZnSe laser systems and demonstrate record output powers of 27.5 W at 2.45 μm and 13.9 W at 2.94 μm with slope efficiencies of 63.7% and 37.4%, respectively. Power scaling of ultra-fast Cr2+:ZnS/ZnSe Kerr mode-locked lasers beyond 2 W level, as well as the shortest pulse duration of 29 fs, are also reported. New development of Fe:ZnSe laser with average output power > 35 W at 4.1 μm output wavelength and 100 Hz pulse repetition rate (PRR) was achieved in a nonselective cavity. With intracavity prim selector, wavelength tunability of 3.88-4.17 μm was obtained with maximum average output power of 23 W. We also report new results on Tm-fiber pumped passively and actively Q-switched Ho:YAG laser systems. High peak power actively Q-switched Ho:YAG laser demonstrates stable operation with pulse energy > 50 mJ, 12 ns pulse duration, and 100-1000 Hz PRR which correspondents to more than 4 MW peak power. The actively Q-switched Ho:YAG laser system optimized for high repetition rate delivers 40 W average output power at 10-100 kHz PRR. The Ho:YAG laser with passive Q-switcher demonstrates constant 5 mJ output energy from 200 Hz to 2.23 kHz PRR with optical slope efficiency with respect to Tm-fiber laser of ~43%.

Precision ablation of dental enamel using a subpicosecond pulsed laser.

PubMed

Rode, A V; Gamaly, E G; Luther-Davies, B; Taylor, B T; Graessel, M; Dawes, J M; Chan, A; Lowe, R M; Hannaford, P

2003-12-01

In this study we report the use of ultra-short-pulsed near-infrared lasers for precision laser ablation of freshly extracted human teeth. The laser wavelength was approximately 800nm, with pulsewidths of 95 and 150fs, and pulse repetition rates of 1kHz. The laser beam was focused to an approximate diameter of 50microm and was scanned over the tooth surface. The rise in the intrapulpal temperature was monitored by embedded thermocouples, and was shown to remain below 5 degrees C when the tooth was air-cooled during laser treatment. The surface preparation of the ablated teeth, observed by optical and electron microscopy, showed no apparent cracking or heat effects, and the hardness and Raman spectra of the laser-treated enamel were not distinguishable from those of native enamel. This study indicates the potential for ultra-short-pulsed lasers to effect precision ablation of dental enamel.

Characterizing and Optimizing Photocathode Laser Distributions for Ultra-low Emittance Electron Beam Operations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhou, F.; Bohler, D.; Ding, Y.

2015-12-07

Photocathode RF gun has been widely used for generation of high-brightness electron beams for many different applications. We found that the drive laser distributions in such RF guns play important roles in minimizing the electron beam emittance. Characterizing the laser distributions with measurable parameters and optimizing beam emittance versus the laser distribution parameters in both spatial and temporal directions are highly desired for high-brightness electron beam operation. In this paper, we report systematic measurements and simulations of emittance dependence on the measurable parameters represented for spatial and temporal laser distributions at the photocathode RF gun systems of Linac Coherent Lightmore » Source. The tolerable parameter ranges for photocathode drive laser distributions in both directions are presented for ultra-low emittance beam operations.« less

Electronic sideband locking of a broadly tunable 318.6 nm ultraviolet laser to an ultra-stable optical cavity

NASA Astrophysics Data System (ADS)

Bai, Jiandong; Wang, Jieying; He, Jun; Wang, Junmin

2017-04-01

We demonstrate frequency stabilization of a tunable 318.6 nm ultraviolet (UV) laser system using electronic sideband locking. By indirectly changing the frequency of a broadband electro-optic phase modulator, the laser can be continuously tuned over 4 GHz, while a 637.2 nm laser is directly stabilized to a high-finesse ultra-stable optical cavity. The doubling cavity also remains locked to the 637.2 nm light. We show that the tuning range depends mainly on the gain-flattening region of the modulator and the piezo-tunable range of the seed laser. The frequency-stabilized tunable UV laser system is able to compensate for the offset between reference and target frequencies, and has potential applications in precision spectroscopy of cold atoms.

Ultra short laser pulse modification of wave guides

NASA Astrophysics Data System (ADS)

Rosenfeld, Arkadi; Ashkenasi, David

2003-11-01

The high peak powers of ultra short (ps and sub-ps) pulsed lasers available at relatively low single pulse energies potentially allow for a precise localization of photon energy, either on the surface or inside (transparent) materials. Three dimensional micro structuring of bulk transparent media without any sign of mechanical cracking has shown the potential of ultra short laser processing. In this study, the micro structuring of bulk transparent media was used to modify fused silica and especially the cladding-core interface in normal fused silica wave guides. The idea behind this technique is to enforce a local mismatch for total reflection at the interface at minimal mechanic stress to overcome the barrier for enhanced optical out-coupling. The laser-induced modifications were studied in dependence of pulse width, focal alignment, single pulse energy and pulse overlap. Micro traces with a thickness between 3 and 8 μm were generated with a spacing of 10 μm in the subsurface region using sub-ps and ps laser pulses at a wavelength of 800 nm. The optical leakage enforced by a micro spiral pattern is significant and can be utilized for medical applications or potentially also for telecommunications and fiber laser technology.

An investigation of laser cutting quality of 22MnB5 ultra high strength steel using response surface methodology

NASA Astrophysics Data System (ADS)

Tahir, Abdul Fattah Mohd; Aqida, Syarifah Nur

2017-07-01

In hot press forming, changes of mechanical properties in boron steel blanks have been a setback in trimming the final shape components. This paper presents investigation of kerf width and heat affected zone (HAZ) of ultra high strength 22MnB5 steel cutting. Sample cutting was conducted using a 4 kW Carbon Dioxide (CO2) laser machine with 10.6 μm wavelength with the laser spot size of 0.2 mm. A response surface methodology (RSM) using three level Box-Behnken design of experiment was developed with three factors of peak power, cutting speed and duty cycle. The parameters were optimised for minimum kerf width and HAZ formation. Optical evaluation using MITUTOYO TM 505 were conducted to measure the kerf width and HAZ region. From the findings, laser duty cycle was crucial to determine cutting quality of ultra-high strength steel; followed by cutting speed and laser power. Meanwhile, low power intensity with continuous wave contributes the narrowest kerf width formation and least HAZ region.

Effects of Laser Frequency and Multiple Beams on Hot Electron Generation in Fast Ignition

NASA Astrophysics Data System (ADS)

Royle, Ryan B.

Inertial confinement fusion (ICF) is one approach to harnessing fusion power for the purpose of energy production in which a small deuterium-tritium capsule is imploded to about a thousand times solid density with ultra-intense lasers. In the fast ignition (FI) scheme, a picosecond petawatt laser pulse is used to deposit ˜10 kJ of energy in ˜10 ps into a small hot-spot at the periphery of the compressed core, igniting a fusion burn wave. FI promises a much higher energy gain over the conventional central hot-spot ignition scheme in which ignition is achieved through compression alone. Sufficient energy coupling between ignition laser and implosion core is critical for the feasibility of the FI scheme. Laser-core energy coupling is mediated by hot electrons which absorb laser energy near the critical density and propagate to the dense core, depositing their energy primarily through collisions. The hot electron energy distribution plays a large role in achieving efficient energy coupling since electrons with energy much greater than a few MeV will only deposit a small fraction of their energy into the hot-spot region due to reduced collisional cross section. It is understood that it may be necessary to use the second or third harmonic of the 1.05 mum Nd glass laser to reduce the average hot electron energy closer to the few-MeV range. Also, it is likely that multiple ignition beams will be used to achieve the required intensities. In this study, 2D particle-in-cell simulations are used to examine the effects of frequency doubling and tripling of a 1 mum laser as well as effects of using various dual-beam configurations. While the hot-electron energy spectrum is indeed shifted closer to the few-MeV range for higher frequency beams, the overall energy absorption is reduced, canceling the gain from higher efficiency. For a fixed total laser input energy, we find that the amount of hot electron energy able to be deposited into the core hot-spot is fairly insensitive to the laser configuration used. Our results hint that the more important issue at hand may be divergence and transport of the hot electrons, which tend to spray into 2pi radians due to instabilities and current filamentation present in the laser-plasma interaction region.

Ultra-Shallow Junctions Fabrication by Plasma Immersion Implantation on PULSION registered Followed by Laser Thermal Processing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Torregrosa, Frank; Etienne, Hasnaa; Sempere, Guillaume

In order to achieve the requirements for P+/N junctions for <45 nm ITRS nodes, ultra low energy and high dose implantations are needed. Classical beamline implantation is now limited in low energies, compared to Plasma Immersion Ion Implantation (PIII) which efficiency is no more to prove for the realization of Ultra-Shallow Junctions (USJ) in semiconductor applications : this technique allows to get ultimate shallow profiles (as implanted) due to no lower limitation of energy and high dose rate. Electrical activation is also a big issue since it has to afford high electrical activation rate with very low diffusion. Laser annealingmore » is one of the candidates for the 45 nm node. This paper presents electrical and physico-chemical characterizations of junctions realized with BF3 PIII followed by laser thermal processing with aim to obtain ultra-shallow junctions. Different implantation conditions (acceleration voltage/dose) and laser conditions (laser types, fluence/number of shots) are used for this study. Pre-amorphization is also used to confine the junction depth, and is shown to have a positive effect on junction depth but leads in higher junction leakage due to the remaining of EOR defects. The characterization is done using Optical characterization tool (SEMILAB) for sheet resistance and junction leakage measurements. SIMS is used for Boron profile and junction depth.« less

Radiation reaction studies in an all-optical set-up: experimental limitations

NASA Astrophysics Data System (ADS)

Samarin, G. M.; Zepf, M.; Sarri, G.

2018-06-01

The recent development of ultra-high intensity laser facilities is finally opening up the possibility of studying high-field quantum electrodynamics in the laboratory. Arguably, one of the central phenomena in this area is that of quantum radiation reaction experienced by an ultra-relativistic electron beam as it propagates through the tight focus of a laser beam. In this paper, we discuss the major experimental challenges that are to be faced in order to extract meaningful and quantitative information from this class of experiments using existing and near-term laser facilities.

Creating Extended and Dense Plasma Channels in Air by Using Spatially and Temporally Shaped Ultra-Intense Laser Pulses

DTIC Science & Technology

2011-08-16

Wolf, Phys. Rev. Lett. 104, 103903 (2010). 6. M. Aközbek, M. Scalora , C. Bowden, and S. L. Chin, Opt. Commun. 191, 353 (2001). 7. A. Couairon, Phys...Aközbek, M. Scalora , C. Bowden, and S. L. Chin, “White-light continuum generation and filamentation during the propagation of ultra-short laser pulses in

Tracking the Speech Signal--Time-Locked MEG Signals during Perception of Ultra-Fast and Moderately Fast Speech in Blind and in Sighted Listeners

ERIC Educational Resources Information Center

Hertrich, Ingo; Dietrich, Susanne; Ackermann, Hermann

2013-01-01

Blind people can learn to understand speech at ultra-high syllable rates (ca. 20 syllables/s), a capability associated with hemodynamic activation of the central-visual system. To further elucidate the neural mechanisms underlying this skill, magnetoencephalographic (MEG) measurements during listening to sentence utterances were cross-correlated…

Experience-Related Structural Changes of Degenerated Occipital White Matter in Late-Blind Humans – A Diffusion Tensor Imaging Study

PubMed Central

Dietrich, Susanne; Hertrich, Ingo; Kumar, Vinod; Ackermann, Hermann

2015-01-01

Late-blind humans can learn to understand speech at ultra-fast syllable rates (ca. 20 syllables/s), a capability associated with hemodynamic activation of the central-visual system. Thus, the observed functional cross-modal recruitment of occipital cortex might facilitate ultra-fast speech processing in these individuals. To further elucidate the structural prerequisites of this skill, diffusion tensor imaging (DTI) was conducted in late-blind subjects differing in their capability of understanding ultra-fast speech. Fractional anisotropy (FA) was determined as a quantitative measure of the directionality of water diffusion, indicating fiber tract characteristics that might be influenced by blindness as well as the acquired perceptual skills. Analysis of the diffusion images revealed reduced FA in late-blind individuals relative to sighted controls at the level of the optic radiations at either side and the right-hemisphere dorsal thalamus (pulvinar). Moreover, late-blind subjects showed significant positive correlations between FA and the capacity of ultra-fast speech comprehension within right-hemisphere optic radiation and thalamus. Thus, experience-related structural alterations occurred in late-blind individuals within visual pathways that, presumably, are linked to higher order frontal language areas. PMID:25830371

Effect of ageing time on suckling lamb meat quality resulting from different carcass chilling regimes.

PubMed

Vieira, C; Fernández, A M

2014-02-01

The effect of ageing on suckling lamb carcasses subjected to three chilling treatments was studied: Conventional (2 °C for 24h), ultra-fast (-20 °C for 3.5h then 2 °C until 24h post mortem) and slow chilling (12 °C for 7h then 2 °C until 24h post mortem) treatments. Meat quality measurements were carried out in carcasses at 24h post mortem and also after 5 days of ageing. Carcass chilling losses were not affected by a chilling regime. Aged meat showed higher cooking losses than non-aged meat (p<0.05). Sarcomere length of ultra-fast t was shorter (p<0.05) than conventional and conventional was shorter than slow chilling treatment (p<0.05), at 24h and after 5 days of ageing. Conventional and ultra-fast chilling treatments resulted in higher shear force values at 24h post mortem (p<0.05) compared to slow treatment. All treatments improved sensory scores with ageing (p<0.05), but ultra-fast chilling treatment did not attain higher values as the other two treatments. © 2013.

Review of laser-driven ion sources and their applications.

PubMed

Daido, Hiroyuki; Nishiuchi, Mamiko; Pirozhkov, Alexander S

2012-05-01

For many years, laser-driven ion acceleration, mainly proton acceleration, has been proposed and a number of proof-of-principle experiments have been carried out with lasers whose pulse duration was in the nanosecond range. In the 1990s, ion acceleration in a relativistic plasma was demonstrated with ultra-short pulse lasers based on the chirped pulse amplification technique which can provide not only picosecond or femtosecond laser pulse duration, but simultaneously ultra-high peak power of terawatt to petawatt levels. Starting from the year 2000, several groups demonstrated low transverse emittance, tens of MeV proton beams with a conversion efficiency of up to several percent. The laser-accelerated particle beams have a duration of the order of a few picoseconds at the source, an ultra-high peak current and a broad energy spectrum, which make them suitable for many, including several unique, applications. This paper reviews, firstly, the historical background including the early laser-matter interaction studies on energetic ion acceleration relevant to inertial confinement fusion. Secondly, we describe several implemented and proposed mechanisms of proton and/or ion acceleration driven by ultra-short high-intensity lasers. We pay special attention to relatively simple models of several acceleration regimes. The models connect the laser, plasma and proton/ion beam parameters, predicting important features, such as energy spectral shape, optimum conditions and scalings under these conditions for maximum ion energy, conversion efficiency, etc. The models also suggest possible ways to manipulate the proton/ion beams by tailoring the target and irradiation conditions. Thirdly, we review experimental results on proton/ion acceleration, starting with the description of driving lasers. We list experimental results and show general trends of parameter dependences and compare them with the theoretical predictions and simulations. The fourth topic includes a review of scientific, industrial and medical applications of laser-driven proton or ion sources, some of which have already been established, while the others are yet to be demonstrated. In most applications, the laser-driven ion sources are complementary to the conventional accelerators, exhibiting significantly different properties. Finally, we summarize the paper.

Block Ignition Inertial Confinement Fusion (ICF) with Condensed Matter Cluster Type Targets for p-B11 Powered Space Propulsion

DOE Office of Scientific and Technical Information (OSTI.GOV)

Miley, George H.; Hora, H.; Badziak, J.

The use of laser-driven Inertial Confinement Fusion (ICF) for space propulsion has been the subject of several earlier conceptual design studies, (see: Orth, 1998; and other references therein). However, these studies were based on older ICF technology using either 'direct' or 'in-direct x-ray driven' type target irradiation. Important new directions have opened for laser ICF in recent years following the development of 'chirped' lasers capable of ultra short pulses with powers of TW up to few PW which leads to the concept of 'fast ignition (FI)' to achieve higher energy gains from target implosions. In a recent publication the authorsmore » showed that use of a modified type of FI, termed 'block ignition' (Miley et al., 2008), could meet many of the requirements anticipated (but not then available) by the designs of the Vehicle for Interplanetary Space Transport Applications (VISTA) ICF fusion propulsion ship (Orth, 2008) for deep space missions. Subsequently the first author devised and presented concepts for imbedding high density condensed matter 'clusters' of deuterium into the target to obtain ultra high local fusion reaction rates (Miley, 2008). Such rates are possible due to the high density of the clusters (over an order of magnitude above cryogenic deuterium). Once compressed by the implosion, the yet higher density gives an ultra high reaction rate over the cluster volume since the fusion rate is proportional to the square of the fuel density. Most recently, a new discovery discussed here indicates that the target matrix could be composed of B{sup 11} with proton clusters imbedded. This then makes p-B{sup 11} fusion practical, assuming all of the physics issues such as stability of the clusters during compression are resolved. Indeed, p-B{sup 11} power is ideal for fusion propulsion since it has a minimum of unwanted side products while giving most of the reaction energy to energetic alpha particles which can be directed into an exhaust (propulsion) nozzle. Power plants using p-B{sup 11} have been discussed for such applications before, but prior designs face formidable physics/technology issues, largely overcome with the present approach.« less

Nonlinear Electron and Ion Density Modulations Driven by Interfering High-Intensity Laser Pulses

NASA Astrophysics Data System (ADS)

Chen, S.; Zhang, P.; Saleh, N.; Sheng, Z. M.; Widjaja, C.; Umstadter, D.

2002-11-01

The optical spectrum from interaction of two crossed ultra short laser beams (400 fs) with underdense plasma is measured at various angles. Enhancement and broadening of the spectrum in the forward direction of one of the beams shows evidence of energy transfer between the two laser beams(G. Shvets, N. J. Fisch, A. Pukhov, and J. Meyer-ter-Vehn, Phys. Rev. E 60, 2218 (1999).), which is confirmed by a 2-D PIC simulation. The spectrum and scattered power indicate that a large amplitude electron density modulation is driven, which is attributed to the ponderomotive force of the interference, in agreement with simple analysis and simulation(δn/n_0>10). Stokes and anti-Stokes satellites reveals that the energy transfer is accompanied by a large amplitude nonlinear ion acoustic wave created by the laser interference in the strongly driven limit. The wavelength shift indicates that the ion acoustic wave's speed is 2.3×10^6m/s, corresponding to the electron temperature 119 keV, which is attributed to stochastic heating, also found in the simulation. Besides being of interest in basic plasma physics, this research is also relevant to fast igniter fusion or ion acceleration experiments, in which a laser pulse may potentially beat with a reflected weaker pulse, with intensities comparable to those used in the experiment(Y. Sentoku, et al., Appl. Phys. B 74, 207-215 (2002).).

Beat frequency quartz-enhanced photoacoustic spectroscopy for fast and calibration-free continuous trace-gas monitoring

PubMed Central

Wu, Hongpeng; Dong, Lei; Zheng, Huadan; Yu, Yajun; Ma, Weiguang; Zhang, Lei; Yin, Wangbao; Xiao, Liantuan; Jia, Suotang; Tittel, Frank K.

2017-01-01

Quartz-enhanced photoacoustic spectroscopy (QEPAS) is a sensitive gas detection technique which requires frequent calibration and has a long response time. Here we report beat frequency (BF) QEPAS that can be used for ultra-sensitive calibration-free trace-gas detection and fast spectral scan applications. The resonance frequency and Q-factor of the quartz tuning fork (QTF) as well as the trace-gas concentration can be obtained simultaneously by detecting the beat frequency signal generated when the transient response signal of the QTF is demodulated at its non-resonance frequency. Hence, BF-QEPAS avoids a calibration process and permits continuous monitoring of a targeted trace gas. Three semiconductor lasers were selected as the excitation source to verify the performance of the BF-QEPAS technique. The BF-QEPAS method is capable of measuring lower trace-gas concentration levels with shorter averaging times as compared to conventional PAS and QEPAS techniques and determines the electrical QTF parameters precisely. PMID:28561065

EDITORIAL: Attosecond and x-ray free-electron laser physics Attosecond and x-ray free-electron laser physics

NASA Astrophysics Data System (ADS)

Moshammer, R.; Ullrich, J.

2009-07-01

Currently, we are witnessing a revolution in photon science, driven by the vision to time-resolve ultra-fast electronic motion in atoms, molecules, and solids as well as by the quest for the characterization of time-dependent structural changes in large molecules and solids. Quantum jumps in the development of light sources are the key technologies for this emerging field of research. Thus, high harmonic radiation bursts now penetrate the attosecond (10-18 s) regime and free-electron lasers (FELs) deliver ultra-brilliant femtosecond, coherent VUV and x-ray pulses. This special issue presents a snapshot of this ongoing revolution and brings together, for the first time, pioneering results in both of these fields that are expected to evolve synergetically in the future. The volume is based on the spirit of the International Conference on Multi-Photon Processes, ICOMP08, which was held at the Max Planck Institute for Nuclear Physics in Heidelberg in summer 2008. The first contributions include articles that envision tracing electronic motion on an attosecond time scale and its relation to nuclear motion. After more technical papers on the generation of attosecond pulses via high harmonic generation (HHG), molecular and two-electron atomic dynamics in strong optical fields at a typical wavelength of 800 nm are presented pointing to sub-cycle, attosecond features. Making the transition to shorter wavelengths, nonlinear dynamics in atoms and molecules is explored via experimental and theoretical methods, where the present measurements are nearly exclusively performed at FEL sources. A substantial number of articles focus on the investigation of the most simple many- (few-) photon two-electron processes in double ionization of helium at optical and VUV wavelengths, with the goal of characterizing this fundamental reaction, not yet consistently solved theoretically, in spite of huge efforts. Finally, the behaviour of more complex nanoscaled systems, i.e. clusters, is investigated bridging the gap from atoms and molecules to solids introduced to intense FEL radiation. Beyond the basic interest in many-particle dynamics in finite systems, these studies are of enormous practical relevance for upcoming research at X-ray FELs. Here, realizing the dream of coherent imaging of the structure of single bio-molecules in the gas phase with atomic resolution is critically dependent on ultra-fast dynamics initiated by the pulse. In other words, it is reduced to the simple question of whether the molecule is first imaged and then destroyed or vice versa! During the preparation of this Editorial, the first lasing at the Stanford Linac Coherent Light Source (LCLS) was achieved at a photon energy of about 8 keV - a further milestone in this exciting revolution in the science related to light.

Comparison of retina damage thresholds simulating the femtosecond-laser in situ keratomileusis (fs-LASIK) process with two laser systems in the CW- and fs-regime

NASA Astrophysics Data System (ADS)

Sander, M.; Minet, O.; Zabarylo, U.; Müller, M.; Tetz, M. R.

2012-04-01

The femtosecond-laser in situ keratomileusis procedure affords the opportunity to correct ametropia by cutting transparent corneal tissue with ultra-short laser pulses. Thereby the tissue cut is generated by a laser-induced optical breakdown in the cornea with ultra-short laser pulses in the near-infrared range. Compared to standard procedures such as photorefractive keratectomy and laser in-situ keratomileusis with the excimer laser, where the risk potential for the eye is low due to the complete absorption of ultraviolet irradiation from corneal tissue, only a certain amount of the pulse energy is deposited in the cornea during the fs-LASIK process. The remaining energy propagates through the eye and interacts with the retina and the strong absorbing tissue layers behind. The objective of the presented study was to determine and compare the retina damage thresholds during the fs-LASIK process simulated with two various laser systems in the CW- and fs-regime.

The LICPA-driven collider—a novel efficient tool for the production of ultra-high pressures in condensed media

NASA Astrophysics Data System (ADS)

Badziak, J.; Krousky, E.; Kucharik, M.; Liska, R.

2016-03-01

Generation of strong shock waves for the production of Mbar or Gbar pressures is a topic of high relevance for contemporary research in various domains, including inertial confinement fusion, laboratory astrophysics, planetology and material science. The pressures in the multi-Mbar range can be produced by the shocks generated using chemical explosions, light-gas guns, Z-pinch machines or lasers. Higher pressures, in the sub-Gbar or Gbar range are attainable only with nuclear explosions or laser-based methods. Unfortunately, due to the low efficiency of energy conversion from a laser to the shock (below a few percent), multi-kJ, multi-beam lasers are needed to produce such pressures with these methods. Here, we propose and investigate a novel scheme for generating high-pressure shocks which is much more efficient than the laser-based schemes known so far. In the proposed scheme, the shock is generated in a dense target by the impact of a fast projectile driven by the laser-induced cavity pressure acceleration (LICPA) mechanism. Using two-dimensional hydrodynamic simulations and the measurements performed at the kilojoule PALS laser facility it is shown that in the LICPA-driven collider the laser-to-shock energy conversion efficiency can reach a very high value ~ 15-20 % and, as a result, the shock pressure ~ 0.5-1 Gbar can be produced using lasers of energy <= 0.5 kJ. On the other hand, the pressures in the multi-Mbar range could be produced in this collider with low-energy (~ 10 J) lasers available on the market. It would open up the possibility of conducting research in high energy-density science also in small, university-class laboratories.

Laser processes and system technology for the production of high-efficient crystalline solar cells

NASA Astrophysics Data System (ADS)

Mayerhofer, R.; Hendel, R.; Zhu, Wenjie; Geiger, S.

2012-10-01

The laser as an industrial tool is an essential part of today's solar cell production. Due to the on-going efforts in the solar industry, to increase the cell efficiency, more and more laser-based processes, which have been discussed and tested at lab-scale for many years, are now being implemented in mass production lines. In order to cope with throughput requirements, standard laser concepts have to be improved continuously with respect to available average power levels, repetition rates or beam profile. Some of the laser concepts, that showed high potential in the past couple of years, will be substituted by other, more economic laser types. Furthermore, requirements for processing with less-heat affected zones fuel the development of industry-ready ultra short pulsed lasers with pulse widths even below the picosecond range. In 2011, the German Ministry of Education and Research (BMBF) had launched the program "PV-Innovation Alliance", with the aim to support the rapid transfer of high-efficiency processes out of development departments and research institutes into solar cell production lines. Here, lasers play an important role as production tools, allowing the fast implementation of high-performance solar cell concepts. We will report on the results achieved within the joint project FUTUREFAB, where efficiency optimization, throughput enhancement and cost reduction are the main goals. Here, the presentation will focus on laser processes like selective emitter doping and ablation of dielectric layers. An indispensable part of the efforts towards cost reduction in solar cell production is the improvement of wafer handling and throughput capabilities of the laser processing system. Therefore, the presentation will also elaborate on new developments in the design of complete production machines.

Ultra-broadband tunable (0.67-2.57 µm) optical vortex parametric oscillator

NASA Astrophysics Data System (ADS)

Araki, Shungo; Suzuki, Kensuke; Nishida, Shigeki; Mamuti, Roukuya; Miyamoto, Katsuhiko; Omatsu, Takashige

2017-10-01

We demonstrate an ultra-broadband (>2-octave band) tunable optical vortex laser comprising an optical-vortex-pumped optical parametric oscillator by employing a nanosecond pulse (˜10 ns) green laser and cascaded non-critical phase-matching LiB3O5 crystals (45 mm long each). With this system, an optical vortex output was produced over an extremely wide wavelength range of 0.67-2.57 µm.

Ultra-fast boriding of metal surfaces for improved properties

DOEpatents

Timur, Servet; Kartal, Guldem; Eryilmaz, Osman L.; Erdemir, Ali

2015-02-10

A method of ultra-fast boriding of a metal surface. The method includes the step of providing a metal component, providing a molten electrolyte having boron components therein, providing an electrochemical boriding system including an induction furnace, operating the induction furnace to establish a high temperature for the molten electrolyte, and boriding the metal surface to achieve a boride layer on the metal surface.

Developing Stabilized Lasers, Measuring their Frequencies, demoting the Metre, inventing the Comb, and further consequences

NASA Astrophysics Data System (ADS)

Hall, John L.

2010-02-01

Michelson's 1907 proposal to define the SI Metre in terms of an optical wavelength was realized only in 1960, based on a ^86Krypton discharge lamp. The same year saw the cw HeNe laser arrive and a future redefinition based on laser technology assured. Separation in the late 60's of the laser's gain and spectral-reference-gas functions led to unprecedented levels of laser frequency stability and reproducibility. In addition to HeNe:CH4 system at 3392 nm and HeNe:I2 at 633 nm, systems at 514 nm and 10600 nm were studied. Absolute frequency measurement became the holy grail and some NBS team experiences will be shared. We measured both frequency and wavelength in 1972, and so obtained a speed of light value, improved 100-fold in accuracy. During the next decade, the NBS value of c was confirmed by other national labs, and frequency metrology was extended to the 473 THz (633 nm) Iodine-based wavelength standard. This frequency to ˜10 digit accuracy was obtained in 1983, thus setting the stage for redefining the SI Metre. By consensus choice the value 299 792 458 m/s was adopted for the speed of light, effectively reducing the Metre to a derived SI quantity. Knowledge of the frequency of the particular laser being utilized was controlled by International intercomparisons, but the need for a fast and accurate means to make these laser frequency measurements was obvious. Creative proposals by H"ansch and by Chebotayev were to use ultra-fast repetitive pulses to create an ``Optical Comb,'' but it was years before any technical basis existed to implement their Fourier dreams. Finally, in 1999 the last needed capability was demonstrated -- continuum production at 100 MHz rates and non-destructive power levels. By May 2000 phase-locked combs were operational in both Garching and Boulder, substantially accelerated by their collaborative interactions. Within 18 months all the known proposed ``optical frequency standards'' had been accurately measured via Comb techniques. )

ZAP! The X-Ray Laser is Born

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ratner, Daniel

2009-11-17

SLAC has converted its giant particle accelerator into the world's first X-ray laser. By a billion fold the world's brightest X-ray source, the laser packs a trillion photons into pulses as short as a millionth of a billionth of a second. The ultra-bright, ultra-short X-ray pulses will drive a wide range of new experiments, as scientists strip electrons from atoms, photograph single molecules and make movies of chemical reactions. How has SLAC accomplished such feats of X-ray wizardry? Attend this public lecture to learn about the basics of an X-ray laser, the technologies at SLAC that make it possible, andmore » the exciting new experiments now underway.« less

Ultra-broad gain quantum cascade lasers tunable from 6.5 to 10.4 μm.

PubMed

Xie, Feng; Caneau, C; Leblanc, H; Ho, M-T; Zah, C

2015-09-01

We present a quantum cascade laser structure with an ultra-broad gain profile that covers the wavelength range from 6.5 to 10.4 μm. In a grating-tuned external cavity, we demonstrated continuous tuning from 1027  cm(-1) to 1492  cm(-1) with this broad gain laser chip. We also fabricated distributed feedback quantum cascade laser arrays with this active region design and varied grating periods. We demonstrated single wavelength lasing from 962 (10.4) to 1542  cm(-1) (6.5 μm). The frequency coverage (580  cm(-1)) is about 46% of center frequency.

D-Cluster Converter Foil for Laser-Accelerated Deuteron Beams: Towards Deuteron-Beam-Driven Fast Ignition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Miley, George H.

Fast Ignition (FI) uses Petawatt laser generated particle beam pulse to ignite a small volume called a pre-compressed Inertial Confinement Fusion (ICF) target, and is the favored method to achieve the high energy gain per target burn needed for an attractive ICF power plant. Ion beams such as protons, deuterons or heavier carbon ions are especially appealing for FI as they have relative straight trajectory, and easier to focus on the fuel capsule. But current experiments have encountered problems with the 'converter-foil' which is irradiated by the Petawatt laser to produce the ion beams. The problems include depletion of themore » available ions in the convertor foils, and poor energy efficiency (ion beam energy/ input laser energy). We proposed to develop a volumetrically-loaded ultra-high-density deuteron deuterium cluster material as the basis for converter-foil for deuteron beam generation. The deuterons will fuse with the ICF DT while they slow down, providing an extra 'bonus' energy gain in addition to heating the hot spot. Also, due to the volumetric loading, the foil will provide sufficient energetic deuteron beam flux for 'hot spot' ignition, while avoiding the depletion problem encountered by current proton-driven FI foils. After extensive comparative studies, in Phase I, high purity PdO/Pd/PdO foils were selected for the high packing fraction D-Cluster converter foils. An optimized loading process has been developed to increase the cluster packing fraction in this type of foil. As a result, the packing fraction has been increased from 0.1% to 10% - meeting the original Phase I goal and representing a significant progress towards the beam intensities needed for both FI and pulsed neutron applications. Fast Ignition provides a promising approach to achieve high energy gain target performance needed for commercial Inertial Confinement Fusion (ICF). This is now a realistic goal for near term in view of the anticipated ICF target burn at the National Ignition Facility (NIF) in CA within a year. This will usher in the technology development Phase of ICF after years of research aimed at achieving breakeven experiment. Methods to achieve the high energy gain needed for a competitive power plant will then be a key developmental issue, and our D-cluster target for Fast Ignition (FI) is expected to meet that need.« less

On specular reflectivity measurements in high and low-contrast relativistic laser-plasma interactions

NASA Astrophysics Data System (ADS)

Kemp, G. E.; Link, A.; Ping, Y.; McLean, H. S.; Patel, P. K.; Freeman, R. R.; Schumacher, D. W.; Tiedje, H. F.; Tsui, Y. Y.; Ramis, R.; Fedosejevs, R.

2015-01-01

Using both experiment and 2D3V particle-in-cell (PIC) simulations, we describe the use of specular reflectivity measurements to study relativistic (Iλ2 > 1018 W/cm2ṡμm2) laser-plasma interactions for both high and low-contrast 527 nm laser pulses on initially solid density aluminum targets. In the context of hot-electron generation, studies typically rely on diagnostics which, more-often-than-not, represent indirect processes driven by fast electrons transiting through solid density materials. Specular reflectivity measurements, however, can provide a direct measure of the interaction that is highly sensitive to how the EM fields and plasma profiles, critical input parameters for modeling of hot-electron generation, evolve near the interaction region. While the fields of interest occur near the relativistic critical electron density, experimental reflectivity measurements are obtained centimeters away from the interaction region, well after diffraction has fully manifested itself. Using a combination of PIC simulations with experimentally inspired conditions and an analytic, non-paraxial, pulse propagation algorithm, we calculate reflected pulse properties, both near and far from the interaction region, and compare with specular reflectivity measurements. The experiment results and PIC simulations demonstrate that specular reflectivity measurements are an extremely sensitive qualitative, and partially quantitative, indicator of initial laser/target conditions, ionization effects, and other details of intense laser-matter interactions. The techniques described can provide strong constraints on many systems of importance in ultra-intense laser interactions with matter.

Noise Suppression on the Tunable Laser for Precise Cavity Length Displacement Measurement.

PubMed

Šmíd, Radek; Čížek, Martin; Mikel, Břetislav; Hrabina, Jan; Lazar, Josef; Číp, Ondřej

2016-09-06

The absolute distance between the mirrors of a Fabry-Perot cavity with a spacer from an ultra low expansion material was measured by an ultra wide tunable laser diode. The DFB laser diode working at 1542 nm with 1.5 MHz linewidth and 2 nm tuning range has been suppressed with an unbalanced heterodyne fiber interferometer. The frequency noise of laser has been suppressed by 40 dB across the Fourier frequency range 30-300 Hz and by 20 dB up to 4 kHz and the linewidth of the laser below 300 kHz. The relative resolution of the measurement was 10 - 9 that corresponds to 0.3 nm (sub-nm) for 0.178 m long cavity with ability of displacement measurement of 0.5 mm.

CO2 laser cutting of ultra thin (75 μm) glass based rigid optical solar reflector (OSR) for spacecraft application

NASA Astrophysics Data System (ADS)

Mishra, Shubham; Sridhara, N.; Mitra, Avijit; Yougandar, B.; Dash, Sarat Kumar; Agarwal, Sanjay; Dey, Arjun

2017-03-01

Present study reports for the first time laser cutting of multilayered coatings on both side of ultra thin (i.e., 75 μm) glass substrate based rigid optical solar reflector (OSR) for spacecraft thermal control application. The optimization of cutting parameters was carried out as a function of laser power, cutting speed and number of cutting passes and their effect on cutting edge quality. Systematic and in-detail microstructural characterizations were carried out by optical and scanning electron microscopy techniques to study the laser affected zone and cutting edge quality. Sheet resistance and water contact angle experiments were also conducted locally both prior and after laser cut to investigate the changes of electrical and surface properties, if any.

All-fibre photonic signal generator for attosecond timing and ultralow-noise microwave

PubMed Central

Jung, Kwangyun; Kim, Jungwon

2015-01-01

High-impact frequency comb applications that are critically dependent on precise pulse timing (i.e., repetition rate) have recently emerged and include the synchronization of X-ray free-electron lasers, photonic analogue-to-digital conversion and photonic radar systems. These applications have used attosecond-level timing jitter of free-running mode-locked lasers on a fast time scale within ~100 μs. Maintaining attosecond-level absolute jitter over a significantly longer time scale can dramatically improve many high-precision comb applications. To date, ultrahigh quality-factor (Q) optical resonators have been used to achieve the highest-level repetition-rate stabilization of mode-locked lasers. However, ultrahigh-Q optical-resonator-based methods are often fragile, alignment sensitive and complex, which limits their widespread use. Here we demonstrate a fibre-delay line-based repetition-rate stabilization method that enables the all-fibre photonic generation of optical pulse trains with 980-as (20-fs) absolute r.m.s. timing jitter accumulated over 0.01 s (1 s). This simple approach is based on standard off-the-shelf fibre components and can therefore be readily used in various comb applications that require ultra-stable microwave frequency and attosecond optical timing. PMID:26531777

Demonstration of ultra-wideband (UWB) over fiber based on optical pulse-injected semiconductor laser.

PubMed

Juan, Yu-Shan; Lin, Fan-Yi

2010-04-26

We experimentally demonstrated the ultra-wideband (UWB) signal generation utilizing nonlinear dynamics of an optical pulse-injected semiconductor laser. The UWB signals generated are fully in compliant with the FCC mask for indoor radiation, while a large fractional bandwidth of 93% is achieved. To show the feasibility of UWB-over-fiber, transmission over a 2 km single-mode fiber and a wireless channel utilizing a pair of broadband antennas are examined. Moreover, proof of concept experiment on data encoding and decoding with 250 Mb/s in the optical pulse-injected laser is successfully demonstrated.

Carrier-envelope phase control using linear electro-optic effect.

PubMed

Gobert, O; Paul, P M; Hergott, J F; Tcherbakoff, O; Lepetit, F; 'Oliveira, P D; Viala, F; Comte, M

2011-03-14

We present a new method to control the Carrier-Envelope Phase of ultra-short laser pulses by using the linear Electro-Optic Effect. Experimental demonstration is carried out on a Chirped Pulse Amplification based laser. Phase shifts greater than π radian can be obtained by applying moderate voltage on a LiNbO3 crystal with practically no changes to all other parameters of the pulse with the exception of its group delay. Time response of the Electro-Optic effect makes possible shaping at a high repetition rate or stabilization of the CEP of ultra short CPA laser systems.

Interaction dynamics of temporal and spatial separated cavitation bubbles in water

NASA Astrophysics Data System (ADS)

Tinne, N.; Ripken, T.; Lubatschowski, H.

2010-02-01

The LASIK procedure is a well established laser based treatment in ophthalmology. Nowadays it includes a cutting of the corneal tissue bases on ultra short pulses which are focused below the tissue surface to create an optical breakdown and hence a dissection of the tissue. The energy of the laser pulse is absorbed by non-linear processes that result in an expansion of a cavitation bubble and rupturing of the tissue. Due to a reduction of the duration of treatment the current development of ultra short laser systems points to higher repetition rates. This in turn results in a probable interaction between different cavitation bubbles of adjacent optical breakdowns. While the interaction of one single laser pulse with biological tissue is analyzed reasonably well experimentally and theoretically, the interaction of several spatial and temporal following pulses is scarcely determined yet. We present a high-speed photography analysis of cavitation bubble interaction for two spatial separated laser-induced optical breakdowns varying the laser pulse energy as well as the spatial distance. Depending on a change of these parameters different kinds of interactions such as a flattening and deformation of bubble shape, asymmetric water streams and jet formation were observed. The results of this research can be used to comprehend and optimize the cutting effect of ultra short pulse laser systems with high repetition rates (> 1 MHz).

FastChem: An ultra-fast equilibrium chemistry

NASA Astrophysics Data System (ADS)

Kitzmann, Daniel; Stock, Joachim

2018-04-01

FastChem is an equilibrium chemistry code that calculates the chemical composition of the gas phase for given temperatures and pressures. Written in C++, it is based on a semi-analytic approach, and is optimized for extremely fast and accurate calculations.

Laser system using ultra-short laser pulses

DOEpatents

Dantus, Marcos [Okemos, MI; Lozovoy, Vadim V [Okemos, MI; Comstock, Matthew [Milford, MI

2009-10-27

A laser system using ultrashort laser pulses is provided. In another aspect of the present invention, the system includes a laser, pulse shaper and detection device. A further aspect of the present invention employs a femtosecond laser and binary pulse shaping (BPS). Still another aspect of the present invention uses a laser beam pulse, a pulse shaper and a SHG crystal.

Flexible, transparent and ultra-broadband photodetector based on large-area WSe2 film for wearable devices

NASA Astrophysics Data System (ADS)

Zheng, Zhaoqiang; Zhang, Tanmei; Yao, Jiandomg; Zhang, Yi; Xu, Jiarui; Yang, Guowei

2016-06-01

Although two-dimensional (2D) materials have attracted considerable research interest for use in the development of innovative wearable optoelectronic systems, the integrated optoelectronic performance of 2D materials photodetectors, including flexibility, transparency, broadband response and stability in air, remains quite low to date. Here, we demonstrate a flexible, transparent, high-stability and ultra-broadband photodetector made using large-area and highly-crystalline WSe2 films that were prepared by pulsed-laser deposition (PLD). Benefiting from the 2D physics of WSe2 films, this device exhibits excellent average transparency of 72% in the visible range and superior photoresponse characteristics, including an ultra-broadband detection spectral range from 370 to 1064 nm, reversible photoresponsivity approaching 0.92 A W-1, external quantum efficiency of up to 180% and a relatively fast response time of 0.9 s. The fabricated photodetector also demonstrates outstanding mechanical flexibility and durability in air. Also, because of the wide compatibility of the PLD-grown WSe2 film, we can fabricate various photodetectors on multiple flexible or rigid substrates, and all these devices will exhibit distinctive switching behavior and superior responsivity. These indicate a possible new strategy for the design and integration of flexible, transparent and broadband photodetectors based on large-area WSe2 films, with great potential for practical applications in the wearable optoelectronic devices.

Laser and Optical Subsystem for NASA's Cold Atom Laboratory

NASA Astrophysics Data System (ADS)

Kohel, James; Kellogg, James; Elliott, Ethan; Krutzik, Markus; Aveline, David; Thompson, Robert

2016-05-01

We describe the design and validation of the laser and optics subsystem for NASA's Cold Atom Laboratory (CAL), a multi-user facility being developed at NASA's Jet Propulsion Laboratory for studies of ultra-cold quantum gases in the microgravity environment of the International Space Station. Ultra-cold atoms will be generated in CAL by employing a combination of laser cooling techniques and evaporative cooling in a microchip-based magnetic trap. Laser cooling and absorption imaging detection of bosonic mixtures of 87 Rb and 39 K or 41 K will be accomplished using a high-power (up to 500 mW ex-fiber), frequency-agile dual wavelength (767 nm and 780 nm) laser and optical subsystem. The CAL laser and optical subsystem also includes the capability to generate high-power multi-frequency optical pulses at 784.87 nm to realize a dual-species Bragg atom interferometer. Currently at Humboldt-Universität zu Berlin.

Reduction of angular divergence of laser-driven ion beams during their acceleration and transport

NASA Astrophysics Data System (ADS)

Zakova, M.; Pšikal, Jan; Margarone, Daniele; Maggiore, Mario; Korn, G.

2015-05-01

Laser plasma physics is a field of big interest because of its implications in basic science, fast ignition, medicine (i.e. hadrontherapy), astrophysics, material science, particle acceleration etc. 100-MeV class protons accelerated from the interaction of a short laser pulse with a thin target have been demonstrated. With continuing development of laser technology, greater and greater energies are expected, therefore projects focusing on various applications are being formed, e.g. ELIMAIA (ELI Multidisciplinary Applications of laser-Ion Acceleration). One of the main characteristic and crucial disadvantage of ion beams accelerated by ultra-short intense laser pulses is their large divergence, not suitable for the most of applications. In this paper two ways how to decrease beam divergence are proposed. Firstly, impact of different design of targets on beam divergence is studied by using 2D Particlein-cell simulations (PIC). Namely, various types of targets include at foils, curved foil and foils with diverse microstructures. Obtained results show that well-designed microstructures, i.e. a hole in the center of the target, can produce proton beam with the lowest divergence. Moreover, the particle beam accelerated from a curved foil has lower divergence compared to the beam from a flat foil. Secondly, another proposed method for the divergence reduction is using of a magnetic solenoid. The trajectories of the laser accelerated particles passing through the solenoid are modeled in a simple Matlab program. Results from PIC simulations are used as input in the program. The divergence is controlled by optimizing the magnetic field inside the solenoid and installing an aperture in front of the device.

All-optical tunable dual Fano resonance in nonlinear metamaterials in optical communication range

NASA Astrophysics Data System (ADS)

Zhou, Yi; Hu, Xiaoyong; Li, Chong; Yang, Hong; Gong, Qihuang

2018-01-01

Low-power, ultra-fast all-optical tunable dual Fano resonance was realized in a metamaterial coated with a non-linear nanocomposite layer composed of gold nanoparticle-doped polycrystalline barium strontium titanate and multilayer tungsten disulphide microsheets. A high non-linear refractive index of -2.148 × 10-11 m2/W was achieved in the nanocomposite material that originated in the non-linearity enhancement associated with the quantum confinement effect, the local-field enhancement effect, and reinforced interactions between photons and the multilayer tungsten disulphide microsheets. An ultra-low threshold pump intensity of 600 kW/cm2 was obtained. An ultra-fast response time of 25.4 ps was maintained because of the fast relaxation dynamics of the bound electrons in the nanoscale polycrystalline barium strontium titanate grains. The large third-order non-linear responses of the metamaterial were confirmed with a high third harmonic generation conversion efficiency of 5.4 × 10-5. This work may help to pave the way towards realization of ultra-high-speed information processing chips and multifunctional integrated photonic devices based on metamaterials.

Laser Drilling Development Trial Final Report CRADA No. TSB-1538-98

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hermann, M. R.; Hebbar, R. R.

This project performed various laser drilling tests to demonstrate femtosecond laser drilling of fuel injector nozzles with minimal recast, minimal heat affected zone and no collateral damage. LLNL had extensive experience in ultra short-pulse laser systems and developed specialized hardware for these applications.

Ultra-bright γ-ray emission and dense positron production from two laser-driven colliding foils.

PubMed

Li, Han-Zhen; Yu, Tong-Pu; Liu, Jin-Jin; Yin, Yan; Zhu, Xing-Long; Capdessus, Remi; Pegoraro, Francesco; Sheng, Zheng-Ming; McKenna, Paul; Shao, Fu-Qiu

2017-12-11

Matter can be transferred into energy and the opposite transformation is also possible by use of high-power lasers. A laser pulse in plasma can convert its energy into γ-rays and then e - e + pairs via the multi-photon Breit-Wheeler process. Production of dense positrons at GeV energies is very challenging since extremely high laser intensity ~10 24  Wcm -2 is required. Here we propose an all-optical scheme for ultra-bright γ-ray emission and dense positron production with lasers at intensity of 10 22-23  Wcm -2 . By irradiating two colliding elliptically-polarized lasers onto two diamondlike carbon foils, electrons in the focal region of one foil are rapidly accelerated by the laser radiation pressure and interact with the other intense laser pulse which penetrates through the second foil due to relativistically induced foil transparency. This symmetric configuration enables efficient Compton back-scattering and results in ultra-bright γ-photon emission with brightness of ~10 25 photons/s/mm 2 /mrad 2 /0.1%BW at 15 MeV and intensity of 5 × 10 23  Wcm -2 . Our first three-dimensional simulation with quantum-electrodynamics incorporated shows that a GeV positron beam with density of 2.5 × 10 22 cm -3 and flux of 1.6 × 10 10 /shot is achieved. Collective effects of the pair plasma may be also triggered, offering a window on investigating laboratory astrophysics at PW laser facilities.

Local Resistance Profiling of Ultra Shallow Junction Annealed with Combination of Spike Lamp and Laser Annealing Processes using Scanning Spreading Resistance Microscope

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abo, Satoshi; Nishikawa, Kazuhisa; Ushigome, Naoya

2011-01-07

Local resistance profiles of ultra shallow boron and arsenic implanted into silicon with energies of 2.0 and 4.0 keV and doses of 2.0x10{sup 15} and 1.0x10{sup 15} ions/cm{sup 2} activated by a combination of conventional spike lamp and laser annealing processes were measured by scanning spreading resistance microscope (SSRM) with a depth resolution of less than 10 nm. The lowest local resistance at the low resistance region in 2.0 keV boron implanted silicon with 1050 deg. C spike lamp annealing followed by 0.35 kW/mm{sup 2} laser annealing was half of that without laser annealing. The lowest local resistance at themore » low resistance region in the arsenic implanted silicon activated by 1050 deg. C spike lamp annealing followed by 0.39 kW/mm{sup 2} laser annealing was 74% lower than that followed by 0.36 kW/mm{sup 2} laser annealing. The lowest local resistances at the low resistance regions in the arsenic implanted silicon with 0.36 and 0.39 kW/mm{sup 2} laser annealing followed by 1050 deg. C spike lamp annealing were 41 and 33% lower than those with spike lamp annealing followed by laser annealing. Laser annealing followed by spike lamp annealing could suppress the diffusion of the impurities and was suitable for making the ultra shallow and low resistance regions.« less

Ultra-fast speech comprehension in blind subjects engages primary visual cortex, fusiform gyrus, and pulvinar – a functional magnetic resonance imaging (fMRI) study

PubMed Central

2013-01-01

Background Individuals suffering from vision loss of a peripheral origin may learn to understand spoken language at a rate of up to about 22 syllables (syl) per second - exceeding by far the maximum performance level of normal-sighted listeners (ca. 8 syl/s). To further elucidate the brain mechanisms underlying this extraordinary skill, functional magnetic resonance imaging (fMRI) was performed in blind subjects of varying ultra-fast speech comprehension capabilities and sighted individuals while listening to sentence utterances of a moderately fast (8 syl/s) or ultra-fast (16 syl/s) syllabic rate. Results Besides left inferior frontal gyrus (IFG), bilateral posterior superior temporal sulcus (pSTS) and left supplementary motor area (SMA), blind people highly proficient in ultra-fast speech perception showed significant hemodynamic activation of right-hemispheric primary visual cortex (V1), contralateral fusiform gyrus (FG), and bilateral pulvinar (Pv). Conclusions Presumably, FG supports the left-hemispheric perisylvian “language network”, i.e., IFG and superior temporal lobe, during the (segmental) sequencing of verbal utterances whereas the collaboration of bilateral pulvinar, right auditory cortex, and ipsilateral V1 implements a signal-driven timing mechanism related to syllabic (suprasegmental) modulation of the speech signal. These data structures, conveyed via left SMA to the perisylvian “language zones”, might facilitate – under time-critical conditions – the consolidation of linguistic information at the level of verbal working memory. PMID:23879896

Compact high-pulse-energy passively Q-switched Nd:YLF laser with an ultra-low-magnification unstable resonator: application for efficient optical parametric oscillator.

PubMed

Cho, C Y; Huang, Y P; Huang, Y J; Chen, Y C; Su, K W; Chen, Y F

2013-01-28

We exploit an ultra-low-magnification unstable resonator to develop a high-pulse-energy side-pumped passively Q-switched Nd:YLF/Cr⁴⁺:YAG laser with improving beam quality. A wedged laser crystal is employed in the cavity to control the emissions at 1047 nm and 1053 nm independently through the cavity alignment. The pulse energies at 1047 nm and 1053 nm are found to be 19 mJ and 23 mJ, respectively. The peak powers for both wavelengths are higher than 2 MW. Furthermore, the developed Nd:YLF lasers are employed to pump a monolithic optical parametric oscillator for confirming the applicability in nonlinear wavelength conversions.

Pump-probe micro-spectroscopy by means of an ultra-fast acousto-optics delay line.

PubMed

Audier, Xavier; Balla, Naveen; Rigneault, Hervé

2017-01-15

We demonstrate femtosecond pump-probe transient absorption spectroscopy using a programmable dispersive filter as an ultra-fast delay line. Combined with fast synchronous detection, this delay line allows for recording of 6 ps decay traces at 34 kHz. With such acquisition speed, we perform single point pump-probe spectroscopy on bulk samples in 80 μs and hyperspectral pump-probe imaging over a field of view of 100 μm in less than a second. The usability of the method is illustrated in a showcase experiment to image and discriminate between two pigments in a mixture.

Second order nonlinear QED processes in ultra-strong laser fields

NASA Astrophysics Data System (ADS)

Mackenroth, Felix

2017-10-01

In the interaction of ultra-intense laser fields with matter the ever increasing peak laser intensities render nonlinear QED effects ever more important. For long, ultra-intense laser pulses scattering large systems, like a macroscopic plasma, the interaction time can be longer than the scattering time, leading to multiple scatterings. These are usually approximated as incoherent cascades of single-vertex processes. Under certain conditions, however, this common cascade approximation may be insufficient, as it disregards several effects such as coherent processes, quantum interferences or pulse shape effects. Quantifying deviations of the full amplitude of multiple scatterings from the commonly employed cascade approximations is a formidable, yet unaccomplished task. In this talk we are going to discuss how to compute second order nonlinear QED amplitudes and relate them to the conventional cascade approximation. We present examples for typical second order processes and benchmark the full result against common approximations. We demonstrate that the approximation of multiple nonlinear QED scatterings as a cascade of single interactions has certain limitations and discuss these limits in light of upcoming experimental tests.

Picosecond and femtosecond lasers for industrial material processing

NASA Astrophysics Data System (ADS)

Mayerhofer, R.; Serbin, J.; Deeg, F. W.

2016-03-01

Cold laser materials processing using ultra short pulsed lasers has become one of the most promising new technologies for high-precision cutting, ablation, drilling and marking of almost all types of material, without causing unwanted thermal damage to the part. These characteristics have opened up new application areas and materials for laser processing, allowing previously impossible features to be created and also reducing the amount of post-processing required to an absolute minimum, saving time and cost. However, short pulse widths are only one part of thee story for industrial manufacturing processes which focus on total costs and maximum productivity and production yield. Like every other production tool, ultra-short pulse lasers have too provide high quality results with maximum reliability. Robustness and global on-site support are vital factors, as well ass easy system integration.

Noise Suppression on the Tunable Laser for Precise Cavity Length Displacement Measurement

PubMed Central

Šmíd, Radek; Čížek, Martin; Mikel, Břetislav; Hrabina, Jan; Lazar, Josef; Číp, Ondřej

2016-01-01

The absolute distance between the mirrors of a Fabry-Perot cavity with a spacer from an ultra low expansion material was measured by an ultra wide tunable laser diode. The DFB laser diode working at 1542 nm with 1.5 MHz linewidth and 2 nm tuning range has been suppressed with an unbalanced heterodyne fiber interferometer. The frequency noise of laser has been suppressed by 40 dB across the Fourier frequency range 30–300 Hz and by 20 dB up to 4 kHz and the linewidth of the laser below 300 kHz. The relative resolution of the measurement was 10−9 that corresponds to 0.3 nm (sub-nm) for 0.178 m long cavity with ability of displacement measurement of 0.5 mm. PMID:27608024

Medical applications of ultra-short pulse lasers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, B M; Marion, J E

1999-06-08

The medical applications for ultra short pulse lasers (USPLs) and their associated commercial potential are reviewed. Short pulse lasers offer the surgeon the possibility of precision cutting or disruption of tissue with virtually no thermal or mechanical damage to the surrounding areas. Therefore the USPL offers potential improvement to numerous existing medical procedures. Secondly, when USPLs are combined with advanced tissue diagnostics, there are possibilities for tissue-selective precision ablation that may allow for new surgeries that cannot at present be performed. Here we briefly review the advantages of short pulse lasers, examine the potential markets both from an investment communitymore » perspective, and from the view. of the technology provider. Finally nominal performance and cost requirements for the lasers, delivery systems and diagnostics and the present state of development will be addressed.« less

Tunable, rare earth-doped solid state lasers

DOEpatents

Emmett, John L.; Jacobs, Ralph R.; Krupke, William F.; Weber, Marvin J.

1980-01-01

Laser apparatus comprising combinations of an excimer pump laser and a rare earth-doped solid matrix, utilizing the 5d-4f radiative transition in a rare earth ion to produce visible and ultra-violet laser radiation with high overall efficiency in selected cases and relatively long radiative lifetimes.

Standoff detection of hidden objects using backscattered ultra-intense laser-produced x-rays

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kuwabara, H.; Mori, Y.; Kitagawa, Y.

2013-08-28

Ultra-intense laser-produced sub-ps X-ray pulses can detect backscattered signals from objects hidden in aluminium containers. Coincident measurements using primary X-rays enable differentiation among acrylic, copper, and lead blocks inside the container. Backscattering reveals the shapes of the objects, while their material composition can be identified from the modification methods of the energy spectra of backscattered X-ray beams. This achievement is an important step toward more effective homeland security.

Ultra Fast, High Rep Rate, High Voltage Spark Gap Pulser

DTIC Science & Technology

1995-07-01

current rise time. The spark gap was designed to have a coaxial geometry reducing its inductance. Provisions were made to pass flowing gas between the...ULTRA FAST, HIGH REP RATE, HIGH VOLTAGE SPARK GAP PULSER Robert A. Pastore Jr., Lawrence E. Kingsley, Kevin Fonda, Erik Lenzing Electrophysics and...Modeling Branch AMSRL-PS-EA Tel.: (908)-532-0271 FAX: (908)-542-3348 U.S. Army Research Laboratory Physical Sciences Directorate Ft. Monmouth

Ultra-fast framing camera tube

DOEpatents

Kalibjian, Ralph

1981-01-01

An electronic framing camera tube features focal plane image dissection and synchronized restoration of the dissected electron line images to form two-dimensional framed images. Ultra-fast framing is performed by first streaking a two-dimensional electron image across a narrow slit, thereby dissecting the two-dimensional electron image into sequential electron line images. The dissected electron line images are then restored into a framed image by a restorer deflector operated synchronously with the dissector deflector. The number of framed images on the tube's viewing screen is equal to the number of dissecting slits in the tube. The distinguishing features of this ultra-fast framing camera tube are the focal plane dissecting slits, and the synchronously-operated restorer deflector which restores the dissected electron line images into a two-dimensional framed image. The framing camera tube can produce image frames having high spatial resolution of optical events in the sub-100 picosecond range.

Ultra high-speed x-ray imaging of laser-driven shock compression using synchrotron light

NASA Astrophysics Data System (ADS)

Olbinado, Margie P.; Cantelli, Valentina; Mathon, Olivier; Pascarelli, Sakura; Grenzer, Joerg; Pelka, Alexander; Roedel, Melanie; Prencipe, Irene; Laso Garcia, Alejandro; Helbig, Uwe; Kraus, Dominik; Schramm, Ulrich; Cowan, Tom; Scheel, Mario; Pradel, Pierre; De Resseguier, Thibaut; Rack, Alexander

2018-02-01

A high-power, nanosecond pulsed laser impacting the surface of a material can generate an ablation plasma that drives a shock wave into it; while in situ x-ray imaging can provide a time-resolved probe of the shock-induced material behaviour on macroscopic length scales. Here, we report on an investigation into laser-driven shock compression of a polyurethane foam and a graphite rod by means of single-pulse synchrotron x-ray phase-contrast imaging with MHz frame rate. A 6 J, 10 ns pulsed laser was used to generate shock compression. Physical processes governing the laser-induced dynamic response such as elastic compression, compaction, pore collapse, fracture, and fragmentation have been imaged; and the advantage of exploiting the partial spatial coherence of a synchrotron source for studying low-density, carbon-based materials is emphasized. The successful combination of a high-energy laser and ultra high-speed x-ray imaging using synchrotron light demonstrates the potentiality of accessing complementary information from scientific studies of laser-driven shock compression.

Laser- and Particle-Beam Chemical Processes on Surfaces. Volume 129

DTIC Science & Technology

1989-12-26

explosive decomposition of organometallic compounds with single pulse laser irradiation . This new... ultrashort , meaning ultra high intensity , excimer laser pulses , two-photon absorption becomes important and limits the penetration depth of the laser ...requires a higher photon load before suffering damage to its chemical structure. With extremely high light intensities , ultrashort excimer laser pulses

Start-to-end simulation of single-particle imaging using ultra-short pulses at the European X-ray Free-Electron Laser

DOE PAGES

Fortmann-Grote, Carsten; Buzmakov, Alexey; Jurek, Zoltan; ...

2017-09-01

Single-particle imaging with X-ray free-electron lasers (XFELs) has the potential to provide structural information at atomic resolution for non-crystalline biomolecules. This potential exists because ultra-short intense pulses can produce interpretable diffraction data notwithstanding radiation damage. This paper explores the impact of pulse duration on the interpretability of diffraction data using comprehensive and realistic simulations of an imaging experiment at the European X-ray Free-Electron Laser. In conclusion, it is found that the optimal pulse duration for molecules with a few thousand atoms at 5 keV lies between 3 and 9 fs.

Start-to-end simulation of single-particle imaging using ultra-short pulses at the European X-ray Free-Electron Laser

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fortmann-Grote, Carsten; Buzmakov, Alexey; Jurek, Zoltan

Single-particle imaging with X-ray free-electron lasers (XFELs) has the potential to provide structural information at atomic resolution for non-crystalline biomolecules. This potential exists because ultra-short intense pulses can produce interpretable diffraction data notwithstanding radiation damage. This paper explores the impact of pulse duration on the interpretability of diffraction data using comprehensive and realistic simulations of an imaging experiment at the European X-ray Free-Electron Laser. In conclusion, it is found that the optimal pulse duration for molecules with a few thousand atoms at 5 keV lies between 3 and 9 fs.

High precision and high aspect ratio laser drilling: challenges and solutions

NASA Astrophysics Data System (ADS)

Uchtmann, Hermann; He, Chao; Gillner, Arnold

2016-03-01

Laser drilling is a very versatile tool to produce high accuracy bores in small and large geometries using different technologies. In large and deep hole drilling laser drilling can be found in drilling cooling holes into turbomachinery components such as turbine blades. In micro drilling, the technology is used for the generation of nozzles and filters. However, especially in macro drilling, the process often causes microstructure changes and induces defects such as recast layers and cracks. The defects are caused by the melt dominated drilling process by using pulse durations in the range of some 100 μm up to a few ms. A solution of this problem is the use of ultrashort pulsed laser radiation with pulse durations in the range of some 100 fs up to a few ps, however with the disadvantage of long drilling times. Thus, the aim of this work is to combine the productive process by using ms pulsed fiber laser radiation with subsequent ablation of existing recast layers at the hole wall by using ultrashort pulsed laser radiation. By using fast scanning techniques the recast layer can be avoided almost completely. With a similar technology also very small hole can be produced. Using a rotating dove prism a circular oscillation of the laser spots is performed and holes are drilled at intervals in 1 mm thick stainless steel (1.4301) by ultra-short laser pulses of 7 ps at 515 nm. The formation of hole and the behavior of energy deposition differ from other drilling strategies due to the helical revolution. The temporal evolution of the hole shape is analyzed by means of SEM techniques from which three drilling phases can be distinguished.

Laser beam welding of new ultra-high strength and supra-ductile steels

NASA Astrophysics Data System (ADS)

Dahmen, Martin

2015-03-01

Ultra-high strength and supra-ductile are entering fields of new applications. Those materials are excellent candidates for modern light-weight construction and functional integration. As ultra-high strength steels the stainless martensitic grade 1.4034 and the bainitic steel UNS 53835 are investigated. For the supra-ductile steels stand two high austenitic steels with 18 and 28 % manganese. As there are no processing windows an approach from the metallurgical base on is required. Adjusting the weld microstructure the Q+P and the QT steels require weld heat treatment. The HSD steel is weldable without. Due to their applications the ultra-high strength steels are welded in as-rolled and strengthened condition. Also the reaction of the weld on hot stamping is reflected for the martensitic grades. The supra-ductile steels are welded as solution annealed and work hardened by 50%. The results show the general suitability for laser beam welding.

The effect of pre-plasma formation under nonlocal transport conditions for ultra-relativistic laser-plasma interaction

NASA Astrophysics Data System (ADS)

Holec, M.; Nikl, J.; Vranic, M.; Weber, S.

2018-04-01

Interaction of high-power lasers with solid targets is in general strongly affected by the limited contrast available. The laser pre-pulse ionizes the target and produces a pre-plasma which can strongly modify the interaction of the main part of the laser pulse with the target. This is of particular importance for future experiments which will use laser intensities above 1021 W cm-2 and which are subject to the limited contrast. As a consequence the main part of the laser pulse will be modified while traversing the pre-plasma, interacting with it partially. A further complication arises from the fact that the interaction of a high-power pre-pulse with solid targets very often takes place under nonlocal transport conditions, i.e. the characteristic mean-free-path of the particles and photons is larger than the characteristic scale-lengths of density and temperature. The classical diffusion treatment of radiation and heat transport in the hydrodynamic model is then insufficient for the description of the pre-pulse physics. These phenomena also strongly modify the formation of the pre-plasma which in turn affects the propagation of the main laser pulse. In this paper nonlocal radiation-hydrodynamic simulations are carried out and serve as input for subsequent kinetic simulations of ultra-high intensity laser pulses interacting with the plasma in the ultra-relativistic regime. It is shown that the results of the kinetic simulations differ considerably whether a diffusive or nonlocal transport is used for the radiation-hydrodynamic simulations.

Research of the Aerophysics Institute for the Strategic Technology Office (DARPA)

DTIC Science & Technology

1975-06-30

19. (continued) 6. Unstable Optical Resonator Cavities 7. Laser Metal Screening Program 8. Ultraviolet & Blue-Green Lasers 9. Efficient Metal...Vapor Lasers 10. Atomic Transition Probabilities 11. Computer Modeling of Laser Dynamic 12. Startified Ocean Wakes L0. (continued) In the... laser area, the major task was the screening of atomic vapors, particularly metal vapors, for new, efficient lasers in the visible and ultra

Plasmonic phased array feeder enabling ultra-fast beam steering at millimeter waves.

PubMed

Bonjour, R; Burla, M; Abrecht, F C; Welschen, S; Hoessbacher, C; Heni, W; Gebrewold, S A; Baeuerle, B; Josten, A; Salamin, Y; Haffner, C; Johnston, P V; Elder, D L; Leuchtmann, P; Hillerkuss, D; Fedoryshyn, Y; Dalton, L R; Hafner, C; Leuthold, J

2016-10-31

In this paper, we demonstrate an integrated microwave phoneeded for beamtonics phased array antenna feeder at 60 GHz with a record-low footprint. Our design is based on ultra-compact plasmonic phase modulators (active area <2.5µm²) that not only provide small size but also ultra-fast tuning speed. In our design, the integrated circuit footprint is in fact only limited by the contact pads of the electrodes and by the optical feeding waveguides. Using the high speed of the plasmonic modulators, we demonstrate beam steering with less than 1 ns reconfiguration time, i.e. the beam direction is reconfigured in-between 1 GBd transmitted symbols.

3D laser printing by ultra-short laser pulses for micro-optical applications: towards telecom wavelengths

NASA Astrophysics Data System (ADS)

Ryu, Meguya; Mizeikis, Vygantas; Morikawa, Junko; Magallanes, Hernando; Brasselet, Etienne; Varapnickas, Simonas; Malinauskas, Mangirdas; Juodkazis, Saulius

2017-08-01

Three dimensional (3D) fast (< 0.5 hour) printing of micro-optical elements down to sub-wavelength resolution over 100 μm footprint areas using femtosecond (fs-)laser oscillator is presented. Using sub-1 nJ pulse energies, optical vortex generators made of polymerised grating segments with an azimuthally changing orientation have been fabricated in SZ2080 resist; width of polymerised rods was 150 nm and period 0.6-1 μm. Detailed phase retardance analysis was carried out manually with Berek compensator (under a white light illumination) and using an equivalent principle by an automated Abrio implementation at 546 nm. Direct experimental measurements of retardance was required since the period of the grating was comparable (or larger) than the wavelength of visible light. By gold sputtering, transmissive optical vortex generators were turned into reflective ones with augmented retardance, Δn × h defined by the form birefringence, Δn, and the height h = 2d where d is the thickness of the polymerised structure. Retardance reached 315 nm as measured with Berek compensator at visible wavelengths. Birefringent phase delays of π (or λ/2 in wavelength) required for high purity vortex generators can be made based on the proposed approach. Optical vortex generators for telecom wavelengths with sub-wavelength patterns of azimuthally oriented gratings are amenable by direct laser polymerisation.

Multi-phase functionalization of titanium for enhanced photon absorption in the vis-NIR region.

PubMed

Thakur, Pooja; Tan, Bo; Venkatakrishnan, Krishnan

2015-10-19

Inadequate absorption of Near Infrared (NIR) photons by conventional silicon solar cells has been a major stumbling block towards the attainment of a high efficiency "full spectrum" solar cell. An effective enhancement in the absorption of such photons is desired as they account for a considerable portion of the tappable solar energy. In this work, we report a remarkable gain observed in the absorption of photons in the near infrared and visible region (400 nm-1000 nm) by a novel multi-phased oxide of titanium. Synthesised via a single step ultra-fast laser pulse interaction with pure titanium, characterisation studies have identified this oxide of titanium to be multi-phased and composed of Ti3O, (TiO.716)3.76 and TiO2 (rutile). Computed to have an average band gap value of 2.39 eV, this ultrafast laser induced multi-phased titanium oxide has especially exhibited steady absorption capability in the NIR range of 750-1000 nm, which to the best of our knowledge, was never reported before. The unique NIR absorption properties of the laser functionalised titanium coupled with the simplicity and versatility of the ultrafast laser interaction process involved thereby provides tremendous potential towards the photon sensitization of titanium and thereafter for the inception of a "full spectrum" solar device.

Measurement and calculation of ternary oxide mixtures for thin films for ultra short pulse laser optics

NASA Astrophysics Data System (ADS)

Jupé, M.; Mende, M.; Kolleck, C.; Ristau, D.; Gallais, L.; Mangote, B.

2011-12-01

The femto-second technology gains of increasing importance in industrial applications. In this context, a new generation of compact and low cost laser sources has to be provided on a commercial basis. Typical pulse durations of these sources are specified in the range from a few hundred femtoup to some pico-seconds, and typical wavelengths are centered around 1030-1080nm. As a consequence, also the demands imposed on high power optical components for these laser sources are rapidly increasing, especially in respect to their power handling capability in the ultra-short pulse range. The present contribution is dedicated to some aspects for improving this quality parameter of optical coatings. The study is based on a set of hafnia and silica mixtures with different compositions and optical band gaps. This material combination displays under ultra-short pulse laser irradiation effects, which are typically for thermal processes. For instance, melting had been observed in the morphology of damaged sides. In this context, models for a prediction of the laser damage thresholds and scaling laws are scrutinized, and have been modified calculating the energy of the electron ensemble. Furthermore, a simple first order approach for the calculation of the temperature was included.

Comparison of microstructure and mechanical properties of ultra-narrow gap laser and gas-metal-arc welded S960 high strength steel

NASA Astrophysics Data System (ADS)

Guo, Wei; Li, Lin; Dong, Shiyun; Crowther, Dave; Thompson, Alan

2017-04-01

The microstructural characteristics and mechanical properties, including micro-hardness, tensile properties, three-point bending properties and Charpy impact toughness at different test temperatures of 8 mm thick S960 high strength steel plates were investigated following their joining by multi-pass ultra-narrow gap laser welding (NGLW) and gas metal arc welding (GMAW) techniques. It was found that the microstructure in the fusion zone (FZ) for the ultra-NGLW joint was predominantly martensite mixed with some tempered martensite, while the FZ for the GMAW joint was mainly consisted of ferrite with some martensite. The strength of the ultra-NGLW specimens was comparable to that of the base material (BM), with all welded specimens failed in the BM in the tensile tests. The tensile strength of the GMAW specimens was reduced approximately by 100 MPa when compared with the base material by a broad and soft heat affected zone (HAZ) with failure located in the soft HAZ. Both the ultra-NGLW and GMAW specimens performed well in three-point bending tests. The GMAW joints exhibited better impact toughness than the ultra-NGLW joints.

Ultra-fast outflows (aka UFOs) from AGNs and QSOs

NASA Astrophysics Data System (ADS)

Cappi, M.; Tombesi, F.; Giustini, M.

During the last decade, strong observational evidence has been accumulated for the existence of massive, high velocity winds/outflows (aka Ultra Fast Outflows, UFOs) in nearby AGNs and in more distant quasars. Here we briefly review some of the most recent developments in this field and discuss the relevance of UFOs for both understanding the physics of accretion disk winds in AGNs, and for quantifying the global amount of AGN feedback on the surrounding medium.

Compact MEMS external cavity tunable laser with ultra-narrow linewidth for coherent detection.

PubMed

Zhang, Di; Zhao, Jianyi; Yang, Qi; Liu, Wen; Fu, Yanfeng; Li, Chao; Luo, Ming; Hu, Shenglei; Hu, Qianggao; Wang, Lei

2012-08-27

A compact and ultra-narrow linewidth tunable laser with an external cavity based on a simple single-axis-MEMS mirror is presented in this paper. We discuss the simulation of this tunable laser using a two-step hybrid analysis method to obtain an optimal design of the device. A wide wavelength tuning range about 40 nm in C-band with a narrow linewidth of less than 50 kHz and wavelength accuracy of ± 1 GHz over the entire tuning range can be achieved experimentally. We also conduct several experiments under different conditions to test the tunable laser. This device shows an excellent performance in both single-carrier polarization-multiplexed quadrature phase-shift keying (PM-QPSK) and multi-carrier orthogonal frequency division multiplexing (OFDM) coherent systems.

Laser-driven ion acceleration: methods, challenges and prospects

NASA Astrophysics Data System (ADS)

Badziak, J.

2018-01-01

The recent development of laser technology has resulted in the construction of short-pulse lasers capable of generating fs light pulses with PW powers and intensities exceeding 1021 W/cm2, and has laid the basis for the multi-PW lasers, just being built in Europe, that will produce fs pulses of ultra-relativistic intensities ~ 1023 - 1024 W/cm2. The interaction of such an intense laser pulse with a dense target can result in the generation of collimated beams of ions of multi-MeV to GeV energies of sub-ps time durations and of extremely high beam intensities and ion fluencies, barely attainable with conventional RF-driven accelerators. Ion beams with such unique features have the potential for application in various fields of scientific research as well as in medical and technological developments. This paper provides a brief review of state-of-the art in laser-driven ion acceleration, with a focus on basic ion acceleration mechanisms and the production of ultra-intense ion beams. The challenges facing laser-driven ion acceleration studies, in particular those connected with potential applications of laser-accelerated ion beams, are also discussed.

Single-shot measurement of >1010 pulse contrast for ultra-high peak-power lasers

NASA Astrophysics Data System (ADS)

Wang, Yongzhi; Ma, Jingui; Wang, Jing; Yuan, Peng; Xie, Guoqiang; Ge, Xulei; Liu, Feng; Yuan, Xiaohui; Zhu, Heyuan; Qian, Liejia

2014-01-01

Real-time pulse-contrast observation with a high dynamic range is a prerequisite to tackle the contrast challenge in ultra-high peak-power lasers. However, the commonly used delay-scanning cross-correlator (DSCC) can only provide the time-consumed measurements for repetitive lasers. Single-shot cross-correlator (SSCC) becomes essential in optimizing laser systems and exploring contrast mechanisms. Here we report our progress in developing SSCC towards its practical use. By integrating both the techniques of scattering-noise reduction and sensitive parallel detection into SSCC, we demonstrate a high dynamic range of >1010, which, to our best knowledge, is the first demonstration of an SSCC with a dynamic range comparable to that of commercial DSCCs. The comparison of high-dynamic measurement performances between SSCC and a standard DSCC (Sequoia, Amplitude Technologies) is also carried out on a 200 TW Ti:sapphire laser, and the consistency of results verifies the veracity of our SSCC.

Moderate repetition rate ultra-intense laser targets and optics using variable thickness liquid crystal films

DOE PAGES

Poole, P. L.; Willis, C.; Cochran, G. E.; ...

2016-10-10

Liquid crystal films are variable thickness, planar targets for ultra-intense laser matter experiments such as ion acceleration. Their target qualities also make them ideal for high-power laser optics such as plasma mirrors and waveplates. By controlling parameters of film formation, thickness can be varied on-demand from 10 nm to above 50 μm, enabling real-time optimization of laser interactions. Presented here are results using a device that draws films from a bulk liquid crystal source volume with any thickness in the aforementioned range. Films form within 2 μm of the same location each time, well within the Rayleigh range of evenmore » tight F/# systems, thus removing the necessity for realignment between shots. As a result, the repetition rate of the device exceeds 0.1 Hz for sub-100nm films, facilitating higher repetition rate operation of modern laser facilities.« less

Enhanced dense attosecond electron bunch generation by irradiating an intense laser on a cone target

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hu, Li-Xiang; Yu, Tong-Pu, E-mail: tongpu@nudt.edu.cn; Shao, Fu-Qiu

By using two-dimensional particle-in-cell simulations, we demonstrate enhanced spatially periodic attosecond electron bunches generation with an average density of about 10n{sub c} and cut-off energy up to 380 MeV. These bunches are acquired from the interaction of an ultra-short ultra-intense laser pulse with a cone target. The laser oscillating field pulls out the cone surface electrons periodically and accelerates them forward via laser pondermotive force. The inner cone wall can effectively guide these bunches and lead to their stable propagation in the cone, resulting in overdense energetic attosecond electron generation. We also consider the influence of laser and cone target parametersmore » on the bunch properties. It indicates that the attosecond electron bunch acceleration and propagation could be significantly enhanced without evident divergency by attaching a plasma capillary to the original cone tip.« less

Laser-driven ultrafast antiproton beam

NASA Astrophysics Data System (ADS)

Li, Shun; Pei, Zhikun; Shen, Baifei; Xu, Jiancai; Zhang, Lingang; Zhang, Xiaomei; Xu, Tongjun; Yu, Yong; Bu, Zhigang

2018-02-01

Antiproton beam generation is investigated based on the ultra-intense femtosecond laser pulse by using two-dimensional particle-in-cell and Geant4 simulations. A high-flux proton beam with an energy of tens of GeV is generated in sequential radiation pressure and bubble regime and then shoots into a high-Z target for producing antiprotons. Both yield and energy of the antiproton beam increase almost linearly with the laser intensity. The generated antiproton beam has a short pulse duration of about 5 ps and its flux reaches 2 × 10 20 s - 1 at the laser intensity of 2.14 × 10 23 W / cm 2 . Compared to conventional methods, this new method based on the ultra-intense laser pulse is able to provide a compact, tunable, and ultrafast antiproton source, which is potentially useful for quark-gluon plasma study, all-optical antihydrogen generation, and so on.

Ultra-low power laser stimulation impairs the adhesion of Staphylococcus aureus to primary human cells, and interferes with the expression of staphylococcal pathogenic factors.

PubMed

Petruzzelli, Sabina; Congiu, Antonio; Gallamini, Michele; Pompei, Raffaello

2014-04-01

Lasers are commonly used in several fields of medicine as a complementary therapy for internal medicine, surgery and also diagnostics. The efficacy of ultra-low level laser therapy (ULLLT) at power levels around 0.15 mW/cm(2) has been demonstrated both in in vitro experiments and in the clinical environment. This work used an ULLLT laser source to analyze its efficacy on Staphylococcus aureus adhesion to cells and on its ability to produce pathogenic factors. Laser stimulation succeeded in impairing the binding of S. aureus to primary human cells in culture and in inhibiting the expression of coagulase, one of the main staphylococcal pathogenic factors. The importance of the extracellular matrix (ECM) and the modification of the ECM redox potential in these activities were also evidenced.

Moderate repetition rate ultra-intense laser targets and optics using variable thickness liquid crystal films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Poole, P. L.; Willis, C.; Cochran, G. E.

Liquid crystal films are variable thickness, planar targets for ultra-intense laser matter experiments such as ion acceleration. Their target qualities also make them ideal for high-power laser optics such as plasma mirrors and waveplates. By controlling parameters of film formation, thickness can be varied on-demand from 10 nm to above 50 μm, enabling real-time optimization of laser interactions. Presented here are results using a device that draws films from a bulk liquid crystal source volume with any thickness in the aforementioned range. Films form within 2 μm of the same location each time, well within the Rayleigh range of evenmore » tight F/# systems, thus removing the necessity for realignment between shots. As a result, the repetition rate of the device exceeds 0.1 Hz for sub-100nm films, facilitating higher repetition rate operation of modern laser facilities.« less

The Optical Society's 2016 topical meeting on optical interference coatings: introduction.

PubMed

Ristau, Detlev; Li, Li; Sargent, Robert; Sytchkova, Anna

2017-02-01

This feature issue of Applied Optics is dedicated to the 13th Topical Meeting on Optical Interference Coatings, which was held June 19-24, 2016, in Tucson, Arizona, USA. The conference, taking place every three years, is a focal point for global technical interchange in the field of optical interference coatings and provides premier opportunities for people working in the field to present their new advances in research and development. Papers presented at the meeting covered a broad range of topics, including fundamental research on coating design theory, new materials, and deposition and characterization technologies, as well as the vast and growing number of applications in electronic displays, communication, optical instruments, high power and ultra-fast lasers, solar cells, space missions, gravitational wave detection, and many others.

Photoinduced piezooptics effect in TeO2-Ga2O3 glasses

NASA Astrophysics Data System (ADS)

Ozga, K.; Fedorchuk, A. O.; Armand, P.

2015-08-01

We have found that during the bicolor illumination by two boicolor coherent wavelengths 1540 nm/770 nm there occurred substantial changes of the elastooptical non-diagonal coefficients at 1150 nm cw laser wavelength. They are maximal at power densities 400 … 500 MW/cm2. The studies have shown that the maximal effect exists for ultra-fast quenching glasses and occurs after the 1-2 min of the treatment. The switching off of the optical treatment leads to the disappearance of the photoinduced piezooptics at about 100 ms. The observed changes are explained within the photoinduced changes of the charge density distribution for the principal structural clusters within a framework of the DFT approach. The studies were done both for diagonal as well as off-diagonal piezooptical effect (POE) tensor components.

Precision and Fast Wavelength Tuning of a Dynamically Phase-Locked Widely-Tunable Laser

NASA Technical Reports Server (NTRS)

Numata, Kenji; Chen, Jeffrey R.; Wu, Stewart T.

2012-01-01

We report a precision and fast wavelength tuning technique demonstrated for a digital-supermode distributed Bragg reflector laser. The laser was dynamically offset-locked to a frequency-stabilized master laser using an optical phase-locked loop, enabling precision fast tuning to and from any frequencies within a 40-GHz tuning range. The offset frequency noise was suppressed to the statically offset-locked level in less than 40 s upon each frequency switch, allowing the laser to retain the absolute frequency stability of the master laser. This technique satisfies stringent requirements for gas sensing lidars and enables other applications that require such well-controlled precision fast tuning.

Multi-level storage and ultra-high speed of superlattice-like Ge50Te50/Ge8Sb92 thin film for phase-change memory application.

PubMed

Wu, Weihua; Chen, Shiyu; Zhai, Jiwei; Liu, Xinyi; Lai, Tianshu; Song, Sannian; Song, Zhitang

2017-10-06

Superlattice-like Ge 50 Te 50 /Ge 8 Sb 92 (SLL GT/GS) thin film was systematically investigated for multi-level storage and ultra-fast switching phase-change memory application. In situ resistance measurement indicates that SLL GT/GS thin film exhibits two distinct resistance steps with elevated temperature. The thermal stability of the amorphous state and intermediate state were evaluated with the Kissinger and Arrhenius plots. The phase-structure evolution revealed that the amorphous SLL GT/GS thin film crystallized into rhombohedral Sb phase first, then the rhombohedral GeTe phase. The microstructure, layered structure, and interface stability of SLL GT/GS thin film was confirmed by using transmission electron microscopy. The transition speed of crystallization and amorphization was measured by the picosecond laser pump-probe system. The volume variation during the crystallization was obtained from x-ray reflectivity. Phase-change memory (PCM) cells based on SLL GT/GS thin film were fabricated to verify the multi-level switching under an electrical pulse as short as 30 ns. These results illustrate that the SLL GT/GS thin film has great potentiality in high-density and high-speed PCM applications.

Pure colloidal metal and ceramic nanoparticles from high-power picosecond laser ablation in water and acetone.

PubMed

Bärsch, Niko; Jakobi, Jurij; Weiler, Sascha; Barcikowski, Stephan

2009-11-04

The generation of colloids by laser ablation of solids in a liquid offers a nearly unlimited material variety and a high purity as no chemical precursors are required. The use of novel high-power ultra-short-pulsed laser systems significantly increases the production rates even in inflammable organic solvents. By applying an average laser power of 50 W and pulse durations below 10 ps, up to 5 mg min(-1) of nanoparticles have been generated directly in acetone, marking a breakthrough in productivity of ultra-short-pulsed laser ablation in liquids. The produced colloids remain stable for more than six months. In the case of yttria-stabilized zirconia ceramic, the nanoparticles retain the tetragonal crystal structure of the ablated target. Laser beam self-focusing plays an important role, as a beam radius change of 2% on the liquid surface can lead to a decrease of nanoparticle production rates of 90% if the target position is not re-adjusted.

Two-color ionization injection using a plasma beatwave accelerator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schroeder, C. B.; Benedetti, C.; Esarey, E.

Two-color laser ionization injection is a method to generate ultra-low emittance (sub-100 nm transverse normalized emittance) beams in a laser-driven plasma accelerator. A plasma beatwave accelerator is proposed to drive the plasma wave for ionization injection, where the beating of the lasers effectively produces a train of long-wavelength pulses. The plasma beatwave accelerator excites a large amplitude plasma wave with low peak laser electric fields, leaving atomically-bound electrons with low ionization potential. A short-wavelength, low-amplitude ionization injection laser pulse (with a small ponderomotive force and large peak electric field) is used to ionize the remaining bound electrons at a wakemore » phase suitable for trapping, generating an ultra-low emittance electron beam that is accelerated in the plasma wave. Using a plasma beatwave accelerator for wakefield excitation, compared to short-pulse wakefield excitation, allows for a lower amplitude injection laser pulse and, hence, a lower emittance beam may be generated.« less

Two-color ionization injection using a plasma beatwave accelerator

DOE PAGES

Schroeder, C. B.; Benedetti, C.; Esarey, E.; ...

2018-01-10

Two-color laser ionization injection is a method to generate ultra-low emittance (sub-100 nm transverse normalized emittance) beams in a laser-driven plasma accelerator. A plasma beatwave accelerator is proposed to drive the plasma wave for ionization injection, where the beating of the lasers effectively produces a train of long-wavelength pulses. The plasma beatwave accelerator excites a large amplitude plasma wave with low peak laser electric fields, leaving atomically-bound electrons with low ionization potential. A short-wavelength, low-amplitude ionization injection laser pulse (with a small ponderomotive force and large peak electric field) is used to ionize the remaining bound electrons at a wakemore » phase suitable for trapping, generating an ultra-low emittance electron beam that is accelerated in the plasma wave. Using a plasma beatwave accelerator for wakefield excitation, compared to short-pulse wakefield excitation, allows for a lower amplitude injection laser pulse and, hence, a lower emittance beam may be generated.« less

Bright betatron X-ray radiation from a laser-driven-clustering gas target

PubMed Central

Chen, L. M.; Yan, W. C.; Li, D. Z.; Hu, Z. D.; Zhang, L.; Wang, W. M.; Hafz, N.; Mao, J. Y.; Huang, K.; Ma, Y.; Zhao, J. R.; Ma, J. L.; Li, Y. T.; Lu, X.; Sheng, Z. M.; Wei, Z. Y.; Gao, J.; Zhang, J.

2013-01-01

Hard X-ray sources from femtosecond (fs) laser-produced plasmas, including the betatron X-rays from laser wakefield-accelerated electrons, have compact sizes, fs pulse duration and fs pump-probe capability, making it promising for wide use in material and biological sciences. Currently the main problem with such betatron X-ray sources is the limited average flux even with ultra-intense laser pulses. Here, we report ultra-bright betatron X-rays can be generated using a clustering gas jet target irradiated with a small size laser, where a ten-fold enhancement of the X-ray yield is achieved compared to the results obtained using a gas target. We suggest the increased X-ray photon is due to the existence of clusters in the gas, which results in increased total electron charge trapped for acceleration and larger wiggling amplitudes during the acceleration. This observation opens a route to produce high betatron average flux using small but high repetition rate laser facilities for applications. PMID:23715033

Partial ablation of Ti/Al nano-layer thin film by single femtosecond laser pulse

NASA Astrophysics Data System (ADS)

Gaković, B.; Tsibidis, G. D.; Skoulas, E.; Petrović, S. M.; Vasić, B.; Stratakis, E.

2017-12-01

The interaction of ultra-short laser pulses with Titanium/Aluminium (Ti/Al) nano-layered thin film was investigated. The sample composed of alternating Ti and Al layers of a few nanometres thick was deposited by ion-sputtering. A single pulse irradiation experiment was conducted in an ambient air environment using focused and linearly polarized femtosecond laser pulses for the investigation of the ablation effects. The laser induced morphological changes and the composition were characterized using several microscopy techniques and energy dispersive X-ray spectroscopy. The following results were obtained: (i) at low values of pulse energy/fluence, ablation of the upper Ti layer only was observed; (ii) at higher laser fluence, a two-step ablation of Ti and Al layers takes place, followed by partial removal of the nano-layered film. The experimental observations were supported by a theoretical model accounting for the thermal response of the multiple layered structure upon irradiation with ultra-short laser pulses.

Ultra-weak FBG and its refractive index distribution in the drawing optical fiber.

PubMed

Guo, Huiyong; Liu, Fang; Yuan, Yinquan; Yu, Haihu; Yang, Minghong

2015-02-23

For the online writing of ultra-weak fiber Bragg gratings (FBGs) in the drawing optical fibers, the effects of the intensity profile, pulse fluctuation and pulse width of the excimer laser, as well as the transverse and longitudinal vibrations of the optical fiber have been investigated. Firstly, using Lorentz-Loren equation, Gladstone-Dale mixing rule and continuity equation, we have derived the refractive index (RI) fluctuation along the optical fiber and the RI distribution in the FBG, they are linear with the gradient of longitudinal vibration velocity. Then, we have prepared huge amounts of ultra-weak FBGs in the non-moving optical fiber and obtained their reflection spectra, the measured reflection spectra shows that the intensity profile and pulse fluctuation of the excimer laser, as well as the transverse vibration of the optical fiber are little responsible for the inconsistency of ultra-weak FBGs. Finally, the effect of the longitudinal vibration of the optical fiber on the inconsistency of ultra-weak FBGs has been discussed, and the vibration equations of the drawing optical fiber are given in the appendix.

What predicts performance in ultra-triathlon races? – a comparison between Ironman distance triathlon and ultra-triathlon

PubMed Central

Knechtle, Beat; Zingg, Matthias Alexander; Rosemann, Thomas; Stiefel, Michael; Rüst, Christoph Alexander

2015-01-01

Objective This narrative review summarizes recent intentions to find potential predictor variables for ultra-triathlon race performance (ie, triathlon races longer than the Ironman distance covering 3.8 km swimming, 180 km cycling, and 42.195 km running). Results from studies on ultra-triathletes were compared to results on studies on Ironman triathletes. Methods A literature search was performed in PubMed using the terms “ultra”, “triathlon”, and “performance” for the aspects of “ultra-triathlon”, and “Ironman”, “triathlon”, and “performance” for the aspects of “Ironman triathlon”. All resulting papers were searched for related citations. Results for ultra-triathlons were compared to results for Ironman-distance triathlons to find potential differences. Results Athletes competing in Ironman and ultra-triathlon differed in anthropometric and training characteristics, where both Ironmen and ultra-triathletes profited from low body fat, but ultra-triathletes relied more on training volume, whereas speed during training was related to Ironman race time. The most important predictive variables for a fast race time in an ultra-triathlon from Double Iron (ie, 7.6 km swimming, 360 km cycling, and 84.4 km running) and longer were male sex, low body fat, age of 35–40 years, extensive previous experience, a fast time in cycling and running but not in swimming, and origins in Central Europe. Conclusion Any athlete intending to compete in an ultra-triathlon should be aware that low body fat and high training volumes are highly predictive for overall race time. Little is known about the physiological characteristics of these athletes and about female ultra-triathletes. Future studies need to investigate anthropometric and training characteristics of female ultra-triathletes and what motivates women to compete in these races. Future studies need to correlate physiological characteristics such as maximum oxygen uptake (VO2max) with ultra-triathlon race performance in order to investigate whether these characteristics are also predictive for ultra-triathlon race performance. PMID:26056498

REU in Physics at Kansas State University--- an Evolving Program

NASA Astrophysics Data System (ADS)

Corwin, Kristan; Glymour, Bruce; Lara, Amy; Weaver, Larry; Zollman, Dean

2009-03-01

The REU site in the Physics Department at Kansas State University, funded by NSF for 13 years between 1992 and 2007, originally focused on atomic collision physics. Now the theme has broadened to include laser-matter interactions on atomic and nanoscales, and an ethics component is incorporated. Students study how atoms and molecules interact with ultra-fast optical and x-ray pulses, reveal the structure of nanoparticle crystallization and gel formation with scattered laser light, and develop computer codes for atomic interactions in Bose-Einstein condensates and nanoparticle self-assembly from lattices to gels; some have traveled to Japan for neutrino experiments. The students we select come primarily from smaller colleges and universities in the Midwest where research opportunities are limited. Prof. Weaver, who has served as PI since 1992, facilitates their transition from a teaching to research environment through lectures and individual interactions. Our program is in a period of transition. While Prof. Weaver continues to be the ``impedance match'' between students and mentors, other leadership roles are gradually being assumed by a team of faculty members who strive to preserve the intimacy and excellence of the program.

Exploration of dynamical regimes of irradiated small protonated water clusters

NASA Astrophysics Data System (ADS)

Ndongmouo Taffoti, U. F.; Dinh, P. M.; Reinhard, P.-G.; Suraud, E.; Wang, Z. P.

2010-05-01

We explore from a theoretical perspective the dynamical response of small water clusters, (H2O)nH3O+ with n=1,2,3, to a short laser pulse for various frequencies, from infrared (IR) to ultra-violet (UV) and intensities (from 6×10^{13} W/cm^2 to 5×10^{14} W/cm^2). To that end, we use time-dependent local-density approximation for the electrons, coupled to molecular dynamics for the atomic cores (TDLDA-MD). The local-density approximation is augmented by a self-interaction correction (SIC) to allow for a correct description of electron emission. For IR frequencies, we see a direct coupling of the laser field to the very light H+ ions in the clusters. Resonant coupling (in the UV) and/or higher intensities lead to fast ionization with subsequent Coulomb explosion. The stability against Coulomb pressure increases with system size. Excitation to lower ionization stages induced strong ionic vibrations. The latter maintain a rather harmonic pattern in spite of the sizeable amplitudes (often 10% of the bond length).

Simultaneous laser cutting and welding of metal foil to edge of a plate

DOEpatents

Pernicka, John C.; Benson, David K.; Tracy, C. Edwin

1996-01-01

A method of welding an ultra-thin foil to the edge of a thicker sheet to form a vacuum insulation panel comprising the steps of providing an ultra-thin foil having a thickness less than 0.002, providing a top plate having an edge and a bottom plate having an edge, clamping the foil to the edge of the plate wherein the clamps act as heat sinks to distribute heat through the foil, providing a laser, moving the laser relative to the foil and the plate edges to form overlapping weld beads to weld the foil to the plate edges while simultaneously cutting the foil along the weld line formed by the overlapping beads.

Ultra-stable high average power femtosecond laser system tunable from 1.33 to 20  μm.

PubMed

Steinle, Tobias; Mörz, Florian; Steinmann, Andy; Giessen, Harald

2016-11-01

A highly stable 350 fs laser system with a gap-free tunability from 1.33 to 2.0 μm and 2.13 to 20 μm is demonstrated. Nanojoule-level pulse energy is achieved in the mid-infrared at a 43 MHz repetition rate. The system utilizes a post-amplified fiber-feedback optical parametric oscillator followed by difference frequency generation between the signal and idler. No locking or synchronization electronics are required to achieve outstanding free-running output power and spectral stability of the whole system. Ultra-low intensity noise, close to the pump laser's noise figure, enables shot-noise limited measurements.

Cluster beam targets for laser plasma extreme ultraviolet and soft x-ray sources

DOEpatents

Kublak, Glenn D.; Richardson, Martin C. (CREOL

1996-01-01

Method and apparatus for producing extreme ultra violet (EUV) and soft x-ray radiation from an ultra-low debris plasma source are disclosed. Targets are produced by the free jet expansion of various gases through a temperature controlled nozzle to form molecular clusters. These target clusters are subsequently irradiated with commercially available lasers of moderate intensity (10.sup.11 -10.sup.12 watts/cm.sup.2) to produce a plasma radiating in the region of 0.5 to 100 nanometers. By appropriate adjustment of the experimental conditions the laser focus can be moved 10-30 mm from the nozzle thereby eliminating debris produced by plasma erosion of the nozzle.

Development of a laser Doppler displacement encoder system with ultra-low-noise-level for linear displacement measurement with subnanometer resolution - Final CRADA Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shu, Deming

An U.S. DOE Cooperative Research and Development Agreement (CRADA) between ANL and Optodyne, Inc. has been established to develop a prototype laser Doppler displacement encoder system with ultra-low noise level for linear measurements to sub-nanometer resolution for synchrotron radiation applications. We have improved the heterodyne efficiency and reduced the detector shot noises by proper shielding and adding a low-pass filter. The laser Doppler displacement encoder system prototype demonstrated a ~ 1 nm system output noise floor with single reflection optics. With multiple-pass optical arrangement, 0.1 nm scale closed-loop feedback control is achieved.

Ultra-low noise dual-frequency VECSEL at telecom wavelength using fully correlated pumping.

PubMed

Liu, Hui; Gredat, Gregory; De, Syamsundar; Fsaifes, Ihsan; Ly, Aliou; Vatré, Rémy; Baili, Ghaya; Bouchoule, Sophie; Goldfarb, Fabienne; Bretenaker, Fabien

2018-04-15

An ultra-low intensity and beatnote phase noise dual-frequency vertical-external-cavity surface-emitting laser is built at telecom wavelength. The pump laser is realized by polarization combining two single-mode fibered laser diodes in a single-mode fiber, leading to a 100% in-phase correlation of the pump noises for the two modes. The relative intensity noise is lower than -140  dB/Hz, and the beatnote phase noise is suppressed by 30 dB, getting close to the spontaneous emission limit. The role of the imperfect cancellation of the thermal effect resulting from unbalanced pumping of the two modes in the residual phase noise is evidenced.

Start-to-end simulation of single-particle imaging using ultra-short pulses at the European X-ray Free-Electron Laser

PubMed Central

Buzmakov, Alexey; Jurek, Zoltan; Loh, Ne-Te Duane; Samoylova, Liubov; Santra, Robin; Schneidmiller, Evgeny A.; Tschentscher, Thomas; Yakubov, Sergey; Yoon, Chun Hong; Yurkov, Michael V.; Ziaja-Motyka, Beata; Mancuso, Adrian P.

2017-01-01

Single-particle imaging with X-ray free-electron lasers (XFELs) has the potential to provide structural information at atomic resolution for non-crystalline biomolecules. This potential exists because ultra-short intense pulses can produce interpretable diffraction data notwithstanding radiation damage. This paper explores the impact of pulse duration on the interpretability of diffraction data using comprehensive and realistic simulations of an imaging experiment at the European X-ray Free-Electron Laser. It is found that the optimal pulse duration for molecules with a few thousand atoms at 5 keV lies between 3 and 9 fs. PMID:28989713

Development of a prototype sensor system for ultra-high-speed LDA-PIV

NASA Astrophysics Data System (ADS)

Griffiths, Jennifer A.; Royle, Gary J.; Bohndiek, Sarah E.; Turchetta, Renato; Chen, Daoyi

2008-04-01

Laser Doppler Anemometry (LDA) and Particle Image Velocimetry (PIV) are commonly used in the analysis of particulates in fluid flows. Despite the successes of these techniques, current instrumentation has placed limitations on the size and shape of the particles undergoing measurement, thus restricting the available data for the many industrial processes now utilising nano/micro particles. Data for spherical and irregularly shaped particles down to the order of 0.1 µm is now urgently required. Therefore, an ultra-fast LDA-PIV system is being constructed for the acquisition of this data. A key component of this instrument is the PIV optical detection system. Both the size and speed of the particles under investigation place challenging constraints on the system specifications: magnification is required within the system in order to visualise particles of the size of interest, but this restricts the corresponding field of view in a linearly inverse manner. Thus, for several images of a single particle in a fast fluid flow to be obtained, the image capture rate and sensitivity of the system must be sufficiently high. In order to fulfil the instrumentation criteria, the optical detection system chosen is a high-speed, lensed, digital imaging system based on state-of-the-art CMOS technology - the 'Vanilla' sensor developed by the UK based MI3 consortium. This novel Active Pixel Sensor is capable of high frame rates and sparse readout. When coupled with an image intensifier, it will have single photon detection capabilities. An FPGA based DAQ will allow real-time operation with minimal data transfer.

MeV proton acceleration at kHz repetition rate from ultra-intense laser liquid interaction

NASA Astrophysics Data System (ADS)

Morrison, John T.; Feister, Scott; Frische, Kyle D.; Austin, Drake R.; Ngirmang, Gregory K.; Murphy, Neil R.; Orban, Chris; Chowdhury, Enam A.; Roquemore, W. M.

2018-02-01

Laser acceleration of ions to ≳MeV energies has been achieved on a variety of Petawatt laser systems, raising the prospect of ion beam applications using compact ultra-intense laser technology. However, translation from proof-of-concept laser experiment into real-world application requires MeV-scale ion energies and an appreciable repetition rate (>Hz). We demonstrate, for the first time, proton acceleration up to 2 MeV energies at a kHz repetition rate using a milli-joule-class short-pulse laser system. In these experiments, 5 mJ of ultrashort-pulse laser energy is delivered at an intensity near 5× {10}18 {{W}} {cm}}-2 onto a thin-sheet, liquid-density target. Key to this effort is a flowing liquid ethylene glycol target formed in vacuum with thicknesses down to 400 nm and full recovery at 70 μs, suggesting its potential use at ≫kHz rate. Novel detectors and experimental methods tailored to high-repetition-rate ion acceleration by lasers were essential to this study and are described. In addition, particle-in-cell simulations of the laser-plasma interaction show good agreement with experimental observations.

Au nanoparticle arrays produced by Pulsed Laser Deposition for Surface Enhanced Raman Spectroscopy

NASA Astrophysics Data System (ADS)

Agarwal, N. R.; Neri, F.; Trusso, S.; Lucotti, A.; Ossi, P. M.

2012-09-01

Using UV pulses from KrF excimer laser, Au targets were ablated in varying pressures of argon to deposit Au nanoparticle (NP) arrays. The morphology of these films from island structures to isolated NPs, observed by SEM and TEM, depends on the gas pressure (10-100 Pa) and pulse number keeping other deposition parameters constant. By fast imaging of the plasma with an iCCD camera at different time delays with respect to the arrival of the laser pulse, we study the plasma propagation regime and we measured its initial velocity. These data and the measured average ablated mass per pulse were introduced to the mixed propagation model to calculate the average asymptotic size of clusters grown in the plume which were compared with NP sizes from TEM measurements. UV-visible Spectroscopy revealed changes of surface plasmon resonance with respect to NP size and spatial density and distribution on the surface. Suitable wavelength to excite the localized surface plasmon was chosen to detect ultra-low concentrations of Rhodamine and Apomorphine as an application to biomedical sensors, using Surface Enhanced Raman Spectroscopy (SERS). A comparison of SERS spectra taken under identical conditions from commercial substrates and from PLD substrates show that the latter have superior performances.

Evaluation of laser-driven ion energies for fusion fast-ignition research

NASA Astrophysics Data System (ADS)

Tosaki, S.; Yogo, A.; Koga, K.; Okamoto, K.; Shokita, S.; Morace, A.; Arikawa, Y.; Fujioka, S.; Nakai, M.; Shiraga, H.; Azechi, H.; Nishimura, H.

2017-10-01

We investigate laser-driven ion acceleration using kJ-class picosecond (ps) laser pulses as a fundamental study for ion-assisted fusion fast ignition, using a newly developed Thomson-parabola ion spectrometer (TPIS). The TPIS has a space- and weight-saving design, considering its use in an laser-irradiation chamber in which 12 beams of fuel implosion laser are incident, and, at the same time, demonstrates sufficient performance with its detectable range and resolution of the ion energy required for fast-ignition research. As a fundamental study on laser-ion acceleration using a ps pulse laser, we show proton acceleration up to 40 MeV at 1 × 10^{19} W cm^{-2}. The energy conversion efficiency from the incident laser into protons higher than 6 MeV is 4.6%, which encourages the realization of fusion fast ignition by laser-driven ions.

Precision and fast wavelength tuning of a dynamically phase-locked widely-tunable laser.

PubMed

Numata, Kenji; Chen, Jeffrey R; Wu, Stewart T

2012-06-18

We report a precision and fast wavelength tuning technique demonstrated for a digital-supermode distributed Bragg reflector laser. The laser was dynamically offset-locked to a frequency-stabilized master laser using an optical phase-locked loop, enabling precision fast tuning to and from any frequencies within a ~40-GHz tuning range. The offset frequency noise was suppressed to the statically offset-locked level in less than ~40 μs upon each frequency switch, allowing the laser to retain the absolute frequency stability of the master laser. This technique satisfies stringent requirements for gas sensing lidars and enables other applications that require such well-controlled precision fast tuning.

Three electron beams from a laser-plasma wakefield accelerator and the energy apportioning question

PubMed Central

Yang, X.; Brunetti, E.; Gil, D. Reboredo; Welsh, G. H.; Li, F. Y.; Cipiccia, S.; Ersfeld, B.; Grant, D. W.; Grant, P. A.; Islam, M. R.; Tooley, M. P.; Vieux, G.; Wiggins, S. M.; Sheng, Z. M.; Jaroszynski, D. A.

2017-01-01

Laser-wakefield accelerators are compact devices capable of delivering ultra-short electron bunches with pC-level charge and MeV-GeV energy by exploiting the ultra-high electric fields arising from the interaction of intense laser pulses with plasma. We show experimentally and through numerical simulations that a high-energy electron beam is produced simultaneously with two stable lower-energy beams that are ejected in oblique and counter-propagating directions, typically carrying off 5–10% of the initial laser energy. A MeV, 10s nC oblique beam is ejected in a 30°–60° hollow cone, which is filled with more energetic electrons determined by the injection dynamics. A nC-level, 100s keV backward-directed beam is mainly produced at the leading edge of the plasma column. We discuss the apportioning of absorbed laser energy amongst the three beams. Knowledge of the distribution of laser energy and electron beam charge, which determine the overall efficiency, is important for various applications of laser-wakefield accelerators, including the development of staged high-energy accelerators. PMID:28281679

Possibilities of lasers within NOTES.

PubMed

Stepp, Herbert; Sroka, Ronald

2010-10-01

Lasers possess unique properties that render them versatile light sources particularly for NOTES. Depending on the laser light sources used, diagnostic as well as therapeutic purposes can be achieved. The diagnostic potential offered by innovative concepts such as new types of ultra-thin endoscopes and optical probes supports the physician with optical information of ultra-high resolution, tissue discrimination and manifold types of fluorescence detection. In addition, the potential 3-D capability promises enhanced recognition of tissue type and pathological status. These diagnostic techniques might enable or at least contribute to accurate and safe procedures within the spatial restrictions inherent with NOTES. The therapeutic potential ranges from induction of phototoxic effects over tissue welding, coagulation and tissue cutting to stone fragmentation. As proven in many therapeutic laser endoscopic treatment concepts, laser surgery is potentially bloodless and transmits the energy without mechanical forces. Specialized NOTES endoscopes will likely incorporate suitable probes for improving diagnostic procedures, laser fibres with advantageous light delivery possibility or innovative laser beam manipulation systems. NOTES training centres may support the propagation of the complex handling and the safety aspects for clinical use to the benefit of the patient.

Investigation of possible fs-LASIK induced retinal damage

NASA Astrophysics Data System (ADS)

Schumacher, S.; Sander, M.; Stolte, A.; Doepke, C.; Baumgaertner, W.; Lubatschowski, H.

2006-02-01

Rapid development of new laser technologies enabled the application of ultra short lasers in refractive surgery. Focused ultra short laser pulses in near-infrared spectral range can generate a laser induced breakdown (LIB) in the cornea, which will disrupt the tissue. Cutting depth and position can be established by varying the laser focus. The fs-LASIK technique allows both flap and lenticule to be formed by using fs-pulses without the presence of any mechanical impact. During the cutting process not all of the pulse energy is deposited into the cornea; approximately half of the remaining energy propagates through the eye and reaches the retina. Though defocused, the transmitted energy can still induce damage to the retina due to absorption by the retinal pigment epithelium and the transfer of thermal energy to surrounding tissue. The fs-LASIK process was simulated with two laser systems; one continous-wave and one in the fs-regime. For the simulation the exposure time and focusing numerical aperature which defines the retinal spot size were varied. The Damage thresholds of the laser beam exposed eyes were determined in terms of ophthalmoscopic and histopathologic observations.

Ultra-narrow-linewidth Brillouin/erbium fiber laser

NASA Astrophysics Data System (ADS)

Chen, Mo; Wang, Chenyu; Wang, Jianfei; Luo, Hong; Meng, Zhou

2018-02-01

Ultra-narrow-linewidth lasers are of great interest in many applications, such as precise spectroscopy, optical communications, and sensors. Stimulated Brillouin scattering (SBS), as one of the main nonlinear effects in fibers, is capable of generating narrow-linewidth light emission. We establish a compact Brillouin/erbium fiber laser (BEFL) utilizing 4-m erbium-doped fiber as both the Brillouin gain and linear media. A 360-kHz-linewidth laser diode is injected into the cavity as the Brillouin pump (BP) light and generates Brillouin Stokes lasing light. Both of the phase noise of the BP and BEFL output are measured by a high-accuracy unbalanced Michelson interferometer. It is demonstrated that 53- dB phase noise reduction is achieved after the BP is transferred into Brillouin Stokes emission. The linewidth of the BEFL is indicated at Hz-range by both calculation and experiment.

Process Properties of Electronic High Voltage Discharges Triggered by Ultra-short Pulsed Laser Filaments

NASA Astrophysics Data System (ADS)

Cvecek, Kristian; Gröschel, Benjamin; Schmidt, Michael

Remote processing of metallic workpieces by techniques based on electric arc discharge or laser irradiation for joining or cutting has a long tradition and is still being intensively investigated in present-day research. In applications that require high power processing, both approaches exhibit certain advantages and disadvantages that make them specific for a given task. While several hybrid approaches exist that try to combine the benefits of both techniques, none were as successful in providing a fixed electric discharge direction as discharges triggered by plasma filaments generated by ultra-short pulsed lasers. In this work we investigate spatial and temporal aspects of laser filament guided discharges and give an upper time delay between the filament creation and the electrical build-up of a dischargeable voltage for a successful filament triggered discharge.

Final Technical Report "Study of Efficiency of Raman Backscattering Amplification in Plasma"

DOE Office of Scientific and Technical Information (OSTI.GOV)

Suckewer, Szymon

2014-03-31

General : Our major scientific achievements in Raman Backscattering (RBS) amplification and compression of short laser pulses in plasma. The laser system based on RBS steps in where the current technology of chirped pulse amplification (CPA) (extremely successful in developing ultra-short and ultra-intense laser pulses in last 2 decades) becomes difficult and very expensive to apply. Good base for such RBS laser was created by our recent experiments, which were supported by GPS grants. The main objective of the present grant was: improvement efficiency of energy transfer from pump to seed. The results surpassed our expectations; we improved the efficiencymore » of energy transfer from pump to seed by a factor of 6 compared to the best of our previous results and amplified seed pulse compressed down to about 50 fsec.« less

High-energy ultra-short pulse thin-disk lasers: new developments and applications

NASA Astrophysics Data System (ADS)

Michel, Knut; Klingebiel, Sandro; Schultze, Marcel; Tesseit, Catherine Y.; Bessing, Robert; Häfner, Matthias; Prinz, Stefan; Sutter, Dirk; Metzger, Thomas

2016-03-01

We report on the latest developments at TRUMPF Scientific Lasers in the field of ultra-short pulse lasers with highest output energies and powers. All systems are based on the mature and industrialized thin-disk technology of TRUMPF. Thin Yb:YAG disks provide a reliable and efficient solution for power and energy scaling to Joule- and kW-class picosecond laser systems. Due to its efficient one dimensional heat removal, the thin-disk exhibits low distortions and thermal lensing even when pumped under extremely high pump power densities of 10kW/cm². Currently TRUMPF Scientific Lasers develops regenerative amplifiers with highest average powers, optical parametric amplifiers and synchronization schemes. The first few-ps kHz multi-mJ thin-disk regenerative amplifier based on the TRUMPF thindisk technology was developed at the LMU Munich in 20081. Since the average power and energy have continuously been increased, reaching more than 300W (10kHz repetition rate) and 200mJ (1kHz repetition rate) at pulse durations below 2ps. First experiments have shown that the current thin-disk technology supports ultra-short pulse laser solutions >1kW of average power. Based on few-picosecond thin-disk regenerative amplifiers few-cycle optical parametric chirped pulse amplifiers (OPCPA) can be realized. These systems have proven to be the only method for scaling few-cycle pulses to the multi-mJ energy level. OPA based few-cycle systems will allow for many applications such as attosecond spectroscopy, THz spectroscopy and imaging, laser wake field acceleration, table-top few-fs accelerators and laser-driven coherent X-ray undulator sources. Furthermore, high-energy picosecond sources can directly be used for a variety of applications such as X-ray generation or in atmospheric research.

An Optical Trap for Relativistic Plasma

NASA Astrophysics Data System (ADS)

Zhang, Ping

2002-11-01

Optical traps have achieved remarkable success recently in confining ultra-cold matter.Traps capable of confining ultra-hot matter, or plasma, have also been built for applications such as basic plasma research and thermonuclear fusion. For instance, low-density plasmas with temperature less than 1 keV have been confined with static magnetic fields in Malmberg-Penning traps. Low-density 10-50 keV plasmas are confined in magnetic mirrors and tokamaks. High density plasmas have been trapped in optical traps with kinetic energies up to 10 keV [J. L. Chaloupka and D. D. Meyerhofer, Phys. Rev. Lett. 83, 4538 (1999)]. We present the results of experiment, theory and numerical simulation on an optical trap capable of confining relativistic plasma. A stationary interference grating with submicron spacing is created when two high-power (terawatt) laser pulses of equal wavelength (1-micron) are focused from orthogonal directions to the same point in space and time in high density underdense plasma. Light pressure gradients bunch electrons into sheets located at the minima of the interference pattern. The density of the bunched electrons is found to be up to ten times the background density, which is orders-of-magnitude above that previously reported for other optical traps or plasma waves. The amplitudes and frequencies of multiple satellites in the scattered spectrum also indicate the presence of a highly nonlinear ion wave and an electron temperature about 100 keV. Energy transfer from the stronger beam to the weaker beam is also observed. Potential applications include a test-bed for detailed studies of relativistic nonlinear scattering, a positron source and an electrostatic wiggler. This research is also relevant to fast igniter fusion or ion acceleration experiments, in which laser pulses with intensities comparable to those used in the experiment may also potentially beat [Y. Sentoku, et al., Appl. Phys. B 74, 207215 (2002)]. The details of a specific application, the injection of electrons into laser-driven plasma waves, will also be presented. With crossed beams, the energy of a laser-accelerated electron beam is increased and its emittance is decreased compared with a single beam, potentially paving the way towards an all-optical monoenergetic electron injector.

Electric energy production from food waste: Microbial fuel cells versus anaerobic digestion.

PubMed

Xin, Xiaodong; Ma, Yingqun; Liu, Yu

2018-05-01

A food waste resourceful process was developed by integrating the ultra-fast hydrolysis and microbial fuel cells (MFCs) for energy and resource recovery. Food waste was first ultra-fast hydrolyzed by fungal mash rich in hydrolytic enzymes in-situ produced from food waste. After which, the separated solids were readily converted to biofertilizer, while the liquid was fed to MFCs for direct electricity generation with a conversion efficiency of 0.245 kWh/kg food waste. It was estimated that about 192.5 million kWh of electricity could be produced from the food waste annually generated in Singapore, together with 74,390 tonnes of dry biofertilizer. Compared to anaerobic digestion, the proposed approach was more environmentally friendly and economically viable in terms of both electricity conversion and process cost. It is expected that this study may lead to the paradigm shift in food waste management towards ultra-fast concurrent recovery of resource and electricity with zero-solid discharge. Copyright © 2018 Elsevier Ltd. All rights reserved.

Microchip capillary gel electrophoresis using programmed field strength gradients for the ultra-fast analysis of genetically modified organisms in soybeans.

PubMed

Kim, Yun-Jeong; Chae, Joon-Seok; Chang, Jun Keun; Kang, Seong Ho

2005-08-12

We have developed a novel method for the ultra-fast analysis of genetically modified organisms (GMOs) in soybeans by microchip capillary gel electrophoresis (MCGE) using programmed field strength gradients (PFSG) in a conventional glass double-T microchip. Under the programmed electric field strength and 0.3% poly(ethylene oxide) sieving matrix, the GMO in soybeans was analyzed within only 11 s of the microchip. The MCGE-PFSG method was a program that changes the electric field strength during GMO analysis, and was also applied to the ultra-fast analysis of PCR products. Compared to MCGE using a conventional and constantly applied electric field, the MCGE-PFSG analysis generated faster results without the loss of resolving power and reproducibility for specific DNA fragments (100- and 250-bp DNA) of GM-soybeans. The MCGE-PFSG technique may prove to be a new tool in the GMO analysis due to its speed, simplicity, and high efficiency.

Organic photovoltaics: elucidating the ultra-fast exciton dissociation mechanism in disordered materials.

PubMed

Heitzer, Henry M; Savoie, Brett M; Marks, Tobin J; Ratner, Mark A

2014-07-14

Organic photovoltaics (OPVs) offer the opportunity for cheap, lightweight and mass-producible devices. However, an incomplete understanding of the charge generation process, in particular the timescale of dynamics and role of exciton diffusion, has slowed further progress in the field. We report a new Kinetic Monte Carlo model for the exciton dissociation mechanism in OPVs that addresses the origin of ultra-fast (<1 ps) dissociation by incorporating exciton delocalization. The model reproduces experimental results, such as the diminished rapid dissociation with increasing domain size, and also lends insight into the interplay between mixed domains, domain geometry, and exciton delocalization. Additionally, the model addresses the recent dispute on the origin of ultra-fast exciton dissociation by comparing the effects of exciton delocalization and impure domains on the photo-dynamics.This model provides insight into exciton dynamics that can advance our understanding of OPV structure-function relationships. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Feasibility and clinical utility of ultra-widefield indocyanine green angiography.

PubMed

Klufas, Michael A; Yannuzzi, Nicolas A; Pang, Claudine E; Srinivas, Sowmya; Sadda, Srinivas R; Freund, K Bailey; Kiss, Szilárd

2015-03-01

To evaluate the feasibility and clinical utility of a novel noncontact scanning laser ophthalmoscope-based ultra-widefield indocyanine green angiographic system. Ultra-widefield indocyanine green angiographic images were captured using a modified Optos P200Tx that produced high-resolution images of the choroidal vasculature with up to a 200° field. Ultra-widefield indocyanine green angiography was performed on patients with a variety of retinal conditions to assess utility of this imaging technique for diagnostic purposes and disease treatment monitoring. Ultra-widefield indocyanine green angiography was performed on 138 eyes of 69 patients. Mean age was 58 ± 16.9 years (range, 24-85 years). The most common ocular pathologies imaged included central serous chorioretinopathy (24 eyes), uveitis (various subtypes, 16 eyes), age-related macular degeneration (12 eyes), and polypoidal choroidal vasculopathy (4 eyes). In all eyes evaluated with ultra-widefield indocyanine green angiography, high-resolution images of choroidal and retinal circulation were obtained with sufficient detail out to 200° of the fundus. In this series of 138 eyes, scanning laser ophthalmoscope-based ultra-widefield indocyanine green angiography was clinically practical and provided detailed images of both the central and peripheral choroidal circulation. Future studies are needed to refine the clinical value of this imaging modality and the significance of peripheral choroidal vascular changes in the diagnosis, monitoring, and treatment of ocular diseases.

Conceptual design of laser fusion reactor KOYO-fast Concepts of reactor system and laser driver

NASA Astrophysics Data System (ADS)

Kozaki, Y.; Miyanaga, N.; Norimatsu, T.; Soman, Y.; Hayashi, T.; Furukawa, H.; Nakatsuka, M.; Yoshida, K.; Nakano, H.; Kubomura, H.; Kawashima, T.; Nishimae, J.; Suzuki, Y.; Tsuchiya, N.; Kanabe, T.; Jitsuno, T.; Fujita, H.; Kawanaka, J.; Tsubakimoto, K.; Fujimoto, Y.; Lu, J.; Matsuoka, S.; Ikegawa, T.; Owadano, Y.; Ueda, K.; Tomabechi, K.; Reactor Design Committee in Ife Forum, Members Of

2006-06-01

We have carried out the design studies of KOYO-Fast laser fusion power plant, using fast ignition cone targets, DPSSL lasers, and LiPb liquid wall chambers. Using fast ignition targets, we could design a middle sized 300 MWe reactor module, with 200 MJ fusion pulse energy and 4 Hz rep-rates, and 1200MWe modular power plants with 4 reactor modules and a 16 Hz laser driver. The liquid wall chambers with free surface cascade flows are proposed for cooling surface quickly enough to a 4 Hz pulse operation. We examined the potential of Yb-YAG ceramic lasers operated at 150˜ 225 K for both implosion and heating laser systems required for a 16-Hz repetition and 8 % total efficiency.

Effects of gap width on droplet transfer behavior in ultra-narrow gap laser welding of high strength aluminum alloys

NASA Astrophysics Data System (ADS)

Song, Chaoqun; Dong, Shiyun; Yan, Shixing; He, Jiawu; Xu, Binshi; He, Peng

2017-10-01

Ultra-narrow gap laser welding is a novel method for thick high strength aluminum alloy plate for its lower heat input, less deformation and higher efficiency. To obtain a perfect welding quality, it is vital to control the more complex droplet transfer behavior under the influence of ultra-narrow gap groove. This paper reports the effects of gap width of groove on droplet transfer behavior in ultra-narrow gap laser welding of 7A52 aluminum alloy plates by a high speed camera, using an ER 5356 filler wire. The results showed that the gap width had directly effects on droplet transfer mode and droplet shape. The droplet transfer modes were, in order, both-sidewall transfer, single-sidewall transfer, globular droplet transfer and bridging transfer, with different droplet shape and transition period, as the gap width increased from 2 mm to 3.5mm. The effect of gap width on lack of fusion was also studied to analyze the cause for lack of fusion at the bottom and on the sidewall of groove. Finally, with a 2.5 mm U-type parallel groove, a single-pass joint with no lack of fusion and other macro welding defects was successfully obtained in a single-sidewall transfer mode.

Tunable multiwavelength SOA fiber laser with ultra-narrow wavelength spacing based on nonlinear polarization rotation.

PubMed

Zhang, Zuxing; Wu, Jian; Xu, Kun; Hong, Xiaobin; Lin, Jintong

2009-09-14

A tunable multiwavelength fiber laser with ultra-narrow wavelength spacing and large wavelength number using a semiconductor optical amplifier (SOA) has been demonstrated. Intensity-dependent transmission induced by nonlinear polarization rotation in the SOA accounts for stable multiwavelength operation with wavelength spacing less than the homogenous broadening linewidth of the SOA. Stable multiwavelength lasing with wavelength spacing as small as 0.08 nm and wavelength number up to 126 is achieved at room temperature. Moreover, wavelength tuning of 20.2 nm is implemented via polarization tuning.

Fourier domain mode locking at 1050 nm for ultra-high-speed optical coherence tomography of the human retina at 236,000 axial scans per second.

PubMed

Huber, R; Adler, D C; Srinivasan, V J; Fujimoto, J G

2007-07-15

A Fourier domain mode-locked (FDML) laser at 1050 nm for ultra-high-speed optical coherence tomography (OCT) imaging of the human retina is demonstrated. Achievable performance, physical limitations, design rules, and scaling principles for FDML operation and component choice in this wavelength range are discussed. The fiber-based FDML laser operates at a sweep rate of 236 kHz over a 63 nm tuning range, with 7 mW average output power. Ultra-high-speed retinal imaging is demonstrated at 236,000 axial scans per second. This represents a speed improvement of approximately10x over typical high-speed OCT systems, paving the way for densely sampled volumetric data sets and new imaging protocols.

Catheter-based time-gated near-infrared fluorescence/OCT imaging system

NASA Astrophysics Data System (ADS)

Lu, Yuankang; Abran, Maxime; Cloutier, Guy; Lesage, Frédéric

2018-02-01

We developed a new dual-modality intravascular imaging system based on fast time-gated fluorescence intensity imaging and spectral domain optical coherence tomography (SD-OCT) for the purpose of interventional detection of atherosclerosis. A pulsed supercontinuum laser was used for fluorescence and OCT imaging. A double-clad fiber (DCF)- based side-firing catheter was designed and fabricated to have a 23 μm spot size at a 2.2 mm working distance for OCT imaging. Its single-mode core is used for OCT, while its inner cladding transports fluorescence excitation light and collects fluorescent photons. The combination of OCT and fluorescence imaging was achieved by using a DCF coupler. For fluorescence detection, we used a time-gated technique with a novel single-photon avalanche diode (SPAD) working in an ultra-fast gating mode. A custom-made delay chip was integrated in the system to adjust the delay between the excitation laser pulse and the SPAD gate-ON window. This technique allowed to detect fluorescent photons of interest while rejecting most of the background photons, thus leading to a significantly improved signal to noise ratio (SNR). Experiments were carried out in turbid media mimicking tissue with an indocyanine green (ICG) inclusion (1 mM and 100 μM) to compare the time-gated technique and the conventional continuous detection technique. The gating technique increased twofold depth sensitivity, and tenfold SNR at large distances. The dual-modality imaging capacity of our system was also validated with a silicone-based tissue-mimicking phantom.

Sensitive detection of nitric oxide using a 5.26 μm external cavity quantum cascade laser based QEPAS sensor

NASA Astrophysics Data System (ADS)

Tittel, Frank K.; Dong, Lei; Lewicki, Rafal; Lee, George; Peralta, Adjani; Spagnolo, Vincenzo

2012-01-01

The development and performance of a continuous wave (CW), thermoelectrically cooled (TEC) external cavity quantum cascade laser (EC-QCL) based sensor for quantitative measurements of nitric oxide (NO) concentrations in exhaled breath will be reported. Human breath contains ~ 400 different chemical species, usually at ultra low concentration levels, which can serve as biomarkers for the identification and monitoring of human diseases or wellness states. By monitoring exhaled NO concentration levels, a fast non-invasive diagnostic method for treatment of patients with asthma and chronic obstructive pulmonary disease (COPD) is feasible. The NO concentration measurements are performed with a 2f wavelength modulation based quartz enhanced photoacoustic spectroscopy (QEPAS) technique, which is very suitable for real time breath measurements, due to the fast gas exchange inside a compact QEPAS gas cell (<5 mm3 typical volume). In order to target the optimal interference free NO R (6.5) absorption doublet at 1900.08 cm-1(λ~5.263 μm) a Daylight Solutions Inc. widely tunable, mode-hop free 100 mW EC-QCL was used. The sensor reference channel includes a 10 cm long reference cell, filled with a 0.5% NO in N2 at 150 Torr, which is used for line-locking purpose. A minimum detection limit (1σ) for the EC-QCL based line locked NO sensor is ~5 ppbv with a 1 sec update time by a custom built control QCL compatible electronics unit.

Full-band error control and crack-free surface fabrication techniques for ultra-precision fly cutting of large-aperture KDP crystals

NASA Astrophysics Data System (ADS)

Zhang, F. H.; Wang, S. F.; An, C. H.; Wang, J.; Xu, Q.

2017-06-01

Large-aperture potassium dihydrogen phosphate (KDP) crystals are widely used in the laser path of inertial confinement fusion (ICF) systems. The most common method of manufacturing half-meter KDP crystals is ultra-precision fly cutting. When processing KDP crystals by ultra-precision fly cutting, the dynamic characteristics of the fly cutting machine and fluctuations in the fly cutting environment are translated into surface errors at different spatial frequency bands. These machining errors should be suppressed effectively to guarantee that KDP crystals meet the full-band machining accuracy specified in the evaluation index. In this study, the anisotropic machinability of KDP crystals and the causes of typical surface errors in ultra-precision fly cutting of the material are investigated. The structures of the fly cutting machine and existing processing parameters are optimized to improve the machined surface quality. The findings are theoretically and practically important in the development of high-energy laser systems in China.

Means and method for characterizing high power, ultra short laser pulses in a real time, on line manner

DOEpatents

Veligdan, J.T.

1994-03-08

An ultra short (<10 ps), high power laser pulse is temporally characterized by a system that uses a physical measurement of a wavefront that has been altered in a known manner. The system includes a first reflection switch to remove a portion of a pulse from a beam of pulses, then includes a second reflection switch, operating in a mode that is opposite to the first reflection switch, to slice off a portion of that removed portion. The sliced portion is then directed to a measuring device for physical measurement. The two reflection switches are arranged with respect to each other and with respect to the beam of ultra short pulses such that physical measurement of the sliced portion is related to the temporal measurement of the ultra short pulse by a geometric or trigonometric relationship. The reflection switches are operated by a control pulse that is directed to impinge on each of the reflection switches at a 90[degree] angle of incidence. 8 figures.

Means and method for characterizing high power, ultra short laser pulses in a real time, on line manner

DOEpatents

Veligdan, James T.

1994-01-01

An ultra short (<10 ps), high power laser pulse is temporally characterized by a system that uses a physical measurement of a wavefront that has been altered in a known manner. The system includes a first reflection switch to remove a portion of a pulse from a beam of pulses, then includes a second reflection switch, operating in a mode that is opposite to the first reflection switch, to slice off a portion of that removed portion. The sliced portion is then directed to a measuring device for physical measurement. The two reflection switches are arranged with respect to each other and with respect to the beam of ultra short pulses such that physical measurement of the sliced portion is related to the temporal measurement of the ultra short pulse by a geometric or trigonometric relationship. The reflection switches are operated by a control pulse that is directed to impinge on each of the reflection switches at a 90.degree. angle of incidence.

Simultaneous laser cutting and welding of metal foil to edge of a plate

DOEpatents

Pernicka, J.C.; Benson, D.K.; Tracy, C.E.

1996-03-19

A method is described for welding an ultra-thin foil to the edge of a thicker sheet to form a vacuum insulation panel comprising the steps of providing an ultra-thin foil having a thickness less than 0.002, providing a top plate having an edge and a bottom plate having an edge, clamping the foil to the edge of the plate wherein the clamps act as heat sinks to distribute heat through the foil, providing a laser, moving the laser relative to the foil and the plate edges to form overlapping weld beads to weld the foil to the plate edges while simultaneously cutting the foil along the weld line formed by the overlapping beads. 7 figs.

Sub-kilohertz excitation lasers for quantum information processing with Rydberg atoms

NASA Astrophysics Data System (ADS)

Legaie, Remy; Picken, Craig J.; Pritchard, Jonathan D.

2018-04-01

Quantum information processing using atomic qubits requires narrow linewidth lasers with long-term stability for high fidelity coherent manipulation of Rydberg states. In this paper, we report on the construction and characterization of three continuous-wave (CW) narrow linewidth lasers stabilized simultaneously to an ultra-high finesse Fabry-Perot cavity made of ultra-low expansion (ULE) glass, with a tunable offset-lock frequency. One laser operates at 852~nm while the two locked lasers at 1018~nm are frequency doubled to 509~nm for excitation of $^{133}$Cs atoms to Rydberg states. The optical beatnote at 509~nm is measured to be 260(5)~Hz. We present measurements of the offset between the atomic and cavity resonant frequencies using electromagnetically induced transparency (EIT) for high-resolution spectroscopy on a cold atom cloud. The long-term stability is determined from repeated spectra over a period of 20 days yielding a linear frequency drift of $\\sim1$~Hz/s.

Single-shot measurement of >1010 pulse contrast for ultra-high peak-power lasers

PubMed Central

Wang, Yongzhi; Ma, Jingui; Wang, Jing; Yuan, Peng; Xie, Guoqiang; Ge, Xulei; Liu, Feng; Yuan, Xiaohui; Zhu, Heyuan; Qian, Liejia

2014-01-01

Real-time pulse-contrast observation with a high dynamic range is a prerequisite to tackle the contrast challenge in ultra-high peak-power lasers. However, the commonly used delay-scanning cross-correlator (DSCC) can only provide the time-consumed measurements for repetitive lasers. Single-shot cross-correlator (SSCC) becomes essential in optimizing laser systems and exploring contrast mechanisms. Here we report our progress in developing SSCC towards its practical use. By integrating both the techniques of scattering-noise reduction and sensitive parallel detection into SSCC, we demonstrate a high dynamic range of >1010, which, to our best knowledge, is the first demonstration of an SSCC with a dynamic range comparable to that of commercial DSCCs. The comparison of high-dynamic measurement performances between SSCC and a standard DSCC (Sequoia, Amplitude Technologies) is also carried out on a 200 TW Ti:sapphire laser, and the consistency of results verifies the veracity of our SSCC. PMID:24448655

Physical Parameters, Modeling, and Methodological Details in Using IR Laser Pulses to Warm Frozen or Vitrified Cells Ultra-Rapidly†

PubMed Central

Kleinhans, F.W.; Mazur, Peter

2015-01-01

We report additional details of the thermal modeling, selection of the laser, and construction of the Cryo Jig used for our ultra-rapid warming studies of mouse oocytes (B Jin, FW Kleinhans, Peter Mazur, Cryobiology 68 (2014) 419–430). A Nd:YAG laser operating at 1064 nm was selected to deliver short 1 msec pulses of sufficient power to produce a warming rate of 1 × 107 °C/min from –190°C to 0°C. A special Cryo Jig was designed and built to rapidly remove the sample from LN2 and expose it to the laser pulse. India ink carbon black particles were required to increase the laser energy absorption of the sample. The thermal model reported here is more general than that previously reported. The modeling reveals that the maximum warming rate achievable via external warming across the cell membrane is proportional to (1/R2) where R is the cell radius. PMID:25724528

Multimodal evaluation of ultra-short laser pulses treatment for skin burn injuries.

PubMed

Santos, Moises Oliveira Dos; Latrive, Anne; De Castro, Pedro Arthur Augusto; De Rossi, Wagner; Zorn, Telma Maria Tenorio; Samad, Ricardo Elgul; Freitas, Anderson Zanardi; Cesar, Carlos Lenz; Junior, Nilson Dias Vieira; Zezell, Denise Maria

2017-03-01

Thousands of people die every year from burn injuries. The aim of this study is to evaluate the feasibility of high intensity femtosecond lasers as an auxiliary treatment of skin burns. We used an in vivo animal model and monitored the healing process using 4 different imaging modalities: histology, Optical Coherence Tomography (OCT), Second Harmonic Generation (SHG), and Fourier Transform Infrared (FTIR) spectroscopy. 3 dorsal areas of 20 anesthetized Wistar rats were burned by water vapor exposure and subsequently treated either by classical surgical debridement, by laser ablation, or left without treatment. Skin burn tissues were non-invasively characterized by OCT images and biopsied for further histopathology analysis, SHG imaging and FTIR spectroscopy at 3, 5, 7 and 14 days after burn. The laser protocol was found as efficient as the classical treatment for promoting the healing process. The study concludes to the validation of femtosecond ultra-short pulses laser treatment for skinburns, with the advantage of minimizing operatory trauma.

Reflectivity and laser ablation of ZrB2/Cu ultra high temperature ceramic

NASA Astrophysics Data System (ADS)

Yan, Zhenyu; Ma, Zhuang; Zhu, Shizhen; Liu, Ling; Xu, Qiang

2013-05-01

Ultra high temperature ceramics (UHTCs) were thought to be candidates for laser protective materials due to their high melting point, thermal shock and ablation resistance. The ablation behaviors of UHTCs like ZrB2 and its composite had been intensely investigated by the means of arc, plasma, oxyacetylene ablation. However, the ablation behavior under laser irradiation was still unknown by now. In this paper, the dense bulk composites of ZrB2/Cu were successfully sintered by spark plasma sintering (SPS) at 1650 degree C for 3min. The reflectivity of the composites measured by spectrophotometry achieved 60% in near infrared range and it decreased with the increasing wavelength of incident light. High intensity laser ablation was carried out on the ZrB2/Cu surface. The phase composition and microstructure changes before and after laser irradiation were characterized by X-ray diffraction and SEM respectively. The results revealed that the oxidation and melting were the main mechanisms during the ablation processing.

High resolution x-ray Thomson scattering measurements from cryogenic hydrogen jets using the linac coherent light source

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fletcher, L. B., E-mail: lbfletch@slac.stanford.edu; Galtier, E.; Gamboa, E. J.

2016-11-15

We present the first spectrally resolved measurements of x-rays scattered from cryogenic hydrogen jets in the single photon counting limit. The 120 Hz capabilities of the LCLS, together with a novel hydrogen jet design [J. B. Kim et al., Rev. Sci. Instrum. (these proceedings)], allow for the ability to record a near background free spectrum. Such high-dynamic-range x-ray scattering measurements enable a platform to study ultra-fast, laser-driven, heating dynamics of hydrogen plasmas. This measurement has been achieved using two highly annealed pyrolytic graphite crystal spectrometers to spectrally resolve 5.5 keV x-rays elastically and inelastically scattered from cryogenic hydrogen and focusedmore » on Cornell-SLAC pixel array detectors [S. Herrmann et al., Nucl. Instrum. Methods Phys. Res., Sect. A 718, 550 (2013)].« less

Ultra-high density aligned Carbon-nanotube with controled nano-morphology for supercapacitors

NASA Astrophysics Data System (ADS)

Ghaffari, Mehdi; Zhao, Ran; Liu, Yang; Zhou, Yue; Cheng, Jiping; Guzman de Villoria, Roberto; Wardle, B. L.; Zhang, Q. M.

2012-02-01

Recent advances in fabricating controlled-morphology vertically aligned carbon nanotubes (VA-CNTs) with ultrahigh volume fractioncreate unique opportunities for developing unconventional supercapacitors with ultra-high energy density, power density, and long charge/discharge cycle life.Continuous paths through inter-VA-CNT channels allow fast ion transport, and high electrical conduction of the aligned CNTs in the composite electrodes lead to fast discharge speed. We investigate the charge-discharge characteristics of VA-CNTs with >20 vol% of CNT and ionic liquids as electrolytes. By employing both the electric and electromechanical spectroscopes, as well as nanostructured materials characterization, the ion transport and storage behaviors in porous electrodes are studied. The results suggest pathways for optimizing the electrode morphology in supercapacitorsusing ultra-high volume fraction VA-CNTs to further enhance performance.

Fiber-laser frequency combs for the generation of tunable single-frequency laser lines, mm- and THz-waves and sinc-shaped Nyquist pulses

NASA Astrophysics Data System (ADS)

Schneider, Thomas

2015-03-01

High-quality frequency comb sources like femtosecond-lasers have revolutionized the metrology of fundamental physical constants. The generated comb consists of frequency lines with an equidistant separation over a bandwidth of several THz. This bandwidth can be broadened further to a super-continuum of more than an octave through propagation in nonlinear media. The frequency separation between the lines is defined by the repetition rate and the width of each comb line can be below 1 Hz, even without external stabilization. By extracting just one of these lines, an ultra-narrow linewidth, tunable laser line for applications in communications and spectroscopy can be generated. If two lines are extracted, the superposition of these lines in an appropriate photo-mixer produces high-quality millimeter- and THz-waves. The extraction of several lines can be used for the creation of almost-ideally sinc-shaped Nyquist pulses, which enable optical communications with the maximum-possible baud rate. Especially combs generated by low-cost, small-footprint fs-fiber lasers are very promising. However due to the resonator length, the comb frequencies have a typical separation of 80 - 100 MHz, far too narrow for the selection of single tones with standard optical filters. Here the extraction of single lines of an fs-fiber laser by polarization pulling assisted stimulated Brillouin scattering is presented. The application of these extracted lines as ultra-narrow, stable and tunable laser lines, for the generation of very high-quality mm and THz-waves with an ultra-narrow linewidth and phase noise and for the generation of sinc-shaped Nyquist pulses with arbitrary bandwidth and repetition rate is discussed.

Impedance self-matching ultra-narrow linewidth fiber resonator by use of a tunable π-phase-shifted FBG.

PubMed

Jing, Mingyong; Yu, Bo; Hu, Jianyong; Hou, Huifang; Zhang, Guofeng; Xiao, Liantuan; Jia, Suotang

2017-05-15

In this paper, we present a novel ultra-narrow linewidth fiber resonator formed by a tunable polarization maintaining (PM) π-phase-shifted fiber Bragg grating and a PM uniform fiber Bragg grating with a certain length of PM single mode fiber patch cable between them. Theoretical prediction shows that this resonator has ultra-narrow linewidth resonant peaks and is easy to realize impedance matching. We experimentally obtain 3 MHz narrow linewidth impedance matched resonant peak in a 7.3 m ultra-long passive fiber cavity. The impedance self-matching characteristic of this resonator also makes itself particularly suitable for use in ultra-sensitive sensors, ultra-narrow band rejection optical filters and fiber lasers applications.

[Investigation of non-ionizing radiation hazards from physiotherapy equipment in 16 medical institutions].

PubMed

He, Jia-xi; Zhou, Wei; Qiu, Hai-li; Yang, Guang-tao

2013-12-01

To investigate the non-ionizing radiation hazards from physiotherapy equipment in medical institutions and to explore feasible control measures for occupational diseases. On-site measurement and assessment of ultra-high-frequency radiation, high-frequency electromagnetic field, microwave radiation, and laser radiation were carried out in 16 medical institutions using the methods in the Measurement of Physical Agents in Workplace (GBZ/T189-2007). All the investigated medical institutions failed to take effective protective measures against non-ionizing radiation. Of the 17 ultra-short wave therapy apparatus, 70.6%, 47.1%, and 17.64% had a safe intensity of ultra-high-frequency radiation on the head, chest, and abdomen, respectively. Of the 4 external high-frequency thermotherapy apparatus, 100%, 75%, and 75%had a safe intensity of high-frequency electromagnetic field on the head, chest, and abdomen, respectively. In addition, the intensities of microwave radiation and laser radiation produced by the 18 microwave therapy apparatus and 12 laser therapeutic apparatus met national health standards. There are non-ionizing radiation hazards from physiotherapy equipment in medical institutions, and effective prevention and control measures are necessary.

An ultra-wideband tunable multi-wavelength Brillouin fibre laser based on a semiconductor optical amplifier and dispersion compensating fibre in a linear cavity configuration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zulkifli, M Z; Ahmad, H; Hassan, N A

2011-07-31

A multi-wavelength Brillouin fibre laser (MBFL) with an ultra-wideband tuning range from 1420 nm to 1620 nm is demonstrated. The MBFL uses an ultra-wideband semiconductor optical amplifier (SOA) and a dispersion compensating fibre (DCF) as the linear gain medium and nonlinear gain medium, respectively. The proposed MBFL has a wide tuning range covering the short (S-), conventional (C-) and long (L-) bands with a wavelength spacing of 0.08 nm, making it highly suitable for DWDM system applications. The output power of the observed Brillouin Stokes ranges approximately from -5.94 dBm to -0.41 dBm for the S-band, from -4.34 dBm tomore » 0.02 dBm for the C-band and from -2.19 dBm to 0.39 dBm for the L-band. The spacing between each adjacent wavelengths of all the three bands is about 0.08 nm, which is approximately 10.7 GHz for the frequency domain. (lasers)« less

Picosecond laser bonding of highly dissimilar materials

NASA Astrophysics Data System (ADS)

Carter, Richard M.; Troughton, Michael; Chen, Jianyong; Elder, Ian; Thomson, Robert R.; Lamb, Robert A.; Esser, M. J. Daniel; Hand, Duncan P.

2016-10-01

We report on recent progress in developing an industrially relevant, robust technique to bond dissimilar materials through ultra-fast microwelding. This technique is based on the use of a 5.9ps, 400kHz Trumpf laser operating at 1030nm. Tight focusing of the laser radiation at, or around, the interface between two materials allows for simultaneous absorption in both. This absorption rapidly, and locally, heats the material forming plasma from both materials. With suitable surface preparation this plasma can be confined to the interface region where it mixes, cools and forms a weld between the two materials. The use of ps pulses results in a short interaction time. This enables a bond to form whilst limiting the heat affected zone (HAZ) to a region of only a few hundred micrometres across. This small scale allows for the bonding of materials with highly dissimilar thermal properties, and in particular coefficients of thermal expansion e.g. glass-metal bonding. We report on our results for a range of material combinations including, Al-Bk7, Al-SiO2 and Nd:YAG-AlSi. Emphasis will be laid on the technical requirements for bonding including the required surface preparation of the two materials and on the laser parameters required. The quality of the resultant bonds are characterized through shear force measurements (where strengths equal to and exceeding equivalent adhesives will be presented). The lifetime of the welds is also discussed, paying particular attention to the results of thermal cycling tests.

Development of sub-100 femtosecond timing and synchronization system

NASA Astrophysics Data System (ADS)

Lin, Zhenyang; Du, Yingchao; Yang, Jin; Xu, Yilun; Yan, Lixin; Huang, Wenhui; Tang, Chuanxiang; Huang, Gang; Du, Qiang; Doolittle, Lawrence; Wilcox, Russell; Byrd, John

2018-01-01

The precise timing and synchronization system is an essential part for the ultra-fast electron and X-ray sources based on the photocathode injector where strict synchronization among RF, laser, and beams are required. In this paper, we present an integrated sub-100 femtosecond timing and synchronization system developed and demonstrated recently in Tsinghua University based on the collaboration with Lawrence Berkeley National Lab. The timing and synchronization system includes the fiber-based CW carrier phase reference distribution system for delivering stabilized RF phase reference to multiple receiver clients, the Low Level RF (LLRF) control system to monitor and generate the phase and amplitude controllable pulse RF signal, and the laser-RF synchronization system for high precision synchronization between optical and RF signals. Each subsystem is characterized by its blocking structure and is also expansible. A novel asymmetric calibration sideband signal method was proposed for eliminating the non-linear distortion in the optical synchronization process. According to offline and online tests, the system can deliver a stable signal to each client and suppress the drift and jitter of the RF signal for the accelerator and the laser oscillator to less than 100 fs RMS (˜0.1° in 2856 MHz frequency). Moreover, a demo system with a LLRF client and a laser-RF synchronization client is deployed and operated successfully at the Tsinghua Thomson scattering X-ray source. The beam-based jitter measurement experiments have been conducted to evaluate the overall performance of the system, and the jitter sources are discussed.

Development of sub-100 femtosecond timing and synchronization system.

PubMed

Lin, Zhenyang; Du, Yingchao; Yang, Jin; Xu, Yilun; Yan, Lixin; Huang, Wenhui; Tang, Chuanxiang; Huang, Gang; Du, Qiang; Doolittle, Lawrence; Wilcox, Russell; Byrd, John

2018-01-01

The precise timing and synchronization system is an essential part for the ultra-fast electron and X-ray sources based on the photocathode injector where strict synchronization among RF, laser, and beams are required. In this paper, we present an integrated sub-100 femtosecond timing and synchronization system developed and demonstrated recently in Tsinghua University based on the collaboration with Lawrence Berkeley National Lab. The timing and synchronization system includes the fiber-based CW carrier phase reference distribution system for delivering stabilized RF phase reference to multiple receiver clients, the Low Level RF (LLRF) control system to monitor and generate the phase and amplitude controllable pulse RF signal, and the laser-RF synchronization system for high precision synchronization between optical and RF signals. Each subsystem is characterized by its blocking structure and is also expansible. A novel asymmetric calibration sideband signal method was proposed for eliminating the non-linear distortion in the optical synchronization process. According to offline and online tests, the system can deliver a stable signal to each client and suppress the drift and jitter of the RF signal for the accelerator and the laser oscillator to less than 100 fs RMS (∼0.1° in 2856 MHz frequency). Moreover, a demo system with a LLRF client and a laser-RF synchronization client is deployed and operated successfully at the Tsinghua Thomson scattering X-ray source. The beam-based jitter measurement experiments have been conducted to evaluate the overall performance of the system, and the jitter sources are discussed.

Power and polarization dependences of ultra-narrow electromagnetically induced absorption (EIA) spectra of 85 Rb atoms in degenerate two-level system

NASA Astrophysics Data System (ADS)

Qureshi, Muhammad Mohsin; Rehman, Hafeez Ur; Noh, Heung-Ryoul; Kim, Jin-Tae

2016-05-01

We have investigated ultra-narrow EIA spectral features with respect to variations of polarizations and powers of pump laser beam in a degenerate two-level system of the transition of 85 Rb D2 transition line. Polarizations of the probe laser beam in two separate experiments were fixed at right circular and horizontal linear polarizations, respectively while the polarizations of the pump lasers were varied from initial polarizations same as the probe laser beams to orthogonal to probe polarizations. One homemade laser combined with AOMs was used to the pump and probe laser beams instead of two different lasers to overcome broad linewidths of the homemade lasers. Theoretically, probe absorption coefficients have been calculated from optical Bloch equations of the degenerate two level system prepared by a pump laser beam. In the case of the circular polarization, EIA signal was obtained as expected theoretically although both pump and probe beams have same polarization. The EIA signal become smaller as power increases and polarizations of the pump and probe beams were same. When the polarization of the pump beam was linear polarization, maximum EIA signal was obtained theoretically and experimentally. Experimental EIA spectral shapes with respect to variations of the pump beam polarization shows similar trends as the theoretical results.

Fabrication et applications des reseaux de Bragg ultra-longs

NASA Astrophysics Data System (ADS)

Gagne, Mathieu

This thesis presents the principal accomplishments realized during the PhD project. The thesis is presented by publication format and is a collection of four published articles having fiber Bragg gratings as a central theme. First achieved in 1978, UV writing of fiber Bragg gratings is nowadays a common and mature technology being present in both industry and academia. The property of reflecting light guided by optical fibers lead to diverse applications in telecommunication, lasers as well as several types of sensors. The conventional fabrication technique is generally based on the use of generally expensive phase masks which determine the obtained characteristics of the fiber Bragg grating. The fiber being photosensitive at those wavelengths, a periodic pattern can be written into it. The maximal length, the period, the chirp, the index contrast and the apodisation are all characteristics that depend on the phase mask. The first objective of the research project is to be able to go beyond this strong dependance on the phase mask without deteriorating grating quality. This is what really sets apart the technique presented in this thesis from other long fiber Bragg grating fabrication techniques available in the literature. The fundamental approach to obtain ultra long fiber Bragg gratings of arbitrary profile is to replace the scheme of scanning a UV beam across a phase mask to expose a fixed fiber by a scheme where the UV beam and phase mask are fixed and where the fiber is moving instead. To obtain a periodic index variation, the interference pattern itself must be synchronized with the moving fiber. Two variations of this scheme were implanted: the first one using electro-optical phase modulator placed in each arm of a Talbot interferometer and the second one using a phase mask mounted on a piezo electric actuator. A new scheme that imparts fine movements of the interferometer is also implemented for the first time and showed to be essential to achieve high quality ultra long fiber Bragg gratings. High quality theory matching ultra long fiber Bragg gratings up to 1 meter long are obtained for the first time. The possibility of fabricating high quality ultra long fiber Bragg grating of more than 10 cm (approximately the maximal phase mask length) opens a variety of new applications otherwise impossible with short fiber Bragg grating technology. Ultra long fiber Bragg gratings have unique characteristics such as high reflectivity, high dispersion and ultra narrow bandwidth. Those characteristics can be used to do advanced signal processing, non linear propagation experiments, distributed feedback fiber lasers and dispersion compensator for telecommunication or optical tomography. The second objective of this project is to use these ultra-long fiber Bragg gratings as an optical cavity for fiber lasers. Alot of research in the past years have been concentrated on those lasers, particularly on distributed feedback fiber lasers where the gratings spans all the gain media. A new random fiber laser configuration is presented. It is based on passive or active insertion of phase shifts along the Bragg grating to obtained a phenomenon called light localization which is the optical equivalent of Anderson localization. This complex wave phenomenon has the unique property to mimic the reflection of a uniform photonic crystal with the random diffusion of light among the elements of a random media. Being commonly obtained in fine powders which must respect a certain set of rules, the realization of 1D structures is vastly simplified in optical fibers. Two random fiber laser schemes based on light localization, one using erbium dopant and the other one Raman scattering, are demonstrated for the first time and compared to traditional distributed feedback fiber lasers.

Study of Volumetrically Heated Ultra-High Energy Density Plasmas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rocca, Jorge J.

2016-10-27

Heating dense matter to millions of degrees is important for applications, but requires complex and expensive methods. The major goal of the project was to demonstrate using a compact laser the creation of a new ultra-high energy density plasma regime characterized by simultaneous extremely high temperature and high density, and to study it combining experimental measurements and advanced simulations. We have demonstrated that trapping of intense femtosecond laser pulses deep within ordered nanowire arrays can heat near solid density matter into a new ultra hot plasma regime. Extreme electron densities, and temperatures of several tens of million degrees were achievedmore » using laser pulses of only 0.5 J energy from a compact laser. Our x-ray spectra and simulations showed that extremely highly ionized plasma volumes several micrometers in depth are generated by irradiation of gold and Nickel nanowire arrays with femtosecond laser pulses of relativistic intensities. We obtained extraordinarily high degrees of ionization (e.g. we peeled 52 electrons from gold atoms, and up to 26 electrons from nickel atoms). In the process we generated Gigabar pressures only exceeded in the central hot spot of highly compressed thermonuclear fusion plasmas.. The plasma created after the dissolved wires expand, collide, and thermalize, is computed to have a thermal energy density of 0.3 GJ cm -3 and a pressure of 1-2 Gigabar. These are pressures only exceeded in highly compressed thermonuclear fusion plasmas. Scaling these results to higher laser intensities promises to create plasmas with temperatures and pressures exceeding those in the center of the sun.« less

Linear and Nonlinear Molecular Spectroscopy with Laser Frequency Combs

NASA Astrophysics Data System (ADS)

Picque, Nathalie

2013-06-01

The regular pulse train of a mode-locked femtosecond laser can give rise to a comb spectrum of millions of laser modes with a spacing precisely equal to the pulse repetition frequency. Laser frequency combs were conceived a decade ago as tools for the precision spectroscopy of atomic hydrogen. They are now becoming enabling tools for an increasing number of applications, including molecular spectroscopy. Recent experiments of multi-heterodyne frequency comb Fourier transform spectroscopy (also called dual-comb spectroscopy) have demonstrated that the precisely spaced spectral lines of a laser frequency comb can be harnessed for new techniques of linear absorption spectroscopy. The first proof-of-principle experiments have demonstrated a very exciting potential of dual-comb spectroscopy without moving parts for ultra-rapid and ultra-sensitive recording of complex broad spectral bandwidth molecular spectra. Compared to conventional Michelson-based Fourier transform spectroscopy, recording times could be shortened from seconds to microseconds, with intriguing prospects for spectroscopy of short lived transient species. The resolution improves proportionally to the measurement time. Therefore longer recordings allow high resolution spectroscopy of molecules with extreme precision, since the absolute frequency of each laser comb line can be known with the accuracy of an atomic clock. Moreover, since laser frequency combs involve intense ultrashort laser pulses, nonlinear interactions can be harnessed. Broad spectral bandwidth ultra-rapid nonlinear molecular spectroscopy and imaging with two laser frequency combs is demonstrated with coherent Raman effects and two-photon excitation. Real-time multiplex accessing of hyperspectral images may dramatically expand the range of applications of nonlinear microscopy. B. Bernhardt et al., Nature Photonics 4, 55-57 (2010); A. Schliesser et al. Nature Photonics 6, 440-449 (2012); T. Ideguchi et al. arXiv:1201.4177 (2012) T. Ideguchi et al., Optics letters 37, 4498-4500 (2012); T. Ideguchi et al. arXiv:1302.2414 (2013)

Applications of Ultra-Intense, Short Laser Pulses

NASA Astrophysics Data System (ADS)

Ledingham, Ken W. D.

The high intensity laser production of electron, proton, ion and photon beams is reviewed particularly with respect to the laser-plasma interaction which drives the acceleration process. A number of applications for these intense short pulse beams is discussed e.g. ion therapy, PET isotope production and laser driven transmutation studies. The future for laser driven nuclear physics at the huge new, multi-petawatt proposed laser installation ELI in Bucharest is described. Many people believe this will take European nuclear research to the next level.

Intense ionizing radiation from laser-induced processes in ultra-dense deuterium D(-1)

NASA Astrophysics Data System (ADS)

Olofson, Frans; Holmlid, Leif

2014-09-01

Nuclear fusion in ultra-dense deuterium D(-1) has been reported from our laboratory in a few studies using pulsed lasers with energy < 0.2 J. The direct observation of massive particles with energy 1-20 MeV u-1 is conclusive proof for fusion processes, either as a cause or as a result. Continuing the step-wise approach necessary for untangling a complex problem, the high-energy photons from the laser-induced plasma are now studied. The focus is here on the photoelectrons formed. The photons penetrating a copper foil have energy > 80 keV. The total charge created is up to 2 μC or 1 × 1013 photoelectrons per laser shot at 0.13 J pulse energy, assuming isotropic photon emission. The variation of the photoelectron current with laser intensity is faster than linear for some systems, which indicates rapid approach to volume ignition. On a permanent magnet at approximately 1 T, a laser pulse-energy threshold exists for the laser-induced processes probably due to the floating of most clusters of D(-1) in the magnetic field. This Meissner effect was reported previously.

Ultrashort laser pulse processing of wave guides for medical applications

NASA Astrophysics Data System (ADS)

Ashkenasi, David; Rosenfeld, Arkadi; Spaniol, Stefan B.; Terenji, Albert

2003-06-01

The availability of ultra short (ps and sub-ps) pulsed lasers has stimulated a growing interest in exploiting the enhanced flexibility of femtosecond and/or picosecond laser technology for micro-machining. The high peak powers available at relatively low single pulse energies potentially allow for a precise localization of photon energy, either on the surface or inside (transparent) materials. Three dimensional micro structuring of bulk transparent media without any sign of mechanical cracking has been demonstrated. In this study, the potential of ultra short laser processing was used to modify the cladding-core interface in normal fused silica wave guides. The idea behind this technique is to enforce a local mismatch for total reflection at the interface at minimal mechanic stress. The laser-induced modifications were studied in dependence of pulse width, focal alignment, single pulse energy and pulse overlap. Micro traces with a thickness between 3 and 8 μm were generated with a spacing of 10 μm in the sub-surface region using sub-ps and ps laser pulses at a wavelength of 800 nm. The optical leakage enforced by a micro spiral pattern is significant and can be utilized for medical applications or potentially also for telecommunications and fiber laser technology.

Local Resistance Profiling of Ultra-Shallow Junction with Spike Lamp and Laser Annealing Using Scanning Spreading Resistance Microscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abo, Satoshi; Tanaka, Yuji; Nishikawa, Kazuhisa

2008-11-03

Local resistance profiles of ultra-shallow arsenic implanted into silicon with an energy of 3.5 keV and a dose of 1.2x10{sup 15} ions/cm{sup 2} activated by conventional spike lamp and laser annealing were measured by SSRM in a nitrogen atmosphere with a depth resolution of less than 10 nm for investigating the combination of the conventional spike lamp and laser annealing. Spike lamp annealing at 1050 deg. C followed by laser annealing at a power density of 0.42 kW/mm{sup 2} was found to give the lowest sheet resistance. The resistance profiles obtained by SSRM also indicated the lowest resistance for themore » sample after spike lamp annealing at 1050 deg. C followed by laser annealing with a power density of 0.42 kW/mm{sup 2}. Laser annealing alone with a power density of 0.42 kW/mm{sup 2} resulted in the higher sheet resistance, though the shallower resistance profile could be obtained. Spike lamp annealing followed by laser annealing procedures are effective in activating shallow arsenic profiles.« less

Atomistic simulations of ultra-short pulse laser ablation of aluminum: validity of the Lambert-Beer law

NASA Astrophysics Data System (ADS)

Eisfeld, Eugen; Roth, Johannes

2018-05-01

Based on hybrid molecular dynamics/two-temperature simulations, we study the validity of the application of Lambert-Beer's law, which is conveniently used in various modeling approaches of ultra-short pulse laser ablation of metals. The method is compared to a more rigorous treatment, which involves solving the Helmholtz wave equation for different pulse durations ranging from 100 fs to 5 ps and a wavelength of 800 nm. Our simulations show a growing agreement with increasing pulse durations, and we provide appropriate optical parameters for all investigated pulse durations.

The improvement of laser induced damage resistance of optical workpiece surface by hydrodynamic effect polishing

NASA Astrophysics Data System (ADS)

Peng, Wenqiang; Guan, Chaoliang; Li, Shengyi; Wang, Zhuo

2016-10-01

Surface and subsurface damage in optical element will greatly decrease the laser induced damage threshold (LIDT) in the intense laser optical system. Processing damage on the workpiece surface can be inevitably caused when the material is removed in brittle or plastic mode. As a non-contact polishing technology, hydrodynamic effect polishing (HEP) shows very good performance on generating an ultra-smooth surface without damage. The material is removed by chemisorption between nanoparticle and workpiece surface in the elastic mode in HEP. The subsurface damage and surface scratches can be effectively removed after the polishing process. Meanwhile ultra-smooth surface with atomic level surface roughness can be achieved. To investigate the improvement of LIDT of optical workpiece, polishing experiment was conducted on a magnetorheological finishing (MRF) silica glass sample. AFM measurement results show that all the MRF directional plastic marks have been removed clearly and the root-mean-square (rms) surface roughness has decreased from 0.673nm to 0.177nm after HEP process. Laser induced damage experiment was conducted with laser pulse of 1064nm wavelength and 10ns time width. Compared with the original state, the LEDT of the silica glass sample polished by HEP has increased from 29.78J/cm2 to 45.47J/cm2. It demonstrates that LIDT of optical element treated by HEP can be greatly improved for ultra low surface roughness and nearly defect-free surface/subsurface.

kW-class direct diode laser for sheet metal cutting based on DWDM of pump modules by use of ultra-steep dielectric filters.

PubMed

Witte, U; Schneider, F; Traub, M; Hoffmann, D; Drovs, S; Brand, T; Unger, A

2016-10-03

A direct diode laser was built with > 800 W output power at 940 nm to 980 nm. The radiation is coupled into a 100 µm fiber and the NA ex fiber is 0.17. The laser system is based on pump modules that are wavelength stabilized by VBGs. Dense and coarse wavelength multiplexing are realized with commercially available ultra-steep dielectric filters. The electro-optical efficiency is above 30%. Based on a detailed analysis of losses, an improved e-o-efficiency in the range of 40% to 45% is expected in the near future. System performance and reliability were demonstrated with sheet metal cutting tests on stainless steel with a thickness of 4.2 mm.

Design and demonstration of ultra-fast W-band photonic transmitter-mixer and detectors for 25 Gbits/sec error-free wireless linking.

PubMed

Chen, Nan-Wei; Shi, Jin-Wei; Tsai, Hsuan-Ju; Wun, Jhih-Min; Kuo, Fong-Ming; Hesler, Jeffery; Crowe, Thomas W; Bowers, John E

2012-09-10

A 25 Gbits/s error-free on-off-keying (OOK) wireless link between an ultra high-speed W-band photonic transmitter-mixer (PTM) and a fast W-band envelope detector is demonstrated. At the transmission end, the high-speed PTM is developed with an active near-ballistic uni-traveling carrier photodiode (NBUTC-PD) integrated with broadband front-end circuitry via the flip-chip bonding technique. Compared to our previous work, the wireless data rate is significantly increased through the improvement on the bandwidth of the front-end circuitry together with the reduction of the intermediate-frequency (IF) driving voltage of the active NBUTC-PD. The demonstrated PTM has a record-wide IF modulation (DC-25 GHz) and optical-to-electrical fractional bandwidths (68-128 GHz, ~67%). At the receiver end, the demodulation is realized with an ultra-fast W-band envelope detector built with a zero-bias Schottky barrier diode with a record wide video bandwidth (37 GHz) and excellent sensitivity. The demonstrated PTM is expected to find applications in multi-gigabit short-range wireless communication.

Nine time steps: ultra-fast statistical consistency testing of the Community Earth System Model (pyCECT v3.0)

NASA Astrophysics Data System (ADS)

Milroy, Daniel J.; Baker, Allison H.; Hammerling, Dorit M.; Jessup, Elizabeth R.

2018-02-01

The Community Earth System Model Ensemble Consistency Test (CESM-ECT) suite was developed as an alternative to requiring bitwise identical output for quality assurance. This objective test provides a statistical measurement of consistency between an accepted ensemble created by small initial temperature perturbations and a test set of CESM simulations. In this work, we extend the CESM-ECT suite with an inexpensive and robust test for ensemble consistency that is applied to Community Atmospheric Model (CAM) output after only nine model time steps. We demonstrate that adequate ensemble variability is achieved with instantaneous variable values at the ninth step, despite rapid perturbation growth and heterogeneous variable spread. We refer to this new test as the Ultra-Fast CAM Ensemble Consistency Test (UF-CAM-ECT) and demonstrate its effectiveness in practice, including its ability to detect small-scale events and its applicability to the Community Land Model (CLM). The new ultra-fast test facilitates CESM development, porting, and optimization efforts, particularly when used to complement information from the original CESM-ECT suite of tools.

The Soft X-ray View of Ultra Fast Outflows

NASA Astrophysics Data System (ADS)

Reeves, J.; Braito, V.; Nardini, E.; Matzeu, G.; Lobban, A.; Costa, M.; Pounds, K.; Tombesi, F.; Behar, E.

2017-10-01

The recent large XMM-Newton programmes on the nearby quasars PDS 456 and PG 1211+143 have revealed prototype ultra fast outflows in the iron K band through highly blue shifted absorption lines. The wind velocities are in excess of 0.1c and are likely to make a significant contribution to the host galaxy feedback. Here we present evidence for the signature of the fast wind in the soft X-ray band from these luminous quasars, focusing on the spectroscopy with the RGS. In PDS 456, the RGS spectra reveal the presence of soft X-ray broad absorption line profiles, which suggests that PDS 456 is an X-ray equivalent to the BAL quasars, with outflow velocities reaching 0.2c. In PG 1211, the soft X-ray RGS spectra show a complex of several highly blue shifted absorption lines over a wide range of ionisation and reveal outflowing components with velocities between 0.06-0.17c. For both quasars, the soft X-ray absorption is highly variable, even on timescales of days and is most prominent when the quasar flux is low. Overall the results imply the presence of a soft X-ray component of the ultra fast outflows, which we attribute to a clumpy or inhomogeneous phase of the disk wind.

Acousto-Optic Tunable Filter for Time-Domain Processing of Ultra-Short Optical Pulses,

DTIC Science & Technology

The application of acousto - optic tunable filters for shaping of ultra-fast pulses in the time domain is analyzed and demonstrated. With the rapid...advance of acousto - optic tunable filter (AOTF) technology, the opportunity for sophisticated signal processing capabilities arises. AOTFs offer unique

Terahertz Imaging of Subjects With Concealed Weapons

DTIC Science & Technology

2006-05-01

pulsed imaging", Advanced Characterization, Therapeutics, and Systems XIV, Proceedings of SPIE, Vol. 5318: 23-33 6. Anthony E. Siegman , Lasers , p667...imagery. Both methods made use of in-house transceivers, consisting of two ultra-stable far-infrared lasers , terahertz heterodyne detection systems...SYSTEM The 1.56THz transceiver system at STL uses two carbon dioxide lasers paired individually with two far-infrared lasers . All four units are

[Flexible Guidance of Ultra-Short Laser Pulses in Ophthalmic Therapy Systems].

PubMed

Blum, J; Blum, M; Rill, M S; Haueisen, J

2017-01-01

In the last 20 years, the role of ultrashort pulsed lasers in ophthalmology has become increasingly important. However, it is still impossible to guide ultra-short laser pulses with standard glass fibres. The highly energetic femtosecond pulses would destroy the fibre material, and non-linear dispersion effects would significantly change beam parameters. In contrast, photonic crystal fibres mainly guide the laser pulses in air, so that absorption and dispersive pulse broadening have essentially no effect. This article compares classical beam guidance with mirrors, lenses and prisms with photonic crystal fibres and describes the underlying concepts and the current state of technology. A classical mirror arm possesses more variable optical properties, while the HCF (Hollow-Core Photonic Crystal Fibre) must be matched in terms of the laser energy and the laser spectrum. In contrast, the HCF has more advantages in respect of handling, system integration and costs. For applications based on photodisruptive laser-tissue interaction, the relatively low damage threshold of photonic crystal fibres compared to classic beam guiding systems is unacceptable. If, however, pulsed laser radiation has a sufficiently low peak intensity, e.g. as used for plasma-induced ablation, photonic crystal fibres can definitely be considered as an alternative solution to classic beam guidance. Georg Thieme Verlag KG Stuttgart · New York.

Developing a new supplemental lighting device with ultra-bright white LED for vegetables

NASA Astrophysics Data System (ADS)

Hu, Yongguang; Li, Pingping; Jiang, Jianghai

2007-02-01

It has been proved that monochromatic or compound light-emitting diode (LED) or laser diode (LD) can promote the photosynthesis of horticultural crops, but the promotion of polychromatic light like white LED is unclear. A new type of ultra-bright white LED (LUW56843, InGaN, \

Ultra-fast photon counting with a passive quenching silicon photomultiplier in the charge integration regime

NASA Astrophysics Data System (ADS)

Zhang, Guoqing; Lina, Liu

2018-02-01

An ultra-fast photon counting method is proposed based on the charge integration of output electrical pulses of passive quenching silicon photomultipliers (SiPMs). The results of the numerical analysis with actual parameters of SiPMs show that the maximum photon counting rate of a state-of-art passive quenching SiPM can reach ~THz levels which is much larger than that of the existing photon counting devices. The experimental procedure is proposed based on this method. This photon counting regime of SiPMs is promising in many fields such as large dynamic light power detection.

Bright Two-Photon Emission and Ultra-Fast Relaxation Dynamics in a DNA-Templated Nanocluster Investigated by Ultra-Fast Spectroscopy

DTIC Science & Technology

2012-01-01

Michigan 3003 S. State St Ann Arbor, MI 48109 -1274 REPORT DOCUMENTATION PAGE b . ABSTRACT UU c. THIS PAGE UU 2. REPORT TYPE New Reprint 17. LIMITATION OF...Figure 1: Steady state absorption for Au25 Au55, Au140, Au2406 and Mie theory calculation using parameter similar to Au25.7 B . Emission Mechanism of...short-lived (hundreds of fs), and it is most likely to be associated with the metal core (State B ).7,17 The near-infrared emission is related to the

Ultra-fast switching blue phase liquid crystals diffraction grating stabilized by chiral monomer

NASA Astrophysics Data System (ADS)

Manda, Ramesh; Pagidi, Srinivas; Sarathi Bhattacharya, Surjya; Yoo, Hyesun; T, Arun Kumar; Lim, Young Jin; Lee, Seung Hee

2018-05-01

We have demonstrated an ultra-fast switching and efficient polymer stabilized blue phase liquid crystal (PS-BPLC) diffraction grating utilizing a chiral monomer. We have obtained a 0.5 ms response time by a novel polymer stabilization method which is three times faster than conventional PS-BPLC. In addition, the diffraction efficiency was improved 2% with a much wider phase range and the driving voltage to switch the device is reduced. The polarization properties of the diffracted beam are unaffected by this novel polymer stabilization. This device can be useful for future photonic applications.

X-ray Emission Characteristics of Ultra-High Energy Density Relativistic Plasmas Created by Ultrafast Laser Irradiation of Nanowire Arrays

NASA Astrophysics Data System (ADS)

Hollinger, R. C.; Bargsten, C.; Shlyaptsev, V. N.; Pukhov, A.; Purvis, M. A.; Townsend, A.; Keiss, D.; Wang, Y.; Wang, S.; Prieto, A.; Rocca, J. J.

2014-10-01

Irradiation of ordered nanowire arrays with high contrast femtosecond laser pulses of relativistic intensity creates volumetrically heated near solid density plasmas characterized by multi-KeV temperatures and extreme degrees of ionization. The large hydrodynamic-to-radiative lifetime ratio of these plasmas results in very efficient X-ray generation. Au nanowire array plasmas irradiated at I 5×1018 Wcm-2 are measured to convert ~ 5 percent of the laser energy into h ν > 0.9 KeV X-rays, and >1 × 10-4 into h ν > 9 KeV photons, creating bright picosecond X-ray sources. The angular distribution of the higher energy photons is measured to change from isotropic into annular as the intensity increases, while softer X-ray emission (h ν >1 KeV) remains isotropic and nearly unchanged. Model simulations suggest the unexpected annular distribution of the hard X-rays might result from bremsstrahlung of fast electrons confined in a high aspect ratio near solid density plasma in which the electron-ion collision mean free-path is of the order of the plasma thickness. Work supported by the U.S Department of Energy, Fusion Energy Sciences and the Defense Threat Reduction Agency Grant HDTRA-1-10-1-0079. A.P was supported by of DFG-funded project TR18.

Noncontact phase-sensitive dynamic optical coherence elastography at megahertz rate

NASA Astrophysics Data System (ADS)

Singh, Manmohan; Wu, Chen; Liu, Chih-Hao; Li, Jiasong; Schill, Alexander; Nair, Achuth; Kistenev, Yury V.; Larin, Kirill V.

2016-03-01

Dynamic optical coherence elastography (OCE) techniques have shown great promise at quantitatively obtaining the biomechanical properties of tissue. However, the majority of these techniques have required multiple temporal OCT acquisitions (M-B mode) and corresponding excitations, which lead to clinically unfeasible acquisition times and potential tissue damage. Furthermore, the large data sets and extended laser exposures hinder their translation to the clinic, where patient discomfort and safety are critical criteria. In this work we demonstrate noncontact true kilohertz frame-rate dynamic optical coherence elastography by directly imaging a focused air-pulse induced elastic wave with a home-built phase-sensitive OCE system based on a 4X buffered Fourier Domain Mode Locked swept source laser with an A-scan rate of ~1.5 MHz. The elastic wave was imaged at a frame rate of ~7.3 kHz using only a single excitation. In contrast to previous techniques, successive B-scans were acquired over the measurement region (B-M mode) in this work. The feasibility of this method was validated by quantifying the elasticity of tissue-mimicking agar phantoms as well as porcine corneas ex vivo at different intraocular pressures. The results demonstrate that this method can acquire a depth-resolved elastogram in milliseconds. The reduced data set enabled a rapid elasticity assessment, and the ultra-fast acquisition speed allowed for a clinically safe laser exposure to the cornea.

Ultra-fast nonlinear optical properties and photophysical mechanism of a novel pyrene derivative

NASA Astrophysics Data System (ADS)

Zhang, Youwei; Yang, Junyi; Xiao, Zhengguo; Song, Yinglin

2016-10-01

The third-order nonlinear optical properties of 1-(pyrene-1-y1)-3-(3-methylthiophene) acrylic keton named PMTAK was investigated by using Z-scan technique. The light sources for picoseconds(ps) and femtosecond(fs) Z-scan were a mode-locked Nd: YAG laser (21 ps, 532 nm,10 Hz) and an Yb: KGW based fiber laser (190 fs, 515 nm,532 nm, 20 Hz), respectively. In the two cases, reverse saturation absorption(RSA) are observed. The dynamics of the sample's optical nonlinearity is discussed via the femtosecond time-resolved pump probe with phase object at 515nm. We believe that the molecules in excited state of particle population count is caused by two-photon absorption(TPA). The five-level theoretical model is used to analysis the optical nonlinear mechanism. Combining with the result of picosecond Z-scan experiment, a set of optical nonlinear parameters are calculated out. The femtosecond Z-scan experiment is taken to confirm these parameters. The obvious excited-state nonlinearity is found by the set of parameters. The result shows that the sample has good optical nonlinearity which indicates it has potential applications in nonlinear optics field.

Particle Streak Velocimetry of Supersonic Nozzle Flows

NASA Technical Reports Server (NTRS)

Willits, J. D.; Pourpoint, T. L.

2016-01-01

A novel velocimetry technique to probe the exhaust flow of a laboratory scale combustor is being developed. The technique combines the advantages of standard particle velocimetry techniques and the ultra-fast imaging capabilities of a streak camera to probe high speed flows near continuously with improved spatial and velocity resolution. This "Particle Streak Velocimetry" technique tracks laser illuminated seed particles at up to 236 picosecond temporal resolution allowing time-resolved measurement of one-dimensional flows exceeding 2000 m/s as are found in rocket nozzles and many other applications. Developmental tests with cold nitrogen have been performed to validate and troubleshoot the technique with supersonic flows of much lower velocity and without background noise due to combusting flow. Flow velocities on the order of 500 m/s have been probed with titanium dioxide particles and a continuous-wave laser diode. Single frame images containing multiple streaks are analyzed to find the average slope of all incident particles corresponding to the centerline axial flow velocity. Long term objectives for these tests are correlation of specific impulse to theoretical combustion predictions and direct comparisons between candidate green fuels and the industry standard, monomethylhydrazine, each tested under identical conditions.

Development of microtitre plates for electrokinetic assays

NASA Astrophysics Data System (ADS)

Burt, J. P. H.; Goater, A. D.; Menachery, A.; Pethig, R.; Rizvi, N. H.

2007-02-01

Electrokinetic processes have wide ranging applications in microsystems technology. Their optimum performance at micro and nano dimensions allows their use both as characterization and diagnostic tools and as a means of general particle manipulation. Within analytical studies, measurement of the electrokinesis of biological cells has the sensitivity and selectivity to distinguish subtle differences between cell types and cells undergoing changes and is gaining acceptance as a diagnostic tool in high throughput screening for drug discovery applications. In this work the development and manufacture of an electrokinetic-based microtitre plate is described. The plate is intended to be compatible with automated sample loading and handling systems. Manufacturing of the microtitre plate, which employs indium tin oxide microelectrodes, has been entirely undertaken using excimer and ultra-fast pulsed laser micromachining due to its flexibility in materials processing and accuracy in microstructuring. Laser micromachining has the ability to rapidly realize iterations in device prototype design while also having the capability to be scaled up for large scale manufacture. Device verification is achieved by the measurement of the electrorotation and dielectrophoretic properties of yeast cells while the flexibility of the developed microtitre plate is demonstrated by the selective separation of live yeast from polystyrene microbeads.

Laser micro machining of medical devices.

PubMed

Rausch, Y

2009-01-01

Excimer and increasingly ultra-short-pulsed lasers are important tools in the creation of microstructures and nanostructures. Capabilities of the latest systems are described, which include drilling 30-microm diameter holes in 50 to 100 microm thick metal foils and subsurface engraving of transparent materials.

Ultra-narrow EIA spectra of 85Rb atom in a degenerate Zeeman multiplet system

NASA Astrophysics Data System (ADS)

Rehman, Hafeez Ur; Qureshi, Muhammad Mohsin; Noh, Heung-Ryoul; Kim, Jin-Tae

2015-05-01

Ultra-narrow EIA spectral features of thermal 85Rb atom with respect to coupling Rabi frequencies in a degenerate Zeeman multiplet system have been unraveled in the cases of same (σ+ -σ+ , π ∥ π) and orthogonal (σ+ -σ- , π ⊥ π)polarization configurations. The EIA signals with subnatural linewidth of ~ 100 kHz even in the cases of same circular and linear polarizations of coupling and probe laser have been obtained for the first time theoretically and experimentally. In weak coupling power limit of orthogonal polarization configurations, time-dependent transfer of coherence plays major role in the splitting of the EIA spectra while in strong coupling power, Mollow triplet-like mechanism due to strong power bring into broad split feature. The experimental ultra-narrow EIA features using one laser combined with an AOM match well with simulated spectra obtained by using generalized time-dependent optical Bloch equations.

Ultra-fast scintillation properties of β-Ga2O3 single crystals grown by Floating Zone method

NASA Astrophysics Data System (ADS)

He, Nuotian; Tang, Huili; Liu, Bo; Zhu, Zhichao; Li, Qiu; Guo, Chao; Gu, Mu; Xu, Jun; Liu, Jinliang; Xu, Mengxuan; Chen, Liang; Ouyang, Xiaoping

2018-04-01

In this investigation, β-Ga2O3 single crystals were grown by the Floating Zone method. At room temperature, the X-ray excited emission spectrum includes ultraviolet and blue emission bands. The scintillation light output is comparable to the commercial BGO scintillator. The scintillation decay times are composed of the dominant ultra-fast component of 0.368 ns and a small amount of slightly slow components of 8.2 and 182 ns. Such fast component is superior to most commercial inorganic scintillators. In contrast to most semiconductor crystals prepared by solution method such as ZnO, β-Ga2O3 single crystals can be grown by traditional melt-growth method. Thus we can easily obtain large bulk crystals and mass production.

The diagnostics of ultra-short pulse laser-produced plasma

NASA Astrophysics Data System (ADS)

Roth, Markus

2011-09-01

Since the invention of the laser, coherent light has been used to break down solid or gaseous material and transform it into a plasma. Over the last three decades two things have changed. Due to multiple advancements and design of high power lasers it is now possible to increase the electric and magnetic field strength that pushed the electron motion towards the regime of relativistic plasma physics. Moreover, due to the short pulse duration of the driving laser the underlying physics has become so transient that concepts like thermal equilibrium (even a local one) or spatial isotropy start to fail. Consequently short pulse laser-driven plasmas have become a rich source of new phenomena that we are just about beginning to explore. Such phenomena, like particle acceleration, nuclear laser-induced reactions, the generation of coherent secondary radiation ranging from THz to high harmonics and the production of attosecond pulses have excited an enormous interest in the study of short pulse laser plasmas. The diagnostics of such ultra-short pulse laser plasmas is a challenging task that involves many and different techniques compared to conventional laser-produced plasmas. While this review cannot cover the entire field of diagnostics that has been developed over the last years, we will try to give a summarizing description of the most important techniques that are currently being used.

Intrinsic beam emittance of laser-accelerated electrons measured by x-ray spectroscopic imaging.

PubMed

Golovin, G; Banerjee, S; Liu, C; Chen, S; Zhang, J; Zhao, B; Zhang, P; Veale, M; Wilson, M; Seller, P; Umstadter, D

2016-04-19

The recent combination of ultra-intense lasers and laser-accelerated electron beams is enabling the development of a new generation of compact x-ray light sources, the coherence of which depends directly on electron beam emittance. Although the emittance of accelerated electron beams can be low, it can grow due to the effects of space charge during free-space propagation. Direct experimental measurement of this important property is complicated by micron-scale beam sizes, and the presence of intense fields at the location where space charge acts. Reported here is a novel, non-destructive, single-shot method that overcame this problem. It employed an intense laser probe pulse, and spectroscopic imaging of the inverse-Compton scattered x-rays, allowing measurement of an ultra-low value for the normalized transverse emittance, 0.15 (±0.06) π mm mrad, as well as study of its subsequent growth upon exiting the accelerator. The technique and results are critical for designing multi-stage laser-wakefield accelerators, and generating high-brightness, spatially coherent x-rays.

Ultra-intense Pair Creation using the Texas Petawatt Laser and Applications

NASA Astrophysics Data System (ADS)

Liang, Edison; Henderson, Alexander; Clarke, Taylor; Lo, Willie; Chaguine, Petr; Dyer, Gilliss; Riley, Nathan; Serratto, Kristina; Donovan, Michael; Ditmire, Todd

2014-10-01

Pair plasmas and intense gamma-ray sources are ubiquitous in the high-energy universe, from pulser winds to gamma-ray bursts (GRB). Their study can be greatly enhanced if such sources can be recreated in the laboratory under controlled conditions. In 2012 and 2013, a joint Rice-University of Texas team performed over 130 laser shots on thick gold and platinum targets using the 100 Joule Texas Petawatt Laser in Austin. The laser intensity of many shots exceeded 1021 W.cm-2 with pulses as short as 130 fs. These experiments probe a new extreme regime of ultra-intense laser - high-Z solid target interactions never achieved before. In addition to creating copious pairs with the highest density (>1015/cc) and emergent e +/e- ratio exceeding 20% in many shots, these experiments also created the highest density multi-MeV gamma-rays, comparable in absolute numbers to those found inside a gamma-ray burst (GRB). Potential applications of such intense pair and gamma-ray sources to laboratory astrophysics and innovative technologies will be discussed. Work supported by DOE HEDLP program.

Kinetic study of terahertz generation based on the interaction of two-color ultra-short laser pulses with molecular hydrogen gas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Soltani Gishini, M. S.; Ganjovi, A., E-mail: Ganjovi@kgut.ac.ir; Saeed, M.

In this work, using a two dimensional particle in cell-Monte Carlo collision simulation scheme, interaction of two-color ultra-short laser pulses with the molecular hydrogen gas (H{sub 2}) is examined. The operational laser parameters, i.e., its pulse shape, duration, and waist, are changed and, their effects on the density and kinetic energy of generated electrons, THz electric field, intensity, and spectrum are studied. It is seen that the best pulse shape generating the THz signal radiation with the highest intensity is a trapezoidal pulse, and the intensity of generated THz radiation is increased at the higher pulse durations and waists. Formore » all the operational laser parameters, the maximum value of emitted THz signal frequency always remains lower than 5 THz. The intensity of applied laser pulses is taken about 10{sup 14} w/cm{sup 2}, and it is observed that while a small portion of the gaseous media gets ionized, the radiated THz signal is significant.« less

Laser Radiation Pressure Acceleration of Monoenergetic Protons in an Ultra-Thin Foil

NASA Astrophysics Data System (ADS)

Eliasson, Bengt; Liu, Chuan S.; Shao, Xi; Sagdeev, Roald Z.; Shukla, Padma K.

2009-11-01

We present theoretical and numerical studies of the acceleration of monoenergetic protons in a double layer formed by the laser irradiation of an ultra-thin film. The stability of the foil is investigated by direct Vlasov-Maxwell simulations for different sets of laser-plasma parameters. It is found that the foil is stable, due to the trapping of both electrons and ions in the thin laser-plasma interaction region, where the electrons are trapped in a potential well composed of the ponderomo-tive potential of the laser light and the electrostatic potential due to the ions, and the ions are trapped in a potential well composed of the inertial potential in an accelerated frame and the electrostatic potential due to the electrons. The result is a stable double layer, where the trapped ions are accelerated to monoenergetic energies up to 100 MeV and beyond, which makes them suitable for medical applications cancer treatment. The underlying physics of trapped and untapped ions in a double layer is also investigated theoretically and numerically.

CASTOR: Widely Distributed Scalable Infospaces

DTIC Science & Technology

2008-11-01

1  i Progress against Planned Objectives Enable nimble apps that react fast as...generation of scalable, reliable, ultra- fast event notification in Linux data centers. • Maelstrom, a spin-off from Ricochet, offers a powerful new option...out potential enhancements to WS-EVENTING and WS-NOTIFICATION based on our work. Potential impact for the warflighter. QSM achieves extremely fast

Characterization of the fast electrons distribution produced in a high intensity laser target interaction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Westover, B.; Lawrence Livermore National Laboratory, Livermore, California 94550; Chen, C. D.

2014-03-15

Experiments on the Titan laser (∼150 J, 0.7 ps, 2 × 10{sup 20} W cm{sup −2}) at the Lawrence Livermore National Laboratory were carried out in order to study the properties of fast electrons produced by high-intensity, short pulse laser interacting with matter under conditions relevant to Fast Ignition. Bremsstrahlung x-rays produced by these fast electrons were measured by a set of compact filter-stack based x-ray detectors placed at three angles with respect to the target. The measured bremsstrahlung signal allows a characterization of the fast electron beam spectrum, conversion efficiency of laser energy into fast electron kinetic energy and angular distribution. A Monte Carlo codemore » Integrated Tiger Series was used to model the bremsstrahlung signal and infer a laser to fast electron conversion efficiency of 30%, an electron slope temperature of about 2.2 MeV, and a mean divergence angle of 39°. Simulations were also performed with the hybrid transport code ZUMA which includes fields in the target. In this case, a conversion efficiency of laser energy to fast electron energy of 34% and a slope temperature between 1.5 MeV and 4 MeV depending on the angle between the target normal direction and the measuring spectrometer are found. The observed temperature of the bremsstrahlung spectrum, and therefore the inferred electron spectrum are found to be angle dependent.« less

Radiotherapy using a laser proton accelerator

NASA Astrophysics Data System (ADS)

Murakami, Masao; Hishikawa, Yoshio; Miyajima, Satoshi; Okazaki, Yoshiko; Sutherland, Kenneth L.; Abe, Mitsuyuki; Bulanov, Sergei V.; Daido, Hiroyuki; Esirkepov, Timur Zh.; Koga, James; Yamagiwa, Mitsuru; Tajima, Toshiki

2008-06-01

Laser acceleration promises innovation in particle beam therapy of cancer where an ultra-compact accelerator system for cancer beam therapy can become affordable to a broad range of patients. This is not feasible without the introduction of a technology that is radically different from the conventional accelerator-based approach. Because of its compactness and other novel characteristics, the laser acceleration method provides many enhanced capabilities

High-flux low-divergence positron beam generation from ultra-intense laser irradiated a tapered hollow target

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Jian-Xun; College of Electronic Engineering, Wuhan 430019; Ma, Yan-Yun, E-mail: yanyunma@126.com

By using two-dimensional particle-in-cell simulations, we demonstrate high-flux dense positrons generation by irradiating an ultra-intense laser pulse onto a tapered hollow target. By using a laser with an intensity of 4 × 10{sup 23 }W/cm{sup 2}, it is shown that the Breit-Wheeler process dominates the positron production during the laser-target interaction and a positron beam with a total number >10{sup 15} is obtained, which is increased by five orders of magnitude than in the previous work at the same laser intensity. Due to the focusing effect of the transverse electric fields formed in the hollow cone wall, the divergence angle of the positronmore » beam effectively decreases to ∼15° with an effective temperature of ∼674 MeV. When the laser intensity is doubled, both the positron flux (>10{sup 16}) and temperature (963 MeV) increase, while the divergence angle gets smaller (∼13°). The obtained high-flux low-divergence positron beam may have diverse applications in science, medicine, and engineering.« less

Spectral and angular distribution of photons via radiative damping in extreme ultra-intense laser-plasma interaction

NASA Astrophysics Data System (ADS)

Pandit, Rishi; Sentoku, Yasuhiko

2012-10-01

Spectral and angular distribution of photons produced in the interaction of extremely intense laser (> 10^22,/cm^2) with dense plasma are studied with a help of a collisional particle-in-cell simulation, PICLS. In ultra-intense laser-plasma interaction, electrons are accelerated by the strong laser fields and emit γ-ray photons mainly via two processes, namely, Bremsstrahlung and radiative damping. We had developed numerical models of these processes in PICLS and study the spectrum and the angular distribution of γ-rays produced in the relativistic laser regime. Such relativistic γ-rays have wide range of frequencies and the angular distribution depends on the hot electron source. From the power loss calculation in PICLS we found that the Bremsstrahlung will get saturated at I > 10^22,/cm^2 while the radiative damping will continuously increase. Comparing the details of γ-rays from the Bremsstrahlung and the radiative damping in simulations, we will discuss the laser parameters and the target conditions (geometry and material) to distinguish the photons from each process and how to catch the signature of the radiative damping in future experiments.

High-power direct diode laser output by spectral beam combining

NASA Astrophysics Data System (ADS)

Tan, Hao; Meng, Huicheng; Ruan, Xu; Du, Weichuan; Wang, Zhao

2018-03-01

We demonstrate a spectral beam combining scheme based on multiple mini-bar stacks, which have more diode laser combining elements, to increase the combined diode laser power and realize equal beam quality in both the fast and slow axes. A spectral beam combining diode laser output of 1130 W is achieved with an operating current of 75 A. When a 9.6 X de-magnifying telescope is introduced between the output mirror and the diffraction grating, to restrain cross-talk among diode laser emitters, a 710 W spectral beam combining diode laser output is achieved at the operating current of 70 A, and the beam quality on the fast and slow axes of the combined beam is about 7.5 mm mrad and 7.3 mm mrad respectively. The power reduction is caused by the existence of a couple resonator between the rear facet of the diode laser and the fast axis collimation lens, and it should be eliminated by using diode laser chips with higher front facet transmission efficiency and a fast axis collimation lens with lower residual reflectivity.

Apparatus and Method to Enable Precision and Fast Laser Frequency Tuning

NASA Technical Reports Server (NTRS)

Chen, Jeffrey R. (Inventor); Numata, Kenji (Inventor); Wu, Stewart T. (Inventor); Yang, Guangning (Inventor)

2015-01-01

An apparatus and method is provided to enable precision and fast laser frequency tuning. For instance, a fast tunable slave laser may be dynamically offset-locked to a reference laser line using an optical phase-locked loop. The slave laser is heterodyned against a reference laser line to generate a beatnote that is subsequently frequency divided. The phase difference between the divided beatnote and a reference signal may be detected to generate an error signal proportional to the phase difference. The error signal is converted into appropriate feedback signals to phase lock the divided beatnote to the reference signal. The slave laser frequency target may be rapidly changed based on a combination of a dynamically changing frequency of the reference signal, the frequency dividing factor, and an effective polarity of the error signal. Feed-forward signals may be generated to accelerate the slave laser frequency switching through laser tuning ports.

Synthesis and x-ray characterization of sputtered bi-alkali antimonide photocathodes

DOE PAGES

Gaowei, M.; Ding, Z.; Schubert, S.; ...

2017-11-10

Advanced photoinjectors, which are critical to many next generation accelerators, open the door to new ways of material probing, both as injectors for free electron lasers and for ultra-fast electron diffraction. For these applications, the nonuniformity of the electric field near the cathode caused by surface roughness can be the dominant source of beam emittance. Therefore, improving the photocathode roughness while maintaining quantum efficiency is essential to the improvement of beam brightness. Here in this article, we report the demonstration of a bi-alkali antimonide photocathode with an order of magnitude improved roughness by sputter deposition from a K 2CsSb sputtermore » target, using in situ and operando X-ray characterizations. We found that a surface roughness of 0.5 nm for a sputtered photocathode with a final thickness of 42 nm can be achieved while still yielding a quantum efficiency of 3.3% at 530 nm wavelength.« less

Synthesis and x-ray characterization of sputtered bi-alkali antimonide photocathodes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gaowei, M.; Ding, Z.; Schubert, S.

Advanced photoinjectors, which are critical to many next generation accelerators, open the door to new ways of material probing, both as injectors for free electron lasers and for ultra-fast electron diffraction. For these applications, the nonuniformity of the electric field near the cathode caused by surface roughness can be the dominant source of beam emittance. Therefore, improving the photocathode roughness while maintaining quantum efficiency is essential to the improvement of beam brightness. Here in this article, we report the demonstration of a bi-alkali antimonide photocathode with an order of magnitude improved roughness by sputter deposition from a K 2CsSb sputtermore » target, using in situ and operando X-ray characterizations. We found that a surface roughness of 0.5 nm for a sputtered photocathode with a final thickness of 42 nm can be achieved while still yielding a quantum efficiency of 3.3% at 530 nm wavelength.« less

High resolution x-ray Thomson scattering measurements from cryogenic hydrogen jets using the linac coherent light source

DOE PAGES

Fletcher, L. B.; Zastrau, U.; Galtier, E.; ...

2016-08-15

Here, we present the first spectrally resolved measurements of x-rays scattered from cryogenic hydrogen jets in the single photon counting limit. The 120 Hz capabilities of the LCLS, together with a novel hydrogen jet design [J. B. Kim et al., Rev. Sci. Instrum. (these proceedings)], allow for the ability to record a near background free spectrum. Such high-dynamic-range x-ray scattering measurements enable a platform to study ultra-fast, laser-driven, heating dynamics of hydrogen plasmas. This measurement has been achieved using two highly annealed pyrolytic graphite crystal spectrometers to spectrally resolve 5.5 keV x-rays elastically and inelastically scattered from cryogenic hydrogen andmore » focused on Cornell-SLAC pixel array detectors [S. Herrmann et al., Nucl. Instrum. Methods Phys. Res., Sect. A 718, 550 (2013)].« less

Ultra-FDst Object Recognition from Few Spikes

DTIC Science & Technology

2005-07-01

Ultra-fast Object Recognition from Few Spikes Chou Hung, Gabriel Kreiman , Tomaso Poggio & James J. DiCarlo AI Memo 2005-022 July 2005 CBCL Memo 253...authors, Chou Hung and Gabriel Kreiman , contributed equally to this work. Supplementary Material is available at http://ramonycajal.mit.edu... kreiman /resources/ultrafast/. _____________________________________________________________________________ This report describes research done at

Electron spin polarization in realistic trajectories around the magnetic node of two counter-propagating, circularly polarized, ultra-intense lasers

NASA Astrophysics Data System (ADS)

Del Sorbo, D.; Seipt, D.; Thomas, A. G. R.; Ridgers, C. P.

2018-06-01

It has recently been suggested that two counter-propagating, circularly polarized, ultra-intense lasers can induce a strong electron spin polarization at the magnetic node of the electromagnetic field that they setup (Del Sorbo et al 2017 Phys. Rev. A 96 043407). We confirm these results by considering a more sophisticated description that integrates over realistic trajectories. The electron dynamics is weakly affected by the variation of power radiated due to the spin polarization. The degree of spin polarization differs by approximately 5% if considering electrons initially at rest or already in a circular orbit. The instability of trajectories at the magnetic node induces a spin precession associated with the electron migration that establishes an upper temporal limit to the polarization of the electron population of about one laser period.

Ultra-short pulse generation in the hybridly mode-locked erbium-doped all-fiber ring laser with a distributed polarizer

NASA Astrophysics Data System (ADS)

Krylov, Alexander A.; Sazonkin, Stanislav G.; Lazarev, Vladimir A.; Dvoretskiy, Dmitriy A.; Leonov, Stanislav O.; Pnev, Alexey B.; Karasik, Valeriy E.; Grebenyukov, Vyacheslav V.; Pozharov, Anatoly S.; Obraztsova, Elena D.; Dianov, Evgeny M.

2015-06-01

We report for the first time to the best of our knowledge on the ultra-short pulse (USP) generation in the dispersion-managed erbium-doped all-fiber ring laser hybridly mode-locked with boron nitride-doped single-walled carbon nanotubes in the co-action with a nonlinear polarization evolution in the ring cavity with a distributed polarizer. Stable 92.6 fs dechirped pulses were obtained via precise polarization state adjustment at a central wavelength of 1560 nm with 11.2 mW average output power, corresponding to the 2.9 kW maximum peak power. We have also observed the laser switching from a USP generation regime to a chirped pulse one with a corresponding pulse-width of 7.1 ps at the same intracavity dispersion.

Enhanced laser absorption from radiation pressure in intense laser plasma interactions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dollar, F.; Zulick, C.; Raymond, A.

The reflectivity of a short-pulse laser at intensities of 2 x 10 21Wcm -2 with ultra-high contrast (10 -15) on sub-micrometer silicon nitride foilswas studied experimentally using varying polarizations and target thicknesses. Furthermore, the reflected intensity and beam quality were found to be relatively constant with respect to intensity for bulk targets. For submicron targets, the measured reflectivity drops substantially without a corresponding increase in transmission, indicating increased conversion of fundamental to other wavelengths and particle heating. The experimental results and trends we observed in 3D particle-in-cell simulations emphasize the critical role of ion motion due to radiation pressure onmore » the absorption process. Ion motion during ultra-short pulses enhances the electron heating, which subsequently transfers more energy to the ions.« less

Method to reduce damage to backing plate

DOEpatents

Perry, Michael D.; Banks, Paul S.; Stuart, Brent C.

2001-01-01

The present invention is a method for penetrating a workpiece using an ultra-short pulse laser beam without causing damage to subsequent surfaces facing the laser. Several embodiments are shown which place holes in fuel injectors without damaging the back surface of the sack in which the fuel is ejected. In one embodiment, pulses from an ultra short pulse laser remove about 10 nm to 1000 nm of material per pulse. In one embodiment, a plasma source is attached to the fuel injector and initiated by common methods such as microwave energy. In another embodiment of the invention, the sack void is filled with a solid. In one other embodiment, a high viscosity liquid is placed within the sack. In general, high-viscosity liquids preferably used in this invention should have a high damage threshold and have a diffusing property.

Enhanced laser absorption from radiation pressure in intense laser plasma interactions

DOE PAGES

Dollar, F.; Zulick, C.; Raymond, A.; ...

2017-06-06

The reflectivity of a short-pulse laser at intensities of 2 x 10 21Wcm -2 with ultra-high contrast (10 -15) on sub-micrometer silicon nitride foilswas studied experimentally using varying polarizations and target thicknesses. Furthermore, the reflected intensity and beam quality were found to be relatively constant with respect to intensity for bulk targets. For submicron targets, the measured reflectivity drops substantially without a corresponding increase in transmission, indicating increased conversion of fundamental to other wavelengths and particle heating. The experimental results and trends we observed in 3D particle-in-cell simulations emphasize the critical role of ion motion due to radiation pressure onmore » the absorption process. Ion motion during ultra-short pulses enhances the electron heating, which subsequently transfers more energy to the ions.« less

Plasma block acceleration based upon the interaction between double targets and an ultra-intense linearly polarized laser pulse

NASA Astrophysics Data System (ADS)

Xu, Yanxia; Wang, Jiaxiang; Hora, Heinrich; Qi, Xin; Xing, Yifan; Yang, Lei; Zhu, Wenjun

2018-04-01

A new scheme of plasma block acceleration based upon the interaction between double targets and an ultra-intense linearly polarized laser pulse with intensity I ˜ 1022 W/cm2 is investigated via two-dimensional particle-in-cell simulations. The targets are composed of a pre-target of low-density aluminium plasma and an overdense main-target of hydrogen plasma. Through intensive parameter optimization, we have observed highly efficient plasma block accelerations with a monochromatic proton beam peaked at GeVs. The underlying mechanism is attributed to the enhancement of the charge separation field due to the properly selected pre-target.

[94 km Brillouin distributed optical fiber sensors based on ultra-long fiber ring laser pumping].

PubMed

Yuan, Cheng-Xu; Wang, Zi-Nan; Jia, Xin-Hong; Li, Jin; Yan, Xiao-Dong; Cui, An-Bin

2014-05-01

A novel optical amplification configuration based on ultra-long fiber laser with a ring cavity was proposed and applied to Brillouin optical time-domain analysis (BOTDA) sensing system, in order to extend the measurement distance significantly. The parameters used in the experiment were optimized, considering the main limitations of the setup, such as depletion, self-phase modulation (SPM) and pump-signal relative intensity noise (RIN) transfer. Through analyzing Brillouin gain spectrum, we demonstrated distributed sensing over 94 km of standard single-mode fiber with 3 meter spatial resolution and strain/temperature accuracy of 28 /1. 4 degree C.

Mid-infrared supercontinuum covering the 1.4-13.3 μm molecular fingerprint region using ultra-high NA chalcogenide step-index fibre

NASA Astrophysics Data System (ADS)

Petersen, Christian Rosenberg; Møller, Uffe; Kubat, Irnis; Zhou, Binbin; Dupont, Sune; Ramsay, Jacob; Benson, Trevor; Sujecki, Slawomir; Abdel-Moneim, Nabil; Tang, Zhuoqi; Furniss, David; Seddon, Angela; Bang, Ole

2014-11-01

The mid-infrared spectral region is of great technical and scientific interest because most molecules display fundamental vibrational absorptions in this region, leaving distinctive spectral fingerprints. To date, the limitations of mid-infrared light sources such as thermal emitters, low-power laser diodes, quantum cascade lasers and synchrotron radiation have precluded mid-infrared applications where the spatial coherence, broad bandwidth, high brightness and portability of a supercontinuum laser are all required. Here, we demonstrate experimentally that launching intense ultra-short pulses with a central wavelength of either 4.5 μm or 6.3 μm into short pieces of ultra-high numerical-aperture step-index chalcogenide glass optical fibre generates a mid-infrared supercontinuum spanning 1.5 μm to 11.7 μm and 1.4 μm to 13.3 μm, respectively. This is the first experimental demonstration to truly reveal the potential of fibres to emit across the mid-infrared molecular ‘fingerprint region’, which is of key importance for applications such as early cancer diagnostics, gas sensing and food quality control.

Multifunctional gold nanorods for selective plasmonic photothermal therapy in pancreatic cancer cells using ultra-short pulse near-infrared laser irradiation.

PubMed

Patino, Tania; Mahajan, Ujjwal; Palankar, Raghavendra; Medvedev, Nikolay; Walowski, Jakob; Münzenberg, Markus; Mayerle, Julia; Delcea, Mihaela

2015-03-12

Gold nanorods (AuNRs) have attracted considerable attention in plasmonic photothermal therapy for cancer treatment by exploiting their selective and localized heating effect due to their unique photophysical properties. Here we describe a strategy to design a novel multifunctional platform based on AuNRs to: (i) specifically target the adenocarcinoma MUC-1 marker through the use of the EPPT-1 peptide, (ii) enhance cellular uptake through a myristoylated polyarginine peptide (MPAP) and (iii) selectively induce cell death by ultra-short near infrared laser pulses. We used a biotin-avidin based approach to conjugate EPPT-1 and MPAP to AuNRs. Dual-peptide (EPPT-1+MPAP) labelled AuNRs showed a significantly higher uptake by pancreatic ductal adenocarcinoma cells when compared to their single peptide or avidin conjugated counterparts. In addition, we selectively induced cell death by ultra-short near infrared laser pulses in small target volumes (∼1 μm3), through the creation of plasmonic nanobubbles that lead to the destruction of a local cell environment. Our approach opens new avenues for conjugation of multiple ligands on AuNRs targeting cancer cells and tumors and it is relevant for plasmonic photothermal therapy.

Bright attosecond γ-ray pulses from nonlinear Compton scattering with laser-illuminated compound targets

NASA Astrophysics Data System (ADS)

Zhu, Xing-Long; Chen, Min; Yu, Tong-Pu; Weng, Su-Ming; Hu, Li-Xiang; McKenna, Paul; Sheng, Zheng-Ming

2018-04-01

Attosecond light sources have the potential to open up totally unexplored research avenues in ultrafast science. However, the photon energies achievable using existing generation schemes are limited to the keV range. Here, we propose and numerically demonstrate an all-optical mechanism for the generation of bright MeV attosecond γ-photon beams with desirable angular momentum. Using a circularly polarized Laguerre-Gaussian laser pulse focused onto a cone-foil target, dense attosecond bunches ( ≲ 170 as ) of electrons are produced. The electrons interact with the laser pulse which is reflected by a plasma mirror, producing ultra-brilliant (˜1023 photons/s/mm2/mrad2/0.1%BW) multi-MeV (Eγ,max > 30 MeV) isolated attosecond ( ≲ 260 as ) γ-ray pulse trains. Moreover, the angular momentum is transferred to γ-photon beams via nonlinear Compton scattering of ultra-intense tightly focused laser pulse by energetic electrons. Such a brilliant attosecond γ-photon source would provide the possibilities in attosecond nuclear science.

Ultra-wideband all-fiber tunable Tm/Ho-co-doped laser at 2 μm.

PubMed

Xue, Guanghui; Zhang, Bin; Yin, Ke; Yang, Weiqiang; Hou, Jing

2014-10-20

We demonstrate an all-fiber tunable Tm/Ho-codoped laser operating in the 2 μm wavelength region. The wavelength tuning range of the Tm/Ho-codoped fiber laser (THFL) with 1-m length of Tm/Ho-codoped fiber (THDF) was from 1727 nm to 2030 nm. Efficient short wavelength operation and ultra-wide wavelength tuning range of 303 nm were both achieved. To the best of our knowledge, this is the broadest tuning range that has been reported for an all-fiber rare-earth-doped laser to date. By increasing the THDF length to 2 m, the obtainable wavelength of the THFL was further red-shifted to the range from 1768 nm to 2071 nm. The output power of the THFL was scaled up from 1810 nm to 2010 nm by using a stage of Tm/Ho-codoped fiber amplifier (THFA), which exhibited the maximum slope efficiency of 42.6% with output power of 408 mW at 1910 nm.

Emerging trends in X-ray spectroscopic studies of plasma produced by intense laser beams

DOE Office of Scientific and Technical Information (OSTI.GOV)

Arora, V., E-mail: arora@rrcat.gov.in; Chakera, J. A.; Naik, P. A.

2015-07-31

X-ray line emission from hot dense plasmas, produced by ultra-short high intensity laser systems, has been studied experimentally in recent years for applications in materials science as well as for back-lighter applications. By virtue of the CPA technology, several laser facilities delivering pulses with peak powers in excess of one petawatt (focused intensities > 10{sup 20} W-cm{sup −2}) have either been commissioned across the globe during the last few years or are presently under construction. On the other hand, hard x-ray sources on table top, generating ultra-short duration x-rays at a repetition rate up to 10 kHz, are routinely available formore » time resolved x-ray diffraction studies. In this paper, the recent experiments on x-ray spectroscopic studies of plasma produced by 45 fs, Ti:sapphire laser pulses (focused iintensity > 10{sup 18} W-cm{sup −2}) at RRCAT Indore will be presented.« less

Few-cycle pulse laser induced damage threshold determination of ultra-broadband optics.

PubMed

Kafka, Kyle R P; Talisa, Noah; Tempea, Gabriel; Austin, Drake R; Neacsu, Catalin; Chowdhury, Enam A

2016-12-12

A systematic study of few-cycle pulse laser induced damage threshold (LIDT) determination was performed for commercially-available ultra-broadband optics, (i.e. chirped mirrors, silver mirrors, beamsplitters, etc.) in vacuum and in air, for single and multi-pulse regime (S-on-1). Multi-pulse damage morphology at fluences below the single-pulse LIDT was studied in order to investigate the mechanisms leading to the onset of damage. Stark morphological contrast was observed between multi-pulse damage sites formed in air versus those in vacuum. One effect of vacuum testing compared to air included suppression of laser-induced periodic surface structures (LIPSS) formation, possibly influenced by a reduced presence of damage debris. Another effect of vacuum was occasional lowering of LIDT, which appears to be due to the stress-strain performance of the coating design during laser irradiation and under the external stress of vacuum ambience. A fused silica substrate is also examined, and a non-LIPSS nanostructuring is observed on the surface. Possible mechanisms are discussed.

Relativistic laser channeling in plasmas for fast ignition

NASA Astrophysics Data System (ADS)

Lei, A. L.; Pukhov, A.; Kodama, R.; Yabuuchi, T.; Adumi, K.; Endo, K.; Freeman, R. R.; Habara, H.; Kitagawa, Y.; Kondo, K.; Kumar, G. R.; Matsuoka, T.; Mima, K.; Nagatomo, H.; Norimatsu, T.; Shorokhov, O.; Snavely, R.; Yang, X. Q.; Zheng, J.; Tanaka, K. A.

2007-12-01

We report an experimental observation suggesting plasma channel formation by focusing a relativistic laser pulse into a long-scale-length preformed plasma. The channel direction coincides with the laser axis. Laser light transmittance measurement indicates laser channeling into the high-density plasma with relativistic self-focusing. A three-dimensional particle-in-cell simulation reproduces the plasma channel and reveals that the collimated hot-electron beam is generated along the laser axis in the laser channeling. These findings hold the promising possibility of fast heating a dense fuel plasma with a relativistic laser pulse.

Numerical investigations of transient heat transfer characteristics and vitrification tendencies in ultra-fast cell cooling processes.

PubMed

Jiao, Anjun; Han, Xu; Critser, John K; Ma, Hongbin

2006-06-01

During freezing, cells are often damaged directly or indirectly by ice formation. Vitrification is an alternative approach to cryopreservation that avoids ice formation. The common method to achieve vitrification is to use relatively high concentrations of cryoprotectant agents (CPA) in combination with a relatively slow cooling rate. However, high concentrations of CPAs have potentially damaging toxic and/or osmotic effects on cells. Therefore, establishing methods to achieve vitrification with lower concentrations of CPAs through ultra-fast cooling rates would be advantageous in these aspects. These ultra-fast cooling rates can be realized by a cooling system with an ultra-high heat transfer coefficient (h) between the sample and coolant. The oscillating motion heat pipe (OHP), a novel cooling device utilizing the pressure change to excite the oscillation motion of the liquid plugs and vapor bubbles, can significantly increase h and may fulfill this aim. The current investigation was designed to numerically study the effects of different values of h on the transient heat transfer characteristics and vitrification tendencies of the cell suspension during the cooling processes in an ultra-thin straw (100 microm in diameter). The transient temperature distribution, the cooling rate and the volume ratio (x) of the ice quantity to the maximum crystallizable ice of the suspension were calculated. From these numerical results, it is concluded that the ultra-high h (>10(4) W/m2 K) obtained by OHPs could facilitate vitrification by efficiently decreasing x as well as the time to pass through the dangerous temperature region where the maximum ice formation happens. For comparison, OHPs can decrease both of the parameters to less than 20% of those from the widely used open pulled straw methods. Therefore, the OHP method will be a promising approach to improving vitrification tendencies of CPA solutions and could also decrease the required concentration of CPAs for vitrification, both of which are of great importance for the successful cryopreservation of cells by vitrification.

Roll-to-roll suitable short-pulsed laser scribing of organic photovoltaics and close-to-process characterization

NASA Astrophysics Data System (ADS)

Kuntze, Thomas; Wollmann, Philipp; Klotzbach, Udo; Fledderus, Henri

2017-03-01

The proper long term operation of organic electronic devices like organic photovoltaics OPV depends on their resistance to environmental influences such as permeation of water vapor. Major efforts are spent to encapsulate OPV. State of the art is sandwich-like encapsulation between two ultra-barrier foils. Sandwich encapsulation faces two major disadvantages: high costs ( 1/3 of total costs) and parasitic intrinsic water (sponge effects of the substrate foil). To fight these drawbacks, a promising approach is to use the OPV substrate itself as barrier by integration of an ultra-barrier coating, followed by alternating deposition and structuring of OPV functional layers. In effect, more functionality will be integrated into less material, and production steps are reduced in number. All processing steps must not influence the underneath barrier functionality, while all electrical functionalities must be maintained. As most reasonable structuring tool, short and ultrashort pulsed lasers USP are used. Laser machining applies to three layers: bottom electrode made of transparent conductive materials (P1), organic photovoltaic operative stack (P2) and top electrode (P3). In this paper, the machining of functional 110…250 nm layers of flexible OPV by USP laser systems is presented. Main focus is on structuring without damaging the underneath ultra-barrier layer. The close-to-process machining quality characterization is performed with the analysis tool "hyperspectral imaging" (HSI), which is checked crosswise with the "gold standard" Ca-test. It is shown, that both laser machining and quality controlling, are well suitable for R2R production of OPV.

Giant enhancement of upconversion in ultra-small Er³⁺/Yb³⁺:NaYF₄ nanoparticles via laser annealing.

PubMed

Bednarkiewicz, A; Wawrzynczyk, D; Gagor, A; Kepinski, L; Kurnatowska, M; Krajczyk, L; Nyk, M; Samoc, M; Strek, W

2012-04-13

Most of the synthesis routes of lanthanide-doped phosphors involve thermal processing which results in nanocrystallite growth, stabilization of the crystal structure and augmentation of luminescence intensity. It is of great interest to be able to transform the sample in a spatially localized manner, which may lead to many applications like 2D and 3D data storage, anti-counterfeiting protection, novel design bio-sensors and, potentially, to fabrication of metamaterials, 3D photonic crystals or plasmonic devices. Here we demonstrate irreversible spatially confined infrared-laser-induced annealing (LIA) achieved in a thin layer of dried colloidal solution of ultra-small ∼8 nm NaYF₄ nanocrystals (NCs) co-doped with 2% Er³⁺ and 20% Yb³⁺ ions under a localized tightly focused beam from a continuous wave 976 nm medium power laser diode excitation. The LIA results from self-heating due to non-radiative relaxation accompanying the NIR laser energy upconversion in lanthanide ions. We notice that localized LIA appears at optical power densities as low as 15.5 kW cm⁻² (∼354 ± 29 mW) threshold in spots of 54 ± 3 µm diameter obtained with a 10 × microscope objective. In the course of detailed studies, a complete recrystallization to different phases and giant 2-3 order enhancement in luminescence yield is found. Our results are highly encouraging and let us conclude that the upconverting ultra-small lanthanide-doped nanophosphors are particularly promising for direct laser writing applications.

Giant enhancement of upconversion in ultra-small Er3+/Yb3+:NaYF4 nanoparticles via laser annealing

NASA Astrophysics Data System (ADS)

Bednarkiewicz, A.; Wawrzynczyk, D.; Gagor, A.; Kepinski, L.; Kurnatowska, M.; Krajczyk, L.; Nyk, M.; Samoc, M.; Strek, W.

2012-04-01

Most of the synthesis routes of lanthanide-doped phosphors involve thermal processing which results in nanocrystallite growth, stabilization of the crystal structure and augmentation of luminescence intensity. It is of great interest to be able to transform the sample in a spatially localized manner, which may lead to many applications like 2D and 3D data storage, anti-counterfeiting protection, novel design bio-sensors and, potentially, to fabrication of metamaterials, 3D photonic crystals or plasmonic devices. Here we demonstrate irreversible spatially confined infrared-laser-induced annealing (LIA) achieved in a thin layer of dried colloidal solution of ultra-small ˜8 nm NaYF4 nanocrystals (NCs) co-doped with 2% Er3+ and 20% Yb3+ ions under a localized tightly focused beam from a continuous wave 976 nm medium power laser diode excitation. The LIA results from self-heating due to non-radiative relaxation accompanying the NIR laser energy upconversion in lanthanide ions. We notice that localized LIA appears at optical power densities as low as 15.5 kW cm-2 (˜354 ± 29 mW) threshold in spots of 54 ± 3 µm diameter obtained with a 10 × microscope objective. In the course of detailed studies, a complete recrystallization to different phases and giant 2-3 order enhancement in luminescence yield is found. Our results are highly encouraging and let us conclude that the upconverting ultra-small lanthanide-doped nanophosphors are particularly promising for direct laser writing applications.

Ultra-narrow-linewidth erbium-doped lasers on a silicon photonics platform

NASA Astrophysics Data System (ADS)

Li, Nanxi; Purnawirman, Purnawirman; Magden, E. Salih; Singh, Gurpreet; Singh, Neetesh; Baldycheva, Anna; Hosseini, Ehsan S.; Sun, Jie; Moresco, Michele; Adam, Thomas N.; Leake, Gerald; Coolbaugh, Douglas; Bradley, Jonathan D. B.; Watts, Michael R.

2018-02-01

We report ultra-narrow-linewidth erbium-doped aluminum oxide (Al2O3:Er3+) distributed feedback (DFB) lasers with a wavelength-insensitive silicon-compatible waveguide design. The waveguide consists of five silicon nitride (SiNx) segments buried under silicon dioxide (SiO2) with a layer Al2O3:Er3+ deposited on top. This design has a high confinement factor (> 85%) and a near perfect (> 98%) intensity overlap for an octave-spanning range across near infrared wavelengths (950-2000 nm). We compare the performance of DFB lasers in discrete quarter phase shifted (QPS) cavity and distributed phase shifted (DPS) cavity. Using QPS-DFB configuration, we obtain maximum output powers of 0.41 mW, 0.76 mW, and 0.47 mW at widely spaced wavelengths within both the C and L bands of the erbium gain spectrum (1536 nm, 1566 nm, and 1596 nm). In a DPS cavity, we achieve an order of magnitude improvement in maximum output power (5.43 mW) and a side mode suppression ratio (SMSR) of > 59.4 dB at an emission wavelength of 1565 nm. We observe an ultra-narrow linewidth of ΔνDPS = 5.3 +/- 0.3 kHz for the DPS-DFB laser, as compared to ΔγQPS = 30.4 +/- 1.1 kHz for the QPS-DFB laser, measured by a recirculating self-heterodyne delayed interferometer (RSHDI). Even narrower linewidth can be achieved by mechanical stabilization of the setup, increasing the pump absorption efficiency, increasing the output power, or enhancing the cavity Q.

Laser Induced Damage of Potassium Dihydrogen Phosphate (KDP) Optical Crystal Machined by Water Dissolution Ultra-Precision Polishing Method

PubMed Central

Gao, Hang; Wang, Xu; Guo, Dongming; Liu, Ziyuan

2018-01-01

Laser induced damage threshold (LIDT) is an important optical indicator for nonlinear Potassium Dihydrogen Phosphate (KDP) crystal used in high power laser systems. In this study, KDP optical crystals are initially machined with single point diamond turning (SPDT), followed by water dissolution ultra-precision polishing (WDUP) and then tested with 355 nm nanosecond pulsed-lasers. Power spectral density (PSD) analysis shows that WDUP process eliminates the laser-detrimental spatial frequencies band of micro-waviness on SPDT machined surface and consequently decreases its modulation effect on the laser beams. The laser test results show that LIDT of WDUP machined crystal improves and its stability has a significant increase by 72.1% compared with that of SPDT. Moreover, a subsequent ultrasonic assisted solvent cleaning process is suggested to have a positive effect on the laser performance of machined KDP crystal. Damage crater investigation indicates that the damage morphologies exhibit highly thermal explosion features of melted cores and brittle fractures of periphery material, which can be described with the classic thermal explosion model. The comparison result demonstrates that damage mechanisms for SPDT and WDUP machined crystal are the same and WDUP process reveals the real bulk laser resistance of KDP optical crystal by removing the micro-waviness and subsurface damage on SPDT machined surface. This improvement of WDUP method makes the LIDT more accurate and will be beneficial to the laser performance of KDP crystal. PMID:29534032

Beam shaping to provide round and square-shaped beams in optical systems of high-power lasers

NASA Astrophysics Data System (ADS)

Laskin, Alexander; Laskin, Vadim

2016-05-01

Optical systems of modern high-power lasers require control of irradiance distribution: round or square-shaped flat-top or super-Gaussian irradiance profiles are optimum for amplification in MOPA lasers and for thermal load management while pumping of crystals of solid-state ultra-short pulse lasers to control heat and minimize its impact on the laser power and beam quality while maximizing overall laser efficiency, variable profiles are also important in irradiating of photocathode of Free Electron lasers (FEL). It is suggested to solve the task of irradiance re-distribution using field mapping refractive beam shapers like piShaper. The operational principle of these devices presumes transformation of laser beam intensity from Gaussian to flat-top one with high flatness of output wavefront, saving of beam consistency, providing collimated output beam of low divergence, high transmittance, extended depth of field, negligible residual wave aberration, and achromatic design provides capability to work with ultra-short pulse lasers having broad spectrum. Using the same piShaper device it is possible to realize beams with flat-top, inverse Gauss or super Gauss irradiance distribution by simple variation of input beam diameter, and the beam shape can be round or square with soft edges. This paper will describe some design basics of refractive beam shapers of the field mapping type and optical layouts of their applying in optical systems of high-power lasers. Examples of real implementations and experimental results will be presented as well.

Beam shaping as an enabler for new applications

NASA Astrophysics Data System (ADS)

Guertler, Yvonne; Kahmann, Max; Havrilla, David

2017-02-01

For many years, laser beam shaping has enabled users to achieve optimized process results as well as manage challenging applications. The latest advancements in industrial lasers and processing optics have taken this a step further as users are able to adapt the beam shape to meet specific application requirements in a very flexible way. TRUMPF has developed a wide range of experience in creating beam profiles at the work piece for optimized material processing. This technology is based on the physical model of wave optics and can be used with ultra short pulse lasers as well as multi-kW cw lasers. Basically, the beam shape can be adapted in all three dimensions in space, which allows maximum flexibility. Besides adaption of intensity profile, even multi-spot geometries can be produced. This approach is very cost efficient, because a standard laser source and (in the case of cw lasers) a standard fiber can be used without any special modifications. Based on this innovative beam shaping technology, TRUMPF has developed new and optimized processes. Two of the most recent application developments using these techniques are cutting glass and synthetic sapphire with ultra-short pulse lasers and enhanced brazing of hot dip zinc coated steel for automotive applications. Both developments lead to more efficient and flexible production processes, enabled by laser technology and open the door to new opportunities. They also indicate the potential of beam shaping techniques since they can be applied to both single-mode laser sources (TOP Cleave) and multi-mode laser sources (brazing).

Laser Diagnostic System Validation and Ultra-Compact Combustor Characterization

DTIC Science & Technology

2008-03-01

conventional non-reheat Brayton cycle. An ITB consist of a fueled-cavity type flame holder combined with an injection of air in an angled manner from the...Applied Combustion Diagnostics. New York, NY: Taylor & Francis, 2002. 23. Kohse-Hoinghaus, K. Laser Techniques for the Quantitative

New set of design rules for resonant refractive index sensors enabled by FFT based processing of the measurement data.

PubMed

Gounaridis, Lefteris; Groumas, Panos; Schreuder, Erik; Heideman, Rene; Avramopoulos, Hercules; Kouloumentas, Christos

2016-04-04

It is still a common belief that ultra-high quality-factors (Q-factors) are a prerequisite in optical resonant cavities for high refractive index resolution and low detection limit in biosensing applications. In combination with the ultra-short steps that are necessary when the measurement of the resonance shift relies on the wavelength scanning of a laser source and conventional methods for data processing, the high Q-factor requirement makes these biosensors extremely impractical. In this work we analyze an alternative processing method based on the fast-Fourier transform, and show through Monte-Carlo simulations that improvement by 2-3 orders of magnitude can be achieved in the resolution and the detection limit of the system in the presence of amplitude and spectral noise. More significantly, this improvement is maximum for low Q-factors around 10⁴ and is present also for high intra-cavity losses and large scanning steps making the designs compatible with the low-cost aspect of lab-on-a-chip technology. Using a micro-ring resonator as model cavity and a system design with low Q-factor (10⁴), low amplitude transmission (0.85) and relatively large scanning step (0.25 pm), we show that resolution close to 0.01 pm and detection limit close to 10^-7 RIU can be achieved improving the sensing performance by more than 2 orders of magnitude compared to the performance of systems relying on a simple peak search processing method. The improvement in the limit of detection is present even when the simple method is combined with ultra-high Q-factors and ultra-short scanning steps due to the trade-off between the system resolution and sensitivity. Early experimental results are in agreement with the trends of the numerical studies.

Fast and broadband detector for laser radiation

NASA Astrophysics Data System (ADS)

Scorticati, Davide; Crapella, Giacomo; Pellegrino, Sergio

2018-02-01

We developed a fast detector (patent pending) based on the Laser Induced Transverse Voltage (LITV) effect. The advantage of detectors using the LITV effect over pyroelectric sensors and photodiodes for laser radiation measurements is the combination of an overall fast response time, broadband spectral acceptance, high saturation threshold to direct laser irradiation and the possibility to measure pulsed as well as cw-laser sources. The detector is capable of measuring the energy of single laser pulses with repetition frequencies up to the MHz range, adding the possibility to also measure the output power of cw-lasers. Moreover, the thermal nature of the sensor enables the capability to work in a broadband spectrum, from UV to THz as well as the possibility of operating in a broad-range (10-3-102 W/cm2 ) of incident average optical power densities of the laser radiation, without the need of adopting optical filters nor other precautions.

Terahertz Sideband-tuned Quantum Cascade Laser Radiation

DTIC Science & Technology

2008-03-31

resolution of 2 MHz in CW regime was observed. ©2008 Optical Society of America OCIS codes: (140.5965) Semiconductor lasers , quantum cascade...diode,” Opt. Lett. 29, 1632 (2004). 6. A. Baryshev, et.al., “ Phase locking and spectral linewidth of a two-mode terahertz quantum cascade laser ,” Appl... optically pumped gas laser . With further improvements in power and spatial mode quality, it should be possible to lock a TQCL to the harmonic of an ultra

Diode Laser Pumped Alkali Vapor Lasers with Exciplex-Assisted Absorption

DTIC Science & Technology

2013-05-14

transfer agent that established the population inversion. The excitation source used in these initial studies was a pulsed optical parametric oscillator ...parametric oscillator . The lasers operated at 703.2 (Ne*), 912.5 (Ar*), 893.1 (Kr*) and 980.2 run (Xe*). Peak powers as high as 27kW/cm2 were observed...Larissa Glebova and Leonid B. Glebov. Ultra-low absorption and laser-induced heating of volume Bragg combiners recorded in photo-thermo- refractive

Atom-chip based quantum gravimetry for the precise determination of absolute local gravity

NASA Astrophysics Data System (ADS)

Abend, S.

2015-12-01

We present a novel technique for the precise measurement of absolute local gravity based on cold atom interferometry. Atom interferometry utilizes the interference of matter waves interrogated by laser light to read out inertial forces. Today's generation of these devices typically operate with test mass samples, that consists of ensembles of laser cooled atoms. Their performance is limited by the velocity spread and finite-size of the test masses that impose systematic uncertainties at the level of a few μGal. Rather than laser cooled atoms we employ quantum degenerate ensembles, so called Bose-Einstein condensates, as ultra-sensitive probes for gravity. These sources offer unique properties in temperature as well as in ensemble size that will allow to overcome the current limitations with the next generation of sensors. Furthermore, atom-chip technologies offer the possibility to generate Bose-Einstein condensates in a fast and reliable way. We show a lab-based prototype that uses the atom-chip itself to retro-reflect the interrogation laser and thus serving as inertial reference inside the vacuum. With this setup it is possible to demonstrate all necessary steps to measure gravity, including the preparation of the source, spanning an interferometer as well as the detection of the output signal, within an area of 1 cm3 right below the atom-chip and to analyze relevant systematic effects. In the framework of the center of excellence geoQ a next generation device is under construction at the Institut für Quantenoptik, that will allow for in-field measurements. This device will feature a state-of-the-art atom-chip source with a high-flux of ultra-cold atoms at a repetition rate of 1-2 Hz. In cooperation with the Müller group at the Institut für Erdmessung the sensor will be characterized in the laboratory first, to be ultimately employed in campaigns to measure the Fennoscandian uplift at the level of 1 μGal. The presented work is part of the center of excellence geoQ (SFB 1128), funded by the Deutsche Forschungsgemeinschaft (DFG). This work is supported by the German Space Agency (DLR) with funds provided by the Federal Ministry for Economic Affairs and Energy (BMWi) due to an enactment of the German Bundestag under grant numbers DLR 50 1131-1137 (QUANTUS-III).

X-Ray Laser Program Final Report for FY92

DTIC Science & Technology

1993-07-01

also produced population inversion. Ultra- intense , femtosecond- pulsed laboratory lasers ranging from the ultraviolet to the infrared represent an...with pulse lengths of 650 femtoseconds normally Incident on a 2p. thick planar aluminum slab. Comparisons are made for two laser Intensities , two...prepulse is subsequently irradiated by the main high intensity pulse . The persistence of the heliumlike ground state raises the possibility that a photon

Method of defining features on materials with a femtosecond laser

DOEpatents

Roos, Edward Victor [Los Altos, CA; Roeske, Franklin [Livermore, CA; Lee, Ronald S [Livermore, CA; Benterou, Jerry J [Livermore, CA

2006-05-23

The invention relates to a pulsed laser ablation method of metals and/or dielectric films from the surface of a wafer, printed circuit board or a hybrid substrate. By utilizing a high-energy ultra-short pulses of laser light, such a method can be used to manufacture electronic circuits and/or electro-mechanical assemblies without affecting the material adjacent to the ablation zone.

Ultra fast quantum key distribution over a 97 km installed telecom fiber with wavelength division multiplexing clock synchronization.

PubMed

Tanaka, Akihiro; Fujiwara, Mikio; Nam, Sae W; Nambu, Yoshihiro; Takahashi, Seigo; Maeda, Wakako; Yoshino, Ken-ichiro; Miki, Shigehito; Baek, Burm; Wang, Zhen; Tajima, Akio; Sasaki, Masahide; Tomita, Akihisa

2008-07-21

We demonstrated ultra fast BB84 quantum key distribution (QKD) transmission at 625 MHz clock rate through a 97 km field-installed fiber using practical clock synchronization based on wavelength-division multiplexing (WDM). We succeeded in over-one-hour stable key generation at a high sifted key rate of 2.4 kbps and a low quantum bit error rate (QBER) of 2.9%. The asymptotic secure key rate was estimated to be 0.78- 0.82 kbps from the transmission data with the decoy method of average photon numbers 0, 0.15, and 0.4 photons/pulse.

Ultra-fast HPM detectors improve NAD(P)H FLIM

NASA Astrophysics Data System (ADS)

Becker, Wolfgang; Wetzker, Cornelia; Benda, Aleš

2018-02-01

Metabolic imaging by NAD(P)H FLIM requires the decay functions in the individual pixels to be resolved into the decay components of bound and unbound NAD(P)H. Metabolic information is contained in the lifetime and relative amplitudes of the components. The separation of the decay components and the accuracy of the amplitudes and lifetimes improves substantially by using ultra-fast HPM-100-06 and HPM-100-07 hybrid detectors. The IRF width in combination with the Becker & Hickl SPC-150N and SPC-150NX TCSPC modules is less than 20 ps. An IRF this fast does not interfere with the fluorescence decay. The usual deconvolution process in the data analysis then virtually becomes a simple curve fitting, and the parameters of the NAD(P)H decay components are obtained at unprecedented accuracy.

Ultra-Rapid Categorization of Meaningful Real-Life Scenes in Adults with and without ASD

ERIC Educational Resources Information Center

Vanmarcke, Steven; Van Der Hallen, Ruth; Evers, Kris; Noens, Ilse; Steyaert, Jean; Wagemans, Johan

2016-01-01

In comparison to typically developing (TD) individuals, people with autism spectrum disorder (ASD) appear to be worse in the fast extraction of the global meaning of a situation or picture. Ultra-rapid categorization [paradigm developed by Thorpe et al. ("Nature" 381:520-522, 1996)] involves such global information processing. We…

First light from the Diocles laser: Relativistic laser-plasmas and beams

NASA Astrophysics Data System (ADS)

Umstadter, Donald

2007-06-01

Reported are first experimental results from a new high-power (150 TW) laser, Diocles, now in operation at the University of Nebraska, Lincoln. Discussed are novel approaches to using the ultra-high-intensity light from this laser to study relativistic laser plasma interactions. Bright, ultrashort duration (femtosecond ) pulses of energetic (keV -- MeV) x-ray and charged-particle beams are generated through these interactions. Also covered in this talk will be applications of these unique radiation sources for research in the physical sciences, as well as biomedicine, defense and homeland security.

Precise ablation of dental hard tissues with ultra-short pulsed lasers. Preliminary exploratory investigation on adequate laser parameters.

PubMed

Bello-Silva, Marina Stella; Wehner, Martin; Eduardo, Carlos de Paula; Lampert, Friedrich; Poprawe, Reinhart; Hermans, Martin; Esteves-Oliveira, Marcella

2013-01-01

This study aimed to evaluate the possibility of introducing ultra-short pulsed lasers (USPL) in restorative dentistry by maintaining the well-known benefits of lasers for caries removal, but also overcoming disadvantages, such as thermal damage of irradiated substrate. USPL ablation of dental hard tissues was investigated in two phases. Phase 1--different wavelengths (355, 532, 1,045, and 1,064 nm), pulse durations (picoseconds and femtoseconds) and irradiation parameters (scanning speed, output power, and pulse repetition rate) were assessed for enamel and dentin. Ablation rate was determined, and the temperature increase measured in real time. Phase 2--the most favorable laser parameters were evaluated to correlate temperature increase to ablation rate and ablation efficiency. The influence of cooling methods (air, air-water spray) on ablation process was further analyzed. All parameters tested provided precise and selective tissue ablation. For all lasers, faster scanning speeds resulted in better interaction and reduced temperature increase. The most adequate results were observed for the 1064-nm ps-laser and the 1045-nm fs-laser. Forced cooling caused moderate changes in temperature increase, but reduced ablation, being considered unnecessary during irradiation with USPL. For dentin, the correlation between temperature increase and ablation efficiency was satisfactory for both pulse durations, while for enamel, the best correlation was observed for fs-laser, independently of the power used. USPL may be suitable for cavity preparation in dentin and enamel, since effective ablation and low temperature increase were observed. If adequate laser parameters are selected, this technique seems to be promising for promoting the laser-assisted, minimally invasive approach.

Optimum hot electron production with low-density foams for laser fusion by fast ignition.

PubMed

Lei, A L; Tanaka, K A; Kodama, R; Kumar, G R; Nagai, K; Norimatsu, T; Yabuuchi, T; Mima, K

2006-06-30

We propose a foam cone-in-shell target design aiming at optimum hot electron production for the fast ignition. A thin low-density foam is proposed to cover the inner tip of a gold cone inserted in a fuel shell. An intense laser is then focused on the foam to generate hot electrons for the fast ignition. Element experiments demonstrate increased laser energy coupling efficiency into hot electrons without increasing the electron temperature and beam divergence with foam coated targets in comparison with solid targets. This may enhance the laser energy deposition in the compressed fuel plasma.

Fast Electron Deposition in Laser Shock Compressed Plastic Targets

NASA Astrophysics Data System (ADS)

Hall, T. A.; Ellwi, S.; Batani, D.; Bernardinello, A.; Masella, V.; Koenig, M.; Benuzzi, A.; Krishnan, J.; Pisani, F.; Djaoui, A.; Norreys, P.; Neely, D.; Rose, S.; Key, M. H.; Fews, P.

1998-08-01

We present the first results of fast electron deposition in a laser shock compressed plasma. The interaction of a 3 ps, 15 J laser pulse with solid polyethylene targets is used to produce fast electrons on one side of foil targets and a 2 ns duration laser pulse is used to drive a shock wave into the target from the opposite side. Kα emission from chlorine fluor buried layers is used to measure the electron transport. The hot electron range in the shock compressed plastic is found to be approximately twice as large as the range in the solid density plastic.

Laser-driven plasma photonic crystals for high-power lasers

NASA Astrophysics Data System (ADS)

Lehmann, G.; Spatschek, K. H.

2017-05-01

Laser-driven plasma density gratings in underdense plasma are shown to act as photonic crystals for high power lasers. The gratings are created by counterpropagating laser beams that trap electrons, followed by ballistic ion motion. This leads to strong periodic plasma density modulations with a lifetime on the order of picoseconds. The grating structure is interpreted as a plasma photonic crystal time-dependent property, e.g., the photonic band gap width. In Maxwell-Vlasov and particle-in-cell simulations it is demonstrated that the photonic crystals may act as a frequency filter and mirror for ultra-short high-power laser pulses.

Room temperature optical anisotropy of a LaMnO 3 thin-film induced by ultra-short pulse laser

DOE Office of Scientific and Technical Information (OSTI.GOV)

Munkhbaatar, Purevdorj; Marton, Zsolt; Tsermaa, Bataarchuluun

Ultra-short laser pulse induced optical anisotropy of LaMnO 3 thin films grown on SrTiO 3 substrates were observed by irradiation with a femto-second laser pulse with the fluence of less than 0.1 mJ/cm 2 at room temperature. The transmittance and reflectance showed different intensities for different polarization states of the probe pulse after pump pulse irradiation. The theoretical optical transmittance and re ectance that assumed an orbital ordering of the 3d eg electrons in Mn 3+ ions resulted in an anisotropic time dependent changes similar to those obtained from the experimental results, suggesting that the photo-induced optical anisotropy of LaMnOmore » 3 is a result of photo-induced symmetry breaking of the orbital ordering for an optically excited state.« less

The new methods of treatment for age-related macular degeneration using the ultra-short pulsed laser

NASA Astrophysics Data System (ADS)

Iwamoto, Yumiko; Awazu, Kunio; Suzuki, Sachiko; Ohshima, Tetsuro; Sawa, Miki; Sakaguchi, Hirokazu; Tano, Yasuo; Ohji, Masahito

2007-02-01

The non-invasive methods of treatments have been studying for the improvement of quality of life (QOL) of patients undergoing treatment. A photodynamic therapy (PDT) is one of the non-invasive treatments. PDT is the methods of treatment using combination of a laser and a photosensitizer. PDT has few risks for patients. Furthermore, PDT enables function preservation of a disease part. PDT has been used for early cancer till now, but in late years it is applied for age-related macular degeneration (AMD). AMD is one of the causes of vision loss in older people. However, PDT for AMD does not produce the best improvement in visual acuity. The skin photosensivity by an absorption characteristic of a photosensitizer is avoided. We examined new PDT using combination of an ultra-short pulsed laser and indocyanine green (ICG).

Fast widely-tunable single-frequency 2-micron laser for remote-sensing applications

NASA Astrophysics Data System (ADS)

Henderson, Sammy W.; Hale, Charley P.

2017-08-01

We are developing a family of fast, widely-tunable cw diode-pumped single frequency solid-state lasers, called Swift. The Swift laser architecture is compatible with operation using many different solid-state laser crystals for operation at various emission lines between 1 and 2.1 micron. The initial prototype Swift laser using a Tm,Ho:YLF laser crystal near 2.05 micron wavelength achieved over 100 mW of single frequency cw output power, up to 50 GHz-wide, fast, mode-hop-free piezoelectric tunability, and 100 kHz/ms frequency stability. For the Tm,Ho:YLF laser material, the fast 50 GHz tuning range can be centered at any wavelength from 2047-2059 nm using appropriate intracavity spectral filters. The frequency stability and power are sufficient to serve as the local oscillator (LO) laser in long-range coherent wind-measuring lidar systems, as well as a frequency-agile master oscillator (MO) or injection-seed source for larger pulsed transmitter lasers. The rapid and wide frequency tunablity meets the requirements for integrated-path or range-resolved differential absorption lidar or applications where targets with significantly different line of sight velocities (Doppler shifts) must be tracked. Initial demonstration of an even more compact version of the Swift is also described which requires less prime power and produces less waste heat.

Semiconductor lasers for versatile applications from global communications to on-chip interconnects

NASA Astrophysics Data System (ADS)

Arai, Shigehisa

2015-01-01

Since semiconductor lasers were realized in 1962, various efforts have been made to enrich human life thorough novel equipments and services. Among them optical fiber communications in global communications have brought out marvelous information technology age represented by the internet. In this paper, emerging topics made on GaInAsP/InP based long-wavelength lasers toward ultra-low power consumption semiconductor lasers for optical interconnects in supercomputers as well as in future LSIs are presented.

New ultra-high resolution dye laser spectrometer utilizing a non-tunable reference resonator

NASA Astrophysics Data System (ADS)

Helmcke, J.; Snyder, J. J.; Morinaga, A.; Mensing, F.; Gläser, M.

1987-06-01

A new dye laser spectrometer utilizing a non-tunable reference resonator is described. The resonator consists of two Zerodur mirrors optically contacted to a Zerodur spacer. Frequency scanning of the laser is provided by acoustooptic modulation. Residual drifts of the resonator frequency — measured on line — are compensated automatically by corresponding corrections of the modulation frequency. The stability during several hours and the resettability of the dye laser frequency are±2.5 kHz and±10 kHz, respectively.

Micro-Laser Range Finder Development: Using the Monolithic Approach

DTIC Science & Technology

1999-02-01

components can be joined together, optically aligned to form the laser cavity and then sliced to produce MLC modules . This batch process can greatly reduce...the overall fabrication costs of the µLRF system. The MLC module is ultra-compact. Its overall size is approximately 56 mm (L) x 3 mm (W) x 3 mm (H) as...MLC module is placed on a laser pallet for stiffness, mechanical stability. The laser pallet size is selected as part of the integration design

X-ray absorption of a warm dense aluminum plasma created by an ultra-short laser pulse

NASA Astrophysics Data System (ADS)

Lecherbourg, L.; Renaudin, P.; Bastiani-Ceccotti, S.; Geindre, J.-P.; Blancard, C.; Cossé, P.; Faussurier, G.; Shepherd, R.; Audebert, P.

2007-05-01

Point-projection K-shell absorption spectroscopy has been used to measure absorption spectra of transient aluminum plasma created by an ultra-short laser pulse. The 1s-2p and 1s-3p absorption lines of weakly ionized aluminum were measured for an extended range of densities in a low-temperature regime. Independent plasma characterization was obtained using frequency domain interferometry diagnostic (FDI) that allows the interpretation of the absorption spectra in terms of spectral opacities. A detailed opacity code using the density and temperature inferred from the FDI reproduce the measured absorption spectra except in the last stage of the recombination phase.

Nearly-octave wavelength tuning of a continuous wave fiber laser

PubMed Central

Zhang, Lei; Jiang, Huawei; Yang, Xuezong; Pan, Weiwei; Cui, Shuzhen; Feng, Yan

2017-01-01

The wavelength tunability of conventional fiber lasers are limited by the bandwidth of gain spectrum and the tunability of feedback mechanism. Here a fiber laser which is continuously tunable from 1 to 1.9 μm is reported. It is a random distributed feedback Raman fiber laser, pumped by a tunable Yb doped fiber laser. The ultra-wide wavelength tunability is enabled by the unique property of random distributed feedback Raman fiber laser that both stimulated Raman scattering gain and Rayleigh scattering feedback are available at any wavelength. The dispersion property of the gain fiber is used to control the spectral purity of the laser output. PMID:28198414

A review of ultra-short pulse lasers for military remote sensing and rangefinding

NASA Astrophysics Data System (ADS)

Lamb, Robert A.

2009-09-01

Advances in ultra-short pulse laser technology have resulted in commercially available laser systems capable of generating high peak powers >1GW in tabletop systems. This opens the prospect of generating very wide spectral emissions with a combination of non-linear optical effects in photonic crystal fibres to produce supercontinuua in systems that are readily accessible to military applications. However, military remote sensing rarely requires bandwidths spanning two octaves and it is clear that efficient systems require controlled spectral emission in relevant bands. Furthermore, the limited spectral responsivity of focal plane arrays may impose further restriction on the usable spectrum. A recent innovation which temporally encodes a spectrum using group velocity dispersion allows detection with a photodiode, opening the prospect for high speed hyperspectral sensing and imaging. At the opposite end of the power spectrum, ultra-low power remote sensing using time-correlated single photon counting (SPC) has reduced the laser power requirement and demonstrated remote sensing over 5km during daylight with repetition rates of ~10MHz with ps pulses. Recent research has addressed uncorrelated SPC and waveform transmission to increase data rates for absolute rangefinding whilst avoiding range aliasing. This achievement opens the prospect of combining SPC with high repetition rate temporal encoding of supercontinuua to realise practical hyperspectral remote sensing lidar. The talk will present an overview of these technologies and present a concept which combines them into a single system for high-speed hyperspectral imaging and remote sensing.

Ultra-Stable Laser Clock.

DTIC Science & Technology

1983-03-01

43. L circumference of ring laser cavity 44. LF pathlength through Faraday rotator 45. 1 distance between resonator mirrors of linear laser 46. M...limited clock stability 68. q mode number 69. Ri reflectivity of mirror i 70. eF angle between magnetic field and direction of light propagation 71...containing low pressure methane. The light reflects off a mirror and passes back through the cell. Then the light reflects from the beam splitter into

All-fiber, ultra-wideband tunable laser at 2 μm.

PubMed

Li, Z; Alam, S U; Jung, Y; Heidt, A M; Richardson, D J

2013-11-15

We report a direct diode-pumped all-fiber tunable laser source at 2 μm with a tuning range of more than 250 nm. A 3 dB power flatness of 200 nm with a maximum output power of 30 mW at 1930 nm was achieved. The laser has a high optical signal-to-noise ratio (OSNR) of more than 40 dB across the whole tuning range.

The radiobiology of laser-driven particle beams: focus on sub-lethal responses of normal human cells

NASA Astrophysics Data System (ADS)

Manti, L.; Perozziello, F. M.; Borghesi, M.; Candiano, G.; Chaudhary, P.; Cirrone, G. A. P.; Doria, D.; Gwynne, D.; Leanza, R.; Prise, K. M.; Romagnani, L.; Romano, F.; Scuderi, V.; Tramontana, A.

2017-03-01

Accelerated proton beams have become increasingly common for treating cancer. The need for cost and size reduction of particle accelerating machines has led to the pioneering investigation of optical ion acceleration techniques based on laser-plasma interactions as a possible alternative. Laser-matter interaction can produce extremely pulsed particle bursts of ultra-high dose rates (>= 109 Gy/s), largely exceeding those currently used in conventional proton therapy. Since biological effects of ionizing radiation are strongly affected by the spatio-temporal distribution of DNA-damaging events, the unprecedented physical features of such beams may modify cellular and tissue radiosensitivity to unexplored extents. Hence, clinical applications of laser-generated particles need thorough assessment of their radiobiological effectiveness. To date, the majority of studies have either used rodent cell lines or have focussed on cancer cell killing being local tumour control the main objective of radiotherapy. Conversely, very little data exist on sub-lethal cellular effects, of relevance to normal tissue integrity and secondary cancers, such as premature cellular senescence. Here, we discuss ultra-high dose rate radiobiology and present preliminary data obtained in normal human cells following irradiation by laser-accelerated protons at the LULI PICO2000 facility at Laser Lab Europe, France.

Creation of ultra-high energy density matter using nanostructured targets

NASA Astrophysics Data System (ADS)

Tommasini, Riccardo; Park, J.; London, R.; Chen, H.; Hollinger, R. C.; Bargsten, C.; Shlyaptsev, V.; Capeluto, M.; Keiss, D.; Townsend, A.; Rocca, J. J.; Kaymak, V.; Pukhov, A.; Hill, M.

2015-11-01

Recent experiments have demonstrated that trapping of 60 femtosecond laser pulses of relativistic intensity deep within ordered nanowire arrays can create a new ultra-hot plasma regime. Here we report on the experiments at the Titan laser at the Lawrence Livermore National Laboratory that aim to scale these results by two orders of magnitude in laser energy. Preliminary analysis of the Titan results show that sub-picosecond laser irradiation of vertically aligned nanostructures of Au, Ag and Ni produces an increase of a factor greater than 1.6 in the suprathermal electron temperatures and an increase by a factor of 3 in the conversion efficiency into continuum x-rays, both with respect to flat targets of the same composition. Kα radiation from nanowire array targets also shows an increase between 3x and 5x over flat targets. The nanowire array targets reflected a 5x smaller fraction of the laser energy, indicating significantly larger absorption of the laser pulse. This work performed under the auspices of the U. S. Department of Energy by Lawrence Livermore National Laboratory under Contract No. DE-AC52-07NA27344, by the Office of Fusion Energy Sciences, U.S Department of Energy, and by the Defense Threat Reduction Agency grant HDTRA-1-10-1-0079.

Laser-driven ion acceleration via target normal sheath acceleration in the relativistic transparency regime

DOE PAGES

Poole, P. L.; Obst, L.; Cochran, G. E.; ...

2018-01-11

Here we present an experimental study investigating laser-driven proton acceleration via target normal sheath acceleration (TNSA) over a target thickness range spanning the typical TNSA-dominant regime (~1 μm) down to below the onset of relativistic laser-transparency (<40 nm). This is done with a single target material in the form of freely adjustable films of liquid crystals along with high contrast (via plasma mirror) laser interaction (~2.65 J, 30 fs, I>1 x 10 21 W cm -2). Thickness dependent maximum proton energies scale well with TNSA models down to the thinnest targets, while those under ~40 nm indicate the influence ofmore » relativistic transparency on TNSA, observed via differences in light transmission, maximum proton energy, and proton beam spatial profile. Oblique laser incidence (45°) allowed the fielding of numerous diagnostics to determine the interaction quality and details: ion energy and spatial distribution was measured along the laser axis and both front and rear target normal directions; these along with reflected and transmitted light measurements on-shot verify TNSA as dominant during high contrast interaction, even for ultra-thin targets. Additionally, 3D particle-in-cell simulations qualitatively support the experimental observations of target-normal-directed proton acceleration from ultra-thin films.« less

Ultra-low emittance electron beam generation using ionization injection in a plasma beatwave accelerator

NASA Astrophysics Data System (ADS)

Schroeder, Carl; Benedetti, Carlo; Esarey, Eric; Leemans, Wim

2017-10-01

Ultra-low emittance beams can be generated using ionization injection of electrons into a wakefield excited by a plasma beatwave accelerator. This all-optical method of electron beam generation uses three laser pulses of different colors. Two long-wavelength laser pulses, with frequency difference equal to the plasma frequency, resonantly drive a plasma wave without fully ionizing a gas. A short-wavelength injection laser pulse (with a small ponderomotive force and large peak electric field), co-propagating and delayed with respect to the beating long-wavelength lasers, ionizes a fraction of the remaining bound electrons at a trapped wake phase, generating an electron beam that is accelerated in the wakefield. Using the beating of long-wavelength pulses to generate the wakefield enables atomically-bound electrons to remain at low ionization potentials, reducing the required amplitude of the ionization pulse, and, hence, the initial transverse momentum and emittance of the injected electrons. An example is presented using two lines of a CO2 laser to form a plasma beatwave accelerator to drive the wake and a frequency-doubled Ti:Al2O3 laser for ionization injection. Supported by the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.

Laser-driven ion acceleration via target normal sheath acceleration in the relativistic transparency regime

DOE Office of Scientific and Technical Information (OSTI.GOV)

Poole, P. L.; Obst, L.; Cochran, G. E.

Here we present an experimental study investigating laser-driven proton acceleration via target normal sheath acceleration (TNSA) over a target thickness range spanning the typical TNSA-dominant regime (~1 μm) down to below the onset of relativistic laser-transparency (<40 nm). This is done with a single target material in the form of freely adjustable films of liquid crystals along with high contrast (via plasma mirror) laser interaction (~2.65 J, 30 fs, I>1 x 10 21 W cm -2). Thickness dependent maximum proton energies scale well with TNSA models down to the thinnest targets, while those under ~40 nm indicate the influence ofmore » relativistic transparency on TNSA, observed via differences in light transmission, maximum proton energy, and proton beam spatial profile. Oblique laser incidence (45°) allowed the fielding of numerous diagnostics to determine the interaction quality and details: ion energy and spatial distribution was measured along the laser axis and both front and rear target normal directions; these along with reflected and transmitted light measurements on-shot verify TNSA as dominant during high contrast interaction, even for ultra-thin targets. Additionally, 3D particle-in-cell simulations qualitatively support the experimental observations of target-normal-directed proton acceleration from ultra-thin films.« less

Bubble formation during pulsed laser ablation: mechanism and implications

NASA Astrophysics Data System (ADS)

van Leeuwen, Ton G. J. M.; Jansen, E. Duco; Motamedi, Massoud; Welch, Ashley J.; Borst, Cornelius

1993-07-01

Holmium ((lambda) equals 2.09 micrometers ) and excimer ((lambda) equals 308 nm) lasers are used for ablation of tissue. In a previous study it was demonstrated that both excimer and holmium laser pulses produce fast expanding and collapsing vapor bubbles. To investigate whether the excimer induced bubble is caused by vaporization of water, the threshold fluence for bubble formation at a bare fiber tip in water was compared between the excimer laser (pulse length 115 ns) and the Q-switched and free-running holmium lasers (pulse length 1 microsecond(s) to 250 microsecond(s) , respectively). To induce bubble formation by excimer laser light in water, the absorber oxybuprocaine-hydrochloride (OBP-HCl) was added to the water. Fast flash photography was used to measure the threshold fluence as a function of the water temperature (6 - 90 degree(s)C) at environmental pressure. The ultraviolet excimer laser light is strongly absorbed by blood. Therefore, to document the implications of bubble formation at fluences above the tissue ablation threshold, excimer laser pulses were delivered in vitro in hemoglobin solution and in vivo in the femoral artery of the rabbit. We conclude that the principal content of the fast bubble induced by a 308 nm excimer laser pulse is water vapor. Therefore, delivery of excimer laser pulses in a water or blood environment will cause fast expanding water vapor bubbles, which may induce mechanical damage to adjacent tissue.

Open Probe fast GC-MS - combining ambient sampling ultra-fast separation and in-vacuum ionization for real-time analysis.

PubMed

Keshet, U; Alon, T; Fialkov, A B; Amirav, A

2017-07-01

An Open Probe inlet was combined with a low thermal mass ultra-fast gas chromatograph (GC), in-vacuum electron ionization ion source and a mass spectrometer (MS) of GC-MS for obtaining real-time analysis with separation. The Open Probe enables ambient sampling via sample vaporization in an oven that is open to room air, and the ultra-fast GC provides ~30-s separation, while if no separation is required, it can act as a transfer line with 2 to 3-s sample transfer time. Sample analysis is as simple as touching the sample, pushing the sample holder into the Open Probe oven and obtaining the results in 30 s. The Open Probe fast GC was mounted on a standard Agilent 7890 GC that was coupled with an Agilent 5977A MS. Open Probe fast GC-MS provides real-time analysis combined with GC separation and library identification, and it uses the low-cost MS of GC-MS. The operation of Open Probe fast GC-MS is demonstrated in the 30-s separation and 50-s full analysis cycle time of tetrahydrocannabinol and cannabinol in Cannabis flower, sub 1-min analysis of trace trinitrotoluene transferred from a finger onto a glass surface, vitamin E in canola oil, sterols in olive oil, polybrominated flame retardants in plastics, alprazolam in Xanax drug pill and free fatty acids and cholesterol in human blood. The extrapolated limit of detection for pyrene is <1 fg, but the concentration is too high and the software noise calculation is untrustworthy. The broad range of compounds amenable for analysis is demonstrated in the analysis of reserpine. The possible use with alternate standard GC-MS and Open Probe fast GC-MS is demonstrated in the analysis of heroin in its street drug powder. The use of Open Probe with the fast GC acting as a transfer line is demonstrated in <10-s analysis without separation of ibuprofen and estradiol. Copyright © 2017 John Wiley & Sons, Ltd. Copyright © 2017 John Wiley & Sons, Ltd.

Progress toward a practical laser driven ion source using variable thickness liquid crystal targets

NASA Astrophysics Data System (ADS)

Poole, Patrick; Cochran, Ginevra; Zeil, Karl; Metzkes, Josephine; Obst, Lieselotte; Kluge, Thomas; Schlenvoigt, Hans-Peter; Prencipe, Irene; Cowan, Tom; Schramm, Uli; Schumacher, Douglass

2016-10-01

Ion acceleration from ultra-intense laser interaction has been long investigated in pursuit of requisite energies and spectral distributions for applications like proton cancer therapy. However, the details of ion acceleration mechanisms and their laser intensity scaling are not fully understood, especially the complete role of pulse contrast and target thickness. Additionally, target delivery and alignment at appropriate rates for study and subsequent treatment pose significant challenges. We present results from a campaign on the Draco laser using liquid crystal targets that have on-demand, in-situ thickness tunability over more than three orders of magnitude, enabling rapid data collection due to <1 minute, automatically aligned target formation. Diagnostics include spectral and spatial measurement of ions, electrons, and reflected and transmitted light, all with thickness, laser focus, and pulse contrast variations. In particular we discuss optimal thickness vs. contrast and details of ultra-thin target normal ion acceleration, along with supporting particle-in-cell studies. This work was supported by the DARPA PULSE program through AMRDEC, by the NNSA (DE-NA0001976), by EC Horizon 2020 LASERLAB-EUROPE/LEPP (654148), and by the German Federal Ministry of Education and Research (BMBF, 03Z1O511).

Triangular laser-induced submicron textures for functionalising stainless steel surfaces

NASA Astrophysics Data System (ADS)

Romano, Jean-Michel; Garcia-Giron, Antonio; Penchev, Pavel; Dimov, Stefan

2018-05-01

Processing technologies that engineer surfaces with sub-micron topographies are of a growing interest to a range of optical, hydrophobic and microbiological applications. One of the promising technologies for creating such topographies employs ultra-short laser pulses to produce laser-induced periodic surface structures (LIPSS) that often result in non-regular, quasi-periodic nanoripples and nanopillars. In this research near infrared ultra-short pulses of 310 fs with a circular polarisation was used to texture ferritic stainless steel workpieces. A single-step process was designed to generate low spatial frequency LIPSS (LSFL) over relatively large areas. Apart from highly regular and homogeneous parallel lines with approximately 900 nm periodicity, extraordinarily uniform triangular-LSFL in hexagonal arrangements was created. The generation of such LSFL was found to be highly repeatable but very sensitive to the used laser processing settings. Therefore, the sensitivity of triangular-LSFL formation to the used laser processing settings, i.e. pulse to pulse distance, pulse fluence and focal plane offsets, were investigated in regard to the resulting morphologies and functional properties, i.e. structural colors and super-hydrophobicity. Finally, the capability of this technology for producing uniform triangular-shaped LSFL on relatively large surface areas of stainless steel plates was studied.

Comparative study between fundus autofluorescence and red reflectance imaging of choroidal nevi using ultra-wide-field scanning laser ophthalmoscopy.

PubMed

Zapata, Miguel Angel; Leila, Mahmoud; Teixidor, Teresa; Garcia-Arumi, Jose

2015-06-01

To explore the utility of fundus autofluorescence (FAF) and red reflectance (RR) imaging using ultra-wide-field scanning laser ophthalmoscope in choroidal nevi. Retrospective observational case study reviewing clinical data, color, FAF, and RR images of patients with choroidal nevi and comparing the findings. The ultra-wide-field scanning laser ophthalmoscope uses green laser 532 nm and red laser 633 nm that enabled FAF and RR imaging, respectively in separate channels. Superimposition of both images yielded a composite color image. The study included 46 eyes of 45 patients. Nevi were unilateral in 44 patients (98%). Forty-one nevi (89.1%) were located temporally between the macula and the equator. All nevi (100%) were deeply pigmented. The most frequent surface changes were lipofuscin pigments, zones of retinal pigment epithelium atrophy, and retinal pigment epithelium pigment clumps in 31 (67.3%), 18 (39.1%), and 8 eyes (17.3%), respectively. Color photographs were superior to FAF in detecting nevus boundaries and surface changes. Red reflectance correlated strongly with color images, although the nevus boundaries and surface changes were better delineated in RR mode. Red reflectance was superior to FAF in delineating the boundaries and surface changes of the nevus; clear visibility (3+) for RR versus no or poor visibility (0/1+) for FAF. Nevertheless, the areas of retinal pigment epithelium atrophy were better delineated in FAF mode; clear visibility (3+) for FAF versus poor visibility (1+) for FAF. Red reflectance imaging is more sensitive than conventional photography for follow-up of choroidal nevi. Fundus autofluorescence should be considered only as a complementary tool to RR imaging.

Waste heat recovery with ultra high-speed turbomachinery

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vakkilainen, E.; Larjola, J.; Lindgren, O.

1984-08-01

A new ORC heat recovery system which converts waste heat to electricity has been developed in Lappeenranta University of Technology with support from Department of Energy in Finnish Ministry of Trade and Industry. Use of ultra high-speed turbomachinery (10 000 rpm - 200 000 rpm) promises lower unit costs, higher efficiencies and fast amortization rate, 2,4 - 3,0 years.

High-performance rechargeable batteries with fast solid-state ion conductors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Farmer, Joseph C.

A high-performance rechargeable battery using ultra-fast ion conductors. In one embodiment the rechargeable battery apparatus includes an enclosure, a first electrode operatively connected to the enclosure, a second electrode operatively connected to the enclosure, a nanomaterial in the enclosure, and a heat transfer unit.

Fast plasmonic laser nanowelding for a Cu-nanowire percolation network for flexible transparent conductors and stretchable electronics.

PubMed

Han, Seungyong; Hong, Sukjoon; Ham, Jooyeun; Yeo, Junyeob; Lee, Jinhwan; Kang, Bongchul; Lee, Phillip; Kwon, Jinhyeong; Lee, Seung S; Yang, Min-Yang; Ko, Seung Hwan

2014-09-03

A facile fast laser nanoscale welding process uses the plasmonic effect at a nanowire (NW) junction to suppress oxidation and successfully fabricate a Cu-NW-based percolation-network conductor. The "nanowelding" process does not require an inert or vacuum environment. Due to the low-temperature and fast-process nature, plasmonic laser nanowelding may form Cu-nanowire networks on heat-sensitive, flexible or even stretchable substrates. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Effect of pulse profile and chirp on a laser wakefield generation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang Xiaomei; Shen Baifei; Ji Liangliang

2012-05-15

A laser wakefield driven by an asymmetric laser pulse with/without chirp is investigated analytically and through two-dimensional particle-in-cell simulations. For a laser pulse with an appropriate pulse length compared with the plasma wavelength, the wakefield amplitude can be enhanced by using an asymmetric un-chirped laser pulse with a fast rise time; however, the growth is small. On the other hand, the wakefield can be greatly enhanced for both positively chirped laser pulse having a fast rise time and negatively chirped laser pulse having a slow rise time. Simulations show that at the early laser-plasma interaction stage, due to the influencemore » of the fast rise time the wakefield driven by the positively chirped laser pulse is more intense than that driven by the negatively chirped laser pulse, which is in good agreement with analytical results. At a later time, since the laser pulse with positive chirp exhibits opposite evolution to the one with negative chirp when propagating in plasma, the wakefield in the latter case grows more intensely. These effects should be useful in laser wakefield acceleration experiments operating at low plasma densities.« less

Plasma mirror implementation on LFEX laser for ion and fast electron fast ignition

NASA Astrophysics Data System (ADS)

Morace, A.; Kojima, S.; Arikawa, Y.; Fujioka, S.; Yogo, A.; Tosaki, S.; Sakata, S.; Abe, Y.; Lee, S. H.; Matsuo, K.; Sagisaka, A.; Kondo, K.; Pirozhkov, A. S.; Norimatsu, T.; Jitsuno, T.; Miyanaga, N.; Shiraga, H.; Nakai, M.; Nishimura, H.; Azechi, H.

2017-12-01

In this work we report the successful implementation of plasma mirror (PM) technology on an LFEX laser facility at the Institute of Laser Engineering, Osaka University. The LFEX laser pulse was successfully refocused at the target chamber center (TCC) by means of a spherical plasma mirror, resulting in 5  ×  1018 W cm-2 laser intensity, with 45% reflectivity at a laser flux of about 90 J cm-2 on the PM. Experimental results show stable focusing and pointing of the LFEX pulse after PM refocusing. The contrast improvement was demonstrated by both cooler fast electron slope temperature distribution as well as by the ability to shoot sub-µm plastic foils obtaining proton beams with maximum energy exceeding 20 MeV. Experimental results are qualitatively reproduced by 2D particle in cell simulations.

BEAM DYNAMICS ANALYSIS FOR THE ULTRA-FAST KICKER IN CIRCULAR COOLER RING OF JLEIC

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huang, Yulu; Wang, Haipeng; Rimmer, Robert A.

An ultra-fast kicker system consisting of four quarter wavelength resonator based deflecting cavities was developed that simultaneously resonates at 10 subharmonic modes of the 476.3MHz bunch repetition frequency. Thus every 10th bunch in the bunch train will experience a transverse kick while all the other bunches are undisturbed. This fast kicker is being developed for the Energy Recovery Linac (ERL) based electron Circular Cooler Ring (CCR) in the proposed Jefferson Lab Electron Ion Collider (JLEIC, previously MEIC). The electron bunches can be reused 10-30 turns thus the beam current in the ERL can be reduced to 1/10 - 1/30 (150mAmore » - 50mA) of the cooling bunch current (1.5A). In this paper, several methods to synthesize such a kicker waveform and the comparison made by the beam dynamics tracking in Elegant will be discussed.« less

Ultra-processed Food Intake and Obesity: What Really Matters for Health-Processing or Nutrient Content?

PubMed

Poti, Jennifer M; Braga, Bianca; Qin, Bo

2017-12-01

The aim of this narrative review was to summarize and critique recent evidence evaluating the association between ultra-processed food intake and obesity. Four of five studies found that higher purchases or consumption of ultra-processed food was associated with overweight/obesity. Additional studies reported relationships between ultra-processed food intake and higher fasting glucose, metabolic syndrome, increases in total and LDL cholesterol, and risk of hypertension. It remains unclear whether associations can be attributed to processing itself or the nutrient content of ultra-processed foods. Only three of nine studies used a prospective design, and the potential for residual confounding was high. Recent research provides fairly consistent support for the association of ultra-processed food intake with obesity and related cardiometabolic outcomes. There is a clear need for further studies, particularly those using longitudinal designs and with sufficient control for confounding, to potentially confirm these findings in different populations and to determine whether ultra-processed food consumption is associated with obesity independent of nutrient content.

3D laser imaging for ODOT interstate network at true 1-mm resolution.

DOT National Transportation Integrated Search

2014-12-01

With the development of 3D laser imaging technology, the latest iteration of : PaveVision3D Ultra can obtain true 1mm resolution 3D data at full-lane coverage in all : three directions at highway speed up to 60MPH. This project provides rapid survey ...

1310 nm quantum dot DFB lasers with high dot density and ultra-low linewidth-power product

NASA Technical Reports Server (NTRS)

Qiu, Y.; Lester, L. F.; Gray, A. L.; Newell, T. C.; Hains, C.; Gogna, P.; Muller, R.; Maker, P.; Su, H.; Stintz, A.

2002-01-01

Laterally coupled distributed feedback lasers using high-density InAs quantum dots-in-a-well (DWELL) active region demonstrate a nominal wavelength of 1310 nm, a linewidth as small as 68 kHz, and a linewidth-power product of 100 kHz-mW.

Intrinsic beam emittance of laser-accelerated electrons measured by x-ray spectroscopic imaging

DOE PAGES

Golovin, G.; Banerjee, S.; Liu, C.; ...

2016-04-19

Here, the recent combination of ultra-intense lasers and laser-accelerated electron beams is enabling the development of a new generation of compact x-ray light sources, the coherence of which depends directly on electron beam emittance. Although the emittance of accelerated electron beams can be low, it can grow due to the effects of space charge during free-space propagation. Direct experimental measurement of this important property is complicated by micron-scale beam sizes, and the presence of intense fields at the location where space charge acts. Reported here is a novel, non-destructive, single-shot method that overcame this problem. It employed an intense lasermore » probe pulse, and spectroscopic imaging of the inverse-Compton scattered x-rays, allowing measurement of an ultra-low value for the normalized transverse emittance, 0.15 (±0.06) π mm mrad, as well as study of its subsequent growth upon exiting the accelerator. The technique and results are critical for designing multi-stage laser-wakefield accelerators, and generating high-brightness, spatially coherent x-rays.« less

Laser-based fast-neutron spectroscopy (Conference Presentation)

NASA Astrophysics Data System (ADS)

Pomerantz, Ishay; Kishon, Itay; Kleinschmidt, Annika; Schanz, Victor A.; Tebartz, Alexandra; Fernández, Juan Carlos; Gautier, Donald C.; Johnson, Randall Philip; Shimada, Tsutomu; Wurden, Glen Anthony; Roth, Markus

2017-05-01

Great progress has been made in recent years in realizing compact, laser-based neutron generators. These devices, however, are inapplicable for conducting energy-resolved fast-neutron radiography because of the electromagnetic noise produced by the interaction of a strong laser field with matter. To overcome this limitation, we developed a novel neutron time-of-flight detector, largely immune to electromagnetic noise. The detector is based on plastic scintillator, only a few mm in size, which is coupled to a silicon photo-multiplier by a long optical fiber. I will present results we obtained at the Trident Laser Facility at Los Alamos National Laboratory during the summer of 2016. Using this detector, we recorded high resolution, low-background fast neutron spectra generated by the interaction of laser accelerated deuterons with Beryllium. The quality of these spectra was sufficient to resolve the unique neutron absorption spectra of different elements and thus it is the first demonstration of laser-based fast neutron spectroscopy. I will discuss how this achievement paves the way to realizing compact neutron radiography systems for research, security, and commercial applications.

EFFECTS OF LASER RADIATION ON MATTER. LASER PLASMA: Conversion of the energy of fast electrons to thermal plasma radiation

NASA Astrophysics Data System (ADS)

Vergunova, G. A.; Rozanov, Vladislav B.

1992-01-01

An analysis is made of the conversion of the energy of highly energetic fast electrons, generated by the action of CO2 laser radiation on a target, into characteristic radiation emitted by a plasma formed from shell targets which, for instance, may be present inside targets irradiated by the CO2 laser. Analytical formulas are obtained for the temperature of the converted radiation. The results show that it is possible to control this radiation by choosing the parameters of the target and of the fast electron flux. The efficiency of conversion into characteristic thermal radiation is found numerically to be 95%. This method of conversion is more favorable than direct interaction of CO2 laser radiation with a target since the emitting region is localized in the target mass. When a laser interacts with a target the mass of this region increases with time and so the temperature of the emitted radiation is lower than in the case when fast electrons act on the target.

Transport and spatial energy deposition of relativistic electrons in copper-doped fast ignition plasmas

DOE PAGES

Jarrott, L. C.; McGuffey, C.; Beg, F. N.; ...

2017-10-24

Fast electron transport and spatial energy deposition are investigated in integrated cone-guided Fast Ignition experiments by measuring fast electron induced copper K-shell emission using a copper tracer added to deuterated plastic shells with a geometrically reentrant gold cone. Experiments were carried out at the Laboratory for Laser Energetics on the OMEGA/OMEGA-EP Laser where the plastic shells were imploded using 54 of the 60 OMEGA60 beams (3ω, 20 kJ), while the high intensity OMEGA-EP (BL2) beam (1 ω, 10 ps, 500 J, I peak > 10 19 W/cm 2) was focused onto the inner cone tip. Here, a retrograde analysis usingmore » the hybrid-PIC electron transport code, ZUMA, is performed to examine the sensitivity of the copper Kα spatial profile on the laser-produced fast electrons, facilitating the optimization of new target point designs and laser configurations to improve the compressed core areal density by a factor of 4 and the fast electron energy coupling by a factor of 3.5.« less

Ultra-fast LC-ESI-MS/MS method for the simultaneous determination of six highly toxic Aconitum alkaloids from Aconiti kusnezoffii radix in rat plasma and its application to a pharmacokinetic study.

PubMed

Liu, Jingjing; Li, Qing; Yin, Yidi; Liu, Ran; Xu, Huarong; Bi, Kaishun

2014-01-01

A fast, sensitive, and efficient ultra-fast LC-ESI-MS/MS method was developed for the simultaneous quantitation of six highly toxic Aconitum alkaloids, that is, aconitine, mesaconitine, hypaconitine, benzoylaconine, benzoylmesaconine, and benzoylhypaconine, in rat plasma after oral administration of crude ethanol extracts from Aconiti kusnezoffii radix by ultrasonic extraction, reflux extraction for 1 h, and reflux extraction for 3 h, respectively. The separation of six Aconitum alkaloids and aminopyrine (internal standard) was performed on an InertSustain® C18 column, and the quantification of the analytes was performed on a 4000Q ultra-fast LC-MS/MS system with turbo ion spray source in the positive ion and multiple-reaction monitoring mode. Absolute recoveries ranged within 65.06-85.1% for plasma samples. The intra- and interday precision and accuracy of analytes were satisfactory. The methods were validated with sensitivity reaching the lower LOQ for aconitine, mesaconitine, hypaconitine, benzoylaconine, benzoylmesaconine, and benzoylhypaconine, which were 0.025, 0.025, 0.050, 0.025, 0.025, and 0.100 ng/mL, respectively. The method was successfully applied to a pharmacokinetic study of six Aconitum alkaloids in rat plasma after oral administration of crude ethanol extracts from the raw root of Aconitum kusnezoffii Reichb. by three different extraction processes. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thirolf, P. G.; Habs, D.; Filipescu, D.

Next-generation {gamma} beams from laser Compton-backscattering facilities like ELI-NP (Bucharest)] or MEGa-Ray (Livermore) will drastically exceed the photon flux presently available at existing facilities, reaching or even exceeding 10{sup 13}{gamma}/sec. The beam structure as presently foreseen for MEGa-Ray and ELI-NP builds upon a structure of macro-pulses ({approx}120 Hz) for the electron beam, accelerated with X-band technology at 11.5 GHz, resulting in a micro structure of 87 ps distance between the electron pulses acting as mirrors for a counterpropagating intense laser. In total each 8.3 ms a {gamma} pulse series with a duration of about 100 ns will impinge on themore » target, resulting in an instantaneous photon flux of about 10{sup 18}{gamma}/s, thus introducing major challenges in view of pile-up. Novel {gamma} optics will be applied to monochromatize the {gamma} beam to ultimately {Delta}E/E{approx}10{sup -6}. Thus level-selective spectroscopy of higher multipole excitations will become accessible with good contrast for the first time. Fast responding {gamma} detectors, e.g. based on advanced scintillator technology (e.g. LaBr{sub 3}(Ce)) allow for measurements with count rates as high as 10{sup 6}-10{sup 7}{gamma}/s without significant drop of performance. Data handling adapted to the beam conditions could be performed by fast digitizing electronics, able to sample data traces during the micro-pulse duration, while the subsequent macro-pulse gap of ca. 8 ms leaves ample time for data readout. A ball of LaBr{sub 3} detectors with digital readout appears to best suited for this novel type of nuclear photonics at ultra-high counting rates.« less

Characteristics of Ions Emission from Ultrashort Laser Produced Plasma

PubMed Central

Elsied, Ahmed M.; Termini, Nicholas C.; Diwakar, Prasoon K.; Hassanein, Ahmed

2016-01-01

The dynamic characteristics of the ions emitted from ultrashort laser interaction with materials were studied. A series of successive experiments were conducted for six different elements (C, Al, Cu, Mo, Gd, and W) using 40 fs, 800 nm Ti: Sapphire laser. Time-of-flight (TOF) ion profile was analyzed and charge emission dependencies were investigated. The effects of incident laser interaction with each element were studied over a wide range of laser fluences (0.8 J/cm2 to 24 J/cm2) corresponding to laser intensities (2.0 × 1013 W/cm2 to 6.0 × 1014 W/cm2). The dependencies of the angular resolved ion flux and energy were also investigated. The TOF ion profile exhibits two peaks corresponding to a fast and a slow ion regime. The slow ions emission was the result of thermal vaporization while fast ions emission was due to time dependent ambipolar electric field. A theoretical model is proposed to predict the total ion flux emitted during femtosecond laser interaction that depends on laser parameters, material properties, and plume hydrodynamics. Incident laser fluence directly impacts average charge state and in turn affects the ion flux. Slow ions velocity exhibited different behavior from fast ions velocity. The fast ions energy and flux were found to be more collimated. PMID:27905553

Guiding of laser pulses in plasma waveguides created by linearly-polarized femtosecond laser pulses

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lemos, N.; Cardoso, L.; Geada, J.

We experimentally demonstrate that plasma waveguides produced with ultra-short laser pulses (sub-picosecond) in gas jets are capable of guiding high intensity laser pulses. This scheme has the unique ability of guiding a high-intensity laser pulse in a plasma waveguide created by the same laser system in the very simple and stable experimental setup. A hot plasma column was created by a femtosecond class laser that expands into an on-axis parabolic low density profile suitable to act as a waveguide for high intensity laser beams. We have successfully guided ~10 15 W cm -2 laser pulses in a 8 mm longmore » hydrogen plasma waveguide with a 35% guiding efficiency.« less

Guiding of laser pulses in plasma waveguides created by linearly-polarized femtosecond laser pulses

DOE PAGES

Lemos, N.; Cardoso, L.; Geada, J.; ...

2018-02-16

We experimentally demonstrate that plasma waveguides produced with ultra-short laser pulses (sub-picosecond) in gas jets are capable of guiding high intensity laser pulses. This scheme has the unique ability of guiding a high-intensity laser pulse in a plasma waveguide created by the same laser system in the very simple and stable experimental setup. A hot plasma column was created by a femtosecond class laser that expands into an on-axis parabolic low density profile suitable to act as a waveguide for high intensity laser beams. We have successfully guided ~10 15 W cm -2 laser pulses in a 8 mm longmore » hydrogen plasma waveguide with a 35% guiding efficiency.« less

Increasing Laser Stability with Improved Electronic Instruments

NASA Astrophysics Data System (ADS)

Troxel, Daylin; Bennett, Aaron; Erickson, Christopher J.; Jones, Tyler; Durfee, Dallin S.

2010-03-01

We present several electronic instruments developed to implement an ultra-stable laser lock. These instruments include a high speed, low noise homodyne photo-detector; an ultrahigh stability, low noise current driver with high modulation bandwidth and digital control; a high-speed, low noise PID controller; a low-noise piezo driver; and a laser diode temperature controller. We will present the theory of operation for these instruments, design and construction techniques, and essential characteristics for each device.

All-Glass Fiber Amplifier Pumped by Ultra-High Brightness Pumps

DTIC Science & Technology

2016-02-15

coated triple-clad fibers, we are developing triple-clad Yb fiber with gold coating for improved thermal management. 2.1 Pump laser The two...amplifier results using gain fiber with metalized fiber coating . Keywords: Fiber laser , specialty fiber, pump laser , beam combining, fiber metal coating ... coating can exceed its long-term damage threshold. Such a concern obviously does not apply to a fiber with gold protective coating [14]. Thus in

Efficient generation of ultra-intense few-cycle radially polarized laser pulses.

PubMed

Carbajo, Sergio; Granados, Eduardo; Schimpf, Damian; Sell, Alexander; Hong, Kyung-Han; Moses, Jeffrey; Kärtner, Franz X

2014-04-15

We report on efficient generation of millijoule-level, kilohertz-repetition-rate few-cycle laser pulses with radial polarization by combining a gas-filled hollow-waveguide compression technique with a suitable polarization mode converter. Peak power levels >85  GW are routinely achieved, capable of reaching relativistic intensities >10(19)  W/cm2 with carrier-envelope-phase control, by employing readily accessible ultrafast high-energy laser technology.

Absolute Two-Photon Absorption Coefficients in UltraViolet Window Materials

DTIC Science & Technology

1977-12-01

fvtt* tld » II ntctHB,-y md Idtnlll’ by block number; The absolute two-photon absorption coefficiehts of u. v. transmitting materials have been...measured using well-calibrated single picosecond pulses, at the third and fourth harmonic of a mode locked Nd:YAG laser systems. Twc photon...30, 1977. Work in the area of laser induced breakdown and multiphoton absorption in ultraviolet and infrared laser window materials was carried

Explaining the apparent impenetrable barrier to ultra-relativistic electrons in the outer Van Allen belt.

PubMed

Ozeke, Louis G; Mann, Ian R; Murphy, Kyle R; Degeling, Alex W; Claudepierre, Seth G; Spence, Harlan E

2018-05-10

Recent observations have shown the existence of an apparent impenetrable barrier at the inner edge of the ultra-relativistic outer electron radiation belt. This apparent impenetrable barrier has not been explained. However, recent studies have suggested that fast loss, such as associated with scattering into the atmosphere from man-made very-low frequency transmissions, is required to limit the Earthward extent of the belt. Here we show that the steep flux gradient at the implied barrier location is instead explained as a natural consequence of ultra-low frequency wave radial diffusion. Contrary to earlier claims, sharp boundaries in fast loss processes at the barrier are not needed. Moreover, we show that penetration to the barrier can occur on the timescale of days rather than years as previously reported, with the Earthward extent of the belt being limited by the finite duration of strong solar wind driving, which can encompass only a single geomagnetic storm.

Efficiency of ablative loading of material upon the fast-electron transfer of absorbed laser energy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gus'kov, Sergei Yu; Kasperczuk, A; Pisarczyk, T

2006-05-31

We present the results of experiments on the short-term irradiation of a solid material by a laser beam. The data testify to a rise in efficiency of the energy transfer from the laser pulse to a shock wave due to the fast-electron energy transfer. The experiments were performed with massive aluminium targets on the PALS iodine laser, whose pulse duration (0.4 ns) was much shorter than the time of shock decay and crater formation in the target (50-200 ns). The irradiation experiments were carried out using the fundamental laser harmonic (1.315 {mu}m) with an energy of 360 J. The greatermore » part of the experiments were performed for the radiation intensity exceeding 10{sup 15} W cm{sup -2}, which corresponded to the efficient generation of fast electrons under the conditions where the relatively long-wavelength iodine-laser radiation was employed. The irradiation intensity was varied by varying the laser beam radius for a specified pulse energy. (interaction of laser radiation with matter. laser plasma)« less

Short spatial filters with spherical lenses for high-power pulsed lasers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Burdonov, K F; Soloviev, A A; Shaikin, A A

We report possible employment of short spatial filters based on spherical lenses in a pulsed laser source (neodymium glass, 300 J, 1 ns). The influence of the spherical aberration on the quality of output radiation and coefficient of conversion to the second harmonics is studied. The ultra-short aberration spatial filter of length 1.9 m with an aperture of 122 mm is experimentally tested. A considerable shortening of multi-cascade pump lasers for modern petawatt laser systems is demonstrated by the employment of short spatial filters without expensive aspherical optics. (elements of laser systems)

193nm high power lasers for the wide bandgap material processing

NASA Astrophysics Data System (ADS)

Fujimoto, Junichi; Kobayashi, Masakazu; Kakizaki, Koji; Oizumi, Hiroaki; Mimura, Toshio; Matsunaga, Takashi; Mizoguchi, Hakaru

2017-02-01

Recently infrared laser has faced resolution limit of finer micromachining requirement on especially semiconductor packaging like Fan-Out Wafer Level Package (FO-WLP) and Through Glass Via hole (TGV) which are hard to process with less defect. In this study, we investigated ablation rate with deep ultra violet excimer laser to explore its possibilities of micromachining on organic and glass interposers. These results were observed with a laser microscopy and Scanning Electron Microscope (SEM). As the ablation rates of both materials were quite affordable value, excimer laser is expected to be put in practical use for mass production.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jarrott, L. C.; McGuffey, C.; Beg, F. N.

Fast electron transport and spatial energy deposition are investigated in integrated cone-guided Fast Ignition experiments by measuring fast electron induced copper K-shell emission using a copper tracer added to deuterated plastic shells with a geometrically reentrant gold cone. Experiments were carried out at the Laboratory for Laser Energetics on the OMEGA/OMEGA-EP Laser where the plastic shells were imploded using 54 of the 60 OMEGA60 beams (3ω, 20 kJ), while the high intensity OMEGA-EP (BL2) beam (1 ω, 10 ps, 500 J, I peak > 10 19 W/cm 2) was focused onto the inner cone tip. Here, a retrograde analysis usingmore » the hybrid-PIC electron transport code, ZUMA, is performed to examine the sensitivity of the copper Kα spatial profile on the laser-produced fast electrons, facilitating the optimization of new target point designs and laser configurations to improve the compressed core areal density by a factor of 4 and the fast electron energy coupling by a factor of 3.5.« less

CITIUS: An infrared-extreme ultraviolet light source for fundamental and applied ultrafast science

DOE Office of Scientific and Technical Information (OSTI.GOV)

Grazioli, C.; Gauthier, D.; Ivanov, R.

2014-02-15

We present the main features of CITIUS, a new light source for ultrafast science, generating tunable, intense, femtosecond pulses in the spectral range from infrared to extreme ultraviolet (XUV). The XUV pulses (about 10{sup 5}-10{sup 8} photons/pulse in the range 14-80 eV) are produced by laser-induced high-order harmonic generation in gas. This radiation is monochromatized by a time-preserving monochromator, also allowing one to work with high-resolution bandwidth selection. The tunable IR-UV pulses (10{sup 12}-10{sup 15} photons/pulse in the range 0.4-5.6 eV) are generated by an optical parametric amplifier, which is driven by a fraction of the same laser pulse thatmore » generates high order harmonics. The IR-UV and XUV pulses follow different optical paths and are eventually recombined on the sample for pump-probe experiments. We also present the results of two pump-probe experiments: with the first one, we fully characterized the temporal duration of harmonic pulses in the time-preserving configuration; with the second one, we demonstrated the possibility of using CITIUS for selective investigation of the ultra-fast dynamics of different elements in a magnetic compound.« less

Rapid generation of three-dimensional microchannels for vascularization using a subtractive printing technique.

PubMed

Burtch, Stephanie R; Sameti, Mahyar; Olmstead, Richard T; Bashur, Chris A

2018-05-01

The development of tissue-engineered products has been limited by lack of a perfused microvasculature that delivers nutrients and maintains cell viability. Current strategies to promote vascularization such as additive three-dimensional printing techniques have limitations. This study validates the use of an ultra-fast laser subtractive printing technique to generate capillary-sized channels in hydrogels prepopulated with cells by demonstrating cell viability relative to the photodisrupted channels in the gel. The system can move the focal spot laterally in the gel at a rate of 2500 mm/s by using a galvanometric scanner to raster the in plane focal spot. A Galilean telescope allows z-axis movement. Blended hydrogels of polyethylene glycol and collagen with a range of optical clarities, mechanical properties and swelling behavior were tested to demonstrate that the subtractive printing process for writing vascular channels is compatible with all of the blended hydrogels tested. Channel width and patterns were controlled by adjusting the laser energy and focal spot positioning, respectively. After treatment, high cell viability was observed at distances greater than or equal to 18 μm from the fabricated channels. Overall, this study demonstrates a flexible technique that has the potential to rapidly generate channels in tissue-engineered constructs. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Highly sensitive graphene biosensor by monomolecular self-assembly of receptors on graphene surface

NASA Astrophysics Data System (ADS)

Kim, Ji Eun; No, Young Hyun; Kim, Joo Nam; Shin, Yong Seon; Kang, Won Tae; Kim, Young Rae; Kim, Kun Nyun; Kim, Yong Ho; Yu, Woo Jong

2017-05-01

Graphene has attracted a great deal of interest for applications in bio-sensing devices because of its ultra-thin structure, which enables strong electrostatic coupling with target molecules, and its excellent electrical mobility promising for ultra-fast sensing speeds. However, thickly stacked receptors on the graphene's surface interrupts electrostatic coupling between graphene and charged biomolecules, which can reduce the sensitivity of graphene biosensors. Here, we report a highly sensitive graphene biosensor by the monomolecular self-assembly of designed peptide protein receptors. The graphene channel was non-covalently functionalized using peptide protein receptors via the π-π interaction along the graphene's Bravais lattice, allowing ultra-thin monomolecular self-assembly through the graphene lattice. In thickness dependent characterization, a graphene sensor with a monomolecular receptor (thickness less than 3 nm) showed five times higher sensitivity and three times higher voltage shifts than graphene sensors with thick receptor stacks (thicknesses greater than 20 nm), which is attributed to excellent gate coupling between graphene and streptavidin via an ultrathin receptor insulator. In addition to having a fast-inherent response time (less than 0.6 s) based on fast binding speed between biotin and streptavidin, our graphene biosensor is a promising platform for highly sensitive real-time monitoring of biomolecules with high spatiotemporal resolution.

New laser machining processes for shape memory alloys

NASA Astrophysics Data System (ADS)

Haferkamp, Heinz; Paschko, Stefan; Goede, Martin

2001-04-01

Due to special material properties, shape memory alloys (SMA) are finding increasing attention in micro system technology. However, only a few processes are available for the machining of miniaturized SMA-components. In this connection, laser material processing offers completely new possibilities. This paper describes the actual status of two projects that are being carried out to qualify new methods to machine SMA components by means of laser radiation. Within one project, the laser material ablation process of miniaturized SMA- components using ultra-short laser pulses (pulse duration: approx. 200 fs) in comparison to conventional laser material ablation is being investigated. Especially for SMA micro- sensors and actuators, it is important to minimize the heat affected zone (HAZ) to maintain the special mechanical properties. Light-microscopic investigations of the grain texture of SMA devices processed with ultra-short laser pulses show that the HAZ can be neglected. Presently, the main goal of the project is to qualify this new processing technique for the micro-structuring of complex SMA micro devices with high precision. Within a second project, investigations are being carried out to realize the induction of the two-way memory effect (TWME) into SMA components using laser radiation. By precisely heating SMA components with laser radiation, local tensions remain near the component surface. In connection with the shape memory effect, these tensions can be used to make the components execute complicated movements. Compared to conventional training methods to induce the TWME, this procedure is faster and easier. Furthermore, higher numbers of thermal cycling are expected because of the low dislocation density in the main part of the component.

Investigation of single lateral mode for 852nm diode lasers with ridge waveguide design

NASA Astrophysics Data System (ADS)

Liu, Chu; Guan, Baolu; Mi, Guoxin; Liao, Yiru; Liu, Zhenyang; Li, Jianjun; Xu, Chen

2016-11-01

852nm Narrow linewidth lasers can be widely used in the field of ultra-fine spectrum measurement, Cs atomic clock control, satellite and optical fiber communication and so on. Furthermore, the stability of the single lateral mode is a very important condition to guarantee the narrow linewidth lasers. Here we investigate experimentally the influence of the narrow ridge structure and asymmetrical waveguide design on the stability single lateral mode of an 852nm diode laser. According to the waveguide theoretical analysis, ridge mesa etch depth (Δη , related to the refractive index difference of parallel to the junction) and ridge mesa width (the narrower the more control force to low order mode) are the main elements for lateral modes. In this paper, we designed different structures to investigate and verify major factors for lateral mode by experiment, and to confirm our thought. Finally, the 5μm mesa ridge laser, 800nm etch depth, with groove structure obtains excellent steady single lateral mode output by 150mA operating current and 30°C temperature. The optical spectrum FWHM is 0.5nm and side mode suppression ratio is 27dBm with uncoated. The laser with 1mm cavity length showed the threshold current of 50mA, a lasing wavelength of λ = 852.6nm, slope efficiency of above 0.7mW/mA. We accomplished single lateral mode of ridge waveguide edge-emitting lasers which can also be used as a laser source in the ultra-narrow linewidth external cavity laser system.

Experimental demonstration of a compact epithermal neutron source based on a high power laser

NASA Astrophysics Data System (ADS)

Mirfayzi, S. R.; Alejo, A.; Ahmed, H.; Raspino, D.; Ansell, S.; Wilson, L. A.; Armstrong, C.; Butler, N. M. H.; Clarke, R. J.; Higginson, A.; Kelleher, J.; Murphy, C. D.; Notley, M.; Rusby, D. R.; Schooneveld, E.; Borghesi, M.; McKenna, P.; Rhodes, N. J.; Neely, D.; Brenner, C. M.; Kar, S.

2017-07-01

Epithermal neutrons from pulsed-spallation sources have revolutionised neutron science allowing scientists to acquire new insight into the structure and properties of matter. Here, we demonstrate that laser driven fast (˜MeV) neutrons can be efficiently moderated to epithermal energies with intrinsically short burst durations. In a proof-of-principle experiment using a 100 TW laser, a significant epithermal neutron flux of the order of 105 n/sr/pulse in the energy range of 0.5-300 eV was measured, produced by a compact moderator deployed downstream of the laser-driven fast neutron source. The moderator used in the campaign was specifically designed, by the help of MCNPX simulations, for an efficient and directional moderation of the fast neutron spectrum produced by a laser driven source.

Characterization and Biomimcry of Avian Nanostructured Tissues

DTIC Science & Technology

2016-01-19

fast-paced courtship displays in a dim environment. Keywords: Animal coloration, inverse- opal , iridescence, Lepidothrix, manakin, ultra-white...on their crown and rump feathers (figure 1), such as ultra- whites, vibrant blues, golds, and iridescent opal -like colours (Kirwan and Green, 2011...feathers of the blue-rumped manakin (L. isidorei); opalescent crown feathers of the opal -crowned manakin (L. iris); pinkish-white rump feathers of

Fast electron propagation in Ti foils irradiated with sub-picosecond laser pulses at Iλ{sup 2}>10{sup 18} Wcm{sup −2}μm{sup 2}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Makita, M.; Nersisyan, G.; McKeever, K.

2014-02-15

We have studied the propagation of fast electrons through laser irradiated Ti foils by monitoring the emission of hard X-rays and K-α radiation from bare foils and foils backed by a thick epoxy layer. Key observations include strong refluxing of electrons and divergence of the electron beam in the foil with evidence of magnetic field collimation. Our diagnostics have allowed us to estimate the fast electron temperature and fraction of laser energy converted to fast electrons. We have observed clear differences between the fast electron temperatures observed with bare and epoxy backed targets which may be due to the effectsmore » of refluxing.« less

Laboratory Directed Research and Development Program

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ogeka, G.J.; Romano, A.J.

This report briefly discusses the following research: Advances in Geoexploration; Transvenous Coronary Angiography with Synchrotron X-Rays; Borehole Measurements of Global Warming; Molecular Ecology: Development of Field Methods for Microbial Growth Rate and Activity Measurements; A New Malaria Enzyme - A Potential Source for a New Diagnostic Test for Malaria and a Target for a New Antimalarial Drug; Basic Studies on Thoron and Thoron Precursors; Cloning of the cDNA for a Human Serine/Threonine Protein Kinase that is Activated Specifically by Double-Stranded DNA; Development of an Ultra-Fast Laser System for Accelerator Applications; Cluster Impact Fusion; Effect of a Bacterial Spore Protein onmore » Mutagenesis; Structure and Function of Adenovirus Penton Base Protein; High Resolution Fast X-Ray Detector; Coherent Synchrotron Radiation Longitudinal Bunch Shape Monitor; High Grain Harmonic Generation Experiment; BNL Maglev Studies; Structural Investigations of Pt-Based Catalysts; Studies on the Cellular Toxicity of Cocaine and Cocaethylene; Human Melanocyte Transformation; Exploratory Applications of X-Ray Microscopy; Determination of the Higher Ordered Structure of Eukaryotic Chromosomes; Uranium Neutron Capture Therapy; Tunneling Microscopy Studies of Nanoscale Structures; Nuclear Techiques for Study of Biological Channels; RF Sources for Accelerator Physics; Induction and Repair of Double-Strand Breaks in the DNA of Human Lymphocytes; and An EBIS Source of High Charge State Ions up to Uranium.« less

Laboratory Directed Research and Development Program. Annual report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ogeka, G.J.; Romano, A.J.

This report briefly discusses the following research: Advances in Geoexploration; Transvenous Coronary Angiography with Synchrotron X-Rays; Borehole Measurements of Global Warming; Molecular Ecology: Development of Field Methods for Microbial Growth Rate and Activity Measurements; A New Malaria Enzyme - A Potential Source for a New Diagnostic Test for Malaria and a Target for a New Antimalarial Drug; Basic Studies on Thoron and Thoron Precursors; Cloning of the cDNA for a Human Serine/Threonine Protein Kinase that is Activated Specifically by Double-Stranded DNA; Development of an Ultra-Fast Laser System for Accelerator Applications; Cluster Impact Fusion; Effect of a Bacterial Spore Protein onmore » Mutagenesis; Structure and Function of Adenovirus Penton Base Protein; High Resolution Fast X-Ray Detector; Coherent Synchrotron Radiation Longitudinal Bunch Shape Monitor; High Grain Harmonic Generation Experiment; BNL Maglev Studies; Structural Investigations of Pt-Based Catalysts; Studies on the Cellular Toxicity of Cocaine and Cocaethylene; Human Melanocyte Transformation; Exploratory Applications of X-Ray Microscopy; Determination of the Higher Ordered Structure of Eukaryotic Chromosomes; Uranium Neutron Capture Therapy; Tunneling Microscopy Studies of Nanoscale Structures; Nuclear Techiques for Study of Biological Channels; RF Sources for Accelerator Physics; Induction and Repair of Double-Strand Breaks in the DNA of Human Lymphocytes; and An EBIS Source of High Charge State Ions up to Uranium.« less

Enhanced water window x-ray emission from in situ formed carbon clusters irradiated by intense ultra-short laser pulses

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chakravarty, U.; Rao, B. S.; Arora, V.

Enhanced water window x-ray emission (23–44 Å) from carbon clusters, formed in situ using a pre-pulse, irradiated by intense (I > 10{sup 17} W/cm{sup 2}) ultra-short laser pulse, is demonstrated. An order of magnitude x-ray enhancement over planar graphite target is observed in carbon clusters, formed by a sub-ns pre-pulse, interacting with intense main pulse after a delay. The effect of the delay and the duration of the main pulse is studied for optimizing the x-ray emission in the water window region. This x-ray source has added advantages of being an efficient, high repetition rate, and low debris x-ray source.

Ultra-pure, water-dispersed Au nanoparticles produced by femtosecond laser ablation and fragmentation

PubMed Central

Kubiliūtė, Reda; Maximova, Ksenia A; Lajevardipour, Alireza; Yong, Jiawey; Hartley, Jennifer S; Mohsin, Abu SM; Blandin, Pierre; Chon, James WM; Sentis, Marc; Stoddart, Paul R; Kabashin, Andrei; Rotomskis, Ričardas; Clayton, Andrew HA; Juodkazis, Saulius

2013-01-01

Aqueous solutions of ultra-pure gold nanoparticles have been prepared by methods of femtosecond laser ablation from a solid target and fragmentation from already formed colloids. Despite the absence of protecting ligands, the solutions could be (1) fairly stable and poly size-dispersed; or (2) very stable and monodispersed, for the two fabrication modalities, respectively. Fluorescence quenching behavior and its intricacies were revealed by fluorescence lifetime imaging microscopy in rhodamine 6G water solution. We show that surface-enhanced Raman scattering of rhodamine 6G on gold nanoparticles can be detected with high fidelity down to micromolar concentrations using the nanoparticles. Application potential of pure gold nanoparticles with polydispersed and nearly monodispersed size distributions are discussed. PMID:23888114

Ultra-Sensitive Photoreceiver Boosts Data Transmission

NASA Technical Reports Server (NTRS)

2007-01-01

NASA depends on advanced, ultra-sensitive photoreceivers and photodetectors to provide high-data communications and pinpoint image-detection and -recognition capabilities from great distances. In 2003, Epitaxial Technologies LLC was awarded a Small Business Innovation Research (SBIR) contract from Goddard Space Flight Center to address needs for advanced sensor components. Epitaxial developed a photoreciever capable of single proton sensitivity that is also smaller, lighter, and requires less power than its predecessor. This receiver operates in several wavelength ranges; will allow data rate transmissions in the terabit range; and will enhance Earth-based missions for remote sensing of crops and other natural resources, including applications for fluorescence and phosphorescence detection. Widespread military and civilian applications are anticipated, especially through enhancing fiber optic communications, laser imaging, and laser communications.

Silicon Carbide Diodes Characterization at High Temperature and Comparison With Silicon Devices

NASA Technical Reports Server (NTRS)

Lebron-Velilla, Ramon C.; Schwarze, Gene E.; Gardner, Brent G.; Adams, Jerry D., Jr.

2004-01-01

Commercially available silicon carbide (SiC) Schottky diodes from different manufacturers rated at 200, 300, 600, and 1200 V, were electrically tested and characterized as a function of temperature up to 300 C. Electrical tests included both steady state and dynamic tests. Steady state tests produced forward and reverse I-V characteristic curves. Transient tests evaluated the switching performance of the diodes in either a hard-switched DC to DC buck converter or a half-bridge boost converter. For evaluation and comparison purposes, the same tests were performed with current state-of-the-art ultra fast silicon (Si) pn-junction diodes of similar ratings and also a Si Schottky diode. The comparisons made were forward voltage drop at rated current, reverse current at rated voltage, and turn-off peak reverse recovery current and reverse recovery time. In addition, efficiency measurements were taken for the buck DC to DC converter using both the SiC Schottky diodes and the Si pn-junction diodes at different temperatures and frequencies. The test results showed that at high temperature, the forward voltage drop for SiC Schottky diodes is higher than the forward drop of the ultra fast Si pn-junction diodes. As the temperature increased, the forward voltage drop of the SiC Schottky increased while for the ultra fast Si pn-junction diodes, the forward voltage drop decreased as temperature increased. For the elevated temperature steady state reverse voltage tests, the SiC Schottky diodes showed low leakage current at their rated voltage. Likewise, for the transient tests, the SiC Schottky diodes displayed low reverse recovery currents over the range of temperatures tested. Conversely, the Si pn-junction diodes showed increasing peak reverse current values and reverse recovery times with increasing temperature. Efficiency measurements in the DC to DC buck converter showed the advantage of the SiC Schottky diodes over the ultra fast Si pn-junction diodes, especially at the higher temperatures and higher frequencies.

Stabilized single-longitudinal-mode erbium fibre laser employing silicon-micro-ring resonator and saturable absorber

NASA Astrophysics Data System (ADS)

Hsu, Yung; Yeh, Chien-Hung; Chow, Chi-Wai; Chang, Yuan-Chia; Cheng, Hao-Yun

2018-07-01

In the paper, a wavelength-tunable erbium-doped fiber (EDF) ring laser with stable single-longitudinal-mode (SLM) oscillation is proposed and investigated. Here, a silicon-micro-ring-resonator can be applied in a laser cavity for tuning wavelength in the C-band range. To complete the SLM oscillation, an unpumped EDF-based saturable absorber is used to act as ultra-narrowband filter for suppressing other oscillation modes. Additionally, the output stabilities of power and wavelength in the proposed EDF ring laser are also executed and discussed.

Is "Teach for All" Knocking on Your Door?

ERIC Educational Resources Information Center

Price, Anne; McConney, Andrew

2013-01-01

Over the past few decades there has been a rapid expansion in alternative "fast track" routes for teacher preparation. Among the most aggressive of these are Teach for All (TFA) schemes characterized not only by their ultra fast entry to teaching (6-7 week course) but also by their underlying philosophy that the so called…

Electronic properties of solids excited with intermediate laser power densities

NASA Astrophysics Data System (ADS)

Sirotti, Fausto; Tempo Beamline Team

Intermediate laser power density up to about 100 GW/cm2 is below the surface damage threshold is currently used to induce modification in the physical properties on short time scales. The absorption of a short laser pulse induces non-equilibrium electronic distributions followed by lattice-mediated equilibrium taking place only in the picosecond range. The role of the hot electrons is particularly important in several domains as for example fast magnetization and demagnetization processes, laser induced phase transitions, charge density waves. Angular resolved photoelectron spectroscopy measuring directly energy and momentum of electrons is the most adapted tool to study the electronic excitations at short time scales during and after fast laser excitations. The main technical problem is the space charge created by the pumping laser pulse. I will present angular resolved multiphoton photoemission results obtained with 800 nm laser pulses showing how space charge electrons emitted during fast demagnetization processes can be measured. Unable enter Affiliation: CNRS-SOLEIL Synchrotron L'Orme des Merisiers , Saint Aubin 91192 Gif sur Yvette France.

Ultra-short wavelength x-ray system

DOEpatents

Umstadter, Donald [Ann Arbor, MI; He, Fei [Ann Arbor, MI; Lau, Yue-Ying [Potomac, MD

2008-01-22

A method and apparatus to generate a beam of coherent light including x-rays or XUV by colliding a high-intensity laser pulse with an electron beam that is accelerated by a synchronized laser pulse. Applications include x-ray and EUV lithography, protein structural analysis, plasma diagnostics, x-ray diffraction, crack analysis, non-destructive testing, surface science and ultrafast science.

Influence of field ionization effect on the divergence of laser-driven fast electrons

NASA Astrophysics Data System (ADS)

Lang, Y.; Yang, X. H.; Xu, H.; Jin, Z.; Zhuo, H. B.

2018-07-01

The effect of field ionization on the divergence of fast electrons (E k ≥ 50 keV), driven by ultrashort-ultraintense laser pulse interaction with plasma, is studied by using 2D3V particle-in-cell simulations. It is found that, due to temperature anisotropy of the fast electrons in the ionizing target, strong fluctuant magnetic fields in the preplasma region is generated through Weibel instability. In turn, the field induces an enhancement of the hot electron divergence for the target with ionization process. Meanwhile, compared with the target without an ionization process, larger divergence of hot electrons can also be seen in the ionizing target with laser intensity varying from 5 × 1019 W/cm2 to 5 × 1020 W/cm2 and the divergence is weakly dependent on target materials for a fixed profile of preplasma. The results here are useful for the application of laser-driven fast electron beams.

Expansion Coefficient on Oxides and Oxide Ceramics.

DTIC Science & Technology

1986-05-01

permeability and cannot be used for laser gyros. Zerodur cannot be used for all laser gyro applications because it is unstable on thermal cycling between -23...and 177*C (-9 and 3500 F), which is the operational range of laser gyros. Furthermore, Zerodur is not of a reproducibly acceptable quality nor is it... Zerodur and Corning’s ULE (type 7971) for use in applications requiring ultra-low thermal expansivity. There are times when neither ULE nor Zerodur are

Au-C allotrope nano-composite films at extreme conditions generated by intense ultra-short laser

NASA Astrophysics Data System (ADS)

Khan, Saif A.; Saravanan, K.; Tayyab, M.; Bagchi, S.; Avasthi, D. K.

2016-07-01

Structural evolution of gold-carbon allotrope nano-composite films under relativistically intense, ultra-short laser pulse irradiation is studied in this work. Au-C nano-composite films, having 4 and 10 at.% of Au, were deposited by co-sputtering technique on silicon substrates. Au-C60 NC films with 2.5 at.% Au were deposited on 12 μm thick Al foil using co-evaporation technique. These samples were radiated with single pulse from 45 fs, 10 TW Ti:Sapphire Laser at RRCAT at an intensity of 3 × 1018 W cm-2. The morphological and compositional changes were investigated using scanning electron microscopy (SEM) and Rutherford back-scattering spectrometry (RBS) techniques. Laser pulse created three morphologically distinct zones around the point of impact on samples with silicon substrates. The gold content in 600 μm circular region around a point of impact is found to reduce by a factor of five. Annular rings of ∼70 nm in diameter were observed in case of Au-C NC film after irradiation. Laser pulse created a hole of about 400 μm in the sample with Al foil as substrate and wavy structures of 6 μm wavelength are found to be created around this hole. The study shows radial variation in nano-structure formation with varying local intensity of laser pulse.

830 nm laser irradiation induces varicosity formation, reduces mitochondrial membrane potential and blocks fast axonal flow in small and medium diameter rat dorsal root ganglion neurons: implications for the analgesic effects of 830 nm laser.

PubMed

Chow, Roberta T; David, Monique A; Armati, Patricia J

2007-03-01

We report the formation of 830 nm (cw) laser-induced, reversible axonal varicosities, using immunostaining with beta-tubulin, in small and medium diameter, TRPV-1 positive, cultured rat DRG neurons. Laser also induced a progressive and statistically significant decrease (p<0.005) in MMP in mitochondria in and between static axonal varicosities. In cell bodies of the neuron, the decrease in MMP was also statistically significant (p<0.05), but the decrease occurred more slowly. Importantly we also report for the first time that 830 nm (cw) laser blocked fast axonal flow, imaged in real time using confocal laser microscopy and JC-1 as mitotracker. Control neurons in parallel cultures remained unaffected with no varicosity formation and no change in MMP. Mitochondrial movement was continuous and measured along the axons at a rate of 0.8 microm/s (range 0.5-2 microm/s), consistent with fast axonal flow. Photoacceptors in the mitochondrial membrane absorb laser and mediate the transduction of laser energy into electrochemical changes, initiating a secondary cascade of intracellular events. In neurons, this results in a decrease in MMP with a concurrent decrease in available ATP required for nerve function, including maintenance of microtubules and molecular motors, dyneins and kinesins, responsible for fast axonal flow. Laser-induced neural blockade is a consequence of such changes and provide a mechanism for a neural basis of laser-induced pain relief. The repeated application of laser in a clinical setting modulates nociception and reduces pain. The application of laser therapy for chronic pain may provide a non-drug alternative for the management of chronic pain.

Extreme Light Infrastructure - Nuclear Physics pillar (ELI-NP) : new horizons in physics with high power lasers and brilliant gamma beams.

PubMed

Gales, Sydney; Tanaka, Kazuo A; Balabanski, D L; Negoita, Florin; Stutman, D; Ur, Calin Alexander; Tesileanu, Ovidiu; Ursescu, Daniel; Ghita, Dan Gabriel; Andrei, I; Ataman, Stefan; Cernaianu, M O; D'Alessi, L; Dancus, I; Diaconescu, B; Djourelov, N; Filipescu, D; Ghenuche, P; Matei, C; Seto Kei, K; Zeng, M; Zamfir, Victor Nicolae

2018-06-28

The European Strategic Forum for Research Infrastructures (ESFRI) has selected in 2006 a proposal based on ultra-intense laser elds with intensities reaching up to 10221023 W/cm2 called \\ELI" for Extreme Light Infrastructure. The construction of a large-scale laser-centred, distributed pan-European research infrastructure, involving beyond the state-of-the-art ultra-short and ultra-intense laser technologies, received the approval for funding in 2011 2012. The three pillars of the ELI facility are being built in Czech Republic, Hungary and Romania. The Romanian pillar is ELI-Nuclear Physics (ELI-NP). The new facility is intended to serve a broad national, European and International science community. Its mission covers scientic research at the frontier of knowledge involving two domains. The rst one is laser-driven experiments related to nuclear physics, strong-eld quantum electrodynamics and associated vacuum eects. The second is based on a Comptonbackscattering high-brilliance and intense low-energy gamma beam (< 20 MeV), a marriage of laser and accelerator technology which will allow us to investigate nuclear structure and reactions as well as nuclear astrophysics with unprecedented resolution and accuracy. In addition to fundamental themes, a large number of applications with signicant societal impact are being developed. The ELI-NP research centre will be located in Magurele near Bucharest, Romania. The project is implemented by \\Horia Hulubei" National Institute for Physics and Nuclear Engineering (IFIN-HH). The project started in January 2013 and the new facility will be fully operational by the end of 2019. After a short introduction to multi-PW lasers and Multi-MeV brilliant gamma beam scientic and technical description of the future ELI-NP facility as well as the present status of its implementation of ELI-NP, will be presented. The science and examples of societal applications at reach with these new probes will be discussed with a special focus on day-one experiments and associated novel instrumentation. © 2018 IOP Publishing Ltd.

High-precision laser microcutting and laser microdrilling using diffractive beam-splitting and high-precision flexible beam alignment

NASA Astrophysics Data System (ADS)

Zibner, F.; Fornaroli, C.; Holtkamp, J.; Shachaf, Lior; Kaplan, Natan; Gillner, A.

2017-08-01

High-precision laser micro machining gains more importance in industrial applications every month. Optical systems like the helical optics offer highest quality together with controllable and adjustable drilling geometry, thus as taper angle, aspect ratio and heat effected zone. The helical optics is based on a rotating Dove-prism which is mounted in a hollow shaft engine together with other optical elements like wedge prisms and plane plates. Although the achieved quality can be interpreted as extremely high the low process efficiency is a main reason that this manufacturing technology has only limited demand within the industrial market. The objective of the research studies presented in this paper is to dramatically increase process efficiency as well as process flexibility. During the last years, the average power of commercial ultra-short pulsed laser sources has increased significantly. The efficient utilization of the high average laser power in the field of material processing requires an effective distribution of the laser power onto the work piece. One approach to increase the efficiency is the application of beam splitting devices to enable parallel processing. Multi beam processing is used to parallelize the fabrication of periodic structures as most application only require a partial amount of the emitted ultra-short pulsed laser power. In order to achieve highest flexibility while using multi beam processing the single beams are diverted and re-guided in a way that enables the opportunity to process with each partial beam on locally apart probes or semimanufactures.

Control of ultra-intense single attosecond pulse generation in laser-driven overdense plasmas.

PubMed

Liu, Qingcao; Xu, Yanxia; Qi, Xin; Zhao, Xiaoying; Ji, Liangliang; Yu, Tongpu; Wei, Luo; Yang, Lei; Hu, Bitao

2013-12-30

Ultra-intense single attosecond pulse (AP) can be obtained from circularly polarized (CP) laser interacting with overdense plasma. High harmonics are naturally generated in the reflected laser pulses due to the laser-induced one-time drastic oscillation of the plasma boundary. Using two-dimensional (2D) planar particle-in-cell (PIC) simulations and analytical model, we show that multi-dimensional effects have great influence on the generation of AP. Self-focusing and defocusing phenomena occur in front of the compressed plasma boundary, which lead to the dispersion of the generated AP in the far field. We propose to control the reflected high harmonics by employing a density-modulated foil target (DMFT). When the target density distribution fits the laser intensity profile, the intensity of the attosecond pulse generated from the center part of the plasma has a flatten profile within the center range in the transverse direction. It is shown that a single 300 attosecond (1 as = 10(-18)s) pulse with the intensity of 1.4 × 10(21) W cm(-2) can be naturally generated. Further simulations reveal that the reflected high harmonics properties are highly related to the modulated density distribution and the phase offset between laser field and the carrier envelope. The emission direction of the AP generated from the plasma boundary can be controlled in a very wide range in front of the plasma surface by combining the DMFT and a suitable driving laser.

Ultra-stable clock laser system development towards space applications.

PubMed

Świerad, Dariusz; Häfner, Sebastian; Vogt, Stefan; Venon, Bertrand; Holleville, David; Bize, Sébastien; Kulosa, André; Bode, Sebastian; Singh, Yeshpal; Bongs, Kai; Rasel, Ernst Maria; Lodewyck, Jérôme; Le Targat, Rodolphe; Lisdat, Christian; Sterr, Uwe

2016-09-26

The increasing performance of optical lattice clocks has made them attractive for scientific applications in space and thus has pushed the development of their components including the interrogation lasers of the clock transitions towards being suitable for space, which amongst others requires making them more power efficient, radiation hardened, smaller, lighter as well as more mechanically stable. Here we present the development towards a space-compatible interrogation laser system for a strontium lattice clock constructed within the Space Optical Clock (SOC2) project where we have concentrated on mechanical rigidity and size. The laser reaches a fractional frequency instability of 7.9 × 10 -16 at 300 ms averaging time. The laser system uses a single extended cavity diode laser that gives enough power for interrogating the atoms, frequency comparison by a frequency comb and diagnostics. It includes fibre link stabilisation to the atomic package and to the comb. The optics module containing the laser has dimensions 60 × 45 × 8 cm 3 ; and the ultra-stable reference cavity used for frequency stabilisation with its vacuum system takes 30 × 30 × 30 cm 3 . The acceleration sensitivities in three orthogonal directions of the cavity are 3.6 × 10 -10 /g, 5.8 × 10 -10 /g and 3.1 × 10 -10 /g, where g ≈ 9.8 m/s 2 is the standard gravitational acceleration.

Numerical studies of acceleration of thorium ions by a laser pulse of ultra-relativistic intensity

NASA Astrophysics Data System (ADS)

Domanski, Jaroslaw; Badziak, Jan

2018-01-01

One of the key scientific projects of ELI-Nuclear Physics is to study the production of extremely neutron-rich nuclides by a new reaction mechanism called fission-fusion using laser-accelerated thorium (232Th) ions. This research is of crucial importance for understanding the nature of the creation of heavy elements in the Universe; however, they require Th ion beams of very high beam fluencies and intensities which are inaccessible in conventional accelerators. This contribution is a first attempt to investigate the possibility of the generation of intense Th ion beams by a fs laser pulse of ultra-relativistic intensity. The investigation was performed with the use of fully electromagnetic relativistic particle-in-cell code. A sub-μm thorium target was irradiated by a circularly polarized 20-fs laser pulse of intensity up to 1023 W/cm2, predicted to be attainable at ELI-NP. At the laser intensity 1023 W/cm2 and an optimum target thickness, the maximum energies of Th ions approach 9.3 GeV, the ion beam intensity is > 1020 W/cm2 and the total ion fluence reaches values 1019 ions/cm2. The last two values are much higher than attainable in conventional accelerators and are fairly promising for the planned ELI-NP experiment.

Three dimensional particle-in-cell simulations of electron beams created via reflection of intense laser light from a water target

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ngirmang, Gregory K., E-mail: ngirmang.1@osu.edu; Orban, Chris; Feister, Scott

We present 3D Particle-in-Cell (PIC) modeling of an ultra-intense laser experiment by the Extreme Light group at the Air Force Research Laboratory using the Large Scale Plasma (LSP) PIC code. This is the first time PIC simulations have been performed in 3D for this experiment which involves an ultra-intense, short-pulse (30 fs) laser interacting with a water jet target at normal incidence. The laser-energy-to-ejected-electron-energy conversion efficiency observed in 2D(3v) simulations were comparable to the conversion efficiencies seen in the 3D simulations, but the angular distribution of ejected electrons in the 2D(3v) simulations displayed interesting differences with the 3D simulations' angular distribution;more » the observed differences between the 2D(3v) and 3D simulations were more noticeable for the simulations with higher intensity laser pulses. An analytic plane-wave model is discussed which provides some explanation for the angular distribution and energies of ejected electrons in the 2D(3v) simulations. We also performed a 3D simulation with circularly polarized light and found a significantly higher conversion efficiency and peak electron energy, which is promising for future experiments.« less

Towards highest peak intensities for ultra-short MeV-range ion bunches

NASA Astrophysics Data System (ADS)

Busold, Simon; Schumacher, Dennis; Brabetz, Christian; Jahn, Diana; Kroll, Florian; Deppert, Oliver; Schramm, Ulrich; Cowan, Thomas E.; Blažević, Abel; Bagnoud, Vincent; Roth, Markus

2015-07-01

A laser-driven, multi-MeV-range ion beamline has been installed at the GSI Helmholtz center for heavy ion research. The high-power laser PHELIX drives the very short (picosecond) ion acceleration on μm scale, with energies ranging up to 28.4 MeV for protons in a continuous spectrum. The necessary beam shaping behind the source is accomplished by applying magnetic ion lenses like solenoids and quadrupoles and a radiofrequency cavity. Based on the unique beam properties from the laser-driven source, high-current single bunches could be produced and characterized in a recent experiment: At a central energy of 7.8 MeV, up to 5 × 108 protons could be re-focused in time to a FWHM bunch length of τ = (462 ± 40) ps via phase focusing. The bunches show a moderate energy spread between 10% and 15% (ΔE/E0 at FWHM) and are available at 6 m distance to the source und thus separated from the harsh laser-matter interaction environment. These successful experiments represent the basis for developing novel laser-driven ion beamlines and accessing highest peak intensities for ultra-short MeV-range ion bunches.

Towards highest peak intensities for ultra-short MeV-range ion bunches

PubMed Central

Busold, Simon; Schumacher, Dennis; Brabetz, Christian; Jahn, Diana; Kroll, Florian; Deppert, Oliver; Schramm, Ulrich; Cowan, Thomas E.; Blažević, Abel; Bagnoud, Vincent; Roth, Markus

2015-01-01

A laser-driven, multi-MeV-range ion beamline has been installed at the GSI Helmholtz center for heavy ion research. The high-power laser PHELIX drives the very short (picosecond) ion acceleration on μm scale, with energies ranging up to 28.4 MeV for protons in a continuous spectrum. The necessary beam shaping behind the source is accomplished by applying magnetic ion lenses like solenoids and quadrupoles and a radiofrequency cavity. Based on the unique beam properties from the laser-driven source, high-current single bunches could be produced and characterized in a recent experiment: At a central energy of 7.8 MeV, up to 5 × 108 protons could be re-focused in time to a FWHM bunch length of τ = (462 ± 40) ps via phase focusing. The bunches show a moderate energy spread between 10% and 15% (ΔE/E0 at FWHM) and are available at 6 m distance to the source und thus separated from the harsh laser-matter interaction environment. These successful experiments represent the basis for developing novel laser-driven ion beamlines and accessing highest peak intensities for ultra-short MeV-range ion bunches. PMID:26212024