bluuebunny/crossref_metadata_2025 huggingface dataset:
CORRELAÇÃO ENTRE ANOMALIAS DE CÓDIGO E PADRÕES DE PROJETO
Authors: Moreira Gabriel Yago de Oliveira , Jose Amancio Macedo Santos
Published: February 2023

A pesquisa tem como objetivo propor uma estratégia de classificação de smells (anomalias). Para isso, vamos selecionar alguns smells de livros de autores já conceituados como Brown et al. (1998), Fowler (1999), e os trabalhos de Marinescu (Lanza, Marinescu, 2005).
Monte Carlo study of the dependence of the image quality of a Wood lens on refractive index profile fluctuations and mounting errors
Authors: Boardman A.D. , Horncastle D.
Published: February 2023

Minimum aberration optical systems can be designed by trading off the adjustable parameters against each other. Some of these parameters are intrinsic and may relate, in the case of gradient index lenses, to the refractive index profile while others may be mechanical in origin, relating, for example, to the degree of tilt and decentration the optical system can tolerate.
Grating Lenses for Optical Components
Authors: Hatakoshi Gen-ichi , Goto Kenya
Published: February 2023

Grating lenses will have wide applications in optical communication and optical information processing. Utilizing their focusing, imaging and Fourier transforming functions, they are applied, for example, to couplers for fiber optics1,2), optical heads in optical disk systems3), X-ray imaging elements4) and Fourier transforming lenses for optical processors5). Applications to waveguide devices6-8) are also reported.
Theoretical Analysis of Reflection Noise in Semiconductor Lasers
Authors: Hori Yoshikazu , Matsui Yasushi , Ohya Jun , Serizawa Hiroyuki , Sato Hisanao
Published: February 2023

Intensity fluctuations of semiconductor lasers due to optical feedback were theoretically analyzed by using modified rate equations which include a refractive index fluctuation. Photon density fluctuations were simulated, and their Fourier transformed spectra were obtained and analyzed. Optical beating of the external cavity modes, which generates the fluctuation of the refractive indices of the semiconductor materials, is proved to be an origin of the reflection noise.
Beam Propagation Modeling of the Total Internal Reflection Electrooptic Diffraction Spatial Light Modulators-Finite Interaction Effects
Authors: Hecht David L. , Johnson Richard V. , Yevick David
Published: February 2023

The total internal reflection electrooptic diffraction spatial light modulators provide unique performance capabilities for laser recording and optical information processing.1,2,3 Recent devices reported incorporate arrays of 4735 elements on 10 micrometer centers with 256 Mpixel/second data rate.4 These devices share some characteristics of both bulk wave and guided wave optical devices, although a number of characteristics are relatively unique. The input and output coupling are bulk processes enabling essentially lossless coupling over apertures up to several inches. The electrooptic interaction occurs in the vicinity of a single guiding boundary surface illuminated with focussed grazing incidence, resulting in efficient interactions. Modeling of this device is complicated by the combination of effects of anamorphically focussed input beam, spatially inhomogeneous modulation, total internal reflection interference, and diffraction and finite interaction length effects. Also, in the TIR EO SLM detailed spatial characteristics of the optical fields are of primary interest along with interaction coupling efficiencies. Beam Propagation Method5 modeling provides accurate detailed simulation of the modulator behavior and imaging characteristics over a wide range of design and operating conditions. Initial results of this modeling have recently been presented6. In this paper we provide additional results, particularly with respect to modeling finite interaction length effects and imaging.
Nonuniform Finite-Difference Method for Modeling of Quasi-TM Smal1-Mode-Size Ti:LiNbO3 Channel Waveguides
Authors: Kim C. M. , Ramaswamy R. V.
Published: February 2023

Among the various computional methods, the finite-difference method (FDM) has been frequently applied to several kinds of structures due to its easy application and simple manupulation. Recently, semi-vectorial FDM was introduced for the rib waveguide, characterized by piecewise constant refractive index distribution with uniform grid size.[1] In this paper, we present a versatile FDM for quasi-TM modes, which can handle the boundary conditions across abrupt index-changes. This method is flexible in that it uses the nonuniform discretization (Fig.1), which allows us to slice the grid finely in the region of the waveguide and sparcely in the region outside. It also allows us to extend the boundary of the metal box to arbitrary points yet using a limited number of grid lines. We can place grid lines at the positions of index discontinuity flexibly. By setting up grid lines and corresponding cell structure in a judicious way, we can reduce the redundant computer calculations and obtain the desirable accuracy with less memory size as little as 1/4 of that needed otherwise and, therefore, calculation amount is by far reduced. Increasing the number of grid lines ,of course, leads to more accurate solutions. Using this nonuniform FDM, we model the low-loss, minimum-mode-size Ti:LiNbO3 diffused channel waveguides fabricated in our laboratory. [2] The waveguides were fabricated on the z_ surface of optical grade LiNbO3 wafers and characterized at 1.3 μm. The smallest quasi-TM mode size (1/e intensity full width of 3.9 μm and full depth of 2.8 μm) was obtained for waveguides fabricated at 1025°C for 6 hours with Ti thickness of 800° A and Ti strip width of 4 μm.
Report on COST-216 Project on Modeling
Authors: Lagasse P.
Published: February 2023

Within the framework of the COST-216 (European Cooperation in the field of Scientific and Technical Research) optical switching project, a group representing 15 companies or institutions works on the comparison of optical modeling techniques for integrated optical waveguides. The results obtained so far by this working group will be presented.
Symbol Analysis and the Construction of One-Way Forward and Inverse Wave Propagation Theories
Authors: Fishman Louis
Published: February 2023

The analysis and fast, accurate numerical computation of the wave equations of classical physics are often quite difficult for rapidly changing, multidimensional environments extending over many wavelengths. This is particularly so for ocean seismo-acoustic environments characterized by a refractive index field with a compact region of arbitrary (n-dimensional) variability superimposed upon a transversely inhomogeneous ((n-1)-dimensional) background profile. For such environments, the entire domain is in the scattering regime, with the subsequent absence of an “asymptotically free” region. While classical, macroscopic methods have resulted in direct wave field approximations, derivations of approximate wave equations, and discrete numerical approximations, mathematicians studying linear partial differential equations have developed a sophisticated, microscopic phase space analysis centered about the theory of pseudo-differential and Fourier integral operators. In conjunction with the global functional integral techniques pioneered by Wiener (Brownian motion) and Feynman (quantum mechanics), and so successfully applied today in quantum field theory and statistical physics, the n-dimensional classical physics propagators can be both represented explicitly and computed directly. The phase space, or microscopic, methods and path (functional) integral representations provide the appropriate framework to extend homogeneous Fourier methods to inhomogeneous environments, in addition to suggesting the basis for the formulation and solution of corresponding arbitrary-dimensional nonlinear inverse problems.
Coherent, Tunable, X-Ray Emission at 5 nm using High-Harmonic Generation
Authors: Chang Zenghu , Rundquist Andy , Wang Haiwen , Kapteyn Henry , Murnane Margaret , Liu Xiuqin , Shan Bing
Published: February 2023

In this work, we demonstrate that the technique of high-harmonic generation, using very short-duration driving pulses, can be used to generate photons of energy up to 240 eV (5 nm), which correspond to the 155th harmonic of the 800 nm driving laser.
Ultrashort high harmonic pulse generated in a highly ionized gas
Authors: Bouhal A. , Breger P. , Salières P. , Agostini P. , Constantinescu R. , Muller H. G. , Grillon G. , Mysyrowicz A. , Antonetti A.
Published: February 2023

High-order harmonics generation in rare gases is one of the most rapidly developing topics in the physics of atoms interacting with intense laser pulses [1]. At long wavelength and high intensity, high-order harmonic generation involves the excitation of electrons to the continuum and rescattering from the parent ion [2,3]. This implies a close relationship between harmonic generation and ionisation. Ionization actually influences the harmonic production through depletion of the ground state and defocusing of the fundamental beam caused by the free electrons.
Single Pass Free Electron Lasers as Sources of Short Wavelength Coherent Radiation
Authors: Yu Li Hua
Published: February 2023

Free electron lasers utilize a relativistic electron beam as the laser medium, which results in unique properties beneficial to the generation and amplification of short wavelength coherent radiation. Since the resonance condition can be adjusted by varying externally controlled parameters such as the electron energy or the wiggler magnetic field strength, these devices are well suited to produce sources with tunable wavelength. Also, there is no problem with the medium having undesirable absorption at particular wavelengths. Development of free electron laser oscillators utilizing optical cavities has proved very successful in the infrared. As one considers moving into the vacuum ultraviolet and x-ray regions, mirrors become more difficult, and it is worthwhile to consider devices based upon single pass amplification. One approach is to utilize an external laser to seed the FEL amplifier. At short wavelengths a seed at the operating wavelength may be unavailable, but one can use a subharmonic seed at longer wavelength and carry out harmonic generation in the FEL. This scheme has many merits especially in the ultraviolet region from 75nm-200nm. The temporal coherence of the output is inherited from the seed laser. Another approach is to start the FEL from the spontaneous radiation emitted at the beginning of the wiggler. This approach is viable at very short wavelengths where even subharmonic seeds are unavailable. Devices based on self-amplified spontaneous radiation are capable of delivering high intensity and good transverse coherence, but the frequency bandwidth cannot be as narrow as achievable in an oscillator or seeded amplifier.
Generation and Stimulated Amplification of High Energy Photon Bursts at Gas Ionization by Few-Optical-Cycle Laser Pulses
Authors: Kim A.V. , Chernobrovtseva M.D. , Kartashov D.V. , Sergeev A.M.
Published: February 2023

The application of laser pulses with supershort duration of the order of 10 fs has recently been proposed [1,2] for enhancement of high order harmonic emission and subfemtosecond pulse production in the soft X-ray range. Such short driving pulses contain only a small number of optical cycles and therefore high energy photon bursts are generated due to atom ionization at rapidly increasing field amplitudes. It is obvious that the efficiency of this process becomes dependent on the concrete field distribution over the pulse or, in the other words, on the absolute phase of the optical field.
Electron dynamics in the strong field limit of photoionization
Authors: Sheehy B. , Walker B. , Lafon R. , Widmer M. , Gambhir A. , DiMauro L.F. , Agostini P. , Kulander K.C.
Published: February 2023

The behavior of atoms in strong fields has been the subject of many investigations, both experimental and theoretical. Previously, the majority of experimental studies have been confined to the multi-photon ionization or mixed regimes while few experiments have been done in the tunneling regime[1,2]. The data we will present is the first to examine the photoionization process over the intensity range from multiphoton ionization to well within the tunneling regime. We have taken photoelectron energy spectra, ion yield curves, and angular distributions of helium and neon over a wide range of intensities using a titanium sapphire laser operating at 1 kHz, 780 nm, and a pulse width of ~120 fs, focused into an UHV chamber with f/4 optics, allowing maximum intensities of 20 PW/cm2. The large dynamic range allowed by the kilohertz repetition rate makes it possible for a quantitative comparison between experiment and theory. Helium and neon were chosen for the study since previous investigations have established that ionization occurs in the tunneling regime [3]. Our investigations show that while the rescattering model [4,5] describes the one electron dynamics quantitatively, the extension of the rescattering model to inelastic rescattering as a mechanism for creating higher charge states fails to provide even a qualitative description.
Time and space resolved density development of a laser-produced plasma waveguide
Authors: Clark T. R. , Nikitin S. P. , Milchberg H. M.
Published: February 2023

The recently developed plasma waveguide has achieved one of the major goals in intense laser-matter interaction physics, that of a large intensity - interaction length product.1 Applications such as highly nonperturbative nonlinear optics and high harmonics generation2, soft x-ray laser development3, and laser-driven electron accelerators4 would benefit from a large laser-plasma interaction length. Important to all these applications is knowledge of the time and space dependent electron density profile forming the waveguide. We present interferometer measurements of the density development of a laser produced plasma waveguide during its initial formation as well as its later evolution during which a second pulse has been guided over many Rayleigh lengths.
Ultrahigh Peak Power Lasers in the 10-fs Regime
Authors: Barty C. P. J. , Guo T. , LeBlanc C. , Raksi F. , Rose-Petruck C. , Squier J. , Walker B. , Wilson K. R. , Yakovlev V. V. , Yamakawa K.
Published: February 2023

We review the evolution of chirped pulse amplification into the 10-fs regime. This evolution has been made possible by the advent of ultrabroadband amplification media such as Ti:sapphire, the development of sub-10-fs laser Kerr-lens-modelocked oscillators [1, 2] to provide stable and reliable seed pulses for amplification and the implementation of new technologies and strategies to minimize or circumvent gain narrowing and higher order phase distortions during amplification. As an example, a three stage, multi-output, laser system, at the University of California at San Diego will be described. This system is designed to produce > 1-J pulses of ~15-fs duration at a 10-Hz repetition. After two stages of amplification, 18-fs, 4-TW pulses have been produced at a repetition rate of 50 Hz and an average power > 4 W.[3] To our knowledge, these are the shortest duration terawatt pulses yet produced by a chirped pulse amplification system. Pulses at this level have been used at UCSD to produce ultrafast x-rays (both broadband and Kα radiation) for use in ultrafast diffraction studies of molecular dissociation, ultrafast near edge absorption studies of molecular dynamics, and time-gated x-ray mammography and angiography. Full system amplification at a 10 Hz repetition rate to energies of approximately 2 J before compression has also been demonstrated and transform limited pulses of ~20 fs have been measured. These pulses will be used for investigations of high field phenomena in the highly relativistic regime (i.e. at intensities > 1020 W/cm2), charged particle acceleration relevant to laser driven nuclear fusion and hard x-ray lasers. Further optimization of both intermediate and full level amplified outputs which to date have been limited to amplified bandwidths of ~ 70 nm is currently underway and should result in compressed pulse durations of < 15-fs and peak powers of > 70 TW.
Design And Performance Of The Petawatt Laser System
Authors: Perry M. D. , Pennington D.M. , Stuart B. C. , Boyd R. , Britten J. A. , Brown C. G. , Herman S. , Miller J. L. , Nguyen H. , Shore B. , Tietbohl G. , Yanovsky V.
Published: February 2023

We recently demonstrated the production of over a petawatt of peak power in the Nova/Petawatt Laser Facility, generating >500 J in 430 fs. The Petawatt Laser Project was initiated to develop the capability to test the fast ignitor concept1 for inertial confinement fusion (ICF), and to provide a unique capability in high energy density physics. The laser was designed to produce near kJ pulses with a pulse duration adjustable between 0.5 and 100 ps and a focused irradiance in excess of 1021 W/cm2.
Extreme Ultraviolet Lithography
Authors: Bokor Jeffrey
Published: February 2023

Some of the highlights of the recent dramatic progress in the development of extreme ultraviolet lithography technology will be reviewed, with emphasis on the challenge of fabricating and testing a diffraction-limited optical imaging system at 13 nm wavelength.
X-ray microscopy: new capabilities and short pulse possibilities
Authors: Jacobsen C. , Kirz J. , Maser J. , Osanna A. , Spector S. , Wang S. , Wirick S. , Calef B. , Howells M. , Lindaas S. , Pinkus D. , Tennant D.
Published: February 2023

Discussions of x-ray holography as a demanding application for high intensity sources date back at least two decades [1, 2], and x-ray lasers have been used in demonstrations of x-ray microscopy [3, 4, 5]. At the same time, synchrotron-based x-ray microscopes have been developed for imaging of hydrated, unsectioned biological specimens at 30-50 nm resolution, and these microscopes are in regular operation at Göttingen/Berlin, Berkeley, Arhus, Stony Brook/Brookhaven, and elsewhere.
Laser Driven Hard X-ray Sources for Angiography
Authors: Jiang Z. , Ikhlef A. , Kieffer J. C. , Krol A. , Bassano D.A. , Chamberlain C.C. , Prasad S.C.
Published: February 2023

The electron-impact x-ray tube has reached its technological limit, and after many years of improvements it is clear that some of the inherent deficiencies of this x-ray source for radiology cannot be overcome. These deficiencies are the heat-dissipation problem which limits the density of the power that can be delivered by the electron beam, and the related problem of the limit on the minimum focal spot size. The relatively large focal spot size prevents effective work in a high magnification regime and limits the ability to image morphology of the coronary artries, after intravenous injection of the iodine contrast agent, with a spacial resolution of 0.5mm-1.
Laser Wakefield Acceleration Experiments
Authors: Kotaki H. , Nakajima K. , Kando M. , Ahn H. , Watanabe T. , Ueda T. , Uesaka M. , Nakanishi H. , Ogata A. , Kinoshita K. , Tani K.
Published: February 2023

Laser-driven particle accelerators have been conceived over the past decade to be the next-generation particle accelerators, promising super-high field particle acceleration and a compact size compared with conventional accelerators 1). Among a number of laser accelerator concepts, laser wakefield accelerators have great potential to produce ultra-high-field gradients of plasma waves excited by intense ultrashort laser pulses 2). Recently wakefield excitation of the order of ~10GeV/m in a plasma has been directly confirmed by the use of a table-top-terawatt (T3) laser 3).
Influence of Relativistic Structure and Retardation In Two-Photon Transitions in Hydrogenic Systems
Authors: Szymanowski C. , Véniard V. , Taïeb R. , Maquet A.
Published: February 2023

The experimental realization of powerful sources of coherent X-ray radiation [1] opens for the first time the possibility to perform two-photon bound-bound absorption experiments involving inner shells in heavy atoms or ions. This would considerably broaden the scope of traditional, (single-photon) X-ray Absorption Spectroscopy (XAS) and related techniques. From the theoretical point of view it is clear that the usual non-relativistic dipole treatment of the atom-field interaction is no longer valid: By considering the two-photon |12S1/2〉 → |22S1/2〉 transition in hydrogenic systems, we test the inherent limitations of such a simplified approach as compared to a treatment taking full care of relativistic and retardation effects.
Absolute measurement of the spectral brilliance of a subpicosecond UV-laser induced soft x-ray source
Authors: Häßner R. , Theobald W. , Sauerbrey R. , Altenbernd D. , Teubner U. , Forster E. , Wilhein T. , Niemann B. , Schmahl G.
Published: February 2023

We have investigated the spectral brilliance of subpicosecond UV-laser-plasmas as a source for the soft x-ray microscopy in the so-called ‘water-window’. The spectral range between the absorption K-edges of carbon (4.36 nm) and oxygen (2.32 nm) is termed ‘water-window’ . The absorption coefficient of both materials differ by one order of magnitude providing a high contrast of the biological samples in their natural environment [1].
100 Femtosecond Laser Absorption in Solid Density Targets
Authors: Price Dwight F. , More R. M. , Walling R. S. , Stewart R. E.
Published: February 2023

Experimental short pulse lasers are rapidly approaching energy levels where target irradiances exceeding 1020 W/cm2 are routinely achievable [1,2,3]. These high intensity levels will open up a new class of solid target interaction physics where relativistic effects must be included and non-traditional absorption mechanisms become significant. However much remains to be understood of the absorption physics at lower intensities where classical absorption is dominated by collisional and resonance absorption. If attention is paid to producing clean laser pulses that do not significantly pre-pulse interact with the target, it is possible to produce plasmas of sufficiently short scale length that near-solid density interactions are observable at intensities exceeding 1018 W/cm2 for 100 fs laser irradiation.
Demonstration of a 0.54 Picosecond X-Ray Streak Camera
Authors: Chang Z. , Rundquist A. , Wang H. , Kapteyn H. C. , Murnane M. M. , Liu X. , Shan B. , Liu J. , Niu L. , Gong M. , Zhang X. , Lee R.W.
Published: February 2023

X-ray streak camera detectors are important as diagnostics for monitoring fast x-ray processes such as the emission from laser-produced plasmas, and also for obtaining high time-resolution in x-ray studies done using quasi-CW x-ray sources such as synchrotrons. In work in 1990, an x-ray streak camera was demonstrated to have 2 ps time resolution;1 however, in subsequent years, progress in obtaining faster resolution has been slow. Progress has been limited by two factors: the intrinsic time response of the streak camera itself, and the time duration of the x-ray source itself (usually a laser-produced plasma with x-ray pulse duration of ~ 1-2 ps).
Intensity Dependent Probabilities for Strong Field Ionization of Xenon
Authors: Walker M.A. , Hansch P. , Van Woerkom L.D.
Published: February 2023

We have employed a novel method, Intensity Selective Scanning [1, 2], to measure time-of-flight mass spectra of ions produced by strong field laser ionization. The hallmark of this technique is that it eliminates a serious problem inherent in traditional experiments: the complex spatial distribution of intensities present in the ionizing pulse. As a consequence, it becomes possible to extract ionization yields as a function of intensity directly from the experimental data, without the previous complication of untangling them from a spatially averaged signal. We present results for xenon ionized by laser pulses at intensities ranging from 1013 to 4x1014 W/cm2.
8- and 9-Photon Resonances in Above Threshold Ionization of Xenon
Authors: Hansch P. , Walker M.A. , Van Woerkom L.D.
Published: February 2023

We have observed for the first time higher order multiphoton resonances in xenon. The clear evolution through parity-allowed resonances at the 8- and subsequent 9-photon level demonstrates the validity of the transient resonance model up to the saturation intensity. At high laser intensities (> 1012 W/cm2) the ionization limit and high lying Rydberg states of xenon shift ponderomotively upward and ionization occurs via transient resonances with specific multiples of the incident photons [1]. We have observed a very clear evolution of transient 8-photon resonances showing the successive appearance of Rydberg states and a large enhancement in photoelectron signal when reaching the higher order 9-photon resonances. This observation furthers our understanding of the fundamental ionization process in strong fields.
Pattern of Interference: Information and Fog in Holographic Images
Authors: Phillips N. J.
Published: February 2023

In many holographic recording regimes polarization and symmetry pose conflicting requirements. We take another look at this problem to look for helpful guidance.
Real-Time Computer-Generated Hologram Via Liquid Crystal Television Spatial Light Modulator
Authors: Mok Fai , Diep Joseph , Liu Hua-Kuang , Psaltis Demetri
Published: February 2023

A novel use of a liquid-crystal television (LCTC) is described. It is shown that, if the phase non-uniformity of the LCTV is corrected by a liquid gate, then a simple computer-generated hologram can be written and coherently reconstructed.
Associative Holographic Memory with Feedback Using Phase Conjugate Mirrors
Authors: Owechko Y. , Dunning G. J. , Soffer B. H. , Marom E.
Published: February 2023

Associative memories and associative processing have many applications in symbolic and parallel computing.1 Optical schemes, in particular those based on holographic principles, are well suited to associative processing because of their high parallelism and storage capacity. Previous workers2 have demonstrated that holographically stored images can be recalled using relatively complicated reference images, but did not utilize nonlinear feedback to reduce the cross-talk which results when multiple images are stored and a partial or distorted input is used in addressing the memory. These earlier approaches were limited in their ability to reconstruct an image from a set of partial input images.
Optical Interconnects with Reflection Holographic Optical Elements
Authors: Kostuk R.K. , Goodman J. W. , Hesselink L.
Published: February 2023

The increasing demands on micrelectronic circuits for small size and high data rates has pushed electronic interconnection technology to its limit. New techniques are being sought to circumvent these difficulties. Among them are optical interconnections. A multiple grating reflection type holographic element can be used in a number of electronic chip to chip interconnection arrangements. To be effective the element should distribute optical radiation incident at one reconstruction angle into a number of signal beam directions with high diffraction efficiency, η. Analytical and numerical models have been developed to describe some aspects of multiple transmission gratings1,2,however except for the "on-Bragg" description by Kowarschik3, relatively little exists for multiple reflection gratings.
Holographic Multiple Exposure Look-up Table For Optical Computing
Authors: Habiby S. F. , Collins S. A.
Published: February 2023

The design, construction, and application of a holographic look-up table for optical computing is presented in this paper. The particular application described here is a residue arithmetic optical matrix-vector multiplier with position coded information1, using a Hughes liquid crystal light valve2. Superimposed multiple exposure phase holograms in a silver halide emulsion are used to store multiple mappings1 in the form of an addition truth table. The angular sensitivity of the emulsion allows constructing and reconstructing a different image in the hologram, corresponding to associated reference and reconstruction beam directions. The reference beam is produced using a single mode optical fiber which is repositioned for each exposure to generate reference beams with different directions.
In-Line Acousto-Optic Architectures for Holographic Interferometry and Sensing
Authors: Riza Nabeel A.
Published: February 2023

Novel two Bragg cell and one Bragg cell acousto-optic (AO) interferometers are introduced in this paper. These interferometers can be used as a variety of optical instruments such as holographic interferometers, interferometric sensors, material characterization tools, and diagnostic measurement systems such as turbulence and flow/temperature assessment. To this date, to the best of the author’s knowledge, no such optical systems have been proposed for interferometric sensing and measurement tools that offer high optical power (e.g., 1 W CW), high speed scanning (e.g., < 50 μs per scan spot) interferometer systems with both heterodyning and almost baseband options for accurate diagnostic measurements. The bulk optics nature of our optical system design allows for high optical power interferometric applications.
High-Speed Holographic Recording of 500 Images in Hole Burning Rare-Earth Doped Crystals
Authors: Kachru R. , Shen X. A.
Published: February 2023

One of the unique and perhaps the most attractive features of an optical memory is its ability to store and retrieve information in a bit-parallel format.1-3 Recently, we have proposed a new scheme for parallel data storage in TDOM.4,5 This scheme was proven to be practical and can be implemented with existing technologies. In a proof-of-principle experiment, four wavelength-multiplexed single-page volume spectral holograms, generated with black-and-white transparencies, were successfully stored in a single spatial location at a speed of approximately 23 μs/frame. The experimental results project system's input/output bandwidth to exceed 40 Gbps, two orders of magnitude faster than a semiconductor cache memory.
2D Phase Unwrapping of a Noise Contaminated Optical Interferogram
Authors: Liao Ching-Wei , Fiddy M. A.
Published: February 2023

Phase unwrapping of interference patterns is a well recognized problem, important in surface profiling and wavefront detection, [e.g. 1]. The wrapped phase function is a non-bandlimited function meaning there is no adequate sampling rate in the neighborhood of the wrapped regions. Previously, authors such as Tribolet [2] have tried to deal with ID unwrapping uncertainties by using an adaptive sampling scheme along with continuity arguments. This approach, while frequently successful, is tedious at best. Other approaches involve taking least squares or Bayesian techniques [e.g. 3].
An Accelerating Reference Frame for Electromagnetic Waves in a Rapidly Growing Plasma: Unruh Radiation and the Dynamic Casimir Effect
Authors: Yablonovitch E.
Published: February 2023

In 1974, Hawking showed1 that Black Holes can evaporate by the emission of low temperature thermal radiation, now named Hawking Radiation. Shortly thereafter, a closely related effect called Unruh Radiation became apparent. According to Unruh2 and Davies2, observers of the electromagnetic field in an accelerating reference frame should see thermal radiation at a temperature T: where a is the acceleration relative to an inertial frame, c is the speed of light and ħ and K are Planck's and Boltzmann's constant respectively. In a frame accelerating at g= 980 cm/sec2, equivalent to the acceleration experienced at the earth's surface3, this thermal radiation is at a temperature of only 4× 10−20 °K. Therefore, physicists hoping to observe this radiation, have sought out systems being subjected to extreme acceleration. For example, J. S. Bell has suggested4 that the spin depolarization of electrons accelerating around a synchrotron storage ring may be interpreted as being due to such radiation.
Relativistic Dynamics of Photoelectrons*
Authors: Bardsley J. N.
Published: February 2023

The relativistic dynamics of single electrons in plane-wave electromagnetic fields can be solved exactly, for arbitrary pulse shapes, in both classical and quantum mechanics. Sarachik and Schappert1 (S-S) provided a particularly lucid account of the classical theory, assuming that the electron is at rest before the pulse arrives, and showed that in the relativistic limit the longitudinal component of momentum Pz increases as the square of the electric field strength whereas the transverse momentum pt rises only linearly. The longitudinal momentum is always in the forward direction (PZ > 0) and it oscillates at double the laser frequency. The non-linearities in the relativistic motion lead to the production of high-order harmonics, which become focussed more strongly as the laser intensity is increased. The solution with more general initial conditions was given by Kruger and Bovyn.2
Absorption of femtosecond laser pulses in high density plasma
Authors: Fedosejevs R. , Ottmann R. , Sigel R. , Kühnle G. , Szatmári S. , Schäfer F.P.
Published: February 2023

The angular dependence of absorption of intense 250 fs KrF laser pulses by solid targets of aluminium and gold has been measured. Maximum absorption of over 60% occurs for p-polarized radiation.
Observations of High Density Plasmas Produced with a Picosecond, High Power KrF Laser
Authors: Willi O. , Kiehn G. , Edwards J. , Barrow V. , Smith R.
Published: February 2023

The interaction of a single picosecond, high power KrF laser pulse with solid targets has been studied using time integrated and time resolved x-ray spectroscopy. Fully ionised aluminium plasmas with temperatures of about 400 eV and densities well above 1023 cm−3 were observed when the ASE prepulse energy was less than 10−5 of the short pulse. About 20% of the incident laser energy was deposited in suprathermal electrons. This value was inferred from titanium Kα emission measurements. The experimental observations were modelled with a 1-D Lagrangian hydrodynamics code.
Multi-Terawatt KrF Lasers and Their Applications
Authors: Watanabe S. F.
Published: February 2023

Summary not available.
Very High Power Density Subpicosecond Laser for X-Ray Laser Development
Authors: Suckewer S.
Published: February 2023

A KrF excimer laser system with a pulse duration of 300 fsec and peak power density of ~1018 W/cm2 is presented. Use of this system for the excitation and ionization of a laser produced, magnetically confined plasma used in the development of a new x-ray laser is discussed.
Multiphoton Excitation of Plasma Waves
Authors: Rae S. C. , Burnett K.
Published: February 2023

Recently developed table-top laser sources are capable of producing intensities on target of 1017Wcm
−2
in femtosecond pulses. This has stimulated interest in the possible mechanisms for laser light absorption in a plasma produced by such a source. The plasma, expanding at approximately the ion sound speed

(

υ
s

=

Z

k
B

T
e

/

m
i

)

, remains at virtually solid density during the pulse. Light incident on such an overdense plasma boundary will be largely reflected, unless there is strong absorption within the skin depth of the target (~ c/w
p
), where the evanescent wave does penetrate.
Physical Processes in Femtosecond Laser-Target Interactions
Authors: More Richard M.
Published: February 2023

We review nonequilibrium atomic, electrodynamic, and radiative processes in short pulse plasma generation to identify which are most important, which pose the most interesting questions.
Remote Sensing of the Troposphere by Infrared Emission Spectroscopy
Authors: Beer Reinhard , Glavich Thomas A.
Published: February 2023

Increasing concern is being expressed about the impact of anthropogenic emissions on the present and future state of the lower and middlr atmosphere: urban pollution; acid rain; stratospheric ozone depletion; climatological effects of the increase in "greenhouse" gases; etc. There is a clear need for instrumentation to study these questions on a global scale. Accordingly, we describe the concept of a cryogenic infrared (600 - 3450 cm−1) imaging Fourier transform spectrometer for observations of the troposphere and lower stratosphere from near-Earth orbit using natural thermal emission and reflected sunlight (when appropriate). It has been demonstrated that such a system can function successfully despite the obvious interferences of clouds, aerosols and water vapor continuum.
The Spectrum and Term System of Ti I
Authors: Forsberg Peter
Published: February 2023

The emission spectrum of neutral titanium has been analysed in the region 1750 - 55 000 Å. For the registrations in the infrared and visible wavelength regions, the Fourier transform spectrometer at Kitt Peak National Observatory has been used, while the recordings in the ultraviolet are from the 10.7-m Eagle spectrograph at National Bureau of Standards, Washington, D.C. In addition to this, a study of the absorption spectrum in the region 1900 - 2315 Å has been performed using plates obtained from Harvard College Observatory.

A total of 3377 lines have been identified as belonging to the Ti I spectrum, combining 439 energy levels. About 115 new energy levels have been found. Almost 15% of the previously listed level values have been discarded but a majority of these could be replaced with new values.
Recent Advances in High Resolution Fourier Transform Spectroscopy
Authors: Buijs H. L.
Published: February 2023

Fourier Transform Spectroscopy is now widely used in many routine measurement applications. In principle, very high resolution can be achieved in FT Spectroscopy rivaling the resolution of infrared laser spectroscopy. In practice however, as resolution is increased, a number of operating parameters must be controlled with rapidly increasing care. Refinements of instrumentation over the last few years based on a fuller understanding of these parameters has led not only to excellent realizations of resolution but also to greater precision in observed line shapes, line intensities and frequency calibration. In FT Spectroscopy, higher resolution is achieved by recording the interferogram over increasingly greater mirror displacement or optical path difference. While the optical path difference is increased, it is necessary to maintain a high level of consistency of interferometer alignment, path difference measurement and path difference consistency for all optical rays going through the interferometer.
CIRS: the Composite Infrared Spectrometer for the Cassini Mission
Authors: Jennings D. E. , Kunde V. G. , Ade P. , Barney R. , Bjoraker G. , Bonnal J.-F. , Brasunas J. , Calcutt S. , Carlson R. , Conrath B. , Courtin R. , Dodge R. , Flasar F. M. , Gautier D. , Herath L. , Hom L. , Jacquemin B. , Kingsmill-Vellacott T. , Leete S. , Marten A. , Michel G. , Romani P.
Published: February 2023

The Cassini spacecraft, to be sent to Saturn later this decade, will carry an infrared Fourier transform spectrometer. Cassini will orbit Saturn for several years, studying the planet and its largest moon Titan with a variety of remote sensing and in-situ instruments. The infrared spectrometer, CIRS, will investigate the composition and thermal structure of the atmospheres of Saturn and Titan.
Far-Infrared Fourier-Transform Spectroscopy of the Stratosphere
Authors: Traub Wesley A.
Published: February 2023

Fourier-transform spectroscopy of the thermal emission spectrum of the Earth’s stratosphere is a technique of growing importance in the study of ozone-layer chemistry. The far-infrared part of this thermal spectrum, here roughly 7-700 cm-1, includes detectable transitions of many species which are key indicators of the degree to which catalytic reactions of chlorine and bromine compounds are able to destroy ozone. A unique advantage of measuring thermal emission is that the instrument can examine the stratosphere at night as easily as it does the day. It is this combination of circumstances, namely the ability to measure species such as OH and HO2, and the ability to measure throughout the day-night cycle, which has made the far-infrared Fourier-transform spectrometer (FTS) a valuable asset in the study of the stratospheric ozone layer.
High Resolution Spectra of Stratospheric Emission in the Spectral Range of 35 to 130 cm-1
Authors: Nolt I. G. , Park J. , Vanek M.D. , Jennings D.A. , Mencaraglia F. , Carli B. , Poggesi M. , Rossi E. , Carlotti M. , Radostitz J. V.
Published: February 2023

High resolution measurements of the far infrared emission spectrum of the stratosphere were first obtained in 1978 following the Italian development of a balloon-borne Fourier transform spectrometer which used new HeNe laser technology to achieve an FTI mirror stroke of 75 cm. In four flights between 1978 and 1983, this instrument provided the highest resolution measurements for validating spectral database models of the far infrared atmospheric emission1, and for retrieving a number of important stratospheric trace species2. In 1988, an International Cooperative Program was instituted by NASA and the Italian Space Agency for the purpose of upgrading the performance of this instrument for use in the Correlative Measurement Program of the Upper Atmosphere Research Satellite.
Portable FTS for Field Spectroscopy
Authors: Døhlen K. , Canas A. A. D.
Published: February 2023

We present the design of a portable heterodyned holographic FTS (HHFTS). The instrument is based on a Michelson interferometer and uses a linear detector array to read out the interferogram. A purpose-built, all-reflecting lens is used for fringe imaging and a cylindrical lens is incorporated for light collection in the along-fringe direction
Noise in a Fourier Transform Spectrometer: Reduction by Design
Authors: Palmer Byron A.
Published: February 2023

Noise in a FTS is characterized by source and by frequency spectrum and can be reduced through the design and operation.
Laboratory Spectroscopy of H2O and N2O
Authors: Toth Robert A.
Published: February 2023

High resolution laboratory measurements of line positions, strengths, and pressure broadening parameters of atmospheric trace molecules are important for the analysis of atmospheric measurements. Two of the several key molecules involved in this scenario are N2O and H2O. This text describes the laboratory measurements, analysis and results of an extensive study on N2O and H2O infrared spectra. The spectra were obtained with a Fourier-transform spectrometer located in the McMath solar telescope facility at the Kitt Peak National Observatory. The spectral resolution was 0.005 cm-1 for the region below 2200 cm-1 and from 2200 to 8000 cm-1, the resolution was 0.01 cm-1.
Strong Anomalous Emission from Ne IX and Ne X Transitions in a Laser-Driven Plasma
Authors: Crane John K. , Ditmire Todd , Nguyen Hoang , Perry Michael D.
Published: February 2023

Recently McPherson et al.1 reported strong, energetic emission(greater than 1 keV) from laser excited, krypton atoms in a pulsed gas source. Audebert et al.2 observed Kα emission from argon in the interaction between a subpicosecond laser and the output of a gas jet. In both cases the emissions are anomalous in the sense that they derive from ions stripped to a higher charge state than predicted by tunneling theory. McPherson et al. postulate that this anomalous emission results from a new type of absorption in the clusters of Kr atoms, formed in the supersonic expansion of the gas nozzle. In this paper we present our observations of fluorescence from He-like and H-like neon, which does not condense into clusters under our experimental conditions. Our results can be simulated using a model that combines a laser-driven collisional excitation term with tunneling ionization.
Investigation of Nonlinear Propagation of Intense Ultrashort Laser Pulses
Authors: Nibbering E.T.J. , Franco M.A. , Prade B.S. , Vinet J.-Y. , Chambaret J.-P. , Mysyrowicz A.
Published: February 2023

The understanding of the effects occuring during propagation of high-intensity ultrashort laser pulses through nonlinear transparent media is of utmost importance for careful transport of the laser beam to the targets and application of these pulses in experiments such as X-ray generation in solids [1] and high-harmonic generation in gases [2]. In the weak perturbation regime the nonlinear index of refraction may cause self-focusing and self-phase modulation of the laser pulses. At higher intensities the onset of filamentation of a laser beam through nonlinear media may be induced, thereby facilitating channeling through laser-induced plasmas [3].
Space and Time Behavior of Backscattering Instabilities in the Modified Decay Regime
Authors: Mounaix Philippe , Pesme Denis
Published: February 2023

The space and time behavior of parametric backscattering instabilities is computed analytically in the so-called modified decay regime defined by the inequality γ0 ≫ ω2, where γ0 is the homogeneous growth rate of the backscattering instability and ω2 is the angular frequency of the longitudinal daughter wave. The theoretical model we have used has been extensively described in Ref. 1 : The plasma is assumed to be homogeneous and of finite length L. The propagation of the pump wave and its finite pulse duration both are taken into account, its depletion is ignored. The parametric growth is described by the coupled mode equations where Vα, ωα and vα respectively denote the group velocity, the angular frequency and the linear damping of wave α.
Plasma Creation in Dense, Preformed Transient Gas Channels by Ultrashort Laser Pulses
Authors: Wood Wm. M.
Published: February 2023

The study of high-intensity (>1014 W/cm2) laser interactions with dense (1017 cm-3 < ρ ≲ 1021 cm-3) plasmas has been limited by the concomitant problems introduced in beam propagation with the creation of a plasma. Typical experiments under these conditions experience severe limiting of the peak intensity which can be achieved. Furthermore, these experiments often have a large uncertainty about the actual plasma density/laser intensity conditions which occur in the interaction region. Experiments such as plasma wakefield acceleration and XUV recombination lasers require long interaction regions with well-characterized intensity and plasma density conditions. To solve the problem of beam propagation limitations in laser plasma interactions, two potential methods for creating transient propagation channels in gaseous targets are investigated. Each method comprises a two-pulse experiment, where the channel is formed by an initial laser pulse, and then is probed by a second, ultrashort, high-intensity pulse.
Hydrodynamic Simulations and X-ray Emission Modelling of Ultra-Short Laser-produced Plasmas
Authors: Peyrusse O. , Busquet M. , Raucourt J.P. , Kieffer J.C. , Côté C.Y.
Published: February 2023

The analysis of x-ray emission is one of the most popular methods for extracting information from laser-produced plasmas. In this vein, the ability to generate x-ray synthetic spectra to be compared with experimental results is a key factor for the understanding of the physical processes involved in short-pulse experiments.
Defocusing effects in intense field harmonic generation experiments
Authors: de Lisio C , Bruzzese R , Beneduce C , Sorrentino S , Vigilante F , Solimeno S , Altucci C
Published: February 2023

In harmonic generation experiments carried out at intensities above 1013 W cm-2, the effect of ionisation becomes significant. The presence of free electrons introduces a space-time dependent change of the refractive index of the medium. The important role of the medium ionisation has been recently discussed in ref. 1,2,3 by including in the phase-matching integral the contribution of the electrons to the refractive index.