bluuebunny/crossref_metadata_2025 huggingface dataset:
Case Report: Acute kidney failure leading to permanent haemodialysis due to hyperoxaluria following one-anastomosis gastric bypass-related rapid weight loss.
Authors: Miranda Angelo , Rosato Andrea , Costanzi Andrea , Pisano Lucia , Colzani Sara , Auricchio Sara , Mari Giulio , Achilli Pietro , Maggioni Dario
Published: February 2020

The one-anastomosis laparoscopic gastric bypass (OAGB) has been proven to provide good weight loss, comorbidity improvement, and quality of life with follow-up longer than five years. Although capable of improving many obesity-related diseases, OAGB is associated with post-operative medical complications mainly related to the induced malabsorption. A 52-year-old man affected by nephrotic syndrome due to a focal segmental glomerulosclerosis underwent OAGB uneventfully. At three months post-surgery, the patient had lost 40kg, reaching a BMI of 32. The patient was admitted to the nephrology unit for acute kidney injury with only mild improvement in renal function (SCr 9 mg/dl); proteinuria was still elevated (4g/24h), with microhaematuria. A renal biopsy was performed: oxalate deposits were demonstrated inside tubules, associated with acute and chronic tubular and interstitial damage and glomerulosclerosis (21/33 glomeruli). Urinary oxalate levels were found to be elevated (72mg/24h, range 13-40), providing the diagnosis of acute kidney injury due to hyperoxaluria, potentially associated to OAGB. No recovery in renal function was observed and the patient remained dialysis dependent. Early and rapid excessive weight loss in patients affected by chronic kidney insufficiency could be associated with the worsening of renal function. Increased calcium oxalate levels associated with OAGB-related malabsorption could be a key factor in kidney injury.
Logic of Social Ontology and Łoś’s Operator
Authors: Malinowski Jacek , Pietrowicz Krzysztof , Szalacha-Jarmużek Joanna
Published: February 2020

In 1947 Jerzy Łoś proposed a positional logic based on the realization operator. We follow his work and present it in the context of fundamental challenges of sociology such as the complexity of social reality and reflexivity of social agents. The paper is an outline of the general concept, as it opens a discussion and sets ground for future elaborations. In this paper, we are considering the concept according to which the expressions put forward by Łoś’s system might be indexed not only by spatial and temporal variables, but also by social contexts. And as such Łoś’s system might be a significant improvement, a valuable addition for social simulations and computational sociology, which use multi-agent systems and agent-based modeling. We consider how Łoś’s operator might be useful for these disciplines, as it gives a chance to combine of formalization with the humanistic coefficient, which represents the issues of complexity and reflexivity of social agents.
Broadband near-perfect terahertz absorber in single-layered and non-structured graphene loaded with dielectrics
Authors: Soleymani Ali , Meymand Roya Ebrahimi , Granpayeh Nosrat
Published: February 2020

In this work, we have done an extensive study on broadband near-perfect absorbers consisting of single-layered and non-structured graphene loaded with periodical arrays of dielectric bricks, including square and elliptical bricks. We also propose and investigate circular cylinder, rectangular brick, and racecourse dielectric structure. Moreover, the calculated

z

component of the electric field enables us to understand the physical mechanism of resonance absorption. Furthermore, we also studied and proposed a new absorber with periodical arrays of stepped rectangle dielectric structure. We could achieve a broadband absorption from 1.6 to 4.2 THz, with a bandwidth of 2.6 THz and absorption over 90%. The proposed absorber is also tunable; the tunability of the terahertz (THz) broadband absorber is achieved via changing the external gate voltage to modify the Fermi energy of graphene. Also, we compared the results and absorption spectra of different dielectric structures. This THz metamaterial structure can be used in different THz applications such as cloaking, sensing, detection, and imaging.
Simultaneous measurement of displacement, pitch, and yaw angles of a cavity output mirror based on phase measuring deflectometry
Authors: Sun Chuang , Zheng Yamin , Zeng Fa , Xue Qiao , Dai Wanjun , Zhao Wenchuan , Huang Lei
Published: February 2020

Accurate and high dynamic range measurement of the three attitude variations (i.e., displacement, pitch, yaw angles) has been widely researched based on various approaches to meet different application requirements. However, none of the existing methods can detect these three attitude variations at the same time. This paper proposes a method based on a classical phase measuring deflectometry (PMD) system and a double iteration algorithm to simultaneously measure the three variations of the output mirror in a laser resonator. The relationship between the attitude variations and the lateral displacement parameters (LDP) of the imaged structural fringes is derived in the PMD system. Through the established relationship, the attitude variations could be calculated once the LDP are detected. Furthermore, a two-step measuring scheme combining the four-step shifting phase and the color-coded fringe is proposed to effectively detect the LDP. Finally, an experiment is conducted to verify the feasibility of the proposed method.
General formula to design a freeform singlet free of spherical
aberration and astigmatism: reply
Authors: González-Acuña Rafael G. , Chaparro-Romo Héctor A. , Gutiérrez-Vega Julio C.
Published: February 2020

The comment made by Valencia-Estrada and García-Márquez [Appl. Opt.
59, 3422 (2020)APOPAI0003-693510.1364/AO.379238] to our
paper [Appl. Opt. 58, 1010
(2019)APOPAI0003-693510.1364/AO.58.001010] consists of a trivial
generalization of our formulation.
Measurement of n2 (λ = 355 nm) the nonlinear refractive-index coefficient at the third harmonic of Nd:YAG lasers
Authors: White W. T. , Smith W. Lee , Milam D.
Published: February 2020

The nonlinear refractive index leads to intensity- dependent phase perturbations such as whole-beam self-focusing and beam breakup. These processes ultimately limit the allowed peak fluence in short- pulsed high-energy lasers. Therefore, to design and work with such systems, one must know n
2
for each optical element in the system.
Nonresonant and band gap resonant optical phase conjugation in Hg1–xCdxTe
Authors: Kruse Paul W. , Khan M. Asif
Published: February 2020

The alloy semiconductor Hg1–xCdxTe has been widely employed as an IR detector material. We have been studying nonlinear optical effects in Hg1–xCdxTe including optical phase conjugation. The ability to tailor the band gap by adjusting the x value during growth makes it possible to match the band gap to the wavelength of the pump laser. For x ≅ 0.22, the band gap at ~77 K is coincident with the 10.6-μm output of a CO2 laser.
Continuous-wave CO2 laser range finder using heterodyne detection and pulse-code modulation
Authors: Lerou R. J. L.
Published: February 2020

A CO2 laser range finder has been built utilizing an acoustooptic modulator to obtain an amplitude- modulated optical beam from a cw laser operating in the TEM00 mode.1 An on-off deflected beam was obtained by driving the modulator by a binary pulse-code modulated 40-MHz carrier. At this frequency the deflection efficiency amounted to 20% (maximum of our modulator), and a deflection rise time of 300 nsec was achieved.
Laser IR-visible double-resonance study of intermolecular and intramolecular energy transfer in methylglyoxal-SF6 mixtures
Authors: Bhatnagar R. , Gu Y. , Guillory W. A.
Published: February 2020

In a recent paper, Bhatnagar and Guillory1 demonstrated the use of an IR—visible laser double-resonance technique to -study the intramolecular and intermolecuiar energy transfer processes in glyoxal-CH3F mixtures. The temporal behavior of various vibrational modes in glyoxal was studied, and some characteristic rate constants are reported. In this paper, we report the results of a similar study on an intermediate size molecule, methylglyoxal (Fig. 1), which has 21 vibrational modes.
Stimulated Raman studies of the IR excitation dynamics of SF6
Authors: Esherick P. , Grimley A. J. , Owyoung A.
Published: February 2020

Recent developments in stimulated Raman spectroscopy offer a means of studying the dynamics of IR photoexcitation processes with unprecedented spectral resolving power (<0.002 cm−1)1,2 and sensitivity. In this paper we report the application of SRS techniques to study the photoexcitation dynamics of SF6 molecules irradiated by a CO2 laser source. The results demonstrate the ability of SRS to monitor in a time-resolved manner both the depletion of the ground state and the population of the vibrationally excited manifolds of the system.
Optical phase modulation in an injection-locked AlGaAs semiconductor laser
Authors: Kobayashi Soichi , Kimura Tatsuya
Published: February 2020

Coherent optical transmission systems, in which the amplitude, frequency, and phase of the coherent optical carrier are modulated and then demodulated through a homodyne or heterodyne scheme, may be useful for reducing received optical power in large capacity transmission systems.1 Phase modulation (PM) is expected to be the most effective mode of modulation for them.
Vacuum insulation experiments from CO2 laser-irradiated targets
Authors: Tan T. H. , Van Hulsteyn D. B. , Williams A. H.
Published: February 2020

The possibility of using vacuum insulation to stop hot electrons from preheating the interior of a fusion target has been investigated for high-power CO2 laser irradiation. In a double-foil flat-target configuration, hot electron energy transported from the front illuminated surface to the back foil is measured as a function of hot electron temperature, foil separation, and front foil parameters such as Z value, thickness, area, and density.
Optical recording on microscopically textured surfaces
Authors: Craighead H. G.
Published: February 2020

Textured surfaces consisting of submicron columns or cones have been formed in metals, semiconductors, and insulators. This structured surface morphology forms a graded-index-matching layer that reduces reflection of visible light to as low as 0.1 %. The optical properties of this surface can be permanently altered on a ≲ 1-μm size scale by irradiation with a focused low-power laser beam. The light energy transforms the optically absorbing textured surface to a nonabsorbing smooth one by melting the structures or initiating a chemical reaction.
Recent studies on electron-beam-pumped triatomic excimer lasers
Authors: Sauerbrey R. , Tittel F. K. , Wilson W. L. , Langhoff H. , Marowsky G.
Published: February 2020

The formation of triatomic rare gas halide excimer molecules (Rg2X*) is of considerable interest both for direct laser action in the visible and near UV1 as well as a loss process in diatomic RgX* lasers. Several experiments are reported in this paper which deal with the kinetics and the optical absorption and gain characteristics of broadband triatomic excimer molecules.
Sodium dimer laser with stable emission
Authors: Weber H. P. , Schmlele R. , Luthy W.
Published: February 2020

The 488.1-nm radiation of a single-mode Ar+ ion laser was used to excite Na2 molecules in a heat-pipe oven. The experimental arrangement is shown in Fig. 1. In a short linear resonator the emitted 532-nm dimer laser light shows strong fluctuations of power. An interferometric experiment revealed that density fluctuations due to temperature gradients in the oven are far too small to explain this observation. As the mechanical stability of the resonator proved to be of great influence, we investigated the possibility that the unstable emission could result from a misfit between the narrow gain profile exhibited by the Na2 laser and the fluctuating position of axial modes in a short mechanically unstabilized linear resonator.
Airborne remote sensing measurements with pulsed CO2 lasers
Authors: Bufton Jack L. , Itabe Toshikazu , A David , .  , Grolemund
Published: February 2020

A lidar instrument based on compact pulsed carbon dioxide (CO2) lasers has been developed for airborne remote sensing of atmospheric trace species. The instrument is now operational on the NASA Wallops Flight Center P3 aircraft. A flight test program was conducted during 1981, and results are available on instrument performance, data quality, and target signatures.
Photodissociation of UF6 excited in the first electronic band
Authors: Catoni F. , Cavaioli M. , D'errico E. , Freddi G. , Morales P.
Published: February 2020

To investigate the IR + UV laser isotope separation scheme (IR selective excitation of the v3 mode + UV dissociation), we study in this work the photodissociation dynamics of UFs excited in the first electronic band. Dissociation is monitored by the formation of laser snow, and the dissociation yield is related by a simple expression to the time of irradiation necessary to observe laser snow.1 Two electronic transitions have been identified in this band,2 and based on these a model was developed that accounts for the fluorescence lifetime measurements.3
Persistant nonphotochemical hole-burning of a molecular vibrational mode in alkali halide lattices
Authors: Moerner W. E. , Sievers A. J. , Silsbee R. H. , Chraplyvy A. R. , Lambert D. K.
Published: February 2020

We report the first observation of persistent nonphotochemical hole-burning in the inhomogeneously broadened IR vibrational mode of a molecular impurity in a crystalline lattice. The system consists of
ReO4− molecules substitutionally doped into alkali halide crystals which were studied at liquid helium temperatures. GO2 and lead salt diode lasers have beers used to measure the hole growth and erasing dynamics at intensities far below the saturation intensity I
s
(≃1–3 W/cm2).
Hybrid bistable optical devices
Authors: Li Chun-Fei
Published: February 2020

This paper reviews some of our work on electrooptical hybrid bistable optical devices (BOD). The following topics will be discussed:
Transverse effects in optical bistability: computations anti observations
Authors: Moloney J. V. , Gibbs Hyatt M. , Jewell J. L. , Tai K. , Watson E. A. , Gossard A. C. , Wiegmann W.
Published: February 2020

The spatial profile of the output intensity of a bistable optical GaAs etalon1 has been studied by imaging the output plane of the etalon onto a 15-μm diam aperture with a magnification of 7X. The aperture was translated across the image plane, and the transmission was monitored with an 8852 photomultiplier tube having ≃ 5-nsec resolution. In the low-intensity linear regime the HWHM radius a at the sample was determined to be ≃5 μm, corresponding to a Fresnel number F = na2/λL of 24 for the etalon of length L = 4.5 μm and refractive index n = 3.5.
Two-dimensional multilevel optical feedback system arrays using a Hughes LC light valve
Authors: Collins Stuart A. , Habiby Sarry F.
Published: February 2020

We present a multilevel optical feedback scheme capable of 2-D/storage of bright or dark spots. Indeed the scheme has the capability of arrays of such storage units. Feedback1,2 in optical systems is art area of active interest because it leads to bistability3 and information storage on one hand and to control of linearity in optical systems on the other hand. Here a new feedback scheme is presented using a Hughes liquid crystal light valve operating in an optically controlled real-time diffraction grating mode as a central element.4
Defect-perturbed metal-atom centers in alkali halides: a new class of highly stable laser-active color centers
Authors: Mollenauer L. F. , Vieira N. , Szeto L.
Published: February 2020

Recently Gellerman et al.1 discovered highly stable laser-active color centers based on TI impurities in alkali halide host crystals, and they have called these F
A
III centers. However, our own investigations of the new centers show that they are instead neutral TI atoms perturbed by the field of an adjacent anion vacancy or so-called

T
I
0

(
1
)

centers.2 The argument is as follows: First recall that the electronic configuration of neutral TI is a single p electron outside a closed shell.
Multiwavelength mid-IR laser emission in Ho:YLF
Authors: Eckardt R. C. , Esterowitz L. , Abella I. D.
Published: February 2020

Until 1979 it had been assumed by most workers in the field that rare earth laser emission in single-crystal hosts was limited to wavelengths shorter than 3 μm due to the overwhelming predominance of nonradiative decay over radiative decay.1 Recently2 It was demonstrated that laser emission beyond 3 μm could be generated by a combination of resonant pumping and cascade emission. In this paper we present the first description of a three-step cascade laser process. In addition all three wavelengths are in the mid-IR spectral region.
Circular aperture arrays for the calibration of droplet sizing instruments
Authors: Hirleman E. D.
Published: February 2020

For many years the near-forward light-scattering signature from ensembles of droplets has been used to estimate parameters of the droplet-size distribution. A typical optical system for this purpose is shown in Fig. 1. Early workers1,2 used rather qualitative parameters of the forward-scattering pattern to determine a volume-to-surface area mean diameter of the distribution, the Sauter mean (SMD). More recently inversion methods are being used which permit reconstruction of the size distribution from forward-scattering measurements.3,4
Isoplanatism and probabilistic diffraction-limited imaging through a turbulent atmosphere
Authors: Bensimon D. , Englander A. , Slatkine M.
Published: February 2020

Atmospheric turbulence may significantly degrade the image of an object below the diffraction limit of the imaging system's aperture. A probabilistic method for overcoming this image degradation has been proposed by Hufnagel and Fried.1 It consists of making short exposure images of the object. At some instants the wave front distortion upon the receiving aperture may be negligible. If a short- exposure (<5-msec) image is made, it will appear to be diffraction-limited.
Demonstration of image transmission through fibers by optical phase-conjugation
Authors: Dunning Gilmore J.
Published: February 2020

We have demonstrated the transmission of images through multimode fibers using phase-conjugation. The transmission of spatial information through fibers is degraded due to modal dispersion. To compensate for this degradation Yariv1 proposed use of the wave front reversal property of certain nonlinear optical techniques. In this paper we describe the first demonstration of image transmission and restoration using the nonlinear optical process of degenerate four-wave mixing (DFWM).
1-kW cw chemical oxygen-iodine laser
Authors: Miller D. J. , Clendening C. W. , English W. D. , Berg J. G. , Trost J. E.
Published: February 2020

Chemical oxygen-iodine lasers are a relatively new type of laser which produces a cw 1.315-μm laser beam. Chemically produced metastable singlet oxygen is used to dissociate molecular iodine and to transfer energy to the iodine atoms.
Continuous-wave photodissociation atomic iodine laser
Authors: Brock J. C. , Johnson R.
Published: February 2020

Growing interest in cw high-power atomic iodine (I*) lasers has generated a requirement for a compact cw I* laser that can be used as a diagnostic probe or as a test bed for developing applications such as direct solar-pumped power transmission systems. To this end, a novel cw photodissociation I * laser has been designed, tested, and used to determine several critical parameters in scaling I* lasers to useful output power.
Optically pumped 16-μm CF4 laser: cw and pulsed oscillation
Authors: Telle John
Published: February 2020

The CF4 laser represents a very challenging and interesting quantum electronic system. It is also useful for a number of applications. This paper will discuss the current status of the optically pumped CF4 laser relative to the fundamental molecular issues involved, the laser results achieved, and the new applications that are suggested. Directions for future research and development will be mentioned.
Ground-based wind measurements using an IR heterodyne Doppler lidar
Authors: Post Madison J. , Erl Noaa
Published: February 2020

The National Oceanic and Atmospheric Administration (NOAA) has constructed a prototype mobile pulsed heterodyne lidar to demonstrate the feasibility of similar satellite-borne systems for measuring global winds such as windsat.1 Table I lists important system parameters.
Wide-angle laser sensor
Authors: Yeh Pochs , Khoshnevisan Monte
Published: February 2020

Laser sensors play an important role as optical countermeasures to laser target designation. It is essential that the sensor be capable of detecting the illumination by a laser beam, the wavelength, and the angle of incidence over a wide field-of-view (FOV). Current laser sensors rely on the temporal coherence of lasers and use Michelson interferometry.1 This paper describes a novel laser sensor which utilizes the interference of polarized light in a wedge-shaped birefringent plate and can be made with a very wide FOV.
Microlithography of integrated circuits with laser-plasma x-ray sources
Authors: Epstein H. M. , Campbell B. E.
Published: February 2020

Very high intensity laser-plasma x-ray sources have been developed over the past ten years. In addition, it has been demonstrated that a relatively small, high repetition rate laser is a most attractive high average power source of x-rays in the ¾ to 2 keV range for general industrial or laboratory applications. This energy range is particularly significant for x-ray microlithogrphy of integrated circuits. A relatively low-cost system with an anticipated output of a few tenths of a watt of x-rays in the above energy range will be discussed. An interesting advantage of the laser plasma x-ray source is the small source diameter, about 50 µm.
High-power amplification of subnanosecond CO2 laser pulses
Authors: Czuchlewski Stephen J. , Romero Victor O.
Published: February 2020

The propagation of nanosecond CO2 laser pulses in high-power high-gain amplifiers has been well understood for several years.1-4 However, the amplification of subnanosecond pulses has not been thoroughly investigated. In a previous experiment5 on the propagation of 570-psec pulses in a low-gain TEA laser, a significant discrepancy between experiment and theory was observed. It was found that the 570-psec pulses broadened to 880 psec upon amplification, whereas theory predicted that they should have narrowed to 370 psec.
Quantitative laser-induced gas breakdown thresholds
Authors: Woods Charles L.
Published: February 2020

Recent advances in laser design provide the smooth reproducible single-mode pulses required1 for the quantitative comparison of theory and experiment in the laser-induced breakdown of gases. This paper applies microwave breakdown diffusion theory2 to our focused CO2 laser measurements and calculates an effective diffusion length L
e
and an effective pulse width T
e
from the measured shape of the laser pulse. Previous laser breakdown measurements3 have used fitting parameters for values of the diffusion length and usually for the laser pulse width.
Anti-Stokes Raman laser
Authors: White J. C. , Henderson D.
Published: February 2020

This paper reports what we believe to be the first observation of a stimulated nonresonant anti-Stokes Raman laser. Thallium vapor which was inverted by selective photodissociation of TICI was used as the Raman medium. Using the second (532-nm) and third (355-nm) harmonics of a Nd:YAG laser as pump sources, stimulated anti-Stokes emission from the

TI

(

6

p
2

P

3
/
2

0

)

to the

TI

(

6

p
2

P

1
/
2

0

)

state was observed at 376 and 278 nm, respectively.
Characterization of an efficient high-gain Raman amplifier
Authors: Goldhar J. , Taylor M. W. , Murray John R.
Published: February 2020

Raman amplifiers have several important applications, such as efficient conversion of laser frequency, pulse compression, and brightness enhancement. We investigated in detail characteristics of a Raman amplifier which uses methane gas pumped by KrF laser radiation at 248.5 nm. A high-quality Stokes beam was generated and amplified in an amplifier with a large Fresnel number, efficiently depleting pump beams of poor spatial quality. This system has a potential for scaling up to energies needed for laser fusion experiments.
Temporal evolution of picosecond pulses of an actively mode-locked semiconductor diode laser
Authors: AuYeung John C. , Bergman Larry A. , Johnston Alan R.
Published: February 2020

The transient buildup behavior preceding the establishment of steady-state forced mode locking in a semiconductor laser diode with an external cavity was investigated both theoretically and experimentally. If the field E in the resonator is expanded as.
Hybrid optoelectronic object recognition
Authors: Dandliker R. , Hess K. , Sidler T.
Published: February 2020

Conventional object recognition systems for robot vision are either fully optical (matched holographic filtering)1 or fully electronic (TV image processing).2 This paper presents a new concept for a hybrid system, which combines the merits of both the optical and the electronic approach but eliminates their respective drawbacks. The resulting system has in its first (optical) part the high speed of parallel Fourier processing1 and in its second (electronic) part the flexibility of digital programming.2 This is realized by replacing the matched holographic filter (hardware) in the Fourier plane by electronic processing (software) of amplitude and phase detected in that same plane. The application of this concept to on-line object tracking and recognition3 will be described.
Study of nickel distribution while laser-surface-alloying 1020 steel
Authors: Chande T. , Mazumder J.
Published: February 2020

The feasibility of fairly uniform surface alloying using high-power continuous lasers has been firmly established.1-3 Experimental studies have produced highly alloyed beads,1 while limited data on the effect of traverse speed on the depth, width, and solute content of the alloyed bead are available.3 Important questions remain unanswered, however,4 and more experimentation is required to examine the nature of the interactions between the process parameters, to establish the reproducibility, and to clarify the role of fluid flow in the molten pool.
Free-electron coherent relativistic scatterer (CORSCAT) tor UV generation
Authors: De Martini F. , Foresti M.
Published: February 2020

A coherent electromagnetic wave traveling in the same direction with a relativistic electron beam in an undulator (buncher) will produce an energy modulation of the beam which is periodic with the same wavelength λ as the wave. The energy modulation is then transformed into a charge density modulation after drifting of the beam through a drift space. This Klystron-type bunching process1 can be thought to consist of the mutual interference of charge density harmonic waves with wavelengths n-1 λ; n=1,2…, which travel with the average speed of the particles V =βc.
Stimulated electromagnetic shock radiation in the visible?
Authors: Cohen L. , Seeman N. , Murray K.
Published: February 2020

A continuous spectrum of electromagnetic radiation is produced when electrons traverse a dispersive medium at speeds exceeding the speed of light in the medium. This phenomenon is the well-known Cerenkov effect and has been studied extensively.1 On the other hand, a discrete spectrum is produced when electrons traveling in vacuum encounter intense laser light.2 Although these are two unrelated phenomena, Schneider and Spitzer3 claimed that they act synergistically to produce stimulated electromagnetic shock radiation (SESR) when relativistic electrons encounter coherent polarized electromagnetic waves in a weakly dispersive medium. The radiation was said to be narrowband, tunable, and the Intensity highly enhanced over Cerenkov as the electron speed crosses the Cerenkov threshold. Other theoretical work4 did not agree with these conclusions.
Carbon dioxide laser system tor ophthalmic surgery
Authors: Patel C. K. N. , Bridges T. J. , Strnad A. R. , Wood O. R. , Karlin D. B.
Published: February 2020

The CO2 laser, with its principal emission wavelength at 10.6 µm, has been extensively used in laser surgery. Its use in ophthalmic surgery, however, has lagged behind its use in other specialties because ocular tissues are essentially opaque to CO2 laser radiation. On the other hand, for some surgical procedures the short penetration depth of CO2 laser radiation can be advantageous, since significant changes can be effected in ocular tissue with negligible damage to underlying or neighboring structures.
High-speed optical waveguide switching
Authors: Haus H. A.
Published: February 2020

An optical waveguide structure for high-speed sampling and switching is described. Preliminary experimental results are presented. Modifications of the structure for multiplexing and demultiplexing are discussed.
Nonlinear optical signal processing using integrated optics
Authors: Stegeman G. , Bundman P. , Karaguleff C. , Normandin R.
Published: February 2020

Optical signal processing can be implemented by the nonlinear mixing of optical waveforms in planar integrated optics waveguides. For example, we have previously1 demonstrated the convolution of optical waveforms of picosecond duration via second-order nonlinearities in LiNbO3 waveguides. Here we report (1) the application of this effect to a transient digitizer with picosecond resolution, and (2) the application of third-order nonlinearities in distributed feedback gratings to signal processing. The three interaction geometries are illustrated in Figs. 1-3.
Recent advances in spatial light modulators for coherent optical processing applications
Authors: Tanguay Armand R.
Published: February 2020

Following the advent of the laser and directly stimulated by its ready availability, there has been tremendous progress in the past two decades in the development of coherent and incoherent optical processing techniques. However, the many advantages of 2-D parallel processing are not fully exploitable in image and data processing systems without the availability of appropriate real-time spatial light modulators. Although a wide range of candidate spatial light modulator technologies have been proposed and extensively researched and developed, no single candidate has yet emerged that at once satisfies the system requirements of low cost, reliability, and ease of operation while simultaneously exhibiting the requisite technical performance characteristics demanded by increasingly complex optical processing applications.
Three-photon resonantly enhanced photoionization of Xe and UV photodissociation of Xe 2 +
Authors: McCown A. W. , Eden J. G.
Published: February 2020

Multiphoton ionization has proven to be a convenient means for selectively producing a variety of atomic and molecular ions. Since the development of rare gas-halide lasers, in particular, rare gas photoionization has considerably simplified study of the collisional kinetics and spectroscopy of several electronically excited molecules, including XeF, XeO, and Xel.1,2
Measuring molecular flow velocities with coherent Raman spectroscopy
Authors: She C. Y. , Herring G. C.
Published: February 2020

Not long ago, we proposed1 use of high-resolution stimulated Raman gain spectroscopy (SRGS) and other related coherent Raman techniques to measure molecular flow velocities. Recently we succeeded in observing the spectral line shifts resulting from a molecular flow and performed our first experimental demonstration of subsonic velocity measurements using SRGS in molecular nitrogen.2 In this paper, we present (1) a summary of our initial subsonic velocity measurements using SRGS, (2) the progress of our much improved molecular flow measurements using high-resolution inverse Raman scattering, and (3) a feasibility study using high- resolution coherent Raman spectroscopy performed on a single-shot basis for real-time measurements of molecular flow.
Flash-pumped single-mode laser operation of Nd: YLF
Authors: McCarthy J. C. , Knights M. G. , Chicklis E. P.
Published: February 2020

Nd:YAG laser systems operating at high average power must be designed to accommodate thermal lensing of YAG for efficient energy removal. Recent results1 have shown that the thermal lens formed by a YLF rod under moderate input powers (700 W) is 1/10 of that of an identically pumped YAG rod. Thermal distortion of a laser rod reduces the available TEM00 mode volume necessitating the use of intraresonator compensating optics suited for a specific thermal operating point.
4×4 optical waveguide switch with single-mode fiber arrays for 1.3-µm wavelength
Authors: Kondo M. , Ohta Y. , Fujiwara M. , Sakaguchi M.
Published: February 2020

In single-mode and high bit-rate optical fiber communication systems at 1.3-µm wavelength, high-speed switching networks are in great demand for a variety of functions. LiNbO3 waveguide switches1 are suitable for constructing such switching networks because of the high-speed capability.
Automated dye laser calibration using microprocessor control and optogalvanic detection
Authors: Nestor J. R.
Published: February 2020

Optogalvanic resonance is the process by which the ionization rate of a glow discharge plasma is influenced by the application of light from an external source.
Semiconductor laser with collimating optics
Authors: Van Ruyven L. J. , Finck J. C.
Published: February 2020

Semiconductor lasers emit a diverging beam of light. This divergence is often quite different in the two perpendicular directions, and, in addition, in the case of gain-guided lasers the beam is also astigmatic.
Continuous-wave Doppler-free two-photon spectroscopy of high Rydberg states of Ca in the deep blue spectral range
Authors: Beigang R. , Lugke K. , Matthias E. , Timmermann A.
Published: February 2020

Doppler-free two-photon spectroscopy with cw dye lasers has opened a new dimension of accuracy for investigation of Rydberg states.1
Wave front reconstruction in the picosecond range
Authors: Ferrier J. L. , Wu Z. , Gazengel J. , Xuan N. Phu , Rivoire G.
Published: February 2020

Four-wave mixing and stimulated backward scattering1,2 allow the production of phase conjugate signals.
Stable suspension of targets by optical levitation
Authors: Roosen Gerald
Published: February 2020

Many studies or experiments deal with the effects of light energy, but the radiation pressure due to the interaction between a light beam and a material body is less often considered. In this paper, we shall show how, using the radiation pressure force exerted by laser beams, we are able to trap and stably maintain submillimeter particles in a fixed position, free from any support.
Laser Raman microscopy and imaging
Authors: Delhaye Michel
Published: February 2020

The Raman effect relates to the change of frequency observed when a monochromatic light beam is scattered by molecules or crystals. Unlike the so-called stimulated or coherent Raman processes, which correspond to strong emissions, the spectral analysis spontaneous Raman scattering exhibits very weak lines or bands whose frequency shifts and intensities unambiguously characterize the polyatomic species present in a sample. Raman spectra complement the IR absorption in studying
Measurements of irreversible laser damage thresholds for thin films
Authors: Martellucci S. , Marchetti R. , Mislano C. , Penco E. , Tomassini M.
Published: February 2020

When a laser beam impinges on a coated surface, absorption of the laser beam energy causes physical modifications of the material itself, which strongly depend on the laser irradiance E(W/m2) and/or the radiant exposure H (J/m2). At low values of the irradiance (and/or the radiant exposure) heating effects dominate, and the material undergoes reversible changes of its physical properties. However, when the irradiance (and/or the radiant exposure) exceeds a threshold value, irreversible damage of the material will result. We have measured the irreversible damage thresholds for various coatings and after laser irradiation by using an interferometric technique developed by some of the present authors.1
Novel photoacoustic measurements using a fiber-optic transducer
Authors: Leslie D. H. , Trusty G. L. , Dandridge A. , Giallorenzi T. G.
Published: February 2020

The operation of an all-fiber spectrophone is described. The pressure sensing transducer was constructed by winding 9.2 m of high N.A. fiber into the shape of a 2.54-cm diam hollow cylinder, 4.1 cm in length. A layer of silicon rubber adhesive on the outside surface allowed expansion of the device, while retaining the cylindrical shape and containing the absorbing gas. The fiber ends were then spliced into one arm of an all-fiber Mach-Zehnder interferometer, details of which have been published.1,2
Surface polariton photography
Authors: Keilmann F. , Bai Y. H.
Published: February 2020

When a free-space light beam hits a dielectric or metallic material, it cart launch electromagnetic modes bound to and traveling along the material’s surface (“surface polariton”1). Coupling is provided, e.g., by discontinuities of either dielectric or geometric properties of the surface. These modes usually decay rapidly on traveling away from their origin. Thus they may be important in the small scales dealt with in the laser surface treatment processes of lithography, annealing, etc.
Two-photon absorption and polarization in UV glasses and selected crystals
Authors: smith W. Lee
Published: February 2020

Highly transparent optical materials are necessary for many applications of laser radiation in the UV spectral region. With low-intensity laser light, adequate transparency is usually obtainable by simply employing wide band-gap materials such as fused silica. However, with intense (~1-GW/cm2) UV laser pulses, transparency is maintained only if the nonlinear absorption strength is also small. Previous work1,2 has shown the two-photon absorption coefficient in pure fused silica to be very small (<0.0005 cm/GW), underwriting the suitability of fused silica for many UV applications.
Picosecond electrooptic sampler
Authors: Valdmanis J. A. , Mourou Gerard , Gabel C. W.
Published: February 2020

With the advent of picosecond photodetectors, photoconductive switches, and other ultrafast devices, the need has arisen for a measurement system capable of characterizing small electrical signals with picosecond accuracy. Techniques for measuring ultrafast electrical signals to date have limitations to their use. Sampling oscilloscopes have temporal resolutions limited by their electronic sampling window.
Optonongenetic enhancement of activity in primary cortical neurons
Authors: Ghirga Silvia , Pagani Francesca , Rosito Maria , Di Angelantonio Silvia , Ruocco Giancarlo , Leonetti Marco
Published: February 2020

It has been recently demonstrated that the exposure of naive neuronal cells to light—at the basis of optogenetic techniques and calcium imaging measurements—may alter neuronal firing. Indeed, understanding the effect of light on nongenetically modified neurons is crucial for a correct interpretation of calcium imaging and optogenetic experiments. Here we investigated the effect of continuous visible LED light exposure (490 nm,

0.18

−

1.3

m
W

/

m
m

2

) on spontaneous activity of primary neuronal networks derived from the early postnatal mouse cortex. We demonstrated, by calcium imaging and patch clamp experiments, that illumination higher than

1.0

m
W

/

m
m

2

causes an enhancement of network activity in cortical cultures. We investigated the possible origin of the phenomena by blocking the transient receptor potential vanilloid 4 (TRPV4) channel, demonstrating a complex connection between this temperature-dependent channel and the measured effect. The results presented here shed light on an exogenous artifact, potentially present in all calcium imaging experiments, that should be taken into account in the analysis of fluorescence data.
Photoacoustic computed tomography by using a multi-angle scanning fiber-laser ultrasound sensor
Authors: Liang Yizhi , Li Lingxuan , Li Qiang , Liang Hao , Jin Long , Wang Lidai , Guan Bai-Ou
Published: February 2020

Photoacoustic computed tomography (PACT) can ultrasonically image optical absorbers in biological tissues by using a linear piezoelectric transducer array, but some features can not be visualized as a result of the limited acceptance angle. The optical ultrasound sensors for photoacoustic imaging have received great interests, because of their compact sizes, comparable sensitivities to their electric counterparts, as well as the extended field/angle-of-view. In this work, we have developed a PACT system based on a fiber-laser based ultrasound sensor. Two-dimensional imaging was performed by horizontally scanning the sensor and image reconstruction via back projection, and three-dimensional imaging was further achieved by repeating such scanning process at multiple angles, based on inverse Radon transform. The axial and lateral resolutions are 93 and 220 µm in three-dimensional imaging. The fiber-based PACT can resolve more features than that with a piezoelectric transducer array, taking advantage of the dual-60-degree vision angles of the sensor.
SDN enabled flexible optical data center network with dynamic bandwidth allocation based on photonic integrated wavelength selective switch
Authors: Xue Xuwei , Nakamura Fumi , Prifti Kristif , Pan Bitao , Yan Fulong , Wang Fu , Guo Xiaotao , Tsuda Hiroyuki , Calabretta Nicola
Published: February 2020

Optical switching techniques featuring the fast and large capacity have the potential to enable low latency and high throughput optical data center networks (DCN) to afford the rapid increasing of traffic-boosted applications. Flexibility of the DCN is of key importance to provide adaptive and dynamic bandwidth to handle the variable traffic patterns generated by the heterogeneous applications while optimizing the network resources. Aiming at providing the flexible bandwidth for optical DCNs, we propose and experimentally investigate a software-defined networking (SDN) enabled reconfigurable optical DCN architecture based on novel optical top of rack (OToR) switch exploiting photonic-integrated wavelength selective switch. Experimental results show that the optical bandwidth per link can be automatically reallocated under the management of the deployed SDN control plane according to the variable traffic patterns. With respect to the network with inflexible interconnections, the average packet loss of the reconfigurable DCN decreases 1 order of magnitude and the server-to-server latency performance improves of 42.2%. Scalability investigation illustrates limited (11.7%) performance degradation as the reconfigurable network scale from 2560 to 40960 servers. Both the numerical and experimental assessments validate the proposed DCN with reconfigurable bandwidth feature and lower latency variations with respect to the inflexible DCNs.
Shack–Hartmann versus reverse Hartmann wavefront sensors: experimental results
Authors: Pannetier Cyril , Hénault François
Published: February 2020

With respect to the classical Shack–Hartmann (SH) wavefront sensor (WFS), the recently proposed reverse Hartmann (RH) sensor inverts the locations of the filtering and observation planes and forms a direct image of the pupil on a detector array. The slopes of the wavefront error (WFE) are then reconstructed by using a double Fourier transform algorithm. It turns out that the same algorithm can also be applied to the raw data acquired by SH sensors. This Letter presents the first, to the best of our knowledge, experimental results obtained with a simplified RH WFS and their comparison to those provided by a reference SH sensor, in both classical and double Fourier transform modes. They demonstrate that similar WFE measurement accuracy is achievable when using the three techniques, at least within the limit of our test bench that is estimated around

λ

/

10

RMS.
Generation and metrology of attosecond XUV pulses
Authors: Agostini P.
Published: February 2020

Sub-femtosecond XUV pulses have recently been achieved. Their production through high harmonics generated by an intense infrared laser interacting with rare gases and their metrology based on electron spectrometry in two-color photo-ionization will be reviewed.
Time-Resolved Photoelectron Spectroscopy: Charge & Energy Flow in Molecules
Authors: Shaffer James P. , Schultz Thomas , Underwood Jonathan G. , Stolow Albert , Hayden Carl C.
Published: February 2020

The coupling of charge and energy flow processes in molecules underlies photochemistry, photobiology and molecular electronics. Time-resolved photoelectron spectroscopy disentangles these processes. Timing-Imaging detection of photoions and photoelectrons in coincidence provides new levels of detail.
Molecular quantum computing: Implementation of global quantum gates applying optimal control theory
Authors: de Vivie-Riedle Regina , Tesch Carmen M.
Published: February 2020

Vibrational modes are selected as qubit basis for a new concept of a molecular quantum computer. Optimal control theory is applied to find the optimized laser fields to realize the quantum gates between these qubits.
Ultrafast Two-Photon Free Induction Decay
Authors: Keusters Dorine , Tian Peifang , Warren Warren S.
Published: February 2020

Direct optical analogs of (two-dimensional) NMR experiments require detection of the phase of a coherence induced by a (series of) laser pulses, which is difficult [1]. Recently it was demonstrated that by using a phase coherent pulse pair created by an acousto optic pulse shaper (AOPS), this phase information can be detected conveniently and fast. [2, 3] This technique was demonstrated on the one-photon transitions in Rubidium [3]. The same technique can be used to detect a coherence that is induced by two photons simultaneously [4], as we demonstrate experimentally by detecting the two-photon free induction decay (TPFID) of Rb and coumarin. Since the two-photon transition in Rb is resonance enhanced, several types of coherences are induced in the two-photon process. An AOPS allows a separation of these types of coherences, and has potential advantages for suppressing scattered light.
Strong Field Control of Photochemistry Using Tailored Laser Pulses
Authors: Levis Robert J. , Menkir Getahun
Published: February 2020

The control of chemical reactivity is possible using tailored laser pulses in the strong field regime. We show that intense laser pulses induce sufficient transient shifting, lifetime broadening and multiphoton excitation to allow manipulation of complex organic molecules.
All-Optical Self-Stabilization of Carrier-Envelope Offset in Few-Cycle Pulses by Optical Parametric Amplifiers
Authors: Baltuška Andrius , Ishii Nobuhisa , Kobayashi Takayoshi
Published: February 2020

We present versatile schemes of white-light-seeded optical parametric amplifiers, which permit generation of extremely short visible and infrared pulses with precisely controlled oscillations of the electric field. Passive locking of carrier-envelope phase is demonstrated without generation of octave-spanning bandwidths and active phase tracking.