bluuebunny/crossref_metadata_2025 huggingface dataset:
PARAMETER ESTIMATE WITH ONLY ONE COMPLETE FAILURE OBSERVATION USING MONTE CARLO EM ALGORITHM
Authors: PANG WAN-KAI , LEUNG PING-KEI , PU XIAO-LONG , MAO SHI-SONG
Published: May 2003

In reliability studies, often we only have one failure data recorded in a life testing experiment. If there are two parameters in the reliability model, such as the model using Weibull distribution, then maximum likelihood estimation of parameters becomes a difficult problem. Mao and Chen published a real data set of the lifetime of a certain type of bearings which only contains one failure data. They used a Bayesian method to analyze the data and obtained some results for model parameter estimation. However, in their method the choice of prior distribution will affect heavily the final results. In this paper, we propose a Monte Carlo EM (MCEM) algorithm to estimate reliability model parameters using the Weibull distribution. Based on the same data set of Mao and Chen, we obtain some results using the MCEM algorithm. Our results do not depend on the choice of arbitrary prior distributions.
CHARACTERIZING FAILURE DURATION IN 2-TERMINAL NETWORK PROBLEMS
Authors: SMITH PETER J. , SILBY HOWARD W. , HAYAKAWA YU , CARLISLE CHRIS
Published: May 2003

To characterize the "reliability" or "robustness" of a network, more information is required than simply the system failure rate. In particular the length of the downtimes can be of great relevance. Hence, in this paper we present two methods for computing the system downtime distribution in 2-terminal network problems. The first method is an importance sampling simulation which allows simulations to capture the tail of the distribution with much greater precision than simple Monte Carlo methods. Hence the statistics of unusually long failures can be investigated by simulation. The second method is an approximate analytical method whereby system failures due to 1 or 2 or … or N component failures are characterized exactly. The error in using N=2 and neglecting greater than three simultaneous component failures is shown to be negligible in many cases of interest. This method can be extended to handle N>2 component failures but the resulting calculations escalate rather quickly and are omitted here. This technique makes it possible to provide approximate failure time distributions very rapidly for arbitrary networks.
ON THE LIKELIHOOD FUNCTION FOR THE THREE PARAMETER BURR XII DISTRIBUTION
Authors: WATKINS A. J.
Published: May 2003

This paper considers the three parameter Burr XII distribution and its likelihood function. We first review a link between this distribution and the two parameter Weibull distribution, in which the latter emerges as a limiting case of the former. Examples of the likelihood function for the three parameter Burr XII distribution are then used to suggest a reparameterization of this distribution. Analysis of the derivatives of the reparameterized likelihood then leads to a test statistic, indicating whether the Burr XII distribution provides an improved fit over its limiting counterpart. We conclude with some computational considerations, and a brief discussion of the practical implications of our work.
HOW TO MONITOR CAPABILITY INDEX CM USING EWMA
Authors: CASTAGLIOLA PHILIPPE
Published: May 2003

This article demonstrates how a two parameter logarithm transformation associated with an EWMA type approach can be used to monitor the machine capability index CM. The computation of the logarithm transformation parameters and the control limits is explained. An easy-to-use table is provided and an illustrative example is given. The performance of the logarithm transformation is discussed in terms of normality.
APPLICATION OF THE TAGUCHI METHOD TO IMPROVE THE PROCESS YIELD RATE FOR AIR CLEANERS IN TOYOTA CORONA VEHICLES
Authors: JHANG JHY-PING , CHAN HSIAO-LING
Published: May 2003

The major purposes of this research are to improve the process yield rate for air cleaners in Toyota Corona vehicles and to find the robust parameters of this process by using the Taguchi method and design for the experiments. Furthermore, in order to reduce the scrap cost, improve the quality of plastic injection and decrease environmental pollution, we aim to reduce the occurrence of nonconformities and increase the use of recycled material.

Within the analysis of the injection mold, we would like to study the correlation between injecting conditions and nonconformities by using the orthogonal table of L18. Based on the results of the S/N ratio, ANOVA, and response surface methods, we have given suggestions for the optimal conditions for the specifications of the parameters and the standard of the process. Moreover, the results of this research can be applied to other products.

Finally, we expect to develop software which can apply the Taguchi methodology and is user friendly for both suppliers and users of video instruction. Furthermore, the Taguchi method will be generally applied to other component processing methods involving other vehicles.
A STOCHASTIC MODEL FOR HYBRID MAINTENANCE POLICIES EVALUATION AND OPTIMIZATION
Authors: CASTANIER BRUNO , GRALL ANTOINE , BÉRENGUER CHRISTOPHE
Published: May 2003

We propose a hybrid maintenance policy which combines periodic (age-based or time-based) regulation-based inspections with aperiodic condition-based inspection/replacements for a stochastically and gradually deteriorating system. The stationary laws of the deterioration state of the maintained system are derived in order to evaluate the long-run average running cost on an infinite span generated by the proposed combined policy. A computable expression of the average cost is established using the regenerative or semi-regenerative properties of the stochastic process describing the maintained system state. The behavior of the proposed maintenance is illustrated through numerical experiments and it is shown that the cost incurred by the optimized combined policy is lower than the cost generated by the regulation-based maintenance alone.
AVAILABILITY OF AN INTERMITTENTLY REQUIRED SYSTEM: APPLICATION TO A FOSSIL FUEL POWER PLANT
Authors: BOUISSOU MARC , LEFEBVRE YANNICK
Published: May 2003

Electricité de France produces about 75% of its electricity with nuclear power plants. Some hydraulic plants and most fossil fuel power plants are used to pass electricity consumption peaks. Therefore these facilities are required only intermittently. For such systems, a breakdown does not result in a production loss during a standby period. This particular feature is not taken into account by conventional availability evaluation methods. The objective of this paper is to introduce a definition of availability which holds in such a context, and to describe a mathematical method suited to the calculation of this new definition of availability.
A SPECIFICATION-BASED COVERAGE METRIC TO EVALUATE TEST SETS
Authors: AMMANN PAUL E. , BLACK PAUL E.
Published: May 2003

Software developers use a variety of formal and informal methods, including testing, to argue that their systems are suitable for building high assurance applications. In this paper, we develop another connection between formal methods and testing by defining a specification-based coverage metric to evaluate test sets. Formal methods in the form of a model checker supply the necessary automation to make the metric practical. The metric gives the software developer assurance that a given test set is sufficiently sensitive to the structure of an application's specification. We also develop the necessary foundation for the metric and then illustrate the metric on an example.
ANALYZING THE REAL-TIME PROPERTIES OF A U.S. NAVY SIGNAL PROCESSING SYSTEM
Authors: GODDARD STEVE , JEFFAY KEVIN
Published: May 2003

The state of the art in verifying the real-time requirements of applications developed using general processing graph models relies on simulation or off-line scheduling. We extend the state of the art by presenting analytical methods that support the analysis of cyclic processing graphs executed with on-line schedulers. We show that it is possible to compute the latency inherent in a processing graph independent of the hardware hosting the application. We also show how to compute the real-time execution rate of each node in the graph. Using the execution rate of each node and the time it takes per execution on a given processor, the resulting CPU utilization can be computed, as shown here for the Directed Low Frequency Analysis and Recording (DIFAR) acoustic signal processing application from the Airborne Low Frequency Sonar (ALFS) system of the SH-60B LAMPS MK III anti-submarine helicopter.
THE AMARANTH FRAMEWORK: POLICY-BASED QUALITY OF SERVICE MANAGEMENT FOR HIGH-ASSURANCE COMPUTING
Authors: HOOVER CAROL L. , HANSEN JEFFERY , KOOPMAN PHILIP , TAMBOLI SANDEEP
Published: May 2003

System resource management for high-assurance applications such as the command and control of a battle group is a complex problem. These applications often require guaranteed computing services that must satisfy both hard and soft deadlines. Over time, their resource demands can also vary significantly with bursts of high activity amidst periods of inactivity. A traditional solution has been to dedicate resources to critical application tasks and to share resources among non-critical tasks. With the increasing complexity of high-assurance applications and the need to reduce system costs, dedicating resources is not a satisfactory solution. The Amaranth Project at Carnegie Mellon is researching and developing a framework for allocating shared resources to support multiple quality of service (QoS) dimensions and to provide probabilistic assurances of service. This paper is an overview of the Amaranth framework for policy-based QoS management, the current results from applying the framework, and the future research directions for the Amaranth project.
A FRAMEWORK FOR A CRYPTOGRAPHIC PROTOCOL EVALUATION WORKBENCH
Authors: YASINSAC ALEC , WULF WILLIAM A.
Published: May 2003

Tools to evaluate Cryptographic Protocols (CPs) exploded into the literature after development of BAN Logic.2,3 Many of these were created to repair weaknesses in BAN Logic. Unfortunately, these tools are all complex and difficult to implement individually, with little or no effort available to implement multiple tools in a workbench environment. We propose a framework that allows a protocol analyst to exercise multiple CP evaluation tools in a single environment. Moreover, this environment exhibits characteristics that will enhance the effectiveness of the CP evaluation methods themselves.
A NONBLOCKING ATOMIC TRANSACTION PROCESSING ALGORITHM WITH REAL-TIME PROPERTY
Authors: YEN I-LING , DAI LIRONG , CHEN BIAO , CHEN ING-RAY
Published: May 2003

Many multiple server systems are now being used for heavily accessed web services. Performance, availability, and real-time transaction processing are important requirements for many of these applications. In this paper, we apply the multi-invariant data structure (MIDS) concept to develop an atomic transaction processing algorithm. We show that our algorithm achieves non-blocking property. It also allows preemption at any point of transaction processing without suffering from inconsistency problems or high recovery costs. Thus, the algorithm is suitable for real-time transaction processing systems. Preliminary performance study results show that our algorithm incurs almost no overhead compared with two phase commit protocol.
FAILURE MODES IN MEDICAL DEVICE SOFTWARE: AN ANALYSIS OF 15 YEARS OF RECALL DATA
Authors: WALLACE DOLORES R. , KUHN D. RICHARD
Published: May 2003

Most complex systems today contain software, and systems failures activated by software faults can provide lessons for software development practices and software quality assurance. This paper presents an analysis of software-related failures of medical devices that caused no death or injury but led to recalls by the manufacturers. The analysis categorizes the failures by their symptoms and faults, and discusses methods of preventing and detecting faults in each category. The nature of the faults provides lessons about the value of generally accepted quality practices for prevention and detection methods applied prior to system release. It also provides some insight into the need for formal requirements specification and for improved testing of complex hardware-software systems.
SIMULTANEOUS SCAPHOID AND GALEAZZI FRACTURES
Authors: Stahl Shalom , Freiman Shay
Published: May 2003

Among wrist injuries, scaphoid fractures are second only in number to fractures of the distal radius, while Galeazzi fractures are relatively infrequent. It is rare for the two fractures to occur concomitantly. We report such a case in a 65-year-old woman.
ANATOMICAL STUDY OF THE DISTAL RADIOULNAR JOINT: DEGENERATIVE CHANGES AND MORPHOLOGICAL MEASUREMENT
Authors: Yoshida Ryo , Beppu Moroe , Ishii Syoji , Hirata Kazuaki
Published: May 2003

A study of the degenerative changes in the distal radioulnar joint compared with morphological measurement of that joint using 91 joints of the hand from 51 systemic anatomy cadavers was conducted. X-ray images of the joints of the hand were taken followed by measurement of radial inclination, ulnar variance, volar tilt, sigmoid notch inclination and ulnar seat inclination. Macroscopic observations of the ulnar notch of the radius and surface of the distal radioulnar joint of the ulnar head were made by dividing them into six and nine areas, respectively. These were then used to classify the degree of cartilage degeneration. In addition, the status of the triangular fibrocartilage complex (TFCC) was also observed.

Arthropathic changes of the distal radioulnar joint were associated with factors including TFC degeneration and UV(+), SNI(-) and USI(+).
DISI DEFORMITY AND POST-OPERATIVE SYMPTOMS OF SCAPHOID NON-UNION
Authors: Wada T. , Aoki M. , Usui M. , Ishii S.
Published: May 2003

The correlation between the residual dorsal intercalated segmental instability (DISI) deformity and symptoms of the wrist was investigated in 20 patients with healed scaphoid non-union who had open reduction and bone grafting. In seven patients, inlay corticocancellous bone grafting (modified Russe procedure) was performed. In four of the seven patients, an additional Herbert bone screw was used for internal fixation. The remaining 13 patients were treated with open reduction, anterior bone grafting, and internal fixation with Herbert bone screw. Average duration of follow-up period after operation was 20 months (range, 6 to 57 months). The average extension-flexion arc of the injured wrists was 129°, which was 31° less than that of the uninjured wrists. The average grip strength of the injured wrists was 89% of that of the uninjured wrist. Before the operation, all 20 patients were symptomatic and complained of wrist pains. Post-operatively, three patients experienced mild pains and only one complained of moderate wrist pains. Post-operative radiolunate angle ranged from 0° to 34° (average 10°). DISI deformity remained uncorrected in eight patients. Post-operative symptoms were compared amongst the eight patients who had DISI deformity and 12 patients who had no deformity. There was no significant difference in range of motion, grip strength, and incidence of pain between these two groups of patients. The presence of DISI deformity after bone grafting for a symptomatic scaphoid non-union was not predictive of post-operative symptoms of the wrist.
NONLINEAR OPTICAL RESPONSE OF CYANOBIPHENYL LIQUID CRYSTALS TO HIGH-POWER, NANOSECOND LASER RADIATION
Authors: LUKISHOVA SVETLANA G.
Published: May 2003

Results from investigations are summarized into: (1) transient refractive and absorptive (two-photon) nonlinearities at 0.532 μm by the Z-scan method, and (2) reflective nonlinearity in the near-IR, of linearly nonabsorbing cyanobiphenyl liquid crystals under nanosecond laser irradiation.

(1) For isotropic liquid crystals at the several-nanosecond time scale and several tens-micrometers beam-waist-diameter, transient molecular-reorientation and thermal/density refractive nonlinearities compete in changing the sign of the total transient refractive nonlinearity. For the different, given pulse durations, the influence of coupled thermal and density effects on nonlinear refraction depends, through buildup time, on the beam-waist diameter. Nonlinear absorption coefficients depend on the incident intensity. For planar nematic layers, cumulative effects in heating (and in refractive nonlinearity) were observed even at low, 2–10 Hz pulse repetition rate. These results are useful for optical power limiting applications, and for intensity and beam-quality sensors of pulsed, high-power lasers.

(2) Reflective nonlinearity of chiral-nematic (cholesteric) mirrors near selective reflection conditions for circular polarized light at λ=1.064 μm was studied both under free space irradiation and inside a laser resonator. Specially chosen experimental irradiation conditions make it possible to attribute the observed changing of reflectivity to athermal helix unwinding by the optical field. The results can find applications in laser-resonator mirrors, Q-switches and soft apertures for beam-profile formation, and also in showing the limits of use cholesteric optical elements in high-power laser beams.
LIMITING DYNAMICS OF C60 IN SOLID MATRICES
Authors: SCHELL J. , LÉVY R. , HÖNERLAGE B.
Published: May 2003

We study the limiting dynamics of C 60-doped porous sol-gel glasses by single- and double-pulse pump-probe experiments. We find that, contrary to crystalline films of C60, reverse saturable absorption (RSA) of these solid samples can be described by a 5-level model developed for C 60-solutions. We observe an ultrafast rise time, a large transmission-decrease at high fluence, a shortened singlet-state lifetime as compared to solutions, but nevertheless an important triplet yield. We explain differences with respect to solutions by the absence of stabilizing aromatic solvents and by the interaction of the amorphous environment with the molecules, broadening considerably the spectral features of RSA.
INVESTIGATION ON NONLINEAR TRANSMISSION PROPERTY OF EXCITED STATE PROTON TRANSFER MOLECULE 2-(2′-HYDROXYPHENYL)BENZOXAZOLE
Authors: XIAO DONG , ZHANG GUILAN , WANG HAIYAN , TANG GUOQING , CHEN WENJU
Published: May 2003

Nonlinear transmission property of excited state proton transfer molecule 2-(2′-hydroxyphenyl)benzoxazole was investigated at 355 nm and 532 nm using picosecond laser pulses. The experiment result shows that the transmissivity of 2-(2′-hydroxyphenyl)benzoxazole is nonlinear at 355 nm but it is linear at 532 nm. The nonlinear transmissivity of 2-(2′-hydroxyphenyl)benzoxazole originates from the larger nonlinearity of tautomer formed in excited state proton transfer process. Therefore 2-(2′-hydroxyphenyl)benzoxazole might be used as ultrafast optical amplitude limit material.
NONLINEAR SCATTERING ORIGIN IN CARBON NANOTUBE SUSPENSIONS
Authors: VIVIEN L. , RIEHL D. , HACHE F. , ANGLARET E.
Published: May 2003

In order to determine the origin of optical limiting in singlewall carbon nanotube (SWNT) suspensions, we carried out Z-scan and pump-probe experiments at 532 nm and 1064 nm, for different input energies. We evidenced strong nonlinear scattering due to heat transfer from the carbon nanotubes to solvent which induced solvent bubble growth and a nonlinear refractive effect. We noticed similar comportment at 1064 nm and at 532 nm, but with a lower bubble growth threshold at 532 nm. At the microsecond timescale, we evidenced cavitation bubbles. We also evidenced, via emission studies, a phase change corresponding to optical limiting threshold, which we associated to carbon nanotube sublimation. Optical limiting performances of water and chloroform suspensions were compared and solvent effects are discussed.
OPTICAL LIMITING AND RELATED UPCONVERTED EMISSION IN FULLERENE COMPLEX
Authors: DOU KAI , KNOBBE EDWARD T.
Published: May 2003

Optical limiting and related upconverted emission were reported in fullerene complex C60[W(CO)3diphos] in toluene solutions at various excitation wavelengths. Upconverted emission associated with the upper-lying excited states was found in both fullerene and its complex. The results indicated that C60[W(CO)3diphos] showed a good optical limiting performance in the visible spectral range.
OPTICAL LIMITING WITH CARBON SUSPENSIONS AT SELECTED WAVELENGTHS AND PULSE LENGTHS
Authors: VINCENT DENIS
Published: May 2003

High-performance liquid suspensions of fine carbon particles have been developed at DREV over the last 10 years to fulfil requirements regarding eye protection against laser radiation over a wide range of wavelengths and pulse lengths. This paper reports on the single-pulse characteristics of DREV's best limiting suspension named CBS-100 at wavelengths of 532, 751 and 1064 nm, and at pulse lengths of 0.01, 0.1, 1 and 100 μs. Some results at higher repetition rate (6 pps) and a comparison with recent retinal damage threshold data are included also.
NANOMATERIALS AS OPTICAL LIMITERS
Authors: SUN YA-PING , RIGGS JASON E. , HENBEST KEVIN B. , MARTIN ROBERT B.
Published: May 2003

Optical limiters based on several different classes of nanomaterials are reviewed. The systems under consideration include metal and semiconductor nanoparticles and nanoscale carbon materials. For the latter, the optical limiting properties of carbon nanoparticles, fullerenes, and suspended and solubilized carbon nanotubes are summarized and compared. Mechanistic implications of the available experimental results are discussed in terms of the comparison between nonlinear scattering versus nonlinear absorption as the dominating optical limiting mechanism for different nanomaterials and for different physico-chemical states of a nanomaterial.
NONLINEAR OPTICAL LIMITERS WITH GRATING SANDWICH STRUCTURE FOR EYE PROTECTION
Authors: LI CHUNFEI , WANG RUIBO , LIU HUA-KUANG
Published: May 2003

A novel optical limiting device by sandwiching a nonlinear liquid between two specially designed diffraction gratings is proposed and demonstrated. Under low intensity of light, the device has a high transmittance because of index matching between the liquid and grating materials. Strong light beam can induce the nonlinear effects such as reverse saturable absorption, nonlinear scattering and self-defocusing to reduce the transmittance of device. On the other hand, the strong light beam can also change the index of the liquid to induce index mismatch and reactivate the gratings to diffract the output light away from the observed direction to protect eyes. In this paper, the different gratings with suppressed zero-order diffraction and nonlinear liquids are analyzed. The new device provides an effective protection of eyes against the ns-pulsed laser in the visible range.
PHOTOGENERATION OF HIGHLY ABSORBING TRANSIENT CHARGE STATES FROM MODEL DENDRITIC MACROMOLECULES BASED ON BIS-(DIPHENYLAMINO)DIPHENYLPOLYENE REPEAT UNITS
Authors: HYFIELD AMY , SONNENBERG WENDI , HAN YANONG , SPANGLER LEE H. , ELANDALOUSSI El HADJ , SPANGLER CHARLES W.
Published: May 2003

Bis-(diphenylamino)diphenylpolyenes form exceptionally stable, highly absorbing, bipolaronic charge states when oxidatively doped in solution, even at the stilbene level. These chromophores also display exceptionally large two-photon absorption cross-sections for ns laser pulses. 1,2-Bis-(diphenylamino)-E-stilbene moieties have now been incorporated into 3-arm and four-arm dendrimer structures as formal repeat units. These new G-0 model dendrimers also form exceptionally stable, highly-absorbing bipolaronic charge states when oxidized in solution. As such these new materials are attractive candidates for various photonic applications which depend on the fast photogeneration of highly absorbing transient states. In the current study we have demonstrated that such states can indeed be photogenerated from the model dendrimers in solution in the presence of efficient electron acceptors, such as C 60. In order to follow both the generation and decay of these excited state transient species, new spectroscopic techniques have been developed that have unique capabilities for examining transient state formation and subsequent dynamics.
THE NONLINEAR OPTICAL CHARACTERIZATION OF MESO-SUBSTITUTED PORPHYRIN DYES
Authors: McEWAN K. J. , BOURHILL G. , ROBERTSON J. M. , ANDERSON H. L.
Published: May 2003

Nine structurally related porphyrins are studied and it is shown how the material parameters that control the optical limiting depend on the molecular structure. Optical limiting measurements at 532 nm on the metal-free, zinc and lead analogues of tetraphenyl porphyrin (TPP), tetra(trimethylsilyethynyl) porphyrin (TTMSAP) and tetra(4-n-butylphenylethynyl) porphyrin (TNBBAP) reveal a strong dependence on the metal atom and peripheral substitution. A double pump/cw probe technique is used to measure the material parameters that control the optical limiting and the results give a strong insight into how the molecular structure influences the individual parameters. These measurements revealed that one of the materials TTMSAP(Pb) has a σex/σgr ratio of ~45 at 532 nm, which is one of the largest values ever reported. Finally, broadband measurements with a picosecond white-light source show that the position and strength of the excited state absorption features also depend strongly on the porphyrin design.
A TRANSIENT, THREE-DIMENSIONAL MODEL OF STIMULATED BRILLOUIN SCATTERING
Authors: AFSHAARVAHID SHAHRAAM , MUNCH JESPER
Published: May 2003

An efficient numerical 3-D model of transient stimulated Brillouin scattering (SBS) is reported. The model is used to examine the effects of transient phenomena on the efficiency of phase conjugation by SBS and the mode structure of the Stokes and pump pulse inside the SBS cell. The effect of parameters such as phonon lifetime, input pulse shape and input energy on the transient fidelity of SBS is investigated. A new transient phenomenon which causes SBS fidelity degradation at high focal intensity (short Rayleigh range) is examined.
PHASE CONJUGATE MIRRORS
Authors: EICHLER HANS J. , MEHL OLIVER
Published: May 2003

Phase conjugate mirrors are attractive devices to improve the beam quality of lasers. At first, the fundamental properties of phase conjugate mirrors (PCMs) are summarized and a basic mathematical description is given. Degenerate four-wave mixing (DFWM) facilitates phase conjugation of weak signals and their amplification at the same time, but requires additional pumping beams. In contrast, self pumped phase conjugation is achieved by stimulated Brillouin scattering (SBS) in appropriate media. Liquids and gases of high purity as well as solid materials like silica fibers can be used with high efficiency. Solid-state laser systems with average output powers up to 500 W have been equipped with SBS phase conjugate mirrors to compensate for phase distortions in active media.
CROSSTALK BY NONLINEAR GRATING COMBINATIONS IN PHOTOREFRACTIVE HOLOGRAMS COMPUTED DIRECTLY FROM THE BAND-TRANSPORT MODEL
Authors: BUCHHAVE PREBEN
Published: May 2003

The crosstalk between two photorefractive holograms caused by nonlinear grating interactions is computed directly from the band-transport equations without using an empirical reduction factor to describe the difference between the modulation index of the impressed intensity grating and the resulting free carrier modulation. The long period grating modulation resulting from the interference between closely spaced object beams cannot write a holographic grating, but is treated as a local modulation of the high frequency part of the grating. The method can be applied as long as the low frequency envelope does not in itself write a photorefractive grating. With this limitation the method can be used for arbitrary values of modulation indices and beam ratios where the simple band-transport equations apply.
OPTICAL NONLINEARITY VIA PHONONS AS AN INTERMEDIARY
Authors: FA OU , MINGGAO HE , FUGEN WU
Published: May 2003

A new model to describe the origin of optical nonlinearity is presented. In this model, the interaction between light and medium is reduced to the coupling of photons with phonons, which occurs in the crystal lattice vibrating anharmonically. Then the optical nonlinearity originates from the nonlinear photon–phonon coupling or the interaction among phonons themselves. In this paper, more attention is drawn to the latter. By the given model, (1) degenerate and (2) nondegenerate parametric oscillations, (3) Stokes and (4) anti-Stokes Raman scattering, (5) sum-frequency and (6) second harmonic generation and (7) two-photon absorption are dealt with systematically and quantum-mechanically. The results of theoretical analysis show that the effects (1)–(4) are associated with threshold phenomenon, whereas the effects (5)–(7) with the saturation phenomenon.
GAUSSIAN BEAM PROPAGATION IN d-DIMENSIONAL CUBIC-QUINTIC NONLINEAR MEDIUM
Authors: JOVANOSKI ZLATKO
Published: May 2003

The variational approach has been applied to study the propagation of Gaussian beams in a medium with d-transverse dimensions and a cubic-quintic nonlinearity. We find implicit conditions for the steady-state propagation and determine the stability of steady-state solutions to symmetric perturbations. In some parameter regime the stationary beam is stable and leads to the formation of light-bullets. We have also investigated the evolution of an initial Gaussian beam with finite radius of curvature into a steady-state beam. The results of the variational approach are congruous with recent numerical simulations.
HIGH-ORDER CORRECTIONS FOR THE ELECTRON CAPTURE AND ACCELERATION BY AN ULTRAINTENSE GAUSSIAN LASER BEAM
Authors: KONG Q. , HO Y. K. , WANG P. X. , YUAN X. Q. , CAO N. , WANG J. X. , SCHEID S.
Published: May 2003

By means of 3D test particle simulation programs, the effect caused by the high-order corrections of Gaussian laser fields on the electron dynamics in a stationary ultraintense laser beam is examined. In this letter, special attention is given to the studying of the capture phenomenon (J. X. Wang et al., Phys. Rev.E58, 6575 (1998)), which shows interesting prospect making it to become a viable mechanism for laser-driven GeV electron accelerators without media involved. It was found that as w0≥50, where w0 is the beam width at the focus center, the paraxial approximation field (PAF) is good enough for reproducing all the electron dynamic characteristics, not only in qualitative detail, but also in quantitative detail.
PROBING ALIGNMENT OF LIQUID CRYSTALS ON SILANE DERIVATIVES BY SECOND HARMONIC GENERATION
Authors: SORIA S. , SCHUHMACHER D. , MAROWSKY G. , BARBERI R. , CIUCHI F. , PAUS S. , RASING T.
Published: May 2003

We studied surface second-harmonic generation from thin films of 4'-n-pentyl-4-cyano-biphenyl (5CB) nematic liquid crystal (NLC) deposited onto layers of several silanes dipped on conductive glasses. We also studied a new liquid crystalline polymer deposited onto silanized substrates. The cinnamoyl side groups of this polymer can be aligned by linearly polarized UV light. The average orientation and surface order of the nematic were determined by Fourier analysis of the reflected and transmitted angular dependent second harmonic signal. The aim was to check the possible use of these materials as a control layer for the anchoring properties of nematics.
ON THE SWING EFFECT OF SPATIAL INHOMOGENEOUS NLS SOLITONS
Authors: SURYANTO A. , VAN GROESEN E.
Published: May 2003

In this paper, we consider the propagation of a spatial soliton in a waveguide with triangular linear refractive index profile. We propose a model that is obtained by starting with a small perturbation of the constant linear refractive index in the displacement vector of the Maxwell equation, and then deriving the NLS equation for this case. Using this model it is shown, both analytically and numerically, that the soliton beam oscillates inside the waveguide. This is as expected, but differs from the model found in the literature in which the inhomogeneity is introduced directly in the standard NLS equation. Finally, the proposed model is used to study the breakup of bound N-soliton in a triangular waveguide.
INTEGRATED OPTICAL HETERODYNE INTERFEROMETER IN LITHIUM NIOBATE
Authors: RUBIYANTO A. , HERRMANN H. , RICKEN R. , TIAN F. , SOHLER W.
Published: May 2003

A high performance integrated acousto-optical heterodyne interferometer has been developed for vibration measurement. All components including an acousto-optical TE–TM mode converters, two electro-optical TE–TM converters, two polarization splitters and two phase shifters are integrated on a X-cut Lithium Niobate substrate. The fully packaged optical integrated circuit (optical-IC) coupling with three fibers optics pigtails gave a signal-to-noise ratio of 69 dB with at 3 kHz bandwidth by using a commercial DFB laser diode as a light source with 1561 nm emission wavelength and a PIN-FET balanced receiver.
REFRACTIVE INDEX PROFILE RECONSTRUCTION OF PLANAR WAVEGUIDE FROM ITS MODE INTENSITY USING CHARACTERISTIC MATRIX METHOD
Authors: URANUS HENRI P. , TJIA M. O.
Published: May 2003

A method is proposed for the reconstruction of refractive index profile of planar waveguide from its fundamental mode intensity profile. The reconstruction is performed by fitting the calculated intensity distribution iteratively with the measured intensity distribution employing nonlinear least-squares regression technique. At each stage of iteration, new trial parameter values are generated and used to form a waveguide model approximated by a multilayer structure with stepwise index distribution, upon which the intensity distribution is then calculated by using the characteristic matrix technique. This method was numerically examined by using samples of either known or unknown analytic expression of the index profile.
OPTICAL FIBER SENSING OF SF6 DEGRADATION IN HIGH-VOLTAGE SWITCHGEAR
Authors: IRAWAN R. , SCELSI G. B. , WOOLSEY G. A.
Published: May 2003

Sulphur hexafluoride ( SF 6) is used as an insulator in high-voltage systems. An electrical breakdown dissociates ( SF 6). Therefore, the insulating efficiency is degraded. If the ( SF 6) is not renewed, failure of the system can occur. A monitoring device for ( SF 6) loss is required, and an optical fiber sensor for continuous monitoring of ( SF 6) degradation in high-voltage switchgear has been developed. Dissociation products of the ( SF 6) discharge include HF and atomic F, both of which react readily with silica. This reactivity is utilized in our sensor, where etching of a glass fiber surface modifies the transmission characteristics of the fiber.
QUADRATIC SIMULTONS IN LINEAR AND NONLINEAR PHOTONIC BANDGAPS
Authors: ASSANTO GAETANO , CONTI CLAUDIO , TRILLO STEFANO
Published: May 2003

Energy localization and Bragg solitons can be sustained by the interplay of distributed feedback and quadratic nonlinearity. With reference to second harmonic generation, we review the main features of slowly-moving and stationary two-color solitons or simultons both in singly and doubly resonant structures, and discuss their experimental feasibility and potential applications. Finally, with reference to the case of purely nonlinear feedback through short-period quasi-phase-matching, we show that cavityless parametric oscillations can occur in the presence of gain.
NONLINEAR WAVEGUIDES FOR OPTICAL LOGIC AND COMPUTATION
Authors: PRAMONO YONO HADI
Published: May 2003

Optical logic gates for OR-AND-NOT, NOR and exclusive-XNOR operations in waveguides consisting of nonlinear material are numerically investigated by means of FD-BPM (Finite Difference Beam Propagation Method). The proposed devices are designed utilizing the self-routing characteristics of nonlinear X-crossing and Y-branching structures when they are operated with one input beam or two. The numerical simulations show that the proposed structures can favorably be applied to optical data processing and computing as fundamental logic gates.
BRIGHT AND DARK SOLITARY WAVES IN KERR MEDIUM WITH HIGHER ORDER LINEAR AND NONLINEAR DISPERSIONS
Authors: ALATAS H. , ISKANDAR A. A. , TJIA M. O.
Published: May 2003

The existence of both bright and dark solitary wave solutions has been demonstrated for higher order nonlinear Schrödinger (HNLS) equation containing up to the fourth order linear and the second order nonlinear dispersion. We found that the solutions are completely characterized by the material properties and free from arbitrary parameters in contrast to solutions of the pure NLS equation. The two types of solution were further shown to have complementary parameter space and share a singularity line of asymptotic values ±∞ for the solitary envelope velocities.
A STUDY OF NONLINEAR COUPLING BETWEEN TWO IDENTICAL PLANAR WAVEGUIDES
Authors: HARSOYONO H. , SIREGAR R. E. , TJIA M. O.
Published: May 2003

A study of coupling characteristics between two optically nonlinear planar waveguides has been performed in terms of their individual analytic solutions. It is shown that with an appropriate choice of guide separation and proper redefinition of effective propagation constants, the commonly adopted dual waveguide coupled equations can be formally retained even when the optical nonlinearity in each guide is fully taken into account. The coupling coefficients are determined explicitly in terms of the individual mode fields and the associated intensity-dependent effective index of refraction. A specific numeric illustration of the power flow pattern was given on the basis of its analytical expression derived from the coupled equations. The result describes the detailed coupling characteristics and its variation with respect to input optical power, demonstrating its viability for active optical device applications.
DEVELOPMENT OF NEW NLO BORATE CRYSTALS
Authors: SASAKI TAKATOMO , MORI YUSUKE , YOSHIMURA MASASHI
Published: May 2003

Interests in the use of borate crystals in ultraviolet nonlinear optics have increased because all-solid-state UV lasers obtained with NLO crystals are in highly demand for scientific and industrial applications. Recently, new borate crystals, CsLiB 6 O 10 and Gd x Y 1-x Ca 4 O ( BO 3)3 have been developed by the present authors. CsLiB 6 O 10 is for fourth- and fifth-harmonic generations of Nd:YAG laser, Gd x Y 1-x Ca 4 O ( BO 3)3 for third-harmonic generation. This paper reviews the growth and nonlinear optical properties of these new borate crystals and the progress in UV light generation.
STIMULATED BRILLOUIN SCATTERING IN n-TYPE III–V PIEZOELECTRIC SEMICONDUCTORS
Authors: GUPTA PRADEEP K. , SEN PRANAY K.
Published: May 2003

Based upon the hydrodynamic model of an one-component semiconductor plasma, a detailed analytical study of stimulated Brillouin scattering (SBS) processes in a doped weakly piezoelectric semiconductor has been made following the coupled mode approach. The nonlinear effective polarization and the corresponding third-order optical susceptibility at Stokes frequency for the SBS processes are obtained. The analysis deals with the qualitative behavior of threshold pump electric field required for the onset of SBS and the Brillouin gain with respect to the doping concentration well above threshold. Numerical analysis has been made for n-type InSb crystal duly irradiated by a nanosecond pulsed 10.6 μm CO 2 laser. The influence of piezoelectric properties of the crystal medium on both threshold pump field and Brillouin gain has been explored and it is found that SBS with significant gain at lower threshold pump field could be achieved in the weakly piezoelectric moderately doped n-type semiconductor. The Brillouin gain is noted to be significantly large only over a very narrow doping range. The theoretical analysis shows that the doped III–V semiconductors have a good potentiality in the fabrication of SBS based phase conjugate mirrors with high reflectivity well below the optical damage threshold.
CUSP SOLITONS IN THE CUBIC QUINTIC NONLINEAR SCHRÖDINGER EQUATION
Authors: PALACIOS S. L.
Published: May 2003

A new set of soliton solutions for the cubic quintic nonlinear Schrödinger (CQNLS) equation is found. When particular cases are analyzed the conventional hyperbolic secant solitons of the NLS and CQNLS equations are obtained.
PHONON EXCITATION IN STIMULATED BRILLOUIN SCATTERING
Authors: HSU HSIUNG , LI TONG-NING , XU YUE
Published: May 2003

Stimulated Brillouin Scattering (SBS) is an example of traveling wave parametric interaction involving photons and phonons. When one of the interacting waves is a backward traveling wave, which yields spatial nonlinear distributed regeneration covering the entire medium, the system exhibits a typical backward traveling wave parametric interaction. It may oscillate with a distinct threshold. The generation of backward traveling light becomes known as optical phase conjugation. In this paper, both pulsed and continuous wave modes of phonon excitations for SBS are described.
EFFECT OF SOLVENT ON NONLINEAR REFRACTION INDEX OF 7-HYDROXYQUINOLINE
Authors: ZHANG GUILAN , XIAO DONG , ZHAO CHUNLIU , TANG GUOQING , CHEN WENJU
Published: May 2003

Nonlinear refraction index n2 of 7-hydroxyquinoline in different solvents was measured using Z-scan techniques with picosecond laser pulse. The effect of solvent on the nonlinear refraction index n2 of 7-hydroxyquinoline was investigated. The origination of this effect was due to the interaction between 7-hydroxyquinoline and the solvent molecules via H-bond.
INTERSUBBAND TRANSITIONS IN DOPED AND UNDOPED QUANTUM WELL STRUCTURES OF In0.53Ga0.47As/In0.52Al0.48As
Authors: TAKAHASHI YUTAKA , KAWAZOE TADASHI , KAWAGUCHI HITOSHI , KAWAMURA YUICHI
Published: May 2003

We have successfully observed the intersubband absorption in doped as well as in undoped, unstrained quantum well structures of In0.53Ga0.47As/In0.52Al0.48As . The absorption is well resolved near the short-wavelength limit in this structure. Within the accuracy of our measurements, the intersubband transition is observed only in TM mode polarizations in both doped and undoped structures.
STRUCTURAL ASPECTS OF KMg1/3Nb2/3PO5 (KMNP), A KTP ANALOGUE — RAMAN AND FTIR SPECTROSCOPIC STUDY
Authors: BUSHIRI M. J. , NAYAR V. U.
Published: May 2003

Raman and FTIR spectra of KMg1/3Nb2/3PO5 (KMNP) crystal are recorded. The observed bands are assigned mainly in terms of vibrations of NbO6 octahedra and PO4 tetrahedra. The NbO6 octahedra in the crystal are distorted. Corner shared octahedra are present in the KMNP structure. The intense ν1 band at 890 cm-1 in the Raman spectra indicates an ordering in the crystal. The TiO6 octahedra in KTP crystal are more distorted than those of NbO6 octahedra in KMNP. The presence of Mg ions disrupts Nb–O–Nb chains leading to a distortion of NbO6 octahedra different from that of TiO6 . The PO4 tetrahedra in the crystal are linearly distorted. No structural phase transition is observed in the crystal when temperature is lowered to 77 K.
OPTICAL GAIN IN AN INHOMOGENEOUS DISTRIBUTION OF CdS QUANTUM DOTS EMBEDDED IN GLASS MATRIX
Authors: BANERJEE SHARMILA , SEN PRATIMA
Published: May 2003

The optical gain spectra of inhomogeneously distributed semiconductor Quantum dots (QDs) embedded in a dielectric matrix has been examined theoretically using density matrix treatment. The expression for the threshold field is required to obtain optical gain. We have examined the role of excitons and biexcitons in gain mechanism and found that the gain arising due to excitonic nonlinearity enhances in presence of biexcitons. A comparison of the optical gain spectra of single quantum dot (SQD) and inhomogeneous distribution of quantum dots (IDQ) shows that the exciton peak in SQD gets red shifted in IDQ while biexciton peak in SQD exhibits a blue shift. A detailed numerical analysis establishes a strong dependence of optical gain on size distribution function and it is found that an increased size distribution width yields larger gain and increased gain bandwidth. The nonlinear gain is also found to increase in a matrix possessing larger dielectric constant.
OPTICAL NONLINEARITY VIA PHONONS AS AN INTERMEDIARY (CONTINUATION) — FOUR-WAVE MIXING AND COHERENT RAMAN PROCESSES
Authors: OU FA , HE MINGGAO , WU FUGEN
Published: May 2003

As a continuation of the work, published in JNOPM 10(1), 65 (2001), in which it is considered that the optical nonlinearity has its origin in multi-phonon processes in the crystalline medium, this paper deals with the optical effects of four-wave mixing and coherent Raman scattering (including first- and higher-order processes), where the phonon modes participating in interaction are more than three.
INVESTIGATION OF THE INFLUENCE OF FINITE APERTURE SIZE ON THE Z-SCAN TRANSMITTANCE CURVE
Authors: LIU XIAODONG , GUO SHENGLI , WANG HUITIAN , MING NAIBEN , HOU LANTIAN
Published: May 2003

For the nonlinear materials, not only the ratio ρ of the imaginary to the real part of the third-order nonlinear susceptibility but also the finite aperture size S exert a great influence upon the appearance of a peak on the Z-scan transmittance curve. This article investigates the ρ dependence of the critical aperture size Sc, which determines whether a transmittance peak occurs or not, and the dependence of the critical value ρc on the parameter S for the thin-sample and low irradiance limits with a Gaussian beam. These results may be applied to the adjustment of experimental conditions at all times and the assessment of the correctness of data analysis. The experiment with CS 2 seeking the critical value Sc has verified above results.
STUDY OF ENERGY TRANSFER IN ORGANIC DYE PAIRS USING THERMAL LENS TECHNIQUE
Authors: KURIAN ACHAMMA , UNNIKRISHNAN K. P. , GOPINATH PRAMOD , NAMPOORI V. P. N. , VALLABHAN C. P. G.
Published: May 2003

It is demonstrated that the dual beam thermal lens technique can be very effectively used for the study of energy transfer processes in organic dye mixtures. The energy transfer rate and critical transfer radius in Rhodamine 6G — Rhodamine B are calculated using this technique. The observed results support Forster type resonance transfer due to long-range dipole–dipole interaction as reported by earlier workers using other techniques.
AN ALTERNATIVE SET OF BRIGHT AND DARK SOLITON SOLUTIONS OF THE NONLINEAR SCHRÖDINGER EQUATION
Authors: PALACIOS S. L.
Published: May 2003

An alternative set of soliton solutions for the nonlinear Schrödinger equation is found. When particular cases are analyzed it is shown that bright picosecond solitons are possible in the normal and anomalous dispersion regions of an optical fibre but dark picosecond solitons can only exist in the normal dispersion regime. Also, pulse peak power and width are determined.
IMPROVEMENT IN FIGURE OF MERIT BY DOPING FOR SQUEEZED STATE GENERATION IN GaAs
Authors: SEN PRATIMA
Published: May 2003

A simplistic theoretical investigation based upon the free electron model of optical nonlinearities has been made to establish the superiority of a doped semiconductor over its intrinsic counterpart in efficient squeezed state generation. Choice of Doping level at a given operating frequency regime has to be carefully choosen to avoid free carrier absorption and scattering losses. The relevant figure of merit is found to favor a doped crystal duly shined by off-resonant low frequency laser as a potential scheme to achieve significant quadrature variance. Numerical calculations have been made for GaAs sample irradiated with 10.6 μm pulsed CO 2 laser of intensity ~ 1.6 × 102 GW/m 2.
A NEW OPTICAL WAVEGUIDE FOR TELECOMMUNICATION APPLICATION
Authors: SHARMA SUDHIR KUMAR
Published: May 2003

Conducting polymer is a physical mixture of non-conducting polymer with electrically conducting material. Polyaniline is a class of conducting polymers that exists in four different forms depending on protonation and doping of the base. Starting with aniline, polyaniline is synthesized and doped with two different metals namely iron and aluminum separately. Using these films optical waveguides are fabricated. Their characteristics viz. Refractive index, propagation loss, number of modes etc., are studied using prism coupling technique. The results are discussed.