bluuebunny/crossref_metadata_2025 huggingface dataset:
VEPs Generated by High Rates Pattern Reversal Stimulation
Authors: Van Toi Vo , Jianguo Sun
Published: February 2023

The effect of high modulation rate on pattern reversal visual evoked potentials (VEP) has not been well explored and no general agreement has been reached. Regan (1978) found that patterned VEPs occurred only at low temporal frequencies up to approximately 30 reversals per second (r/s) i.e 15 Hz. After that, the VEPs fall off sharply as frequency increases. By contrast, Tyler et al. (1980) found VEP responses, with signal-to-noise ratios of about 2:1, up to 90 r/s i.e 45 Hz. Moreover, it is recognized that unpatterned flicker stimuli over 60 Hz still elicited VEPs.
Visual Correlates of Vehicle Accidents in Older Drivers
Authors: Sloane Michael E. , Owsley Cynthia , Ball Karlene
Published: February 2023

Older drivers have more accidents and traffic citations and incur more fatalities per miles driven than any other age group [1]. Because driving is a highly visual task, it is important to note that many older adults also tend to have significant deficits in visual function [2]. Yet, despite intuitions that older adults’ impaired vision should be related to an increased risk for accidents, research to date has failed to establish a strong link between vision and driving in the elderly. For example, several large-sample studies [3-6] have found statistically significant correlations between accidents and various vision tests (e.g., static acuity, dynamic acuity, disability glare), but these correlations are so low (accounting for <5% of variance) that they are insignificant from the practical standpoint of identifying older adults at risk for accidents. Johnson & Keltner [7] have reported a large-sample study in which the small subset of drivers with severe visual field loss in both eyes (196 out of 10,000 studied) had accident and conviction rates twice those of the general population. However, no study to date has established a link between driving and the more typical types of visual field loss found in the elderly. Thus it still remains to be determined if there are any visual variables which have a strong and widespread relationship with driving performance in older adults.
Measurement of Pupil Size, Direction of Gaze, and Refractive State by On-Line Analysis of Digitized Video Images
Authors: Schaeffel Frank , Howland Howard C.
Published: February 2023

During infrared photoretinoscopy (see Schaeffel, Farkas and Howland, 1987, and "Topical Meeting on Noninvasive Assessment of the Visual System", Monterey, California, 1986), the refractive state is calculated from the intensity profile of the fundus reflex in the pupils of a subject (Howland, 1985). The size of the pupils can also be easily measured in the video image. And, finally, the direction of gaze can be determined from the relative position of the Purkinje reflex in the pupil. While all three of these parameters are basically accessible to direct measurement in single stored video frames, their temporal properties cannot be recorded.
The Effect of a Topical Beta-Adrenergic Receptor Antagonist on the Dynamics of Steady-State Accommodation
Authors: Owens H , Winn B , Gilmartin B. , Pugh J R
Published: February 2023

Temporal fluctuations in the steady-state human ocular accommodation response are characterised by two principal frequency components: a high frequency component (HFC: 1-2.2Hz) and a low frequency component (LFC:<0.5Hz) (Campbell, Robson and Westheimer, 1959; Kotulak and Schor, 1986; Winn et al, 1989). Recent work has demonstrated that the location of the HFC is significantly correlated with arterial pulse (Winn et al, 1990). These findings have led to the proposal that the HFCs are not governed by an accommodative control system, although they may potentially be utilised in conjunction with the LFCs by a sensory detection system which monitors retinal image contrast during steady-state accommodation. Further, HFCs could provide a useful non-invasive technique for investigating the ocular consequences of arterial pulse (AP).
Non-Invasive Assessment of the Visual System by Magnetic Stimulation
Authors: Marg Elwin
Published: February 2023

Electrical stimulation of nerves can be elicited by a capacitor-discharge magnetic stimulator. The stimulation is painless and non-invasive. The principle of operation is that a magnetic field induces an electric current in the volume conductor of the tissue and triggers the depolarization of the nerve fibers. Magnetostimulation is a safe, convenient and simple method of stimulating the nervous system without pain but with less precision of localization than by electrostimulation with electrodes.
Real-Time Measurement of the Red Blood Cell Column Width of Retinal Vessels
Authors: Milbocker Michael T. , Feke Gilbert T. , Reznichenko Yakov , Goger Douglas G. , Ogasawara Hironobu
Published: February 2023

The diameter of the red blood cell column (RBCC) in retinal vessels is a useful measure of retinal vascular response to physiological perturbations and pathological conditions. A modular instrument capable of measuring the RBCC of retinal vessels in realtime can be coupled with simultaneous measurement of mean RBC speed to obtain an instantaneous measure of blood flow. An instrument which provides a real-time and continuous measure of RBC speed such as the stabilized laser Doppler Velocimeter is uniquely suited to this application. In practice the diameter of the RBCC is generally based on a measure of the width of the retinal vessel image on fundus photographs or fluorescein angiograms. An article by Delori et al3 describes and evaluates different methods which have been used to determine the width of the RBCC image.
Sws-Cone Defects In Photoreceptor Degenerations
Authors: Swanson William H. , Birch David G.
Published: February 2023

Retinal disease often affects color vision, and one of the most common acquired color vision defects is the “blue defect,” in which performance is decreased for discriminations normally mediated by the short-wavelength-sensitive (SWS) cone pathways (reviewed by Pokorny & Smith, 1986). In recent years there has been considerable interest in the mechanisms underlying blue defects. Analysis of these mechanisms could result in a better understanding of the etiology of the diseases and development of tests useful for following patients and assessing the effectiveness of treatments. In particular it would be useful to know if SWS cones are selectively affected by photoreceptor degenerations. As compared to the long-wavelength-sensitive (LWS) and middle-wavelength-sensitive (MWS) cones, the SWS cones are morphologically distinct (Ahnelt, Kolb & Pflug, 1987), their membranes are more permeable to some molecules (DeMonasterio, Schein & McCrane, 1981), and their calcium metabolism may be more like that of rods (Zrenner, 1983).
A Computer-Based Optotype Acuity Test System Suitable for Evaluation of Acuity Charts
Authors: Arditi Aries , Cagenello Ron
Published: February 2023

Although computerized visual acuity testing is psychophysically more flexible than “manual” testing using printed or projected optotype charts, the quality of currently available and affordable pixel-oriented computer images makes computers poorly suited for clinical testing. This is mainly because low spatial resolution in one or both dimensions limits the range of sizes available for testing at a single optical distance.
Improvement in Acuity, Glare and Contrast Sensitivity following Cataract Surgery
Authors: Rubin Gary S. , Adamsons Ingrid A. , Stark Walter J.
Published: February 2023

Visual acuity has long been used as the primary vision test for determining when cataract surgery is warranted and as the measure of its effectiveness. However over the past two decades several studies have been published which indicate that other aspects of visual function may be impaired in cataract patients who have reasonably good visual acuity (e.g. better than 20/40). With the advent of extracapsular cataract extraction and the widespread use of intraocular lenses, the indications for surgery have changed. No longer is it required that the patient’s acuity drop to 20/70 or worse. Surgery is often performed on eyes with 20/40 or better acuity when there are other symptoms of visual impairment, particularly a decline in contrast sensitivity or increased sensitivity to glare.
Tracking Strategy in Normal Subjects with Computer Generated Scotoma
Authors: Pidcoe P. E. , Zuber B. L. , McMahon T.
Published: February 2023

Visual tracking experiments were conducted on five visually unimpaired subjects. During each of four 1 hour sessions, each subject was asked to track a computer generated target using their eyes only. The stimulus target occupied 0.2° of visual angle and moved horizontally through a range of ± 5°, in periodic sinusoidal and non-periodic patterns. Head stabilization was achieved with a head-rest and bite-bar. Horizontal eye movements were computer sampled at 500 samples/sec from the output of a limbus tracker, and vertical eye movements were sampled from the output of a video based pupil tracker (ISCAN). The first session was used to collect baseline tracking data from each subject. In each of the last three sessions, a software control algorithm allowed horizontal eye position to be utilized as a feedback signal, thus simulating experimenter designed central scotomas. These scotomas had the properties shown in the figure below, and were defined to have horizontal widths of ± 1°, ±2° and ±3° degrees. The vertical eye position data was used in conjunction with know cross-talk characteristics to identify and remove trials in which vertical eye position deviations corrupted the horizontal eye position measure.
Postural Stability in Low-Vision Subjects: A Preliminary Investigation
Authors: Turano Kathleen , Herdman Susan , Spears Teresa
Published: February 2023

It is widely recognized that postural stabilization is multisensory. The normal anterior-posterior (AP) body sway of an individual results in visual cues of postural instability such as changes in apparent stimulus movement, image size and retinal disparity. Changes in pressure on the skin, muscle and joint receptors as well as changes in angular/translational head movements and head position also serve as somatosensory and vestibular cues to postural instability. Although it is known that information about postural stability is available from each of the three sensory modalities, little is known about how they interact.
The Visual Activities Questionnaire: Developing an Instrument for Assessing Problems in Everyday Visual Tasks
Authors: Sloane Michael E. , Ball Karlene , Owsley Cynthia , Bruni John R. , Roenker Daniel L.
Published: February 2023

This paper describes the development of a questionnaire for assessing an individual's problems in performing visual activities typical of everyday life. We were particularly interested in an instrument which would be useful with the elderly population, because eye disease is especially prevalent in this age group (Leibowitz et al., 1980), and even in the absence of significant eye disease, older adults can still experience losses in visual function (Owsley & Sloane, 1990). This type of instrument could be useful from a number of perspectives. First, in many research settings it is desirable to have some sort of metric for assessing the extent to which a subject is having problems in everyday visual tasks. Ideally it would be best to obtain performance measures on the visual tasks under study, but the reality is that this is not possible in many studies. Thus, researchers often resort to asking subjects about their self-perceived problems in performing the activity in question, but without a valid and reliable instrument, subjects' answers are often useless from a scientific standpoint. Examples of settings in which a psychometrically solid questionnaire might be helpful are: evaluating the effects of a treatment or procedure (e.g., cataract surgery) on visual functioning; assessing how self-perceived visual difficulties relate to an adverse outcome such as a vehicle crash or a fall; and gathering information about visual tasks especially difficult for certain subpopulations of older adults (e.g., those with age-related maculopathy). A second way a questionnaire may be useful is in collecting epidemiological data on visual problems in the elderly population. Epidemiological studies on eye health and visual functioning are costly, and from the standpoint of actually carrying out the project, these studies are not particularly challenging or stimulating for research oriented clinicians (see Ederer, 1983). Coren and Hakstian (1987; 1988) have suggested that a suitably constructed questionnaire could be a much cheaper way to obtain some types of epidemiological data. A third way in which a questionnaire instrument might be useful is in developing hypotheses about the mechanisms underlying vision problems in the elderly. When visiting the laboratory or clinic, older adults often articulate visual problems, and a questionnaire could provide them the opportunity to do so in a systematic fashion. Fourth, a questionnaire might also be useful to clinicians since subjective information from the patient can yield clues about an undiagnosed disease process or condition.
Psychometric Functions for Rayleigh Matches
Authors: Swanson William H.
Published: February 2023

Rayleigh matches gathered with anomaloscopy have been used to study polymorphisms of human cone photopigments and causes of acquired color vision defects. Anomaloscopy typically requires a skilled and trained tester following a standard protocol. The endpoints of the matching range can be readily determined if the responses of the observer are consistent, but if the observer gives varying responses to the same mixture then the tester must develop decision criteria to determine the matching range endpoints. Since the number of trials is small, it is not possible to quantify response variability. These factors reduce test-retest reliability and introduce a source of test site dependence for Rayleigh match data.
Development of Pattern Responses to Contrast-Increment and -Decrement Stimuli in Infants: A VEP Measure of Functional Subsystems in the Visual Pathway
Authors: Hartmann E. Eugenie , Hitchcox Susan M. , Zemon Vance M.
Published: February 2023

Visual scientists have frequently proposed dichotomous subsystems as the basis for analysis and organization of incoming visual information. One such subsystem is the ON- versus OFF-pathways. These pathways can be thought of as processing contrast-increment versus contrast-decrement information. Based on center-surround receptive field organization, ON- and OFF-center cells have been shown to exist in a wide variety of species (Hartline, 1938; Kuffler, 1953; Hubel and Wiesel, 1961). This subdivision begins with the retinal bipolar cells. At the retinal level, the distinction has been demonstrated both morphologically and pharmacologically (Famiglietti and Kolb, 1976; Slaughter and Miller, 1981). The segregation is further maintained in the lateral geniculate nucleus, with no interaction between the pathways occurring until the level of the visual cortex (Schiller, 1982).
Temporal patterns and the topography of the visual-evoked potential
Authors: Thompson Dorothy A. , Drasdo Neville
Published: February 2023

This study was prompted by our interest in the relationship of the visual evoked potential to the multiple specialized visual areas in the cortex. Scalp recorded visual-evoked potentials, (VEPs), are considered the result of radially oriented dipole generators situated on gyral crests. A change in the distribution of evoked potential activity might therefore indicate the activation of different neural tissue. Some 32 specialized visual areas have been described in the macaque cortex (1), each of which may be expected to have a human homologue. Physiological evidence suggests these specialized areas maintain some of the functional segregation first encountered at the lateral geniculate nucleus.
A New Psychophysical Method to Assess Ocular Light Scatter
Authors: Wolfe Jeremy M
Published: February 2023

Developing cataracts have a variety of deleterious effects on the quality of the retinal image. The most notable of these is light scatter. Assessing the visual impact of lens opacities is somewhat problematical. Standard measures like acuity and contrast sensitivity have two drawbacks. First, the impact of the cataract may be fairly minimal (e.g. Hess, & Woo, 1978; Lasa et al., 1991). It is perfectly possible to have a significant cataract and 20/20 acuity. Second, acuity and contrast sensitivity are affected by many forms of pathology. Cataract does not create a unique pattern of losses that allow its CSF to be distinguished from, say, a CSF in a macular degeneration patient (see Davis, Sherman, Bass, & Schnider, 1991 for a discussion).
ERG Components from Achromatic and L-M Opponent Mechanisms
Authors: Sutter E.E. , Wu S. , Reeves Adam
Published: February 2023

It is generally accepted that most of the photopic ERG response to luminance stimulation originates from sources in the distal retina. At best a very small contribution is attributed to amacrine and ganglion cells. This assertion finds support in our recent topographic study. Using the same systems analysis technique applied in the present study, we have shown that the topography of the response density to achromatic local flicker stimulation mirrors that of cone densities (Sutter and Tran, 1992). Thus, the largest signal contribution attributed to Muller cells (b-wave) can be directly related to receptor response. Based on these findings, it seemed reasonable to ask how much of this response is mediated by L- and M-cones. (S-cones add little to the response and the contribution of rods is negligible with fast photopic stimulation.) If there are ERG components originating from the two receptors populations and if they are devoid of any lateral mechanisms, they must reflect the densities of L- and M-cones (assuming equal response properties of the two cone types). These components might be found in the early a-wave obtained under stimulation conditions of M-silent and L-silent substitution.
Symmetry Discrimination in Patients with Retinitis Pigmentosa
Authors: Szlyk Janet P. , Seiple William , Xie Wei , Fishman Gerald A.
Published: February 2023

Sloan letters, grating patterns, and bar offsets have been used to assess foveal spatial function. Because of the inherent redundancy of these stimuli and the "filling in" due to perceptual completion processes, these tests may not be sensitive enough to changes in the retinal sampling mosaic. An alternative to these stimuli is a spatially random block pattern which has been used to test symmetry discrimination.1 These block patterns consist of elements of a constant size. The intensity of each element is randomly chosen to be either maximum or minimum, and the subsequent patterns range from those with a symmetrical distribution to those with an asymmetrical distribution (Figure 1). Due to the unpredictable location of each pattern element, and the lack of predictable redundancy, subjects cannot rely on perceptual completion processes to make accurate symmetry judgments. The present report tests whether a symmetry paradigm is useful to assess losses in the retinal sampling mosaic in patients in whom a loss of photoreceptors has been reported (e.g., retinitis pigmentosa [RP]2,3)
Interpretations of Naka-Rushton parameters from patients with ADRP and CRD.
Authors: Hood Donald C. , Shady Sherif , Birch David G.
Published: February 2023

Since the Naka-Rushton eq was first shown to fit the change in trouh-to-peak b-wave amplitude with flash intensity1,2, it has been fitted to b-wave data from a large number of patients. The parameters estimated from these fits, the semisaturation intensity (K) and the maximum response (Vmax) are affected in different ways by different diseases. Fig. 1, from Birch et a13, shows the deviations from the normal parameters for 41 patients with cone-rod dystrophy (CRD) or autosomal dominant retinitis pigmentosa (ADRP) retaining measurable rod ERGs. Each data point represents an individual patient and shows the change in log K and the change in log Vmax from the log of the mean normal. Typical of diseases of the receptors, these patients show large changes
Spatial Instability and Bifurcations in the Nonlinear Third-Order Three-Wave Mixing Interaction in Single-Mode Fibers
Authors: Trillo S. , Cappellini G.
Published: February 2023

When pump depletion is fully taken into account the nonlinear parametric interaction of an intense central frequency wave with a couple of Stokes and antiStokes frequency-shifted waves in a single-mode optical fiber exhibits bifurcations of spatial eigensolutions and spatial instabilities. Potential applications of such instability are discussed.
Picosecond Resolution in Field Cross-Correlation Experiments with Nanosecond Sources
Authors: Bouchène A. , Débarre A. , Keller J.-C. , Le Gouët J.-L. , Tchénio P.
Published: February 2023

Field cross correlation is used to attain picosecond or sub-picosecond resolution in the time domain analysis of coherent optical emission triggered by long broad bandwidth light pulses. Optical data recording and retrieval is demonstrated in gaseous and in solid samples.
Instabilities of Nearly Degenerate Stimulated Brillouin Scattering
Authors: Postan A. , Sung C. C. , Bowden C. M. , Haus J. W.
Published: February 2023

Temporal instabilities in stimulated Brillouin scattering of two counter-propagating mutually detuned laser beams depend on the intensity of the beams, the length of the interaction region and the frequency detuning. The detuning increases the threshold of stability and shifts the oscillation frequency of the unstable perturbations at the threshold.
Looking for Polarization Catastrophies in Quasi-Isotropic Lasers
Authors: Bourouis M. , Laniepce S. , Stephan G. , Glanznig P. , Paddon P. , Xiong W. , May A. D.
Published: February 2023

Quasi-isotropic lasers with anisotropic feedback display a rich variety of polarization behaviour. In this article we present calculations that predict sudden discontinuities (catastrophies) in the width of the polarization hysteresis loop.
Dynamics of CO2/CO2 Laser
Authors: Anishchenko V. S. , Safonova M. A. , Tatarkova S. A. , Tuchin V. V.
Published: February 2023

Numerically we study the five-dimensional dynamical system which describes a laser with saturable absorber. The bifurcation diagrams are plotted for the parameters corresponding to real CO2-laser with CO2 as the saturable absorber. The influence of external noise is investigated.
Unstable Oscillation of the Cryogenic H Maser
Authors: Maan A. C. , Stoof H. T. C. , Verhaar B. J. , Mandel Paul
Published: February 2023

The room-temperature hydrogen maser1 is the most stable existing frequency standard for a wide range of measuring times. As such it has been used very successfully for tests of general relativity, for Very Long Baseline Interferometry (VLBI) and for interplanetary navigation (Voyager mission). Since some years work is going on to build a sub-Kelvin H maser for improving the frequency stability by one or more orders of magnitude.2
Instabilities in a Bimode CO2 Laser with a Saturable Absorber
Authors: Hennequin D. , Dangoisse D. , Glorieux P.
Published: February 2023

We report on the observation of mode hopping in a bimode CO2 laser with a saturable absorber. When the control parameters are changed, the output intensity of this laser shows a succession of periodic regimes that may become completely erratic. Each of these regimes may be explained considering the role played alternatively by two unstable fixed points corresponding to the steady state intensity of each mode. In a particular range of the parameter space, a description of multipeaked regimes is given using the Farey arithmetic, and it resembles that observed in the Belousov-Zhabotinskii reaction. Transverse effects are observed that result from the nonlinear coupling of transverse cavity modes with both the active and passive media.
Dynamics of a Multimode, Short-Cavity Dye Laser
Authors: Gadomski W. , Hodges S. E. , Raymer M. G.
Published: February 2023

A short-cavity dye laser has been constructed to study cw fluctuations. The cavity is short enough so that the population and field time scales are similar. We obtain different values for the correlation dimension and entropy from the time evolution of the total intensity and individual modes. In both cases the dimension and entropy increase with excess above lasing threshold. Moreover, semi-regular oscillations of the total intensity have been observed to occur in short bursts separating intervals of nearly constant cw laser output.
Codimension Two Bifurcation in a Laser with Injected Signal
Authors: Oppo Gian-Luca , Solari Hernan G.
Published: February 2023

The equations of a laser with injected signal have attracted interest not only in optics but also from the community of nonlinear dynamics physicists. After the pioneering works of Ref. [1] and [2] where the proper set of Maxwell-Bloch equations has been derived and integrated numerically, interesting dynamical effects ranging from the coexistence of conservative and dissipative behaviours [3] to the existence of codimension two bifurcations (CTB) [4] have been analysed. In Ref. [4], for example, a CTB was recognised to be responsible of the appearance of frequency pushed solutions which are counter-intuitive in a problem majorly related to locking phenomena. Recently, partial attempts of characterizing the degenerate nature of the CTB have been published [5]. However a complete unfolding of the CTB capable of showing analytically all the dynamical behaviours of the solutions is presently lacking.
Analysis of LSA Models without Adiabatic Elimination of the Absorber Polarization
Authors: de Tomasi F. , Zambon B. , Arimondo E.
Published: February 2023

The laser with an intracavity saturable absorber has been theoretically investigated within a model including the polarization of the molecular absorber.
Dispersive and Dynamical Effects in Laser Phase Evolution
Authors: de Valcárcel G. J. , Roldán E. , Vilaseca R.
Published: February 2023

Phase dynamics in two- and three-level lasers is analysed using two different rotating reference frames, Rotation invariant attractor's representations are obtained, which evidence different features and physical factors influencing phase dynamics.
Instabilities and Chaos in Solid-State Lasers as a Result of Mode Coupling
Authors: Victorov E. A. , Vitrishchak I. B. , Novikov G. E. , Orlov O. A. , Mak A. A. , Sokolov V. A. , Ustyugov V. I. , Khaleev M. M.
Published: February 2023

The theoretical and experimental investigations concerning nonlinear dynamic processes in a multi-axial-mode CW solid-state lasers including the case of intracavity frequency doubling are reported; phase mode coupling was taken into account. It was shown that mode-frequency nonequidistancy may originate instabilities and chaos in laser intensity.
Statistical Features of a CO2 Laser with Pump Modulation
Authors: Ciofini M. , Meucci R. , Arecchi F. T.
Published: February 2023

We report the behaviour of a single mode homogeneously broadened CO2 laser when the gain parameter is swept from a negative value (laser below threshold) to a positive one (laser above threshold), so that the dynamical system goes through a bifurcation point. The modulation of the control parameter (gain) is done by repeatedly applying a linear ramp to the discharge current. As the gain never takes the stationary value associated with the instantaneous current value, the observed bifurcation is delayed with respect to the time at which the control parameter passes through the instability [1].
Switching Dynamics and Transient Response of Kerr Nonlinear-Optical Heterostructures
Authors: Cauwenberghs Gert , Thienpont Hugo , Veretennicoff Irina
Published: February 2023

Analytic expressions, describing the dynamic behaviour of arbitrary multilayered Kerr nonlinear structures, accounting for linear absorption and Debye relaxation, are derived and implemented numerically. The formalism is applied to the special case of Bragg reflectors with a two layer unit cell.We report on the switching behaviour and relaxation mechanisms in the cavity as influenced by the physical parameters. It is found that, due to strong coupling between forward and backward waves in the Bragg structure, a more complex transient response in the switching behaviour occurs, leading towards sustained aperiodical pulsations as the coupling increases. Absorption damps the transient fluctuations, whereas Debye relaxation tends to enhance them. A more profound investigation of the dynamic intensity distribution inside the cavity reveals the mechanisms of switching and pulsing response.
Chaos in the Four-Level Raman Far-Infrared Lasers
Authors: Raj Suranjana , Izatt Jerald R. , Rai Jagdish , Bowden Charles M.
Published: February 2023

The full set of Maxwell-Bloch equations for the four-level atomic systems is numerically integrated to obtain the time dynamics. Specific applications to the CH3F optically pumped far-infrared lasers are considered.
Acausal Filters for Chaotic Signals
Authors: Mitschke F. , Dämmig M.
Published: February 2023

Experimental chaotic signals inevitably contain a certain amount of noise. Low pass filtering is known to alter the signal such that subsequent dimension analysis yields false results. We show that a certain acausal filter reduces the noise but avoids the filter-induced error. A discussion reveals that the Kaplan-Yorke equation, which relates attractor dimension to Lyapunov exponents, implicitly relies on the forward direction of time.
Different Chaotic Regimes in LSA
Authors: Fioretti A. , Papoff F. , Zambon B. , Arimondo E.
Published: February 2023

The chaotic regimes of a CO2 laser with intracavity absorber have been recorded and investigated by means of return time maps and symbolic dynamics. Evidence of two different kinds of chaotic signals has been found
Generic Chaotic Behavior of Stimulated Brillouin Scattering
Authors: Uppal J. S. , Lu Weiping , Johnstone A. , Harrison R. G.
Published: February 2023

We report first evidence of chaotic emission in stimulated Brillouin scattering under cw pump conditions involving a single Stoke and pump signal. Single mode optical fibre is used as the nonlinear medium. First analysis of this fundamental process establishes chaotic dynamics to be prevalent in both the Stokes and transmitted pump signals; existing over a very wide parameter region including that close to the SBS threshold. The interplay of nonlinear dispersion with Brillouin gain is identified as a key mechanism responsible for this behaviour.
Behavior of a Bidirectional CO2 Ring Laser
Authors: Dennis Michael L. , Diels Jean-Claude
Published: February 2023

We report both stable antiphase modulation and bidirectional CW operation of a DC pumped CO2 ring laser. Complex dynamics is observed for low frequency gain modulation.
Dynamics Of Lateral Modes In Semiconductor Laser Arrays
Authors: Wang Shawe-Shiuan , Winful Herbert G.
Published: February 2023

A continuum model is presented to analyze the dynamics of semiconductor laser arrays. Simulations of both gain-guided and index-guided arrays yield stable or unstable outputs, depending on array parameters.
Synchronization of Chaotic Orbits in Semiconductor Laser Arrays
Authors: Rahman Lutfur , Winful Herbert G.
Published: February 2023

A subset of lasers in an array of coupled lasers can produce identical, synchronized, chaotic signals. When synchronization fails, spatio-temporal chaos results.
Space-Modulation Pattern of the Stripe-Geometry DH Injection Laser Emission
Authors: Rabinovich E. M. , Smolyakov G. A. , Tuchin V. V.
Published: February 2023

Space - modulation characteristics of the emission (SMCE) of stripe - geometry DH lasers without lateral confinement have been studied both experimentally and theoretically.

Experimentally , the modulation phase dependence on the lateral beam coordinate was found. We suggest the displacement of a laser lateral pattern under the direct current modulation to be responsible for this phenomenon.

Theoretically, the injection current - induced laser pattern displacement has been demonstrated by direct numerical solution of the corresponding one - dimensional wave equation, with the complex permittivity being taken of the asymmetric Epstein layer form.
Transverse-Mode Competition in Gain-Guided Semiconductor Laser Arrays Modeled as a Single Strongly Coupled Multimode Laser
Authors: Menendez-Valdes Pedro , Garmire Elsa , Ohtaka M.
Published: February 2023

A modal approach to solving gain-guided arrays is presented. It is demonstrated how transverse mode competition causes one mode to rob power from another, with a steady-state in which either two modes exist simultaneously, or in which one mode is entirely suppressed by the other. Interference effects have not been included; mode-beating within a single high-gain element, but no chaotic instabilities result from this calculation. It is found that the quantitative results are sensitive to the number of modes which are included, and in some cases modes with initially small gain become important under conditions of strong stimulated emission.
Instabilities in an All-Optical Passive Driven System with Transverse Effects
Authors: Jones Darlena , Bundy Donna , Protensko Igor
Published: February 2023

The dynamical effects of a resonant absorber contained in a ring cavity with lenses is considered using the Maxwell-Bloch equations and Kirchoff’s diffraction integral. We see considerable differences in dynamical behavior and injection-locking threshold between systems that consider polarization and systems where the polarization is adiabatically eliminated. By ramping the external signal, hysteresis effects are clearly different.
Transverse Laser Patterns, Spatial Multistability, and Phase Singularities
Authors: Brambilla M. , Battipede F. , Lugiato L. A. , Penna V. , Prati F.
Published: February 2023

The stationary transverse laser patterns correspond to the minima of an appropriate generalized free energy. The calculated patterns agree with the experimental observations at P.T.B. in Braunschweig, and display exotic structures called phase singularities.
Conical Ring Emission from a Microcavity Dye Laser
Authors: Hodges S. E. , Gadomski W. , Raymer M. G.
Published: February 2023

Conical ring emission from a micro-cavity dye laser has been observed and modeled. The presence of rings is surprising since the dye used is spectrally broad enough to allow emission into the angles between rings.
Encoded and Spontaneous Dark and Bright Solitary Wave Patterns in a Nonlinear Optical Feedback System
Authors: Wenden S. G. , Adachihara H. A. , Moloney J. V.
Published: February 2023

Spatially robust dark/bright solitary wave patterns can be induced on a switched-on 2D beam, either through external phase encoding or a spontaneous modulational instability.
Spatiotemporal Structures in Bistable Optical Schemes
Authors: Rosanov N. N. , Fedorov A. V. , Khodova G. V.
Published: February 2023

We present the results of theoretical analysis and computer simulations of field structures in passive bistable optical systems: increasing absorption devices. nonlinear cavities (interferometers), and two-beam nonlinear schemes. New opportunities for parallel optical processing are discussed.
Dynamical Effects Induced by the Variation of the Squeezing Phase
Authors: Galatola P. , Lugiato L. A. , Porreca M. G. , Tombesi P.
Published: February 2023

We show that the switchings of a standard single- mode optical bistable system can be obtained by varying the phase of a squeezed vacuum field interacting with the atomic medium, without changing any other control parameter, and in particular the input field.
Self-Oscillations in Fabry-Perot Cavities Containing CdS Platelets
Authors: Oberle J. , Daunois A. , Walker A. C.
Published: February 2023

Thin CdS platelets, placed in Fabry-Pérot cavities, show slow periodic oscillations of the transmitted intensity under a cw laser beam illumination. This phenomenon, unexpected in such a system, can be related to two different thermal effects, the first on the sample itself, the second on the dielectric mirrors, whose absorption is not very important but not negligible.
Chaos vs. noise in experimental data
Authors: Mitschke F. , Dämmig M. , Boden C.
Published: February 2023

It is common to quantify chaos through determination of certain invariants. Among experimentalists, the most popular ones are the attractor dimension D2 and entropy K2 with an algorithm by Grassberger and Procaccia /1/ and the largest Lyapunov exponent with an algorithm due to Wolf et al. /2/.
Quantum Noise Reduction in a Spatial Dissipative Structure
Authors: Lugiato L.A. , Castelli F.
Published: February 2023

We present a novel nonlinear optical effect which arises in a spatial structure of electromagnetic field. Our analysis establishes also, for the first time, a link between the fields of spatial instabilities [1] and of quantum noise reduction [2,3], in nonlinear optical systems.
Two-peaked passage time statistics in a Q-switched CO2 laser near threshold
Authors: Meucci R. , Ciofini M. , Arecchi F.T. , Wang Peng-ye
Published: February 2023

In this paper we report experimental evidence of two-peaked transient time statistics in a single mode CO2 laser and we show that this phenomenon is due to the population inversion fluctuations. The same statistical feature has been also observed in dye1 and semiconductor2 lasers. However, in the first case two-peaked passage time distributions arise from the coupling between two transverse modes, while in the second case they are induced by the correlation between two successive pulses.
Physical Origin of the Self-Mode-Locking Regime in Solid-State Lasers
Authors: Piché Michel , Salin François
Published: February 2023

During the last two years, it has been found that many solid-state lasers can naturally emit trains of ultrashort laser pulses. This regime of emission, called self-mode-locking, does not require the use of any passive or active modulation element such as loss or phase modulators, saturable absorbers or nonlinear coupled cavities. Indeed, the first report by Spence et al1 indicated that self-mode-locking could be induced by misaligning the resonator. Many similar observations2-5, combined with simple estimates of the nonlinear phase retardation in the laser material, have indicated that nonlinear transverse effects (self-focussing, self-bending) are playing a key role in the dynamics of pulse formation. In this paper, we describe how the nonlinear lensing effect caused by self-focussing in the laser material produces an effective nonlinear gain when an aperture is properly positioned or gain saturation is taken in account.
Optical Pulse Evolution in Fibre Laser Additive Pulse Modelocking
Authors: Shore K.A. , Geisler T. , Sorenson M.P. , Christiansen P.L. , Mork J. , Mark J.
Published: February 2023

The large optical gain bandwidth available in optical fibre amplifiers holds the prospect of optical pulse production of the order of 100 fs. In the present paper it is wished to report on a theoretical study of the utilisation of a fibre amplifier coupled to a nonlinear fibre external cavity configured to permit interferometric additive pulse modelocking (APM).
Stable operation of a passive fiber resonator in the bistable and period-doubling regimes
Authors: Coen S. , Haelterman M. , Emplit Ph. , Delage L. , Reynaud F.
Published: February 2023

Synchronously driven passive fiber resonators constitute a class of devices of growing interest from both fundamental and applied points of view. They can be found in practice as the basic elements of a large number of fiber-based devices such as APM lasers, fiber Raman lasers or fiber loop memories. From a more fundamental point of view, a passive nonlinear fiber resonator is structurally so simple and such a broad spectrum of complex behaviors that it is considered as the paradigm of an optical system prone to instabilities and chaos. A first experimental attempt was made to explore the chaotic dynamics of passive fiber resonators in 1983 [1]. The resonator was driven synchronously with Q-switched picosecond laser pulse trains in order to reach the power levels required for sufficient nonlinearity and the onset of chaos. Because of the lack of control of the driving field and of the cavity phase shift (i.e., cavity round-trip phase change), a clean demonstration of chaos and comparison with theory were proved to be much harder to do than originally anticipated. Since then, other authors have attempted to do better using cw mode-locked lasers [2-4]. In refs. 3 and 4 a measure of the cavity phase shift is made which allows for meaningful comparison with theory. However, no direct control of the cavity phase shift is performed in these experiments. As a result, the cavity phase shift fluctuates which makes difficult a systematic study of the complex dynamical behaviors and their potential applications.
Simple Expression of the Conjugate-Power Generated by Four-Wave Mixing of Signal and a Single Pump
Authors: Larsson S. N. , Hermansson B.
Published: February 2023

Spectral inversion conducted half-way in a transmission link is one way of taking the bitrate length product beyond the dispersion limit in a fiber-optic communication system. This spectral inversion, or phase-conjugation, is most easily achieved by four-wave mixing between the signal-wave and a degenerated pump-wave.
Quantum-Noise in Multi-Mode Parametric Amplifiers—Noiseless Amplification in Bulk QPM LiNbO3
Authors: Lovering D. J. , Levenson J. A. , Vidakovic P. , Webjörn J. , Russell P. St. J.
Published: February 2023

Noiseless optical amplification–a non-classical process in which a weak
optical signal may be amplified without any
degradation in the signal to noise ratio (SNR)–is generating interest
in the telecommunications community. Although successfully
demonstrated in bulk KTP crystals1, practical applications
are severely hampered by the enormous pump-field strength required to
obtain a sizeable gain. Efforts to reduce this requirement are centred
on the search for better non-linear materials and stronger confinement
of the interacting fields. In this article a noiseless optical
parametric amplifier (OPA) is demonstrated with tightly-focused
incident fields in quasi-phase-matched (QPM) lithium niobate
(LiNbO3), for the first time. The quantum noise properties
are analysed within a quantised field framework which reveals a strong
similarity between guided and free wave interactions.
Motion and Steering of Optical Vortex Solitons
Authors: Christou Jason , Tikhonenko Vladimir , Luther-Davies Barry , Kivshar Yuri S.
Published: February 2023

Optical vortex solitons have been the subject of a significant amount of recent interest [1-4], a result of their potential for use in all-optical information processing devices. This potential is based on the waveguiding properties of optical solitons, which, for the vortex, allows fibre-like structures to be written into a self-defocusing medium. These structures can then serve as steerable conduits for information carrying beams, as has been demonstrated with spatial solitons in planar geometry [5,6]. However, the optical vortex soliton has an additional spatial degree of freedom over its planar counterparts, implying a greater choice of possible device configurations. In this paper we will introduce an approximate model for the motion of vortex solitons nested in arbitrary carrying fields. This model will be applied to the case of a vortex in a defocused laser beam and then compared with simulation and experiment. A useful method of steering vortex solitons, partially based on these results, will then be discussed.
Noise reduction of 20 Gbit/s pulse train using spectrally filtered optical solitons
Authors: Asobe Masaki , Hirano Akira , Miyamoto Yutaka , Sato Kenji , Hagimoto Kazuo , Yamabayashi Yoshiaki
Published: February 2023

The ‘particle-like’ nature of optical solitons is attractive for realizing several types of optical functionality. The application of solitons to long distance optical transmission has been studied intensively [1]. On the other hand, optical solitons are also useful for realizing optical signal processing, such as all-optical switching. Recently, photon number squeezing has been demonstrated by spectrally filtering of the pulses whose energy is slightly larger than that of the fundamental soliton [2]. It is not easy to take advantage of the sub-Poissonian state generated by squeezing in real optical transmission systems at present because of the intrinsic finite noise figure of the widely used Er3+doped fiber amplifier (EDFA). However, the spectrally filtered soliton scheme should be useful for reducing noise caused by intersymbolic interference or amplified spontaneous emission (ASE) in EDFAs. In this paper, we demonstrate that the spectrally filtered soliton scheme is effective in improving the signal to noise ratio in optical communication equipment.
Non-Kerr Spatial Solitons
Authors: Snyder Allan W
Published: February 2023

Non-Kerr spatial solitons are the building blocks to an all-optical,
virtual circuitry, technology, whereby light can guide, steer and
manipulate light in a bulk nonlinear material1. In this
paper, I concentrate on bright solitons. These are free standing beams
that are localized in space. In particular, I discuss some recent
predictions including: splitting a strong (soliton) beam with a weak
(signal) beam, the propagation of beams in nonlinear materials with an
arbitrary amount of spatial nonlocality and new findings about big
incoherent solitons - those launched by a diffuse illumination as
recently observed by Mitchell and Segev2 and studied
theoretically by Christodoulides, et al3.
Periodic structure generated in a nonlinear fiber resonator
Authors: Mitschke F. , Schwache A. , Halama I.
Published: February 2023

Inside a fiber resonator, pulse shaping due to dispersion and nonlinearity is modified considerably by cavity boundary conditions. For example it is well known that periodic modulation of a relatively broad pulse may emerge due to modulational instability in standard fiber; it was pointed out by Haelterman et. al.1 that inside a cavity this modulation exhibits a threshold, its frequency differs from that in free propagation, and it can occur even for normal dispersion. We experimentally and numerically study a fiber ring resonator driven by picosecond pulses from a modelocked laser. The repetition rate of the driving pulses is chosen in synchronism with the round trip time of the resonator. The experiment allows flexible choice of fiber dispersion. This system has been shown before to exhibit period doubling and chaos for some parameters.2 In other cases, an ensemble of solitons in perpetual relative motion (a soliton gas) is formed.3 This gas may transform into a regular lattice of solitons, a process closely related to modulational instability.4 In both experiment and numerical simulations we verify the predictions of Haelterman et al.1 There is a threshold power for the onset of modulation, and the frequency of modulation is shifted with respect to the free propagation value. Close to the zero dispersion wavelength, however, we also find a modulation based on a different mechanism. Its frequency depends sensitively on cavity length fine tuning, but is insensitive to dispersion details. We find that this latter type of modulation is related to the temporal shift due to a mismatch between cavity length and drive pulse repetition time as described in Gatz and Herrmann.5