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We describe a family of paraxial and quasi-monochromatic optical wave packets with finite energy and smoothly shaped amplitude in space and time that develops a singularity in the intensity when spatio-temporally focused by imparting a converging spherical wavefront and a negative temporal chirp. This singular behavior upon ideal focusing is manifested in actual focusing with finite apertures and in media with high-order dispersion with "exploding" behavior featuring an indefinitely increasing concentration of the energy when opening the aperture radius, thus exercising continuous control on the focal intensity and spatial and temporal resolution. These wave packets offer a new way of focusing that outperforms what can be achieved with standard Gaussian wave packets in terms of focal intensity and resolution, providing new possibilities in applications where energy concentration and its control are crucial. [ABSTRACT FROM AUTHOR]

The laser-induced damage observed in optics has rendered compressor grating the most limited component in petawatt (PW) lasers, owing to the considerable challenges associated with manufacturing gratings possessing both a sufficiently high damage threshold and large dimensions. An asymmetric four-grating compressor (AFGC) based multistep pulse compressor method was proposed recently to alleviate the requirement of such gratings. The viability of AFGC is further investigated experimentally in SEL-100 PW frontend with spectral bandwidth of over 200 nm in this study. It is verified that the AFGC has the ability of beam-smoothing resulting from the introduced spatial dispersion. Meanwhile, the spatial dispersion scarcely impacts temporal contrast and focal spot of the output beam. By reducing the laser spatial intensity modulations from 2.0 to 1.3, the pulse energy capacity of the AFGC can be increased by more than 1.5 times through simple translation. The results mark a breakthrough toward experimentally renovating the grating compressor, and pave the way for a reliable and efficient constructions of 100 s PW lasers. [ABSTRACT FROM AUTHOR]

A novel structure based on electrically small resonators is proposed for harvesting the infrared energy and yielding more than 80% harvesting efficiency. The dispersion effect of the dielectric and conductor materials of the resonators is taken into account by applying the Drude model. A new scheme to channel the infrared waves from an array of split ring resonators is proposed, whereby a wide-bandwidth collector is utilized by employing this new channeling concept. [ABSTRACT FROM AUTHOR]

CsTiOAsO4 has been found to be phase-matchable for type-2 second-harmonic generation and sum-frequency generation in the 0.5321-1.5915 μm range at 20.0 °C. The Sellmeier equations that correctly reproduce these experimental data as well as the 90° phase-matched optical parametric oscillator wavelengths in the 0.7337-2.4793 μm range are presented together with the thermo-optic dispersion formula. [ABSTRACT FROM AUTHOR]

CsTiOAsO4 has been found to be phase-matchable for type-2 second-harmonic generation and sum-frequency generation in the 0.5321-1.5915 μm range at 20.0 °C. The Sellmeier equations that correctly reproduce these experimental data as well as the 90° phase-matched optical parametric oscillator wavelengths in the 0.7337-2.4793 μm range are presented together with the thermo-optic dispersion formula. [ABSTRACT FROM AUTHOR]

Angle-resolved transmission of s-polarized light in triple-film hetero-opals has been investigated in the spectral range including high-order photonic band gaps, and compared to the transmission of its constituent single-film opals. The interfaces do not destroy the predominantly ballistic light propagation over the studied frequency and angular ranges, but heterostructuring leads to a smoothed angular distribution of intensity of the transmitted light and to the reconstruction of the transmission minima dispersion. The interface transmission function has been extracted by comparing the transmission of the hetero-opal and its components in order to demonstrate the difference. This deviation from the superposition principle was provisionally assigned to light refraction and reflection at the photonic crystal interfaces and to the mismatch between mode group velocities in hetero-opal components. [ABSTRACT FROM AUTHOR]

The performance of CoCrPt–SiO2 perpendicular recording media, which incorporate synthetic nucleation layers for inducing grain size control, was evaluated with regard to the crystallographic, microstructural, magnetic, interfacial, and recording properties. The media structure consisted of a 14 nm thick CoCrPt–SiO2 recording layer sputtered on two stacked Ru intermediate layers. When a submonolayer thick synthetic nucleation layer was inserted between the two Ru intermediate layers, the grain size and grain size dispersion were significantly reduced in both the upper Ru layer and the recording layer. An average grain size of 5.8 nm with 20% dispersion was achieved for the recording layer. The crystallographic growth of the Co (00·2) perpendicular texture remained unaffected with the Δθ50 at ∼4.4°; the coercivity was ∼2800 Oe and the coercivity squareness was ∼0.6. The roughness of the interface between the synthetic nucleation layer and the upper Ru intermediate layer did not significantly change, and the surface roughness was also relatively unchanged at ∼2.5 Å. An improvement in the signal-to-noise ratio by 1.5 dB was observed due to the synthetic nucleation layer. The effectiveness of the synthetic nucleation layer approach toward achieving grain size control and improving the performance of the CoCrPt–SiO2 perpendicular recording media is demonstrated. [ABSTRACT FROM AUTHOR]

A dispersion relation for the combined effect of scattering and absorption of electromagnetic waves is presented for a large class of linear and passive material models. By invoking the optical theorem, the result states that the extinction cross section integrated over all frequencies is equal to the static limit of the extinction volume. The present paper focuses on an attempt to experimentally verify this sum rule by measuring the monostatic radar cross section of a fabricated sample of metamaterial. In particular, the paper utilizes the idea that, for a specific class of targets, the scattered fields in the forward and backward directions are identical. It is concluded that the theoretical findings are in good agreement with measurements performed in the frequency range [3.2,19.5] GHz. [ABSTRACT FROM AUTHOR]

A theoretical formalism designed to quantify linear optical and second-order nonlinear optical responses of achiral or chiral anisotropic materials in planar structure is presented. In particular, the theory includes linear optical activity that is governed by the gyrotropic components and second-harmonic generation optical rotatory dispersion, the magnitude of which depends on the ratio of chiral and achiral χ(2) components. Examples are given which reproduce complex interference effects and other subtle optical effects that are encountered in layered structures. Detailed experimental second harmonic generation studies of quartz and dihydrogen phosphate that quantify linear and nonlinear optical activities of these materials are reported. [ABSTRACT FROM AUTHOR]

We present ab initio calculations of the phonon dispersions and density of states for wurtzite, zinc-blende, and rocksalt AlN under hydrostatic pressure using density functional perturbation theory. The calculations predict the full phonon dispersions throughout the Brillouin zone. Our results regarding zone-center modes for wurtzite and zinc-blende structures show generally good agreement with Raman measurements and previous theoretical data. For rocksalt structure, the present results are predictions. The different behavior of the lattice vibration properties under pressure in the three phases being studied here is discussed. The pressure coefficients and mode Grüneisen parameters are determined from the pressure dependence of vibration modes. [ABSTRACT FROM AUTHOR]

We have recently introduced a model of the dispersion interaction based on the position-dependent dipole moment of the exchange hole [J. Chem. Phys. 122, 154104 (2005)]. The original derivation, involving simple dipole-induced-dipole electrostatics, was somewhat heuristic, however, and lacking in rigor. Here we present a much more satisfying derivation founded on second-order perturbation theory in the closure approximation and a semiclassical evaluation of the relevant interaction integrals. Expressions for C6, C8, and C10 dispersion coefficients are obtained in a remarkably straightforward manner. Their values agree very well with ab initio reference data on dispersion coefficients between the atoms H, He, Ne, Ar, Kr, and Xe. We also highlight the importance of the exchange-hole contribution to the dispersion coefficients, especially to C6. [ABSTRACT FROM AUTHOR]

Recently, we suggested the idea of an optical superlens based on the extraordinary dispersion properties of plasmonic nanochains. In the present paper we discuss the results of numerical simulations of the imaging of point sources in this superlens. The simulations show that sub-wavelength resolution can be obtained in much thicker structures than usual. A distance of nearly λ/2 between the source and the image plane is achieved. In addition the effects of stochastic deviations in geometrical parameters are studied. [ABSTRACT FROM AUTHOR]

Optical properties of the fluorocarbon (FC) films plasma deposited on Si substrates are evaluated in this work using multiple sample analysis (MSA)-based spectroscopic ellipsometry (SE) with representing the film optical constants by the Forouhi-Bloomer (FB) and Tauc-Lorentz (TL) optical dispersions. This SE analysis supported also with other film investigations results in a two-layer optical model consisting of an interface assimilated to FC species-permeated Si layer beneath a surface smooth, homogeneous, and isotropic FC bulk film. Both dispersions yield a low-dielectric constant quality visible range refractive index of 1.39 and almost identical model layer thicknesses. Deposition-dominated linear film growth is thus asserted. Specifically, the FB dispersion better describes the region near absorption cutoff with taking up a lower optical band gap (OBG) than that of the TL dispersion, indicating thereby that particular FC film absorptions included in the FB dispersion are excluded in the other. Also, the FB index spectrum tends to peak towards a broad maximum in the ultraviolet (UV) wavelength range, whereas this trend is absent in the TL index spectrum probably removed by the TL parameter cross correlations although reduced by MSA. Sample to sample analysis further shows that the TL parameter correlation is accentuated by the instrument-limited UV range. The FB parameters are much less affected by cross correlation such that even the sample to sample analysis may be readily used in conjuncture with the FB dispersion for thicker FC films above 150 nm to monitor their index and OBG in tailoring desired film physical properties through deposition conditions. [ABSTRACT FROM AUTHOR]

Confined optical phonons are discussed for a semiconductor nanowire of the Ge (Si) prototype on the basis of a theory developed some years ago. In the present work this theory is adapted to a nonpolar material and generalized to the case when the phonon dispersion law involves both linear and quadratic terms in the wave vector. The treatment is considered along the lines of a continuous medium model and leads to a system of coupled differential equations describing oscillations of mixed nature. The nanowire is modeled in the form of an infinite circular cylinder and the solutions of the fundamental equations are found. We are thus led to a description of long-wavelength optical phonons, which should show a closer agreement with experimental data and with calculations along atomistic models. The presented theory is applied to the calculation of optical phonons in a Ge nanowire. We have found the dispersion curves for various optical phonon modes. We also normalize the modes and discuss the electron-phonon interaction within the deformation potential approximation. [ABSTRACT FROM AUTHOR]

A scheme using a lens array and the technique of spectral dispersion is presented to improve target illumination uniformity in laser produced plasmas. Detailed two-dimensional simulation shows that a quasi-near-field target pattern, of steeper edges and without side lobes, is achieved with a lens array, while interference stripes inside the pattern are smoothed out by the use of the spectral dispersion technique. Moving the target slightly from the exact focal plane of the principal focusing lens can eliminate middle-scale-length intensity fluctuation further. Numerical results indicate that a well-irradiated laser spot with small nonuniformity and great energy efficiency can be obtained in this scheme. [ABSTRACT FROM AUTHOR]

The refractive indices, birefringence, and linear electro-optic (EO) effect of 0.62Pb(Mg1/3Nb2/3)O3–0.38PbTiO3 single crystals have been characterized as a function of wavelength. The dispersions of refractive indices for both ordinary and extraordinary rays were accurately described by a two-term Sellmeier dispersion equation, in which the parameters connected to the energy band structure were determined. A strong dispersion was found for birefringence and EO coefficient γc=γ33-(no/ne)3γ13. With the increasing wavelengths, both of them decrease fast. The two-term Sellmeier dispersion model, in which one oscillator frequency is polarization dependent, was shown to represent closely all the results. The polarization potential, which specifies the magnitude of the oscillator frequency shift, was 0.40 eV m4 C-2. [ABSTRACT FROM AUTHOR]

We introduce a method for the determination of the optical retardation, its wavelength dispersion, the cell twist angle, and the orientation of the input director in a reflective liquid crystal (LC) cell. These parameters are found from the extremes of a characteristic function defined as a sum of two spectral reflectivities of the LC cell placed between a pair of linear polarizers. The reflectivities are measured for two cell orientations, one of which is arbitrary and the other one is turned through 45°. Both theoretical analysis and experimental procedures are presented. Excellent agreement between the experiment and our theory has been found. The proposed method can be applied to the measurement of reflective LC cells with small and large cell gaps, as well as cells with small and large twist angles. [ABSTRACT FROM AUTHOR]

Two vertically coupled asymmetric InGaAsP ridge waveguides were fabricated and tested as a tunable dispersion compensator. In this waveguide, two coupled modes, symmetric and antisymmetric, exist simultaneously and have a significant amount of group-velocity dispersion (GVD), making it possible to reduce the size of the dispersion compensators. Since the GVD can be continuously controlled by changing the temperature of the asymmetric coupled waveguide, a semiconductor asymmetric coupled waveguide has great potential as a basis for a compact tunable dispersion compensator. To demonstrate tunable dispersion compensation, we carried out an experiment on the pulse compression of frequency-chirped pulses by using the InGaAsP asymmetric coupled waveguide at various temperatures of the waveguide. We observed a change in the compression ratio, ranging from 42.7% to 84.2%, as the temperature of the waveguide changed from 8 to 48.9 °C. A theoretical study showed that the observed change in the compression ratio was well explained by a temperature tuning of the GVD of the coupled modes resulting from temperature-induced change in the refractive indices of the waveguide materials. [ABSTRACT FROM AUTHOR]

The influence of dc electric fields (EFs) on the development of buoyancy-driven instabilities of reaction fronts is investigated experimentally in a modified Hele-Shaw cell for the arsenous acid-iodate system. Assessment of effects of external EFs is made both visually and through dispersion curves. It is shown that density fingering, observed on ascending fronts, is suppressed by the EF if the front propagates towards the positive electrode and is enhanced when the front propagates towards the negative electrode. The stabilizing (destabilizing) effects include slower (faster) development of fingers and the decrease (increase) in their numbers. The descending front, stable under no EF conditions, remains stable when an EF is applied with the positive electrode facing the approaching front. When the descending front faces the negative electrode, the tiny fingerlike structure develops after quite a long time. [ABSTRACT FROM AUTHOR]

We present a numerical study of resonant negative refractive index (NRI) metamaterials in which their effective parameters are calculated. For a periodic media consisting of split-ring resonators and metallic wires the effective refractive index is compared by means of two different methods. The first one is an inversion procedure in which the effective refractive index is calculated from the reflection and transmission coefficients of a finite structure and the second one consists its calculation from the phase velocity issued from the dispersion diagram. A significant difference between the two cases is highlighted in the frequency interval of interest (NRI regime) and for the finite media, counterintuitive observations are made. These anomalous features are observed in a frequency range in which there is a non-negligible contribution of the higher-order modes to propagation inside the periodic metamaterial. Hence in this particular frequency interval, the media cannot be described by an effective refractive index in a Fresnel sense. In other frequency regions, both methods converge and it will be shown that the metamaterial exhibits a negative refractive index. [ABSTRACT FROM AUTHOR]

The frequency-dependent electric field-induced second harmonic generation (ESHG) second hyperpolarizabilities γ of neon, argon, and krypton are calculated using the approximate coupled cluster triples model CC3. Systematic basis set investigations are carried out to establish basis set limits, and scalar relativistic effects are accounted for by direct perturbation theory. To estimate higher-order correlation effects, full configuration-interaction results are used to benchmark the accuracy of CC3. The best theoretical estimates obtained thereby for the static second hyperpolarizabilities γ0 are 107.4, 1159, and 2589 a.u. for neon, argon, and krypton, respectively. These values as well as the results for the dispersion curve of the parallel component γ∥ agree well with the latest experimental values from electric field-induced second harmonic generation. In addition, the dispersion of the perpendicular component γ⊥ and the hyperpolarizability ratios γ∥/γ⊥ has been studied for the first time on a consistently correlated ab initio level. The analysis of the results indicates that, in particular for neon and krypton, the presently available experimental values are flawed. [ABSTRACT FROM AUTHOR]

We present triplet and singlet scattering lengths for X–133Cs collisions (X=6,7Li, 23Na, 39,40,41K, and 85,87Rb). We consider the short-range potential-energy curves based on high-quality ab initio calculations and the long-range potential described by accurate dispersion coefficients available in the literature. Using a Fermi function to smoothly connect the short- and long-range terms we construct the potential for all R and evaluate the scattering length for each mixed species X–Cs. In particular, we predict that the cross section for inelastic processes between 23Na and 133Cs and between 40K and 133Cs will be small as compared with the respective elastic cross sections. [ABSTRACT FROM AUTHOR]

We study phonon dispersion in layered prismatic nanowires that can have an arbitrary cross-sectional geometry. We calculate phonon dispersion using a hybrid analytical/numerical approach that models propagation along the wire analytically, but deformation in the plane of the cross section using the finite element method. In our results we consider only two layers, but the calculational approach is applicable to multiple layers. [ABSTRACT FROM AUTHOR]

First principles calculations of the phonon dispersion relations and the phonon density of states for three zero-pressure zirconia phases are presented. The phonon dispersion relations of the tetragonal and monoclinic phases do not exhibit the imaginary frequencies, contrary to the cubic phase for which the imaginary soft mode is seen. For tetragonal and monoclinic phases the free energies versus temperature are calculated in harmonic approximation. They cross at 1560 K indicating the phase transition. [ABSTRACT FROM AUTHOR]

First principles calculations of the phonon dispersion relations and the phonon density of states for three zero-pressure zirconia phases are presented. The phonon dispersion relations of the tetragonal and monoclinic phases do not exhibit the imaginary frequencies, contrary to the cubic phase for which the imaginary soft mode is seen. For tetragonal and monoclinic phases the free energies versus temperature are calculated in harmonic approximation. They cross at 1560 K indicating the phase transition. [ABSTRACT FROM AUTHOR]

We numerically investigate the characteristics of surface acoustic waves (SAWs) in AlN/GaN/γ-LiAlO2 heterostructures. The markedly large sound velocity in AlN in comparison to that in GaN leads to an expulsion of SAWs from the top AlN layer and their resultant relocation to the middle GaN layer in the short-wavelength regime. The SAW velocity in the limit of zero wavelength is given by a bulk sound velocity of GaN, owing to the capping by the AlN barrier layer. The extra confinement of the SAW power in the acoustic well is advantageous in manipulating the operation of GaN-based devices by SAWs. The threshold velocity for the appearance of guided Rayleigh-like modes is found to be smaller than the bulk transverse sound velocity in the substrate. The present system exhibits furthermore unusual bowing behavior in the SAW dispersion. [ABSTRACT FROM AUTHOR]

Colloidal aggregation processes arising at different electrolyte concentrations were studied by means of experiments and confronted with theoretical predictions of different kinetic aggregation models. For this purpose, aqueous dispersions of relatively large polystyrene microspheres were chosen as experimental systems. Aggregation was induced by adding KBr electrolyte to the initially stable particle dispersions. During the aggregation processes, the cluster-size distribution was monitored by means of single cluster light scattering. Analyzing the time evolution of the monomer concentration, we found that the processes arising even at moderate electrolyte concentrations cannot be described by pure time-independent irreversible aggregation models. Hence, alternative models such as time-dependent irreversible aggregation and several reversible aggregation models were also tested. The model that considers a time-dependent sticking probability was found to fit the data quite satisfactorily. Nevertheless, the fitted was so slow that it seems not very likely to find such a behavior in real systems. The aggregation-fragmentation models reported in the literature were unable to reproduce the experimental observations. Hence, a more realistic reversible aggregation model was developed. This model accounts also for reenforced or double bonds between the constituent particles. The corresponding fit improved significantly and reached the same quality as the time-dependent model. Moreover, the obtained fitting parameters were in qualitative agreement with the DLVO predictions and so, reversible aggregation seems to be a more reasonable explanation for the experimental data than time-dependent irreversible aggregation. However, no definite statement on the possible secondary bond fragmentation mechanism may be made since both the applied shear stress in the measuring cell and thermal fluctuations can cause weaker bonds to break. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

The properties of nonsteady-state surface plasmon modes are analyzed for general grating structures and in particular for short pitch, high aspect ratio gratings and lamellar gratings. Numerical simulations of grating structures are described including a transformed coordinate, coupled plane wave approach known as the Chandezon method. A model of radiating light-surface plasmon coupling is then developed that allows for the extension of steady-state calculations involving time independent incident and reflected intensities to nonsteady-state situations involving no incident light but exponentially time dependent decaying emission intensity. Properties such as surface plasmon dispersion curves, electromagnetic field profiles, incident light-surface plasmon coupling efficiency, surface plasmon-radiating light coupling efficiency, overall radiation efficiency, and lifetime or decay constant are analyzed. It is seen that the surface plasmon modes of several structures couple strongly to incident and radiating light producing high surface plasmon-radiating light conversion and short lifetimes. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

We develop a model to study coupled cavity waveguides (CCWs) in photonic crystals, composed of linear chains of coupled cavities. By extending previous work on single mode cavities, we have developed a model applicable to any finite number of quasi-degenerate cavity modes. Our model, which uses a multimode tight-binding approach, allows us to study the interaction between the cavity modes as well as the coupling between the CCW bands. In contrast to previous work the coupling parameters are calculated ab initio from the single cavity field profile. The calculated dispersion relations are shown to be in good agreement with those obtained from the plane wave expansion method. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Using both simulated and experimental data, detailed comparisons are made between the different physical interpretations and responses of several important models commonly employed for fitting and analyzing conductive-system data sets, such as those for ionic glasses. Those considered are one following directly from stretched-exponential temporal response, designated the Kohlrausch K0; several ones indirectly associated with such stretched-exponential response: the original modulus formalism (OMF) model and corrected modulus formalism (CMF) ones; and the ZC model, one whose real-part conductivity expression has been termed "universal dynamic response." In addition, several models involving dielectric dispersion, rather than resistive dispersion, are found to be less appropriate for the present data than are the CMF ones. Of the four main conductive-system models the CMF approach fits data for a wide variety of materials much better than do the others. The OMF is shown to be both experimentally and theoretically defective and leads to poor and inconsistent fitting results. The simple ZC model involves nonphysical low-frequency-limiting real-part conductivity response and is usually less appropriate even than the K0. High- and low-frequency expressions and fit results for the various dielectric elements are presented, along with discussion of characteristic, peak, and mean relaxation times for the various models, failing to confirm some proposed relations between these quantities suggested earlier. [ABSTRACT FROM AUTHOR]

Presents a study in which a revised fringe equation is proposed for the hook method in anomalous dispersion for the case of thick plate compensation. Introduction to Rozhdestvenskii's discovery on the basis of Sethi's transit time criterion; Derivation of equations; Details of high-order white light fringes.

Deals with a study which investigated the effects of deviations from the ideal structure on the subband dispersion and optical properties of quantum wires and quantum-wire arrays. Effects due to lateral intermixing; Crystallographic effects; Conclusions.

Presents a study which examined the optical dispersion relations for GaP, GaAs, GaSb, InP, InAs, InSb, Al[subx]Ga[sub1-x]As, and In[sub1-x]Ga[subx]As[suby]P[sub1-y]. Calculation of the optical constraints; Derivation of the imaginary part of the dielectric function; Expression of the optical dispersion relations.

• This study introduces innovative multi-band chirped mirror designs that enable the management of group delay differences both within and between bands, further optimizing group delay dispersion across specific spectral regions. • Our investigation deepens the typical emphasis on chirped mirrors by revealing how transmission properties within coating structures are intricately connected to the resulting reflective group delay. • By analyzing, integrating, and optimizing coating subunits as predetermined structures, we have realized dispersion control across specific frequency bands, resulting in improved group delay management. • We have successfully developed a dual-band chirped mirror pair, distinguished by band separations exceeding an octave. This design exemplifies our achievement by attaining group delay dispersion values of −100 fs2 in the 0.6–0.8 µm range and −260 fs2 in the 1.7–2.2 µm range. • We have also implemented a dual-band chirped mirror pair in a two-photon and three-photon fluorescence microscopy system, utilizing a high-numerical-aperture microscope objective lens. This integration exemplifies the practical utility and the significant impact of our research on optical system design and performance. Effective dispersion management for broadband and highly dispersive optical systems becomes increasingly vital in ultrafast applications. While chirped mirrors provide a compact solution, their attainable dispersion is often limited by the operational bandwidth. This study introduces innovative multi-band chirped mirror designs that enable the management of group delay differences both within and between bands, further optimizing group delay dispersion across specific spectral regions. Here, we highlight the critical role of transmission group delay within multilayer coatings for broadband dispersion management, shifting the traditional interpretation which relies on the wavelength-dependent penetration of these coatings. We have thus developed a dual-band chirped mirror pair achieving group delay dispersion values of −100 fs2 in the 0.6–0.8 µm range and −260 fs2 in the 1.7–2.2 µm range, with the bands separated by more than an octave. Remarkably, this design outperformed a state-of-the-art ultrabroadband mirror pair by three and four times of group delay dispersion in the respective bands. We have also designed and implemented a specialized dual-band mirror pair for nonlinear light microscopy—a prime example of ultrafast applications—and successfully achieved transform-limited pulses for targeted fluorophore excitations. This research emphasizes the transformative potential of strategic group delay distribution, heralding a breakthrough in dispersive optical operations across specific wavelength ranges. [ABSTRACT FROM AUTHOR]

The present study deals with the effect of γ-irradiation doses in the range of (100-500 kGy) on the optical properties of quaternary (AsTe)5(GeSe2)95 film. The complex index of refraction (real (n) and real (k)) and the film thickness for the as-prepared and exposed films were determined precisely based only the measured transmittance spectra. A clear red shift of the absorption edge was noted by increasing γ-irradiating doses. Such a shift leading to the observed decrease in the optical gap Eog. Such a behavior of Eog can be due to the induced defects in the films due to γ-irradiation. The index of refection (n) has been discussed in terms of the dispersion model. The dispersion parameters were determined and well discussed in detail. The observed results show that, the (AsTe)5(GeSe2)95) thin films can be employed as radiation dosimeter for radiation measurements. [ABSTRACT FROM AUTHOR]

Dynamics of platicons caused by the third-order dispersion is studied. It is shown that under the influence of the third-order dispersion platicons obtain angular velocity depending both on dispersion and on detuning value. A method of tuning of platicon associated optical frequency comb repetition rate is proposed. Graphical abstract: [ABSTRACT FROM AUTHOR]

A new approach to a dispersive Michelson interferometer (DMI) is introduced. Rings of Equal Chromatic Order (RECO) are formed by a DMI illuminated by a white light source and crossed with an auxiliary dispersion spectrograph. The theoretical foundations are developed and then applied to different glass plates (BAK1, BK7, N-LAF35 and SK4) of thicknesses (12.101, 12.473, 9.930 and 6.602 mm), respectively. The sample is introduced in one of the arms of the interferometer. The refraction and dispersion of the samples are deduced from a single RECO interferogram. The refractive index and its variation are measured across the spectral range: 0.500–0.650 µm with relative errors of 10 −3 and 1.6 × 10 −4 , respectively. A good agreement between our measurements and reference data is found. [ABSTRACT FROM AUTHOR]

The design of high-quality imaging lenses continues to strive for the best color trueness over wider and wider wavelength ranges such as for multiwavelength fluorescence microscopy or hyperspectral imaging. Glasses suitable for sharp images at more than two wavelengths must differ in their dispersion from the classical crown and flint glass types, which gather along a straight line in a plot of the relative partial dispersion against the Abbe number. Glasses suitable for multicolor correction can be recognized by a considerable deviation of their relative partial dispersion from this normal line. Originally, the normal lines for different relative partial dispersions were defined by using the SCHOTT glass types K7 and F2. Today's data sheets of all glass manufacturers contain numerical values for deviations of relative partial dispersions from the normal lines. A comparison of almost identical glasses shows differences between these deviations being too large, obviously coming from different versions of K7 and F2 dispersion curves used. For preselection in designs and for direct comparison of glass types, it is necessary to agree on common dispersion curves each for K7 and for F2 in order to obtain really comparable values for deviations of the relative partial dispersion from the normal line. [ABSTRACT FROM AUTHOR]