We report the study of light polarization property upon scattering off a dielectric nanorod in which the direction of the incident light is at an angle with respect to the cylinder main axis. The numerical work is done on the basis of the cylindrical Mie theory. It is shown that for incident light with different polarization, the resulted scattering cross-section spectra will also show different characteristics

In this paper, one of the most modern random lasers known as random distributed feedback fiber laser is investigated when the third-order dispersion (TOD) is taken into account. The laser characteristics are simulated based on the nonlinear Schrödinger equations (NLSEs) where the power evolution of three interacting waves: the pump, the forward and the backward Stokes waves, are investigated as they

Strong localized surface plasmon resonance (LSPR) field, which is generated from gold nanoparticles, may enhance photons absorption of dyes in dye-sensitized solar cells (DSSCs), resulting in the improvement of their power conversion efficiency (PCE). In this paper, we report the incorporation of oleylamine capped gold nanoparticles (AuOA NPs) into the N-719 dye layer in DSSCs. The cells were prepared

In this paper, we consider terahertz sources based on Čerenkov difference frequency generation in a dual-wavelength mid-infrared quantum cascade laser and calculate analytically the optical external efficiency of the out-going terahertz wave. The mid-infrared pumps operate simultaneously and have a common upper level. For short cavity lengths and low terahertz losses in the substrate, we find that

The study of nonlinear absorption has potential applications as saturable absorption and optical limiting character in scientific and engineering technology. In this work, we report on the Gaussian vortex beam z-scan to study the saturable absorption in the two-level model. For a given material and laser beam parameters, even though vortex beam shows less saturable absorption nature than the conventional

The model of the composite symmetric waveguide consisting of self-focusing slab between defocusing nonlinear media separated by interfaces characterized by own nonlinearity response is proposed. Two new types of nonlinear surface waves propagating along it with anti-phase amplitude oscillations at interface planes are found. The frequencies of the nonlinear surface waves existing near the interfaces

Magneto-optic Kerr effect (MOKE) enhancement is studied for Yttrium Iron Garnet (YIG) nanoparticle. The MOKE is quantified by the ratio of the polarization components of reflected wave, namely between the perpendicular component to the parallel component with respect to the polarization of the incident wave. Thus, the enhancement of MOKE can be obtained by increasing the perpendicular component or

The classical problem of three-wave mixing in a nonlinear optical medium is investigated using the homotopy analysis method (HAM). We show that the power series basis builds a generic polynomial expression that can be used to study three-wave mixing for arbitrary input parameters. The phase-mismatched and perfectly phase matched cases are investigated. Parameters that result in generalized sum- and

A silicon-based all-optical wavelength conversion (AOWC) chip is proposed and designed for two-dimensional hybrid multiplexing signals, including mode-division multiplexing (MDM) and wavelength-division multiplexing (WDM). The AOWC chip is structured by mode (de) multiplexers and highly nonlinear silicon waveguide. Tapered directional coupler-based mode (de) multiplexers are used to convert between

Generally, high-order harmonic generation (HHG) from atoms and molecules can be explained by the “ionization-acceleration-recombination” model and the classical results are agreement with the quantum results. In this paper, we report a multiple-acceleration process in the “W” waveform structure. It is found that due to the nonzero initial velocity in the multiple-acceleration process, the emitted photon

In this work, we demonstrate and evaluate the viability of SrAl2O4:Eu2+, Dy3+ crystals for long-term light storage applications at low temperatures that can be activated at higher temperatures for on-demand lighting applications. The switching mechanism is discussed from the point of view of the possible interplay between charge transport and the persistent luminescence in this system. Step-wise t

We report the theoretical and experimental investigations of structure–property relationships for χ(3) at the wavelength of 800nm in three D-π-A-π-A type chalcone derivatives. Theoretically, the second hyperpolarizability γRthe at the wavelength of 800nm is numerically computed from the combination of density functional theory and semi-empirical method. Experimentally, we synthesize these three chalcone

We present a theoretical analysis of multi-photon absorption processes. We find an approximate closed-form expression of the normalized transmittance for a thin sample with two successive nonlinear absorption processes at a time (n- and (n+1)-photon absorption) in the presence of residual linear absorption. Our approach allows for simultaneous identification and evaluation of the nonlinear absorption

In this study, short Q-switching laser pulses are generated by drop-casting two-dimensional Molybdenum Disulfide (MoS2) nanoparticles as saturable absorbers (SA) on a side polished optical fiber in a C-band laser cavity. The proposed laser is capable of generating highly stable Q-switched laser pulses at the wavelength of 1559.42nm with a maximum repetition rate of 73.96kHz, and a minimum pulse width

This paper discusses the propagation characteristics of astigmatic mixed-pattern solitons in strongly nonlocal nonlinear media. From the initial expression of the astigmatic mixed-pattern soliton, it is found that the propagation pattern of solitons can be divided into three different cases: oval type, two-petal type and four-petal type. We further derive the beam propagation expression, and solve

Optically good quality Diglycine Perchlorate (DGPCL) single crystals were grown by the solution growth slow evaporation method. Single crystal X-ray diffraction of DGPCL was analyzed in this paper. From the FTIR study, the functional groups of crystal were identified and confirmed. UV–Vis absorption spectrum was examined, which shows that large transmittance in the entire visible and NIR region and

Ag-enriched ZnO nanoparticles (NPs) are prepared by using silver nitrate, zinc acetate, and N,N-dimethylformamide (DMF) as source elements, a novel method under particular conditions without any additives added as stabilizing or reducing agent. The transmission electron microscopic (TEM) studies reveal that the ZnO layer is well formed onto the Ag core. The photoluminescence shows the energy transfer

As of the writing of this work, generation of white light continuum (WLC) in hollow-core photonic crystal fibers (HCPCF) filled with gases is being thoroughly researched. These structures allow the possibility of adjusting light generation properties by changing the fill gas pressure. Kagomé hollow-core PCF and silica capillaries have been used to study the nonlinear effects in gases as they facilitate

Optically transparent good quality single crystal of 3-Aminonitrobenzene (3-ANB) was grown by slow evaporation technique using methanol as solvent. The grown crystal was subjected to single crystal X-ray diffraction analysis in order to reveal its cell parameters, crystal structure and space group. Powder X-ray diffraction analysis was carried out in order to verify the crystalline nature. UV-Vis study

In this work, we study the influence of Doppler broadening on cross-Kerr nonlinearity in a four-level inverted-Y atomic system under electromagnetically induced transparency (EIT) condition. The first- and third-susceptibilities in the presence of Doppler effect are derived as a function of probe, signal and coupling beams and temperature of medium. Under EIT condition, cross-Kerr nonlinearity is enhanced

We investigate propagation dynamics of cosh- and cosine-Airy beams in Kerr nonlinear media. The cosh-Airy and cosine-Airy beam can be considered as a superposition of two Airy beams with different decay factors and different propagation trajectories, respectively. It is shown that the solitons shedding from cosh-Airy and cosine-Airy beams and their interaction in both in-phase and out-of-phase cases

Surface-enhanced Raman scattering (SERS) has attracted much attention as an important technique for studying and monitoring the behavior of molecules. Coherent control by shaping femtosecond pulses is an efficient method for controlling molecular vibration state, rotation state, ionization state, and other molecule dynamics. In this paper, we propose a theoretical scheme of selective excitation of

We report on Z-scan investigations of the nonlinear optical properties of thin pyrolytic carbon films and two- and three-layer graphene films, utilizing an 800nm pulsed laser generating ultrashort 180fs pulses. We analyze the sign and magnitude of nonlinear refraction and absorption in these materials, given contradictory results in this respect in the literature. In particular, we find that nonlinear

Newly identified organic single crystals of 8-hydroyquinolinium 2-chloro 4-nitrobenzoate (HQ2ClNB) were grown by the slow evaporation solution growth technique (SEST) using methanol as a solvent. It crystallizes in monoclinic crystal system with a space group of P21/c. Crystalline nature and phases were confirmed by powder X-ray diffraction (XRD). The existence of various functional groups in the molecule

A cuprous oxide (Cu2O) thin film was prepared by radio-frequency (RF) magnetron sputtering. The crystal structure, linear transmission spectrum and film thickness were characterized by X-ray diffraction (XRD), ultraviolet–visible–near infrared (UV–Vis–NIR) absorption spectroscopy and ellipsometry. By performing the pump-probe and Z-scan technique, respectively, nondegenerate and degenerate two-photon

We report an experimental observation of a singular soliton dynamics in a mode-locked erbium doped fiber laser. This is the first time, to our knowledge, that output intensity exhibits a cyclic transition from a single-pulse to a multi-pulse regime for a fixed value of both pumping power and polarization controllers orientation. Moreover, the pulse duration of the single- and multi-pulse regimes is

A theoretical framework and the computational infrastructure for optical characterization of a waveguide (WG) photodetector (PD) are presented based on multiples quantum well (MQW) with a rib structure that is able to resolve a light pulse with a temporal width of 10fs. Such pulses are limited to the C-band of optical telecommunications. This pulse width is shorter than the temporal resolution limit

A potential scheme to obtain the high-intensity KeV isolated attosecond pulses (IAPs) from the high-order harmonic generation (HHG) has been proposed and studied via the superposition of the multi-color inhomogeneous laser beams. The scheme can be separated into three steps. Firstly, with the superposition of two-color mid-infrared field and a few-cycle infrared field at the proper delay time and the

We investigate numerically the existence and stability of defect solitons in nonlinear fractional Schrödinger equation. For positive defects, defect solitons are only existent in the semi-infinite gap and are stable in their whole existence domain irrespective of Lévy index. For moderate deep defects, defect solitons are existent in both the semi-infinite gap and first gap, and their instability domains

In this work, MoSe2 film is synthesized by the chemical vapor deposition method. Saturable absorber (SA) is assembled with the tapered fiber and MoSe2 films. Q-switched operation is achieved with the MoSe2-based SA. The experimental result reveals that the MoSe2-based SA has excellent saturable absorption characteristic with 23.41% modulation depth. When the pump power is greater than 289.2mW, Q-switched

Using nonlinear coupled mode equations, the spectral properties of long-period fiber grating are studied analytically taking into account the Kerr type optical nonlinearity in the medium. The nonlinear coupled-mode equations were solved for co-propagating core and cladding mode amplitudes and expressions for transmittivity and phase factor at high excitation intensity are obtained. It is observed that

Simultaneous co-propagation of red nondiffracting Bessel beam and green Gaussian beam at milliwatt powers in a photosensitive azobenzene liquid crystal has been studied. The fine displacement of the narrow-width Gaussian beam relative to the Bessel beam central maximum showed the Bessel beam distortion and controlled bending of its core in the direction opposite to the location of green Gaussian beam

The optical amplification performance of the proposed Zirconia Yttria Aluminum Erbium co-doped fiber (Zr-EDF) was compared for two different pumping schemes; 1480 and 980nm. An efficient L-band amplifier was achieved using 3m length of Zr-EDF while 1480nm pumping is found to provide higher attainable gain and better noise figure as compared to 980nm pumping. At a pumping wavelength of 1480nm and an

We have derived a set of equations for beam waist at lens focus as a function of variable spot size and demonstrated their physical validity. The derived equations are useful for the estimation of the beam waist size of high peak power lasers focused with high numerical aperture lenses and for spot size measurement of long-range collimated Gaussian beams for several meters. We have described an indirect

Nonlinear plasmonic metasurfaces have recently attracted considerable interest, due to their potential for enabling nanoscale nonlinear optics. Here, we review the current progress in this topic while paying special attention to existing challenges. In order to limit our scope, we concentrate on nonlinear metasurfaces utilizing inter-particle and lattice effects and focus on metasurfaces operating

In this work, Silicon oxide (SiO2) nanoparticles, graphene oxide nanosheet (GO) and GO–SiO2 nanohybrid composites have been synthesized. The role of GO concentration in the starting solution was investigated and correlated to the morphological, structural and optical properties of the studied samples. The structural studies for nanohybrid composites showed that by increasing GO:weight ratio from 0

Dual-band unidirectional reflectionlessness is investigated in a system consisting of three stub resonators side-coupled to a metal-insulator-metal plasmonic waveguide based on near-field coupling in terahertz domain. Reflectivities of ∼0(∼0.65) and ∼0(∼0.97), respectively, at two exceptional points 4.11THz and 4.695THz are obtained for forward (backward) direction. More than that multi-band unidirectional

The paper focuses on a problem that describes propagation of transverse-electric (TE) waves in a plane dielectric waveguide filled with nonlinear medium. The nonlinearity is characterized by the power term α|E|2q, where α, q>0 are constants and E is the electric term of the guided electromagnetic field. The layer is located between two half-spaces filled with linear media having constant permittivities

A series of branched styryl derivatives based on 1,3,5-triazine were studied by nonlinear optical property measurement, degenerated pump-probe, and time-resolved fluorescence anisotropy methods to elucidate the two-photon absorption (TPA) properties and intramolecular interactions between branches. Significant enhancement of the TPA cross-section was observed in multi-branched derivatives. The anisotropy

We present a theoretical analysis of a single n-photon absorption process. We found an approximate analytical but closed-form expression of the normalized transmittance for a thin nonlinear material under an elliptic Gaussian incident beam. The obtained expression can be used to fit the experimental Z-scan traces, allowing the determination of material’s multiphoton absorption coefficient and Rayleigh

In this paper, wavelength conversion based on optofluidic infiltration of photonic crystal fibers (PCFs) is investigated to achieve the suitable wavelength over wide tunable range. For this purpose, two designs of PCFs (the so-called PCF1 and PCF2) with appropriate dispersion properties are simulated, and wavelength conversion via four-wave mixing process for pump wavelengths in both normal and anomalous

We study the fundamental nonlinear modes in a dual-cylinder waveguide shell, which features a self-focusing Kerr effect, coupled by a double-well connection. This double-well connection is twisted by a pitch rate and creates a spatial dependent linear mixing, which plays the role of an effective rotating double-well potential. Symmetry transition between the waveform and the power distribution of the

We study the thermodynamic properties of coherent photons in self-focusing nonlinear waveguides. The equation of the superfluid state of photons has been derived. There is a transition temperature Tc, above which the photon gas is in the coherent state, but below which the photon gas is in the superfluid state. At Tc, the photon system undergoes a first-order phase transition from the coherent to the

Vector beams with the desired polarization structure interacting with matter result in many novel nonlinear optical effects. Herein, we review the tight focusing and weak focusing properties of three types of light beams, namely, linearly polarized beams, cylindrical vector beams, and hybridly polarized beams. In particular, we revisit the second- and third-order nonlinear optical effects in nonlinear

The first-, second- and third-order nonlinear optical properties of N-(6-hydroxyhexyl)-5-nitroazophenyl carbazole in gas phase employing sum-over-states (SOS) method have been calculated for the first time. The ground state molecular structure of N-(6-hydroxyhexyl)-5-nitroazophenyl carbazole was obtained by the geometrical optimizations based on the B3LYP/6-31+G(d) level. The energy of excited states

We propose and demonstrate a dispersion-independent erbium-doped mode-locked fiber laser by incorporating a chirped fiber Bragg grating (CFBG) into the laser cavity. Our experimental results show that the fiber laser has similar output characteristics, no matter which section of the CFBG is connected to the laser cavity through a circulator, i.e., opposite dispersion is introduced into the laser cavity

Based on the Collins formula in strongly nonlocal nonlinear media (SNNM), the analytical expression for Lorentz beam passing through SNNM has been derived. It is found that the propagation behavior of Lorentz beam is variable and closely related to the parameters of initial ellipticity p and input power. The beam has its own critical power in x and y directions, respectively. If the Lorentz beam with

Effects of spectral diffusion on the third-order nonlinear susceptibility for two- and three-level quantum systems, immersed in a thermal reservoir, are evaluated with a four-wave mixing (FWM) signal through the density matrix formalism. For this, inhomogeneously broadened two- and three-level quantum systems are used. In these models, the distribution of natural frequencies follows a Lorentzian function

The equations governing nonlinear light beam propagation in nematic liquid crystals form a (2+1)-dimensional system consisting of a nonlinear Schrödinger-type equation for the electric field of the wavepacket and an elliptic equation for the reorientational response of the medium. The latter is “nonlocal” in the sense that it is much wider than the size of the beam. Due to these nonlocal, nonlinear

Investigations were made for optimizing ZnTe as a THz detector at 1560-nm probe beam wavelength, and was compared with its performance at 780nm. High-sensitive THz detection was achieved when phase matching was maintained for long coherence lengths between the probe beam and the incident THz waves. A 1-mm thick ZnTe crystal enabled detection bandwidths of THz radiation up to 2 and 3 THz with probe

Nonlinear frequency conversion is the important method to get coherent radiation in all-optical waveband. The intentional manipulation of nonlinear harmonic wave, which has some special phase, amplitude, polarization, and so on, is also important to realize all kinds of optical micro-manipulation, optical micro-fabrication, and optical communication in all-optical waveband. There are three methods

This study deals with numerical simulations to optimize the parameters of the Dark Filed Z-scan (DFZ-scan) in a microscopic configuration for third-order nonlinear (NL) refraction measurements into thin films. The method allows dynamic, transparent, nonlinear phase shifts to be clearly visible. The simulations of such images are obtained for very low-induced refractive indices. Darkfield illumination

The crucial role of nonlinear propagation effects in the self-guiding of femtosecond laser pulses required accurate representation of nonlinearities to describe them. In this paper, an improved theoretical model has been proposed to study the height distribution of the atmospheric nonlinear refractive index. The results show that the revised model obviously improves accurate estimation of nonlinear

By measuring the ultraviolet-light-induced absorption in Sc-, Mg- and Zn-doped near-stoichiometric lithium niobate (LiNbO3), we find that the steady-state ultraviolet-light-induced absorption coefficient changes with respect to the doping concentration. There is a strong ultraviolet-light-induced absorption when doping concentration is below its photorefractive threshold and a really weak absorption

Designing low-loss waveguides for terahertz waves is challenging as most materials are very lossy in this frequency band. Most scientists simply consider transmitting the waves through low-loss air, which however also has its own difficulties as index-guiding is not possible. In this paper, we report on the design of low-loss waveguides for terahertz waves and associated results by using a finite element

We consider nonlinear optical systems describing the propagation of beams in Kerr-type nonlinear media, experiencing diffraction in transverse and longitudinal directions. The first model investigated, under nonparaxial approximation, is the complex nonlinear Helmholtz equation, recast into a coupled, real system of partial differential equations. We construct and apply its conserved vectors to determine

The optical properties of quantum dots (QDs) are of interest to many researchers. In this study, the optical coeefficients analyzed include the optical absorption, the refractive index; both the linear and nonlinear cases together with the electric field effect. The electronic structures of the disc-like and spherical QDs are calculated by using the effective-mass approximation. The results show that

Three tri-branched oligomers based on 1,3,5-triazine with large two-photon absorption cross-sections and good optical limiting properties were investigated by UV–Visible, femtosecond Z-scan and one/two-color pump-probe measurements. The two-photon absorption cross-section results measured at a wavelength of 800nm were found decreasing with the number of fluorene groups in each branches. The optical

The optical properties of benign and malignant human brain tumors were investigated to provide a new diagnosis method. We studied various samples of adult human brain tissue (male and female) in two linear (by Optical density) and nonlinear (by Z-scan method) regimes. The obtained experimental results show that optical density for malignant is more than benign tissues and the nonlinear behavior of

We study the effect of Kerr type nonlinear medium in quantum state transfer (QST). We have investigated the effect of different coupling schemes and Kerr medium parameters p and ωK. We found that the Kerr medium introduced in the connection channel can act like a controller for QST. The numerical simulations are performed without taking the adiabatic approximation. Rotating wave approximation is used