Kerr Nonlinear Material Research Articles

Collapse Dynamics of Vector Vortex Beams in Kerr Medium with Parity–Time-Symmetric Lattice Modulation

Based on the two-dimensional (2D) nonlinear Schrödinger equation, we investigate the collapse dynamics of a vector vortex optical field (VVOF) in nonlinear Kerr media with parity–time (PT)-symmetric modulation. The critical power for the collapse of a VVOF in a Kerr-ROLP medium (Kerr medium with a real optical lattice potential) is derived. Numerical simulations indicate that the number, position, propagation distance, and collapse profile of the collapse of a VVOF in sine and cosine parity–time-symmetric potential (SCPT) Kerr media are closely related to the modulation depth, initial powers, and the topological charge number of a VVOF. The VVOF collapses into symmetric shapes during propagation in a Kerr-ROLP medium, and collapse shapes are sensitively related to the density of the PT-symmetric optical lattice potential. In addition, due to gain–loss, the VVOF will be distorted during propagation in the Kerr-SCPT medium, forming an asymmetric shape of collapse. The power evolution of the VVOF in a Kerr-SCPT medium as a function of the transmission distance with different modulating parameters and topological numbers is analyzed in detail. The introduction of PT-symmetric optical lattice potentials into nonlinear Kerr materials may provide a new approach to manipulate the collapse of the VVOF.

Study of temperature distribution in a metallic nanograting based on a Kerr nonlinear material irradiated by a nanosecond pulsed laser

Study of temperature distribution in a metallic nanograting based on a Kerr nonlinear material irradiated by a nanosecond pulsed laser

Colossal Kerr nonlinearity without absorption in a five-level atomic medium

In this work, we present an analytical method to achieve giant Kerr nonlinearity without absorption in a five-level atomic medium. By using iterative perturbation technique on density matrix equations, we have derived the analytical expressions of nonlinear susceptibility and Kerr nonlinear coefficient in the presence of spontaneously generated coherence (SGC) and relative phase between applied laser fields. It shows that, this five-level atomic medium exhibits multiple electromagnetically induced transparency (EIT) at three different frequencies, at the same time, the Kerr nonlinear coefficient is enhanced around three transparent spectral regions; in each such EIT region appears a pair of positive–negative peaks of Kerr nonlinear coefficient. In particular, these nonlinear peaks are moved to the center of the EIT windows via SGC. This means that the Kerr nonlinear coefficient is enhanced with completely suppressed absorption at different transparency frequencies. Furthermore, the magnitude and the sign of the Kerr nonlinear coefficient are easily controlled according to the SGC strength, the coupling laser intensity, and the relative phase between applied laser fields. Such a giant nonlinear medium can be useful for photonic devices working in the resonant frequency region without absorption. As a typical application, this giant Kerr nonlinear material has been applied to an interferometer for the formation of optical bistability, and showed the appearance of OB at the resonant frequency with significantly reduced threshold intensity and OB width.

Dual control all-optical switch based on MIM door-type waveguide

In this paper, a simple plasma switch structure based on metal-insulator-metal (MIM) waveguide with dual control of pressure and light intensity is proposed and numerically simulated by finite element method. This structure consists of two rectangular cavities and a door-type bus waveguide with a circular barrier, and produces multiple resonances which can be adjusted independently by changing structural parameters. Pressure can effectively and selectively control the switch at different working wavelengths, and light intensity can also do this when the structure is filled with Kerr nonlinear materials instead of air. The transmission responses of the structure induced by pressure and light intensity are approximate S-curve, which proves that pressure and light intensity can realize switching effect. Furthermore, when only the bottom of a rectangular cavity is filled with Kerr nonlinear materials, an Off-On-Off switching process is achieved, in which the structure is switched from Off state to On state under pressure control and then from On state to Off state under light intensity control, and the extinction parameters are larger than 0.98. The dual control switch may be a suitable candidate for composite all-optical device in optical integrated circuits.

A multimaterial sensor with Janus characteristics based on enhanced particle swarm optimization algorithm

This paper presents an enhanced particle swarm optimization (EPSO) algorithm for optimizing the parameters of a layered photonic structure. By dynamically adjusting the thickness and refractive index of each dielectric layer, the phase and absorption properties of the transmitted electromagnetic waves (EWs) can be modified, effectively achieving high absorption rates by incorporating defects formed by the Kerr nonlinear material. The proposed EPSO algorithm facilitates the identification of the global optimal solution, resulting in the formation of sharp absorption peaks with values exceeding 0.9 for incident EWs from various directions. Leveraging the Janus properties, the EW exhibits distinct physical characteristics when incident from the front and back directions, enabling the creation of sensors tailored for thickness, angle, and pressure sensing. The forward angle sensing demonstrates a high sensitivity (S) of 0.32 nm/degree, a quality factor (Q) of 543.9, and a figure of merit (FOM) of 0.32 degree−1. Both pressure and thickness can be sensed in both forward and backward directions, with S of 5.46 nm/GPa and 10.24 nm/GPa, mean Q of 563.9 and 316.7, and FOM of 5.5 GPa−1 and 3.3 GPa−1, respectively. Thus, it can be stated that the proposed EPSO holds promising prospects for optical sensor design.

Numerical investigation of optical bistability in a nonlinear plasmonic structure containing a phase change material

In this paper, a controllable nonlinear plasmonic structure is proposed based on a phase change material (PCM) layer to achieve tunable bistability characteristics. To this end, the Ge2Sb2Te5 (GST) layer (as a PCM) is sandwiched between a thin film of Ag and a Kerr material substrate. Then, this multilayered structure is used as a substrate for the ZnSiAs2 grating whose grooves are filled with the Kerr nonlinear material. Next, the grating is covered with a layer of CaF2. In this structure, we first calculate the reflection spectrum for different crystallization fractions using the finite element method (FEM) in the linear regime. The reflectance spectrum shows a dip in the near-infrared region, which is redshifted with increasing the crystallization fraction of the GST layer. This effect results from the movement of surface plasmon resonance to longer wavelengths with increasing the crystallization fraction. Then, we find that the dip in the reflectance spectrum is redshifted with enhancing the input intensity of the incident wave for different crystallization fractions in the nonlinear regime. This behavior confirms the existence of optical bistability through the proposed structure. So, we calculate the bistability curves at a fixed operating wavelength of 1550 nm for different crystallization fractions. Our results demonstrate that as the phase transition from the amorphous to the crystalline state occurs at a fixed operating wavelength, the bistability thresholds reduce while the hysteresis width also decreases and the bistability effect eventually disappears. Therefore, for each crystallization fraction of the GST layer we find a special wavelength at which a reasonable bistability curve with a reasonable hysteresis width is obtained. This operating wavelength is shifted by 33 nm as the crystallization fraction varies from 0.2 to 0.8. Finally, the effects of increasing the thickness of the GST layer on the bistability characteristics are examined. Our results show that stronger tunability of the operating wavelength by 50 nm with variation of crystallization degree from 0.2 to 0.8 is achieved when a thicker GST layer is used instead of a thinner one.

Design of an agile optical switcher based on a 1D silver plasmonic nanograting filled with a nonlinear Kerr material

In this paper, we investigate the nonlinear optical response characteristics of a metallic nanograting with nonlinear Kerr media within its slits using the finite element method. The proposed nanograting system is illuminated by a nanosecond Gaussian pulse laser under normal incidence and the electric filed pointing across the slits. The results show a perfect linear absorption at resonance wavelength thanks to the coupling of the surface plasmon resonance (SPR) mode and photon cavity mode. We simulate the transient nonlinear absorption variation of the system when the pulse laser is set up at either resonance or off-resonance wavelengths. The results indicate that the unit linear absorption drastically decreases by increasing the laser fluence around the center of the pulse. Interestingly, one can also enhance the weak linear off-resonance absorption to the value of unit by increasing the pulse laser fluence. The higher the laser fluence, the higher the maximum absorption contrast between linear and nonlinear regimes occurs owing to the nonlinear Kerr effect. Indeed, when the laser fluence reaches a critical value, it can excite the Kerr nonlinearity, which changes the coupling strength of SPR mode and the photon cavity mode leading to the absorption adjustment in the nanograting. These properties indicate the possibility of utilizing the proposed nanograting in dual functional absorber and nonabsorber systems, which make it an appropriate candidate for agile optical switching devices.

Optical Kerr nonlinear material for expressing the trigonometric ratios of compound angles

Optical Kerr nonlinear material for expressing the trigonometric ratios of compound angles

Ultra-compact all-optical plasmonic switch for three telecommunication windows using a nonlinear Kerr material and Fano resonance.

In this study, an all-optical plasmonic switch based on a metal-insulator-metal (MIM) waveguide coupled to two rectangular cavities that are perpendicularly connected to each other through a vertical stub is proposed and analyzed both theoretically and numerically. Rectangular cavities are filled with a nonlinear Kerr material, and the switching operation is achieved by applying a high-intensity pump input into the MIM waveguide to obtain nonlinear cross-phase modulation (XPM) effect. The proposed structure is designed so that it can realize the switching operation at each of the three telecommunication windows of 850, 1310, and 1550nm. Realizing the switching operation at these three wavelength bands is accomplished by the Fano resonance. In fact, the Fano resonance is utilized to create a band-stop area that is crucial for building a suitable OFF state for the switching operation at two of the three telecommunication windows of 1310 and 1550nm. The theoretical and numerical results are obtained using the transmission-line model (TLM) and the finite difference time domain (FDTD) method, respectively, the results of which comply well. The proposed ultra-compact all-optical switch has significant applications in photonic integrated circuits (PICs).

Recent Progress of Supercontinuum Generation in Nanophotonic Waveguides

AbstractSupercontinuum (SC) has opened up possibilities for numerous applications in optical communications, signal processing, metrology, and spectroscopy. Supercontinuum generation (SCG) in the integrated nonlinear platforms has attracted much interest recently, due to its fundamental advantages in terms of complementary metal oxide semiconductor compatibility, low power consumption, compact size, and cost‐effectiveness. In this paper, the latest progress on various types of nanophotonic waveguides for SCG is reviewed. The material properties of silicon, germanium, silicon–germanium alloy, silicon nitride, silica, chalcogenide, III–V materials, lithium niobate, and other materials, which are used as nonlinear media for SCG are discussed. The wavelength‐dependent nonlinear Kerr index, material, and nonlinear loss of the waveguides are taken into account. This review mainly focuses on the SCG resulting from the cubic χ(3) nonlinearity processes pumped by the femtosecond pulse. The recent representative SCG works based on the integrated optical waveguides are summarized, and further classified according to the dispersion characteristics. Furthermore, different types of spectra broadening mechanisms in details according to the classifications are analyzed. Perspectives on the SC spectral coverage, the realization of various dispersion curves, and the novel materials, which are the key aspects of the SCG in nanophotonic waveguides are provided.

Design and analysis of series and parallel circuits based on plasmonic waveguides for high-performance computing devices

Abstract Nowadays, mental–insulator–metal (MIM) waveguides are widely used in the design of optical plasmonic waveguides due to their superior ability to confine surface plasmons up to sub wavelength scale. This research proposes the design of series and parallel circuits using cascaded plasmonic Mach–Zehnder interferometers (PMZIs). Each PMZI employs a nonlinear arm to switch light across the output port via the insertion of the nonlinear Kerr material poly(2-methoxy-5-(28-ethylhexyloxy)-PPV). The proposed design is having footprint of 104 µm × 11 µm. The finite-difference time-domain method is used to study, design, and analysis all optical series and parallel circuit proposals.

Discrete vector light bullets in coupled [formula omitted] nonlinear cavities

We consider coupled weakly birefringent cavities filled-in with nonlinear Kerr material and subject to linearly polarized optical injection. Light propagation in such a system is described by a system of discrete Lugiato–Lefever-type equations for each linear polarization component of the electric field into each cavity, coupled by the cross-phase modulation terms and the neighboring waveguides field overlap integrals. We demonstrate that this system supports stable three-dimensional vector localized structures often called discrete vector light bullets. We consider both anomalous and normal dispersion and show that it results in the generation of, respectively, bright and dark discrete vector light bullets. Due to the polarization multistability of the system, we demonstrated coexisting light bullets with polarization at the light bullets peaks as different as predominantly linear to predominantly circular. We have shown that chaotic spatio-temporal dynamics can be realized even for such an injection strengths for which the light bullets distribution in the system is stationary by increasing the coupling strength C between the cavities.

Integrated plasmonic full adder based on cascaded rectangular ring resonators for optical computing

A novel and integrated plasmonic full adder based on cascaded rectangular ring resonators for optical computing is presented. This full adder consists of cascaded rectangular ring resonators covered by graphene layer and resonator-enhanced waveguide crossings. Owing to the nonlinear optical properties of graphene, the plasmonic resonators can work as all-optical switches with low power consumption and ultrashort response time to change the propagation path of surface plasmon polaritons (SPPs). Finite-difference time-domain (FDTD) simulation results numerically verify the realization of full-adder operations. This proposed plasmonic device can realize the optical full-adder operations with small feature size, fast response time, and lower power consumption than when using other traditional nonlinear optical Kerr materials. It can provide new concepts to design novel optical computing devices.

Collapse Dynamics of Vortex Beams in a Kerr Medium with Refractive Index Modulation and PT-Symmetric Lattices

Using the two-dimensional nonlinear Schrödinger equation, the collapse dynamics of vortex beams in a Kerr medium with refractive index modulation and parity–time (PT) symmetric lattices are explored. The critical power for the collapse of vortex beams in a Kerr medium with real optical lattices (i.e., refractive index modulation lattices) was obtained and discussed. Numerical calculations showed that the number of self-focusing points, the locations of the collapse, and the propagation distances for collapse are sensitively dependent on the modulation factors, topological charge numbers, and initial powers. When the vortex optical field propagates in a Kerr medium with real optical lattices, the optical field will collapse into a symmetrical shape. However, the shape of the vortex beam will be chaotically distorted and collapse in asymmetric patterns during propagation in a Kerr medium with PT-symmetric lattices because of the presence of the complex refraction index. Introducing PT-symmetric lattices into nonlinear Kerr materials may offer a new approach to controlling the collapse of vortex beams.

Optical Kerr nonlinear material for calculating the coefficient of binomial expansion under any positive integral index

Optical Kerr nonlinear material for calculating the coefficient of binomial expansion under any positive integral index

Femtosecond laser inscriptions in Kerr nonlinear transparent media: dynamics in the presence of K-photon absorptions, radiative recombinations and electron diffusions

Femtosecond lasers interacting with Kerr nonlinear optical materials, propagate in form of filaments due to the balance of beam diffraction by self-focusing induced by the Kerr nonlinearity. Femtosecond laser filamentation is a universal phenomenon that belongs to a general class of processes proper to ultrashort lasers processing systems, associated with the competition between nonlinearity and dispersion also known to promote optical solitons. The present work considers a model describing femtosecond laser inscriptions in a transparent medium with Kerr nonlinearity. Upon inscription, the laser stores energy in the optical material which induces an electron plasma. The model consists of a cubic complex Ginzburg-Landau equation, in which an additional K-order nonlinear term takes into account K-photon absorption processes. The complex Ginzburg-Landau equation is coupled to a time first-order nonlinear ordinary differential equation, accounting for time evolution of the plasma density. The main objective of the study is to examine effects of the competition between multi-photon absorptions, radiative recombination and electron diffusion processes, on temporal profiles of the laser amplitude as well as of the plasma density. From numerical simulations, it is found that when the photon number (i.e. K) contributing to multiphoton ionization is large enough, taking the electron diffusion processes into account favours periodic structures in temporal profiles both of the laser and the plasma density. The pulse repetition rate in the optical soliton train is increased with increase of the electron diffusion coefficient, while the plasma density is a train of multi-periodic anharmonic wave patterns.

Investigation and analysis of the optical Kerr nonlinear effect caused by metal nanocomposite on the performance of nonlinear hybrid plasmonic waveguide

In this paper, a nonlinear hybrid plasmonic waveguide (HPW) with a layer of metal-nanocomposite as nonlinear Kerr material with the high nonlinear response, long propagation length and tight light confinement for processing and active control of optical signals for nonlinear applications has been proposed. The effective parameters of the nonlinear layer due to third-order susceptibility in the HPW structure, which includes the nonlinear metal-nanocomposite layer, have been analyzed by using the Maxwell-Garnett theory. The presence of metal nanoparticles in the nanocomposite host medium improves the nonlinear effect of the proposed HPW structure. Also, the effect of radius, volume fraction, host medium permittivity related to nanoparticles and nanocomposite on the performance and output results of effective nonlinearity coefficient, propagation length, effective mode area, confinement factor has been simulated by using FEM numerical solution method in TM mode. The proposed nonlinear hybrid plasmonic waveguide is an ideal option for design and application in nonlinear all-optical integrated circuits.

Kerr nonlinearity in asymmetric disc-like quantum dot and its controllability

Nonlinear Kerr materials have the potential to be used as principal components for developing optical quantum computers. Among these materials, quantum dots have high nonlinearity and high Kerr-dispersion. This paper investigated the Kerr effect in a doped asymmetric quantum dot. The results showed that third-order nonlinear optical property such as the Kerr effect can be controlled by Rashba coupling. Experimentally, the strength of Rashba coupling can be changed and thus manipulated by applying a voltage to the electrostatic gate installed on the two-dimensional plane of quantum dots. The numerical calculations illustrated that the presence of attractive impurity and enhancement of the strength of Rashba coupling in an asymmetric quantum dot increase the Kerr nonlinearity. Furthermore, the results demonstrated that the magnitude of the Kerr effect of a symmetric doped quantum dot is larger than an asymmetric doped quantum dot.

Tunable bandpass plasmonic filter based on graphene as the nonlinear Kerr material

In this paper, a band-pass plasmonic filter is introduced based on metal–insulator–metal waveguide coupled with two narrow slabs. Our reported plasmonic structure is investigated using the numerical solution of finite element method. The filter performance is analyzed for two cases of linear and nonlinear. The selected Kerr nonlinear material is a single graphene layer. The simulation results show that, we can tune the resonant wavelength by considering the Kerr effect of the graphene layer, performance and by adjusting the incident light signal without changing the physical characteristics of the structure. The simplicity of the structure and a compact size are the advantages of the proposed nonlinear plasmonic filter which make that suitable to design the integrated all-optical circuits.

The tailored saturated-unsaturateddefect modes obtained by nonlinear threshold light in graphene-based hyperbolicmetamaterial

The tailored saturated-unsaturated defect modes are realized in the proposed graphene-based hyperbolic metamaterials (HMs) in the mid-infrared and near-infrared bands by using the threshold light. In the case of saturated absorption, graphene is identified as a transparent and lossless medium. The effects of the incident angle, the number of periods, and the chemical potential of graphene are also taken into consideration. The computed results show that the greater saturated defect mode (SDM) can be observed at a smaller incident angle and a larger period. The unsaturated defect mode (USDM) cannot be affected by the incident angle while it can be controlled by the chemical potential. In addition, two novel threshold lights (0.2 MW/cm2 and 60 MW/cm2) producing bistable graphene absorption are analyzed by adopting nonlinear Kerr (NLK) materials. These results can be applied to nonlinear optical switches and logic devices.