Optical Physics Research Articles

Research of the design of a solar radiation concentrator for autonomous photoenergy installation

Significant increase in power due to the use of concentrators of solar radiation confirms the feasibility of using concentrated radiation, and the development of concentrators makes a separate task of optical physics. Hubs deserve special attention to obtain a high degree of radiation concentration, their development requires a number of innovative technical solutions. The complex researches on optimization of concentrators of solar radiation for use as a part of high-concentration photovoltaic systems by research of optical properties and features of degradation of facet, vacuum and segment concentrators are carried out in the work. According to the results of field testing of the experimental sample of the facet concentrator, it was found that the procedure of adjusting the concentrator is associated with individual adjustment of the position of each of the 400 mirrors, which is extremely difficult. And due to the insufficient rigidity of the structure, the concentrator needs to be adjusted in the settings after the operations of moving or assembling-disassembling the experimental sample of the concentrator. As the concentrator needs regular cleaning due to natural pollution from dust, rain and other natural factors, this operation is associated with mechanical impact on the mirrors, which leads to a violation of their settings. According to the results of testing the vacuum type concentrator, it was found that such concentrators are very sensitive to the quality of the base because due to design features cannot be adjusted after manufacture and they had too large a focal spot larger than the heat sink. According to the results of field testing, it is established that the design of a segment-type concentrator is promising for use in the high-concentration photovoltaic systems, which is a circular array of segments made of mirror material, the integrated reflection coefficient of which reaches 95% and made an experimental sample with an area of 3.6 m2, which allows to obtain a focal spot with a diameter of 120 mm with a trapezoidal light distribution with a radiation concentration factor of 360 units.

Tutorials in vibrational sum frequency generation spectroscopy. III. Collecting, processing, and analyzing vibrational sum frequency generation spectra.

In this Tutorial series, we aim to provide an accessible introduction to vibrational sum frequency generation (VSFG) spectroscopy, targeted toward people entering the VSFG world without a rigorous formal background in optical physics or nonlinear spectroscopy. In this article, we discuss in detail the processes of collecting and processing VSFG data, and user-friendly processing software (sfgtools) is provided for use by people new to the field. Some discussion of analyzing VSFG spectra is also given, specifically with a discussion of fitting homodyne VSFG spectra, and a discussion of what can be learned (both qualitatively and quantitatively) from VSFG spectra.

Abundant optical soliton structures to the Fokas system arising in monomode optical fibers

Abstract Three effective methods, namely, the simplified extended tanh-function method (SETFM), variational method (VM) and He’s frequency formulation method (HFFM) are employed to investigate the Fokas system that arises in the monomode optical fibers. Fifteen sets of the soliton solutions such as the bright soliton, dark soliton, bright-dark soliton, double-dark soliton, double-bright soliton, triple-bright soliton, kinky periodic soliton and perfect periodic soliton solutions are developed. The dynamic performances of the different soliton solutions are plotted via the 3-D contours and 2-D curves to interpret the physical behaviors by assigning reasonable parameters. From the results obtained from this study, it is found that three proposed methods are promising ways to seek various soliton solutions of the PDEs in optical physics.

The Goos Hänchen shifts in the reflection/transmission beams under Kerr nonlinearity, Doppler broadening and Compton scattering

Reflection, transmission as well as absorption coefficients and the corresponding Goos Hänchen shift in reflection and transmission is controlled and modified under the effects of Kerr nonlinearity, Doppler broadening as well as Compton scattering. The summation of the absolute values of these coefficients gives a unit value in the presence of all these effects. Modification of the coefficients follows the normalization condition. Maximum GH-shift in the reflection/transmission is investigated to ±3λ. Above ϕc=π/6, the GH-shift is saturated at the value λ in both reflection/transmission. The positive as well as negative GH-shift is measured in the absence and presence of Compton scattered reflected/transmitted beam. The GH-shift is the function of control fields, Kerr nonlinearity, incoherent effect of Doppler broadening and incident as well as the Compton scattered angles. The results show potential applications in nano-optics, trapping of optical data, micro-optics, acoustics, sensor technology and plasma physics.

Some invariant solutions of coupled Konno-Oono equations arising in electromagnetic and quantum fields

The goal of this study is to construct a novel family of travelling wave solutions for the system of (1 + 1)-coupled Konno-Oono equations (CKOEs). It occurs in optical nonlinear media, electromagnetic fields, plasma physics, and quantum fields. The invariant property of Lie symmetry analysis is exploited to extract analytical solutions. Lie symmetry analysis provides new similarity solutions for the system. A new variety of eighteen analytical solutions are compared to the reported results and the authors’ recently published work. In the previous results, a specific form of CKOEs with only two components, u and v, was solved in almost all cases, whereas in this study, a family of solutions was attained for three variables, u, v, and w. Solution profiles are portrayed via numerical simulation in order to make the solutions physically relevant.

Thickness-dependent slow light gap solitons in three-dimensional coupled photonic crystal waveguides.

The thickness-dependent multimodal nature of three-dimensional (3D) coupled photonic crystal waveguides is investigated with the aim of realizing a medium for controlled optical gap soliton formation in the slow light regime. In the linear case, spectral properties of the modes (dispersion diagrams), location of the gap regions versus the thickness of the 3D photonic crystal, and the near-field distributions at frequencies in the slow light region are analyzed using a full-wave electromagnetic solver. In the nonlinear regime (Kerr-type nonlinearity), we infer an existence of crystal-thickness-dependent temporal solitons with stable pulse envelope and use the solitonic pulses for driving quantum transitions in localized quantum systems within the photonic crystal waveguide. The results may be useful for applications in optical communications, multiplexing systems, nonlinear physics, and ultrafast spectroscopy.

Magnetic modulation of topological polarization singularities in momentum space.

The polarization singularities in momentum space, rather than in real space, are capturing interest for active singular optics with exotic light scattering and various topological phenomena, which have potential applications in vortex nano-lasers, valley exciton emission, and others. Here, we propose to magnetically control the polarization singularities in momentum space in the photonic crystal slabs with inversion spatial symmetry (P symmetry). A pair of C points (circular polarization points) with the same topological charge is spawned from a V point (polarization vortex center), and they can be dynamically shifted in momentum space with the variation of the magnetic field. Moreover, the coupling between transverse electric (TE) and transverse magnetic (TM) modes induced by the magnetic field gives rise to a hybrid mode, which can close certain leaky channels to achieve an accidental V point. Such active manipulation of polarization singularities with magnetic field is promised for various applications in light-matter interactions and reveals novel phenomena and physics in singular optics and topological photonics.

Possible realization of optical Dirac points in woodpile photonic crystals.

The simulation of fermionic relativistic physics, e.g., Dirac and Weyl physics, has led to the discovery of many unprecedented phenomena in photonics, of which the optical-frequency realization is, however, still challenging. Here, surprisingly, we discover that the woodpile photonic crystals commonly used for optical frequency applications host exotic fermion-like relativistic degeneracies: a Dirac nodal line and a fourfold quadratic point, as protected by the nonsymmorphic crystalline symmetry. Deforming the woodpile photonic crystal leads to the emergence of type-II Dirac points from the fourfold quadratic point. Such type-II Dirac points can be detected by its anomalous refraction property which is manifested as a giant birefringence in a slab setup. Our findings provide a promising route towards 3D optical Dirac physics in all-dielectric photonic crystals.

STEM Education Implementation to Enhance Student Learning Outcomes in Optics Concept

This paper reports the implementation of the STEM learning strategy to the 20 physics students on optical physics concepts. Previously, student understanding on this subject was categorized as weak, this was caused by not only learning just carried out theoretically but also the student's limitation to figure out the optical phenomenon. This research is to identify the student learning outcomes before and after STEM implementation by using simple experimental work with a set of pre-test and post-test. The calculation results show that the student's outcome has a medium enhancement which is about 0.53. Certainly, a Stem learning strategy is a good choice as a teaching strategy in the Optical Physics subject.

Investigation on molecular alignment induced by the few-cycle laser pulse and its phase evolution

BackgroundMolecular alignment and orientation are the hot topics in the ultrafast optics and the atomic, molecular and optical physics, since they are involved the laser field interaction with the atoms and the molecules. Objective and methodHere, we investigate the alignment of gaseous carbon monoxide induced by the strong few-cycle laser pulse based on the rigid rotor approximation theory. ResultsThe simulations show that there is a periodic recurrence in the alignment degree depending on the laser intensity, which is reduced by the dephasing-rephasing processes of molecules’ rotation. The carrier-envelope phase of the few-cycle laser also affects the alignment of the molecules, and produces a phase evolution alignment. The underlying physical mechanisms are discussed. SignificanceOur results might give a clue to understand the controlling the rotations of the gaseous molecules by the few-cycle laser pulse, and other revolved high-density physics processes.

Dark, bright and singular optical solutions of the Kaup–Newell model with two analytical integration schemes

We have searched for optical solutions of Kaup–Newell equation (KNE) used in nonlinear optical and plasma physics, which have a very important role in the class of derivative nonlinear Schrödinger equations (dNLSEs). To obtain exact wave solutions of the proposed model, two analytical techniques, recently presented as new Kudryashov’s method and the generalized projective Riccati equations method (GPREM) have been applied for the first time. These two methods are based on traveling wave transformation and homogeneous balance principles . The presented nonlinear partial differential equation (NLPDE) has been converted to ordinary differential equation (ODE) using traveling wave transformation. Thus, new analytical solutions have been obtained by applying the proposed methods. The new solitons and other traveling wave solutions acquired will be a motivation to researchers working in engineering and applied physics. Various constraints have been used to ensure the validity of the obtained solutions and to get the most appropriate solutions. To illustrate the physical phenomena of this model, 2D, 3D and contour plots of some derived solutions have been depicted with explanatory graphics.

Novel exact and approximate solutions to the family of the forced damped Kawahara equation and modeling strong nonlinear waves in a plasma

In this investigation, a set of novel exact and approximate analytic solutions to the family of the forced damped Kawahara equation (KE) are derived in detail. This work is divided into four main parts: in the first part, the ansatz method is employed to obtain some novel exact solutions to the integrable Extended KE (EKE). In this part, we use some different hypotheses to derive many exact traveling wave solutions (including solitary waves (SWs) and cnoidal waves (CWs)). In the second part, the ansatz method is devoted for deriving some exact SWs and CWs solutions to the forced KE. In the same part, two different general formulas to the analytical approximations to the forced damped KE are obtained. In the third part, the family of forced damped modified KE (mKE) is analyzed comprehensively via several different techniques in order to obtain several approximations. At the beginning, two different general formulas with different accuracy to the forced damped mKE are derived. Also, a particular soliton solution to the forced damped mKE is obtained using a direct ansatz. After that, a general formula for the approximate solution to the forced undamped mKE is obtained. In the fourth part, we focus our efforts on obtaining some approximations to forced EKE. The validity of all exact solutions is checked. Moreover, the maximum global residual error to the analytical approximations is estimated. This investigation can help all researchers interested in studying the characteristics of many nonlinear phenomena in various fields of science such as physics of plasmas, physics of fluids, nonlinear optics, Veins and capillaries, Oceans and seas, etc.

ReflectSim: an open-source software for teaching optical light reflection of nanostructured materials

Leveraging computational resources for modern physics education has become increasingly prevalent, especially catalyzed by the COVID-19 pandemic when distance learning is widely implemented. Herein, we report an open-source software for students and instructors to on-demand simulate optical reflection behaviors of one-dimensional photonic crystals (1D-PCs), a model system for understanding light–matter interactions relevant to materials science and optical physics. Specifically, our MATLAB application, ReflectSim, employs an adapted transfer matrix method simulation and can account for the effects of several critical material design parameters, including interfacial roughness and layer geometry, to determine the reflectance spectrum of user-defined 1D-PCs. By packing our codes into a graphical user interface, this software is simple to use and bypass the requirement of any coding experiences from users, which can be widely used as an education tool in high school/undergraduate classrooms and K-12 outreach activities. We believe that ReflectSim provides great potential for assisting students in understanding optical phenomenon in nanostructured layered materials and relevant scientific concepts through enabling more engaging learning experiences.

Dark Matter Meets Atomic, Molecular, and Optical Physics

Dark Matter Meets Atomic, Molecular, and Optical Physics

Manipulating and measuring single atoms in the Maltese cross geometry.

Background: Optical microtraps at the focus of high numerical aperture (high-NA) imaging systems enable efficient collection, trapping, detection and manipulation of individual neutral atoms for quantum technology and studies of optical physics associated with super- and sub-radiant states. The recently developed "Maltese cross" geometry (MCG) atom trap uses four in-vacuum lenses to achieve four-directional high-NA optical coupling to single trapped atoms and small atomic arrays. This article presents the first extensive characterisation of atomic behaviour in a MCG atom trap. Methods: We employ a MCG system optimised for high coupling efficiency and characterise the resulting properties of the trap and trapped atoms. Using current best practices, we measure occupancy, loading rate, lifetime, temperature, fluorescence anti-bunching and trap frequencies. We also use the four-directional access to implement a new method to map the spatial distribution of collection efficiency from high-NA optics: we use the two on-trap-axis lenses to produce a 1D optical lattice, the sites of which are stochastically filled and emptied by the trap loading process. The two off-trap-axis lenses are used for imaging and single-mode collection. Correlations of single-mode and imaging fluorescence signals are then used to map the single-mode collection efficiency. Results:We observe trap characteristics comparable to what has been reported for single-atom traps with one- or two-lens optical systems. The collection efficiency distribution in the axial and transverse directions is directly observed to be in agreement with expected collection efficiency distribution from Gaussian beam optics. Conclusions: The multi-directional high-NA access provided by the Maltese cross geometry enables complex manipulations and measurements not possible in geometries with fewer directions of access, and can be achieved while preserving other trap characteristics such as lifetime, temperature, and trap size.

Some solutions for a stochastic NLSE in the unstable and higher order dispersive environments

The nonlinear Schrödinger equations (NLSEs) arise from a large variety of fields, such as quantum mechanics, optical fiber communication, plasma physics, superfluid and many others. In this article, we consider the stochastic unstable nonlinear Schrödinger equation (UNLSE) and higher order dispersive nonlinear Schrödinger equation (HODNLSE). Namely, we consider these equations by a multiplicative noise in Itô sense. We applied the efficient solver in order to get the vital solutions. The forms of presented solutions are rational; trigonometric; hyperbolic functions. Some of acquired stochastic solutions are new and practical. The presented solutions perform an important factor for understanding the qualitative interpretation in various physical environments, such as optical fibers, plasma fluids and new physics. With the help of Matlab software, some graphs were given to depict the behavior of the gained solutions.

Characteristic behaviour of N-order ion acoustic rogue waves solution in electron-positron-ion plasmas

The characteristic behaviour of breathers as well as N-order Rogue wave (RW) solution in homogeneous unmagnetized electron-positron-ion plasmas (consisting of cold ions, and isothermal Maxwellian electrons and positrons) has been studied theoretically. Nonlinear Schrödinger (NLS) equation is derived employing Krylov-Bogoliubov-Mitropolosky (KBM) perturbation technique in solving the concerned problems. The analytical solution of the NLS equation in the forms of breathers such as Akhmediev breather (AB), Kuznetsov-Ma breather (KM) solitons, as well as first-, second-, third-, and fourth-order RWs solution are obtained. The characteristic behaviour of breathers’ and their dependency on the relevant physical parameters are examined. The different orders of RWs are analyzed to obtain the region of existence of ion acoustic (IA) rogue waves (IARWs) with respect to unstable region. The potential profiles concerning different orders of RWs depend on the ratio of positron to electron concentrations () and wave number (). Analysis reveals that the spatial difference between the two adjacent peaks of AB profiles are increasing with the enhancement of transformer physical parameter (), while the temporal evolution between the two neighboring peaks of KM profiles decreases with increasing and the amplitudes become large as well. The amplitudes of first-, second-, and third-order RWs profiles are decreasing with increasing while the amplitude of fourth-order RWs profile is increasing. The results obtained in this study may be useful in understanding the propagation of nonlinear waves in optical fibers, Bose-Einstein condensates, plasma physics and atmospheric physics.

Highly accurate THz-CT including refraction effects

The principles of algebraic image reconstruction are applied to THz computed tomography (THz-CT) in order to account for refraction within the sample. Using the nominal sample geometry as a priori knowledge, a highly accurate and robust image reconstruction algorithm based on the physics of geometric optics is presented. The validity of the geometric forward model is verified by a numerical simulation of Maxwell's equations. Furthermore, the developed method is experimentally tested using measurements performed with a fast THz-CT system based on a THz time-domain spectrometer in transmission mode. Automated evaluations of the reconstructed sample cross sections showed an accuracy of <150 μm.

Analytical soliton solutions for cold bosonic atoms (CBA) in a zigzag optical lattice model employing efficient methods

This research finds an equation in a continuous domain and a discrete equation governing the system of cold bosonic atoms (CBA) in a zigzag optical lattice using a continuum approximation. Many solutions to the equation were obtained using two distinct methods: the three-wave approach (multi-wave interaction, rational solutions, and rational solution interaction) and the extended sub-equation method. These analytical approaches are more effective, consistent, and comprehensive mathematical tools for obtaining various exact closed-form solutions for a wide range of fractional space-time nonlinear evolution equations encountered in optical physics, condensed matter physics, and plasma physics. The solutions generated are in the form of hyperbolic and trigonometric solutions, and other-form solutions are obtained. Three-dimensional graphics and contour plots are often used to depict the graphical representations of the combined soliton solutions. These findings will aid our understanding of the dynamics of the zigzag optical grids and many other structures formed by colder bosonic atoms. The applied approaches are more simple, efficient, and straightforward to obtain the closed-form solutions for various nonlinear evolution equations in the fields of nonlinear sciences and physical engineering.

Tutorials in vibrational sum frequency generation spectroscopy. I. The foundations.

Interfaces between bulk media are often where critical molecular processes occur that can dictate the chemistry of an entire macroscopic system. Optical spectroscopy such as IR or Raman spectroscopy is often challenging to apply to interfaces due to contributions from bulk phases that dominate the spectra, masking any detail about the interfacial layer. Vibrational sum frequency generation (VSFG) spectroscopy is a nonlinear spectroscopy that allows vibrational spectra of molecules at interfaces to be directly measured. This Tutorial series is aimed at people entering the VSFG world without a rigorous formal background in optical physics or nonlinear spectroscopy. In this article, we present the fundamental theory of VSFG spectroscopy, with a focus on qualitative, intuitive explanation of the relevant physical phenomena, with minimal mathematics, to enable a newcomer to VSFG spectroscopy to quickly become conversant in the language and fundamental physics of the technique.