Transactions in Optics and Photonics

Determination of the Baseline in the IR Spectra of External Reflection of Polymers for 3D Objects

2025-03-05T09:21:08+08:00

A methodology for forming a baseline of infrared (IR) spectra of external reflection for objects with a smooth non-flat surface is proposed. The procedure for forming a baseline provides conditions for the correct application of the Kramers-Kronig method. The method is tested in determining the complex refractive index of 3D objects made of polymeric materials.

Multisoliton Bound States in the Fourth-Order Concatenation Model of the Nonlinear Schrödinger Equation Hierarchy

2024-12-13T15:33:38+08:00

We present a comparative analysis of exact soliton solutions that form multisoliton bound states arising in the hierarchy of the even-order nonlinear Schrödinger equations. Specifically, we consider two-soliton bound states in three models: the nonlinear Schrödinger equation, the fourth-order nonlinear equation, and the Lakshmanan-Porsezian-Daniel equation (LPDE). The LPDE may be viewed as one example of aninfinite concatenation hierarchy. The exact integrability of these equations is ensured by the Lax pairs constructed using the Ablowitz, Kaup, Newell, and Segur formalism of the Inverse Scattering Transform method. We confirm that the main property of solitons-to interact elastically and attract or repel each other in the collision region depending on the difference of their initial phases-is also preserved for LPDE solitons, and this property should take place in the entire hierarchy of concatenation models. We present the detailed dynamics of two-soliton bound states periodically breathing in space and time, the conditions of their formation, and analytical formulas for their oscillation periods in all the considered models.

On the Theory of Digital Modulation of Light Transmitted Through a Step-Index Optical Fiber

2025-03-28T14:27:50+08:00

Analog modulation of wireless micro/radio waves as well as optical light waves by multiplexing. An input signal is well established in practice due to technological breakthroughs. The basic methods of modulation of a carrier wave are amplitude modulation Amplitude Shifted Keying (ASK), frequency modulation Frequency Shifted Keying (FSK), and phase modulation Phase Shifted Keying (PSK). Quadrature Amplitude Modulation (QAM) is a combination of amplitude and phase modulation. Among these methods, the simple amplitude modulation is suitable and of practical use in fiber-optic communication as extraneous errors are prevented are prevented by the jacket of the cable containing the fiber-a scenario not applicable in wireless communication. The wave-guide action in a cylindrical optical fiber enables the development of a theoretical model of light propagation which has undergone amplitude modulation. This theory is presented in this paper for a step-index fiber consisting of a homogeneous core with a cladding of slightly less refractive index. The input signal is assumed to be a batch of N bits, which is multiplexed to the carrier light wave, and a general formula is developed for the field intensity measured by the axial component of the Hertz vector of the associated electromagnetic wave at a receiving point. The expression of that field is found in the form of a Fourier integral, which is computed by Fast Fourier Transform (FFT) for simple numerical cases. The theory covers both single mode fibers which can transmit only the fundamental mode of propagation, as well as multimode fibers of greater diameters. The theory provides the character of the wave at a distant receiving station, when the input is in bits for which demodulation techniques are available. In addition the theory provides a method of serial transmission of a number of bits in a batch, provided suitable demodulation technique is available at the receiver end. A simple maximum field strength measure is suggested in the paper.

Vortex Structures in Optical Fibers Under the Influence of Third-Order Dispersion and Self-Steepening Effect

2024-11-20T16:39:51+08:00

The present paper for the first time it is investigated the generation and formation of amplitude-type vortices, propagating in single-mode optical fibers with step-index profile under the influences of third-order dispersion and selfsteepening effect or so called dispersion of nonlinearity of the medium. The main model includes the vector nonlinear amplitude equation, from which a system of two scalar partial differential equations is derived. They describe the evolution of the x and y components of the vector amplitude function of an optical pulse under the influences of these higher order nonlinear and dispersive phenomena. New exact analytical solutions of the resulting system of equations were obtained in the form of optical vortices. They have amplitude type singularity and they are observed as ring structures in the components of the laser pulses. Numerical simulations of the found solutions are performed. It is shown that the vortex parameter m is related to the number of these ring structures. Significant depolarization of the vector electric field in the spot of the laser radiation is registered.

Energy Exchange Between the Polarization Components of an Optical Pulse Under the Influence of Degenerate Four-Photon Parametric Processes

2025-03-11T09:19:13+08:00

The present paper investigates the process of energy exchange between the components of an optical pulse that is propagating in a nonlinear dispersive medium under the influence of degenerate four-photon parametric processes. The effects of self-phase modulation (SPM) and cross-phase modulation (XPM) have been taken into account. The obtained results demonstrate that no energy exchange takes place between the optical components of the pulse when the initial polarization is linear or circular. In the presence of initial elliptical polarization, energy exchange can be observed. The intensity of the energy transmission and its period can be determined using the values of the initial energies and the initial phase difference between the optical components of the pulse.

Pure-Cubic Optical Soliton Perturbation Having Cubic-Quintic Law of Self-Phase Modulation via the New Kudryashov Integration Scheme

2025-03-25T10:18:29+08:00

This paper secures dark and bright pure-cubic optical soliton solution to the perturbed third-order nonlinear Schrödinger’s equation having the cubic-quintic law nonlinearity of self-phase modulation with a couple of self-frequency shift and nonlinear dispersion perturbation terms which related to the Hamiltonian. The recently introduced new Kudryashov integration scheme is used to retrieve these soliton solutions. The suitable parameter selections for the existence of such solitons are also presented. In the second stage, the effects of these terms on the soliton forms are investigated by the cubic-quintic form of the problem under study. The findings obtained are supported by 3D and 2D figures and necessary explanations are presented.

Improving the Photon-Electron Coupling Efficiency in GaN-Based Square Microdisks

2025-06-18T09:15:21+08:00

In this work, two types of GaN-based square microdisks, which are suspended microdisks and microdisks with a porous bottom layer based on standard blue/green Light-Emitting Diode (LED) structures grown on Si substrates, are studied. At room temperature, resonant emission was observed in the suspended square microdisk, and the porous microdisk achieved optically pumped lasing at a wavelength of 479 nm with a threshold of 4.37 mW. Optical field simulations reveal that the bridges of the suspended microdisk not only facilitate the transport of light from the microdisk into the bridges for directed propagation but also have no impact on the internal light field distribution. On the other hand, the lasing results of the microdisks with the porous bottom layer demonstrate that the presence of the porous layer enables a high degree of photon confinement within the active region. The results from both types of microdisks confirm that the electron-photon coupling efficiency can be significantly enhanced in the square microcavities, and furthermore that the optical signals can be effectively transmitted through the bridges of the suspended microdisks. This work presents a highly promising approach for Si-based optoelectronic integration.

Complexity in Nonlinear and Quantum Optics by Considering Kolmogorov Derivatives and Change Complexity Information Measures

2024-12-10T09:20:56+08:00

One of the most challenging tasks in studying phenomena in nonlinear and quantum optics is determining the contributions of the complexities of individual components to the complexity of the entire system (master complexity). To examine these contributions, we considered this issue using information measures: Kolmogorov derivatives based on Kolmogorov complexity (KC) [KC spectrum, KC plane], change complexity (CC), and Lyapunov exponent (λ). We applied these measures to daily time series measured from 2003 to 2005 in Novi Sad (Serbia) for ultraviolet (UV) radiation, which represents a physical complex system, and water vapor pressure as individual components of that system. Based on the measures applied to UV radiation, we determined: (i) the level of chaos and randomness of the measured time series; (ii) the coordinates of points in the KC plane where master and individual amplitudes interact; and (iii) the range of UV radiation amplitudes in which changes in the interaction between the master and individual amplitudes are most pronounced.

Optical Properties of Nanometer Epitaxial Nickel Oxide Films on LiNbO₃ Substrates

2025-03-26T18:10:01+08:00

Nanometer epitaxial nickel oxide films have been successfully fabricated on LiNbO₃ substrates by magnetron sputtering. Optical properties of NiO films were studied in the wavelength range of 250-800 nm, and transmission and reflection spectra of these structures were simulated. The dispersion of the complex refractive index of the grown films was obtained, which ensures good agreement between the calculated and experimental transmission and reflection spectra. The band gap energy of NiO films was evaluated using Ultraviolet (UV)-visible spectroscopy. It is in the range of 3.57-3.59 eV. These studies allowed us to determine the thicknesses of the grown epitaxial films using optical methods and compare them with the results obtained based on the film growth rate and atomic force microscopy data.