This PDF file contains the front matter associated with SPIE Proceedings Volume 13168, including the Title Page, Copyright information, Table of Contents, and Conference Committee information.

In 2020, the fifth-generation fixed network research group ETSI ISG F5G published technical specifications to define fixed network generations F1G-F5G, similar to mobile network generations. The working materials of this group identified the basic principles for the implementation of fixed-line networks that should appear in the near future. Recently, a number of additions and extensions to F5G concept have been proposed, which have received the collective name F5G Advanced. The article presents an analysis of the main directions of development of F5G Advanced networks based on new optical technologies in the future by 2030.

The paper presents the results of experimental studies of variants of construction of intermediate frequency paths of microwave radiometric systems based on the traditional scheme of construction using copper coaxial transmission lines of intermediate frequency signals of microwave radiometric receivers and promising radiophotonic fiber-optic transmission line of microwave signals with internal modulation. The aim of the work is to evaluate the possibility of realization of the radiophotonic path for transmission of intermediate frequency signals as a part of perspective microwave radiometric systems for remote sensing of the atmosphere. The objectives of the work are to analyze the characteristics of radiophotonic transmitting and receiving modules as part of the intermediate frequency path of a multi-frequency microwave radiometric system for remote sensing of the atmosphere in comparison with a coaxial radio-frequency transmission line.

The article considers the prospects of introducing an optical measurement channel into the composition of a complex radiophysical system of remote sensing of the atmosphere. Lidar systems of atmospheric monitoring for distribution of aerosol and chemical composition of air, as well as wind speed and direction are the most widespread. The study of aerosol and gas composition of air is especially important in the tasks of environmental monitoring of areas associated with hazardous industries and global transport of pollutants, including greenhouse gases. Molecular (gas) atmosphere at laser sounding is manifested in absorption, in the phenomena of molecular (Rayleigh), Raman, resonance scattering and fluorescence. These phenomena differ in their intensity or interaction cross sections and, consequently, in the possibilities for reliable registration of signals. Atmospheric parameters such as wind speed and direction, visibility, density and height of cloud layers change both temporally and spatially, which can lead to the formation of dangerous meteorological phenomena. Atmospheric aerosol plays an important role in climate change, so monitoring its composition and dynamics is essential for assessing climate change on a global scale.

Quantum technology based on the quantum mechanics and optical physics to meet the grand challenge of new principles for sensing and information transfer in the photonic layer. An important aspect of the is quantum technologies is the development of new cryptosystem. Quantum networking research is giving rise to the field of quantum internet. This will involve the use of quantum computing in the application layer, quantum repeaters in the quantum transport or teleportation layer, and quantum end nodes or gateways in the quantum network layer. Photonic quantum sensors based on avalanche photodiodes for entangled photon detection will be included in the sensor nodes for the quantum internet of things as an example. Quantum optical sensors can be used for quantum metrology, quantum lithography or for the quantum radar and detecting gravitational waves. The quantum internet of things as a part of the quantum internet will utilize a quantum approach to security. Since the implementation of quantum networks with quantum internet of things would allow for quantum cryptography. This paper provides a brief analysis of quantum techniques for modern communications. The paper discusses the main entities of a quantum network, quantum sensor, and quantum internet. It considers an architecture for quantum internet of things representation based on the quantum networks. A proposed integrated functional architecture for quantum internet of things will be presented, which will include quantum key distribution, quantum teleportation, and quantum sensing will be proposed.

Orthogonal Frequency Division Multiplexing (OFDM) technology1 has found wide application in optical communication systems due to its efficient use of available bandwidth, absence of intersymbol interference, and mitigation of dispersion and nonlinearity effects in the optical channel. However, OFDM has several drawbacks, the key one is the problem of high peak-to-average power ratio (PAPR)2 . In optical transmission systems3 , this becomes particularly relevant as it leads to nonlinear distortions caused not only by power amplifiers but also by LED emitters, thereby reducing the efficiency of converting light into communication and significantly impacting the lifespan of the LED and laser diode. This paper describes a new PAPR reduction method based on the application of the Kronecker product in the transmitter and receiver matrices formation in asymmetrically-clipped optical OFDM. It is applied in the transmitter side by the Kronecker product of the IFFT matrix and the data matrix, and then in the receiver by the Kronecker product of the FFT matrix and the channel matrix. Creating these matrices can distribute the signal power across all subcarriers and maintain orthogonality, thereby contributing to reducing the peak-factor. Numerical experiments were conducted to evaluate the effectiveness of the method. Simulation results show that this approach can reduce the peak-factor value by 2.3%. Overall, the developed method based on the Kronecker product provides a promising solution for reducing PAPR in OFDM optical systems and can be used to improve the performance and efficiency of data transmission in optical communication systems, moreover, this signal undergoes further transformation - the formation of quasi-orthogonal multiplexing methods for transmission on the air network.

The article is devoted to the problems of modern communications, namely – to custom experimental fibers that be used in future communication systems. We consider a non-standard optical fiber which, due to its structure, offers an advantage in multi-channel transmission via different modes. This fiber has a hollow-core structure which means that traditional light coupling methods can be not efficient. In the experimental part, the conductivity of the fiber tested by finding a solution to improve the radiation coupling into the fiber. The conclusion presents the final with the experimental results and summarizes the topic of the paper.

The article is devoted to the consideration of the possibility of using the chirp function of optical pulses as a resource for radio segment control in RoF-systems. Such a resource does not belong to the traditional telecommunication resource, is realized at the physical level and is characterized by high speed. The scheme of RoF-segment construction is proposed - using the developed components: the converter «Chirp To Amplitude» and interference splitter. In the case when the antenna array forms a spatial separation of VLANs, it is shown that the parameter of payload of device interfaces improves in relation to the VLANs traditionally formed on the radio segment.

Background. The subterahertz and terahertz frequency ranges are very promising for development of high speed wireless communications systems because of possibility to get the bandwidth about some tens of GHz, which provides the high channel capacity. However fast signal attenuation at its propagation in atmosphere complicate the operation of communications systems in these ranges. Aim. Use of fixed narrow-beam antennas with high antenna power gain allows to provide the direct surface communications distance to some kilometers. The communications distance limitation can be partially removed decreasing the frequency down to 200 GHz and narrowing the channel bandwidth down to some GHz. Methods. The model of transmitter-receiver system (200-220 GHz) based of modern semiconductor devices is described in the manuscript. Results. The possibility of digital signals transmission with speed up to 1 Gbit/s at the distance of 1 km is experimentally shown. Conclusion. According to calculations the output power of transmitter about some hundreds mW is enough for data transmission at the distance up to 1.5 km with antenna power gain of no less than 50 dB.

The article discusses the optoelectronic properties of the new poly[2-ethyl-3-methylindole]. Samples of phototransistors were obtained in which thin films of polyindole were used as a transport layer, their characteristics were measured and analyzed under the influence of ultraviolet radiation with a wavelength of 350 nm. Organic field-effect transistors based on synthesized pyrrolidinofullerenes have also been created. The family of output characteristics for pyrrolidinofullene and polyindole was determined. The mobility of charge carriers in thin films of polyindole and pyrrolidinofullerene has been estimated. The kinetics of the current photoresponse in transistors based on polyindole and pyrrolidinofullerene films has been studied.

The main objective of this paper is to create scientifically based principles for design of two-component asymmetric address fiber Bragg structures (λ+λ/π)-AFBS of the combined type. As can be seen from the name of such a structure, it consists of two sequentially installed FBG and FBG with a phase shift, having different wavelengths spaced apart at the address frequency. Additional requirements for the structure of an asymmetric (λ+λ/π)-AFBS are defined as the same bandwidth of both FBGs, which will determine the difference in the power of radiation reflected from them without and with a transparency window. Wave FBG, λ-FBG, is an important part of fiber-optic sensors, which has many advantages, such as compact structure, the ability to organize quasi-distributed measurements, low transmission losses and resistance to electromagnetic interference. In addition, a conventional λ-FBG is practically insensitive to bending and the external refractive index. This makes measuring strain, temperature and other parameters more convenient and accurate. FBG with a phase shift, in particular with a phase shift of π, π-FBG, has attracted widespread attention. π-FBGs not only have the advantages of λ-FBGs, but also have many special sensory characteristics, which are determined by different quantities and methods of generating the phase shift. It should be noted that the presence of narrow-band transparency windows in the π-FBG makes it possible to increase the resolution of sensors compared to the λ-FBG by a number of times equal to the ratio of the transmission bands of the λ-FBG and the transparency window of the π-FBG. Therefore, they have high advanced applied value in various sensor systems. Two-component asymmetric (λ+λ/π)-AFBS of the combined type according to our evaluations should allow us to obtain a synergistic effect from their use in various systems, including intellectual energy systems built according to the Smart Grid Plus concept.

The work presents an overview and classification of combined fiber-optic resonant structures, which are essentially a combination of a Fabry-Perot interferometer (FPI) and a fiber Bragg structure. The latter can be represented either as a conventional fiber Bragg grating (FBG), or an addressed fiber Bragg structure (AFBS) of various types. It is shown that such combined resonant structures can serve as sensing elements of various fiber-optic measurement systems, detecting such physical impacts as temperature, pressure, acoustic waves, etc. One of the proposed structures is a fiber optic FabryPerot interferometer based on an open macro cavity at the end face of an optical fiber. Immersing the end face of the optical fiber with macro cavity in liquid leads to the formation of an air bubble where interfacial surfaces act as FabryPerot mirrors, which allows to use the structure for detecting pressure or acoustic waves in liquids. Another considered type of an FPI is composed of layer of borosilicate glass at the end of an optical fiber, acting as a temperature sensor. It is demonstrated that the combination of FPI and fiber Bragg structure can be used as a unified basic element for the various optical fiber sensors, utilizing the Fabry-Perot cavity at the end face of the fiber and the Bragg structure as fundamental sensing elements.

This article is devoted to the generation of surface plasmon at the interface “graphene coating – quartz glass”, as well as on the surface of a round conducting particle. Such plasmons are of interest for creating sensor devices in medicine and biology due to the neutrality of graphene coatings. It is said that to increase the sensitivity of the sensor, the plasmon should be amplified. It has also been shown that the presence of conductive particles in the substance under study affects the overall refractive index of the substance and changes it even at the most insignificant concentration of additional substances (analytes).

This work reports comparative results of mode analysis, performed for earlier on designed silica microstructured optical fiber with ideal equiangular spiral six-ray geometry (ESSR-MOF) and for its real fabricated sample, differing from the model by weak asymmetry and deformed air holes. We discuss issues of input data preparation to specify analyzed complicated non-ideal fiber optic structure for computation by using rigorous finite-element method. Some results of the comparison between mode field patterns as well as guided mode effective refractive index spectral characteristics are represented. It is demonstrated, that potential deviations from the desired MOF geometry, occurring due to features of silica MOF fabrication technological process, should be taken into account during the design to predict real values of mode parameters for manufactured MOF.

The paper proposes a conversion method «ILCF-to-amplitude» based on an erbium fiber-optic amplifier. The main design parameters of the conversion device are estimated. It is proposed to select the parameters of the erbium medium in such a way as to obtain the largest steepness of the amplifying characteristic of the converter in the region of the operating wavelength of the segment radiation. On the basis of the stationary model of signal conversion processes in EDFA the basic parameters of the converter are obtained, after which their refinement is performed. Using a specialized simulator, the transfer function of the proposed converter and the possible noise level in the system are determined.

A technological feature of optoelectronic oscillators (OEO) is the combined use of solid-state components of modern RF and microwave optoelectronics, fiber light guides and the traditional element base of microwave equipment. According to the principle of operation and the scheme of construction of the OEO is similar to the classical radio frequency oscillator with a delay line in the feedback circuit. A feature of his work is the multi-frequency nature of the generated oscillations, for which the conditions of amplitude balance and phase balance are met. Of particular interest is the process of self-excitation of the oscillator from noise to stable signal generation.

The study explores the potential applications of fiber optic sensors for user verification tasks. An experimental validation of the considered methods for recognizing speech signals obtained from acoustic sensors is conducted. In the experiment, voices of four different speakers were recorded. Each speaker sequentially uttered the same text simultaneously using a capacitor microphone and a fiber optic distributed sensor. To create the dataset, each speaker read three prepared texts. After training the system on the dataset and achieving speech signal recognition with sufficiently high accuracy recorded from the capacitor microphone, attention was turned to addressing the challenge of noise elimination. For this purpose, background noise was separately recorded at the experimental site. The conclusion is drawn regarding the applicability of mel-frequency cepstral coefficients for solving the task of identifying individuals based on the sound signal obtained from the fiber optic sensor with a specified accuracy.

Earlier on we introduced model of piece-wise regular fiber optic link, operating in a few-mode regime: laser-based data transmission over large core optical fiber. Presented model is based on piecewise regular representation with general approach of split-step method application. It allows to take into account laser-excited optical signal launching conditions, differential mode delay, differential mode attenuation, higher-order mode chromatic dispersion and mode mixing / power diffusion, occurring due to optical fiber irregularity and fiber optic cable bends / twisting / stress / tension. While optical fiber irregularity can be directly set by protocols of optical fiber outer diameter monitoring system of drawing tower, cable external mechanical influences are simulated via equivalent angular misalignment at the splices of regular spans. Therefore, this work is concerned with issues of selection of this equivalent angular misalignment (EAM). We performed a computational test series under various values of mentioned above EAM under following comparison with experimentally measurements of few-mode optical pulse responses at the output of multimode optical fibers with strong differential mode delay effect.

This work intends to present various Photonic Crystal fibers (PCF) for the propagation of orbital angular momentum(OAM) modes. Hexagonal, spiral and octagonal-shaped fibers are designed for the observation of OAM modes. The proposed fiber designs have shown high purity of nearly 90% and has proved that the hexagonal design has the highest mode confinement. The finite element method is employed to obtain 12 OAM modes at the operating wavelength of 1.55 μm.

All-optical computing has drawn increased interest from researchers in recent years to meet the need for fast optical signal processing. This paper demonstrates the design of an all-optical CNOT logic gate using a silicon nitride (Si3N4) based optical ring resonator (ORR). Two optical ring resonators have been employed to design the CNOT logic gate. The simulation results obtained from MATLAB using the mathematical equations of the ring resonator validates the proposed CNOT logic gate. The proposed CNOT logic gate is compact and elementary.

This work presents results of test series, performed for earlier on designed and successfully fabricated silica few-mode microstructured optical fibers (MOF) with six GeO2-doped cores, induced twisting 50 revolutions per meter, typical “telecommunication” outer diameter 125 µm, core diameter 8.7 µm, air hole diameter 4.6 µm, pitch 7.2 µm, and core graded refractive index profiles with height 0.0275. While Part I introduced results of differential mode delay map measurements with laser source excitation / laser-based data transmission over multimode optical fibers (MMFs) with core diameters 50 and 100 µm, combined with 6-core MOF, Part II was concerned with researches of spectral responses, measured for fiber Bragg gratings, recorded in these MOFs, and Part III was focused on laser beam profile measurements, performed for weakly and strong twisted 6-core-MOFs, Part IV reports results of MMF-MOF-MMF fiber optic structure spectral response measurements under direct tension with pull load 0…300 g.

The paper presents a photonic integrated circuit (PIC) concept for dual-band swept-source optical coherence tomography (SS-OCT). We designed the PIC for work with two swept sources with operation bands 820-880 nm and 1260-1360 nm. The PIC contains reference and sample arms and k-clocks for both bands. In both cases, k-clocks are unbalanced MachZehnder interferometers with a free spectral range greater or equal to the light sources’ operation bands. The PIC is developed for a silicon nitride manufacturing platform with minimum losses.

In the course of work, a fiber optical system for the temperature of high-voltage busbars, conflicts and other loaded nodes of electrical networks was developed based on the control of fiber Bragg gratings. The system has a temperature determination error of ±1 °C and a resolution of 0.1 °C. Observed temperature changes for high voltage applications have also been considered and observed. The main advantage of the developed system is the ability to quickly use export-optical deliveries as an increase in the level of the system, which in turn is associated with a significant cost of one channel measurement and use per system deployment. In the course of study, the sensor part of the system was developed in the form of two temperature sensors, a sensor interrogation device and its software. Further, a number of experiments on detection of sensors calibration curves was carried out, studies of sensors were carried out for the occurrence of a breakdown between phases, trial operation was carried out at the operating object for selecting electrical networks for one month. The results of the studies show that the system can perform its functions in various operating conditions, the ways of developing the system functions were outlined, which consist in the number of measurements and the use of the system to control the wear of superconducting radiation on contact groups.

The presented work compares the methods of probing classical fiber Bragg gratings and targeted fiber Bragg structures in problems of monitoring the parameters of mechanical vibrations. In the course of the work, a prototype of an acoustic system for continuous monitoring of processes based on Bragg gratings was developed and experimentally studied within the framework of trial operation; the limitations of measurement methods based on FBGs were shown. In the course of a comparative analysis of the response of the sensor to a homogeneous FBG and an equivalent AFBS circuit, it was revealed that the transition to addressable structures makes it possible to reduce the lower detected frequency by 3.3 times due to operation in the region of lower noise of the photodetector.

The main objective of this paper is to create scientifically based principles for the development of two-component symmetrical wave address fiber Bragg structures with a phase π shift (2λ/π-AFBS) as new sensitive elements of microwave photonic sensor systems. As can be seen from the model of such a combined structure, it consists of two sequentially installed FBGs with a phase shift. Additional requirements for the structure of a symmetrical 2λ/π-AFBS are defined as the same bandwidth of both FBGs and the transparency windows in them. In asymmetrical 2λ/π-AFBS these values may differ from each other. Phase Nπ-AFBS and wave Nπ-AFBS have their advantages and disadvantages. The corresponding development and elimination of their shortcomings is aimed at the creation of 2λ/π-AFBS with a certain frequency difference between the Bragg frequencies of the first and second FBGs, which is called the main address frequency for transmission, and at which the central wavelengths of the transparency windows are located. The width of the transparency window at the level of maximum reflection of symmetrical FBG components allows the formation of an additional address frequency for reflection, which is one order of magnitude lower in frequency than the main one. In FBG components, transparency windows that are not identical in bandwidth can also be formed, and, accordingly, different additional address frequencies. Two-component symmetric 2λ/π-AFBS of the combined type according to our evaluations should allow us to obtain a synergistic effect from their use in various systems, including intellectual energy systems built according to the Smart Grid Plus concept.

The work presents a concept of a fiber-optic sensing element, which allows to simultaneously measure humidity, pressure and temperature, and is based on a multi-layer Fabry-Perot interferometer (FPI). The basic element of the proposed FPI is a droplet-shape air-filled cavity obtained using the catastrophic fuse effect of a single-mode fiber. The opening of the cavity is covered with a diaphragm composed of a double-layer film, the first (inner) layer of which has an increased thermo-optical coefficient, while the second (outer) layer’s refractive index is sensitive to humidity of the ambient medium. The outer pressure causes the deflection of the diaphragm, which leads to the change of the length of the air-filled cavity. The work also discusses the requirements for the parameters of the materials constituting the sensor, based on the results of the reflected optical spectrum modeling of the sensing structure at various ambient conditions, which would provide the desired measurement performance.

The article proposes the concept of constructing a comprehensive fiber-optic sensor (CFOS) for simultaneous measurement of relative humidity and air temperature, as well as the temperature of a solar cell. The sensor is represented by a double structure, consisting of a two-stage Fabry-Perot interferometer for measuring relative humidity and air temperature and a two-component wave addressable fiber Bragg structure for measuring the temperature of a solar cell. The sensor is inserted orthogonally to the plane of the solar photovoltaic panel into the technological hole formed in it so that the distance between the addressable fiber Bragg structure(s) and the Fabry-Perot interferometer module allows simultaneous measurement of relative humidity and air temperature, as well as the temperature of the solar panel. A change in relative humidity affects only the refractive index of the outer interferometer, while a change in air temperature affects the refractive index of both interferometers. Changing the temperature of the solar cell only affects the central wavelength of the addressable fiber Bragg structure. By solving a system of equations using the specified parameters, relative humidity and air temperature, as well as the temperature of the solar battery, can be controlled simultaneously. The structure and design of an integrated fiber-optic sensor and the results of the first experiments are presented, which confirmed the possibility of simultaneous measurement of the parameters under consideration that affect the efficiency of solar panels.

The paper presents a comparison results of three different photonic-assisted instantaneous frequency measurement methods. The working principles of the photonic time stretch enhanced recording scheme, the parallel low-speed optical sampling technique and channelization method with image-rejection down-conversion are presented. Each of the presented schemes was modelled through multiple simulations in the VPIphotonics Design Suite 9.8 software environment. The overall results showed that frequency measurement accuracy for the photonic time stretch technique was around 100 MHz, as for the parallel low-speed optical sampling approach was 0.5 MHz and for the channelization method was 0.4 MHz. The advantages and disadvantages of each scheme were also pointed out.

This work reports results of dispersion analysis, performed for the fundamental mode of silica microstructured optical fiber (MOF) with six GeO₂-doped cores. We used commercially available software COMSOL Multiphysics® 6.1 with rigorous full vectorial finite element method, while earlier on fabricated and presented MOF with six step-index GeO2- doped cores end face photo image was applied to get averaged parameters for input data. Therefore, modeled multi-core MOF has typical “telecommunication” outer diameter 125 µm, it contains six cores with diameter 9.0 µm and step refractive index profile with height n=0.0275, 121 air holes with diameter 5.0 µm and pitch 7.8 µm. In this work we present results of the fundamental mode 1st…3rd order dispersion parameters, computed over all ratified “telecommunication” wavelength bands.

This work presents results of mode analysis and dispersion spectral characteristic computation, performed for recently presented successfully fabricated silica few-mode microstructured optical fiber (MOF) with hollow-GeO₂-doped-ring core (HRC). Here, we utilized manufactured HRC MOF end face photo image to get averaged parameters for input data. Therefore, following simplified model HRC MOF was simulated and researched: it has outer diameter 67 µm; inner diameter of hollow ring-core is 10 µm, wall thickness 4 µm and refractive index difference Δn = 0.030 (percent of GeO2 dopant is about 20.5 mol%); 90 air holes, placed over typical hexagonal geometry in the periphery region with averaged diameter 1.85 µm and pitch 3.9 µm. According to simulation results (mode analysis, performed by rigorous finite element method via commercially available software COMSOL Multiphysics® 6.1), modeled HRC MOF provides two guided LP-modes (fundamental LP₀₁ and the first higher-order LP₁₁) or 4 HE/EH odd and even eigenmodes – HE₁₁/EH₁₁ and HE₂₁/EH₂₁, respectively: therefore, two orbital angular momentum (OAM) modes (OAM₁₁ and OAM₂₁) are localized and supported by the researched and simulated HRC MOF design. In this work we present results of spectral characteristics, computed for mode effective refractive indexes as well as for mode group delays and chromatic dispersion parameters, calculated both for eigen and OAM modes.

In this work, using the finite differences time domain (FDTD) method, we calculated the diffraction of a polarized Gaussian laser beam both on a set of elliptical and circular dielectric plates rotated relative to each other which can be considered as a twisted waveguide. The possibility of forming beams resembling a helical photonic jet and light traps is shown.

The speckle reduction on the multidimensional television signals is an important task in measurement machine vision systems. The greatest error due to speckle is detected in triangulation optical sensors if measuring objects have a periodic structure. When measuring such objects, a random interference pattern determines speckle noise. Speckle noise can be reduced by a two-camera profile sensor. Cameras capture the multidimensional image of an object in different angles and the interference pattern on the images will also be different. This allows removing it from the image. The first feature of processing is signal superposition in conditions of distortion. This problem is solved by preprocessing. The second problem is speed processing of superposition. It is solved using pyramid transformation and optical flow estimation. The developed speckle noise reducing technique was tested on multidimensional television signals with images of drill-pipe threads. In the comparison of single-camera profile sensors the error of the shape estimation of the object decreased from 0.20 mm to 0.05 mm.

Multidimensional television images processing for panorama creation is an important problem. A panorama is defined by images alignment. The television images have been shot from an unmanned aerial vehicle. And panorama is made by post-processing regime. All snapshots have been transmitted to the computer for processing. In this case the most of the time is wasted not for image processing, but for transmitting from a data storage device of an unmanned aerial vehicle to a computer with software. The solution with data post-processing is not suitable for prompt decision-making. The article describes the algorithm with high performance, which allows solving the task of the panorama creation during the fly time. The computing resources of an unmanned aerial vehicle are used for data processing.

In this paper, a comparative simulation of 3D image formation during phase apodization of an optical system by a zone spiral element and a Laguerre-Gauss (LG) rotating beam generator was is carried out. The formation features of rotating point spread functions (PSF) and their rotation rates were investigated. The obtained results showed that the rotating LG beam has more universal properties in comparison with the beam from the zone spiral element, since the rotation speed can be changed due to the combination of mode indices, while the beam structure is preserved along the whole length. These results can be useful for selecting a 3D imaging method in various applications including optical measurements, coding microscopy.

This report presents results for focusing a field with an inhomogeneous polarization distribution: the incident field has elliptical polarization with parameters of the ellipse of polarization depending on the position. We primarily consider the case of fixed value of inclination of the polarization ellipse and the varying ratio of the semi-axes. Calculations were performed using the Richards-Wolf formulas. Results show the ability to obtain various distributions when changing the initial parameters. Special attention is paid to the properties of the Umov-Poynting vector.

The propagation of optical vortices with different polarizations through subwavelength elements with standard and GRIN substrates was simulated in this paper. The possibility of recognizing circular, radial, and azimuthal polarization at different heights of relief elements is shown. The possibility of selecting an element and polarizing laser radiation in such a way as to obtain a long focal segment (DOF = 6.16λ, radial polarization), a narrow focal spot (FWHM = 0.42λ, azimuthal polarization), and optical traps has also been demonstrated. Numerical simulations were performed using the finite difference time domain method.

This work presents results of test series, performed for earlier on designed and successfully fabricated silica few-mode microstructured optical fibers (MOF) with six GeO₂-doped cores, induced twisting 100 and 600 revolutions per meter, typical “telecommunication” outer diameter 125 µm, core diameter 8.7 µm, air hole diameter 4.6 µm, pitch 7.2 µm, and core graded refractive index profiles with height 0.0275. While Part I introduced results of differential mode delay map measurements with laser source excitation / laser-based data transmission over multimode optical fibers (MMFs) with core diameters 50 and 100 µm, combined with 6-core MOF, and Part II was concerned with researches of spectral responses, measured for fiber Bragg gratings, recorded in these MOFs, Part III reports results of far-field white light beam profile measurements, performed for weakly and strong twisted 6-core-MOFs.

Intelligent systems significantly reduce routine work for doctors and improve diagnostic accuracy in medical diagnostics. However, the algorithms' effectiveness may be hindered by the heterogeneity of medical data and intermediate phases of a patient's clinical presentation. Additionally, not all intelligent systems can provide sufficient interpretability to analyze the clinical correlation between the system's responses and the actual clinical picture, thereby limiting their implementation in real medical practice. This article presents a solution for developing an intelligent algorithm to stage age-related macular degeneration of the fundus, a socially significant disease, including the challenging-to-detect intermediate stage, and an approach to visualize the algorithm's work in predicting disease stages. The algorithm's performance, developed based on a multimodal approach, was compared with deep neural networks and other multimodal approaches with commonly used data fusion algorithms. The comparison results demonstrate the elimination of the class imbalance effect due to the difficulty of detecting the intermediate disease stage, resulting in a reduction in the dynamic range of specificity and sensitivity values for all classes to no more than 5% for the developed approach. Moreover, the accuracy for the intermediate stage increased by 20% compared to existing commonly accepted data fusion algorithms.

This work reports results of laser beam profile measurements, performed for earlier on designed and successfully fabricated silica few-mode microstructured optical fiber (MOF) with hollow-GeO₂-doped-ring core (HRC). We compared two drawn from the same preform HRC MOF samples without and with induced during the drawing process twisting of 790 revolutions per meter. Researched silica HRC MOF with outer diameter 65 µm contains hollow ring-core inner diameter of 30.5 µm with wall thickness of 1.7 µm and refractive index difference Δn = 0.03; 90 air holes, placed over typical hexagonal geometry in the periphery domain from the outside HRC at the distance 14 µm, with hole averaged diameter 2.5 µm and pitch 7.5 µm. According to simulation results (mode analysis, performed by rigorous finite element method via commercially available software COMSOL Multiphysics®), it supports two guided LP-modes (fundamental LP₀₁ and the first higher-order LP₁₁) or 4 HE/EH odd and even eigenmodes – HE₁₁/EH₁₁ and HE₂₁/EH₂₁, respectively. We present some results of laser beam profile measurements, performed under various launching conditions (different laser sources as well as excited optical fibers (both commercially available single-mode optical fiber of ITU-T Rec. G.652 and multimode optical fiber 50/125 of ISO/IEC Cat. OM2+/OM3)) at the output ends of researched HRC MOF twisted and untwisted samples as well as at the output end of large core multimode optical fiber 100/125, aligned with excited HRC MOF.

The purpose of the study is to develop a method for predicting the development of observed processes of various natures using their digital images containing information that is inaccessible to visual perception. The scientific novelty lies in the transformation of digital images, which allows us to qualitatively and quantitatively assess the state of the observed process (system). In this case, a qualitative analysis of the dynamics of changes in a digital image is carried out visually with an accuracy of one pixel. To quantify the stability of the system, the Hurwitz criterion was used. The developed method was used to assess the surface strength of fatigue specimens under bending loading. As a result, it was found that small changes on the surface of the specimen, which are not visually recorded, make it possible to determine the moment when the system starts to lose its steady state.

In this paper, a random noise study is carried out, generated by an optical random number generator based on an InGaAs p-i-n photodiode. The influence of the procedure of equalization of the energy values of the of the continuous wavelet transform on the efficiency of passing the test for the FFT randomness from the set of NIST statistical tests.

It is well known that the speed limitations inherent in conventional electronics can be overcome using photonic circuits, one of the main building blocks of which is a time differentiator. This device provides the time derivative of the complex envelope of an arbitrary input optical signal. Possible applications include optical pulse shaping, optical computing, information processing systems and ultra-high-speed coding, among other applications. The paper discusses the principles of constructing fractional order differentiators. Using the example of an asymmetric fiber Bragg grating with a π-phase shift operating in reflection, based on addressed fiber Bragg structure of Moiré type, the possibility of implementing a photonic fractional differentiator is shown. We present modeling of the characteristics of the spectral structures of a differentiator, which uses gratings of the same length, but with different modulation depths on both sides of the localization of the π-phase shift, using a new method of homogeneous layers.

Based on the analysis of methods and devices development for all-optical differentiation of signals and addressable fiber Bragg structures as sensitive elements of sensors, the possibility of combining the advantages of the latest versions of their implementation based on symmetric Moiré Bragg gratings has been found. For differentiators, which, as a rule, are considered as separate devices, the issues of their network multiplexing for a single module of photonic processing and computing of multiple signals, as well as the stability of differentiation characteristics with deviations in the temperature regimes of the laser and differentiator with a corresponding mismatch of their central wavelengths, are not touched upon. The advantages of microwave photonic processing of information used for addressable fiber Bragg structures will make it possible to solve the above problems of photonic differentiators when they are combined into a network. This conclusion is proved by the procedure presented in the report for the synthesis of addressable fiber Bragg structures of the Moiré type and the unity of their structure with the structure of photon differentiators.

This article presents the results of a comparative analysis of isofields and isolines of the distribution of the main tensile stresses, indicating the orientation of the elementary areas of their application in a bendable reinforced concrete slab, obtained using the SCAD Office software package, with the results of an experimental research using fiber-optic sensors based on fiber Bragg gratings (fiber Bragg grating - FBG). The results of modeling and experimental research were obtained with a balanced loading of the slab over the entire surface with free support along the perimeter. A model made of organic glass with isotropic elastic characteristics was considered as the tested sample. The article shows the fabricated experimental setup and presents the results of a survey of sixteen fiber-optic sensors placed on the internal and external surfaces of the tested sample.

The paper presents the study of a phase-sensitive reflectometer's potential for recording acoustic emission signals from the early stages of optical fiber defect growth. The methods of registering acoustic emissions and two possible ways of forming defects in the optical fiber are described. As a result, it is demonstrated that pulsed acoustic emissions can be recorded during the process of defect formation on the optical fiber surface.

The article presents the results of an experimental study of the possibility of application a phase-sensitive reflectometer to register nonlinear acoustic emissions during the formation of defects in optical fibers. The method for control of nonlinear acoustic emission parameters in optical fibers was proposed and the peculiarities of using a phase-sensitive optical reflectometer was considered.

The paper presents a method of underground dielectric optical fiber cable route tracing using a distributed acoustic sensing based on phase-sensitive optical reflectometer. The results of field tests are presented, demonstrating the performance of the method and the ability to determine the location of the cable route with an accuracy of ± 0.2 meters.

The article analyzes possible options for solving the problem of finding the laying route and localizing damage locations for all-dielectric optical cables and transport multichannel communication of fiber-optic communication lines. Based on the analysis, two most promising methods were identified. This is the use of electronic marking systems and acoustic monitoring systems using cable optical fibers as a distributed acoustic sensor. Practical recommendations for the implementation of the proposed methods are given.

The article discusses the problem of reducing the transmission speed of images and any other digital data in mobile networks when errors occur. The decrease in speed is explained by a different approach to the issue of data transmission quality in communication networks and in IP networks - if in communication networks a very small, but non-zero probability of error is acceptable, then in IP networks the TCP protocol ensures guaranteed delivery, and the data packet is delivered either without errors, or a connection failure is detected. The solution to the problem is to increase the noise immunity of the communication channel and reduce the probability of error at the decoder output to 0.000001. This requires a method of noise-resistant coding with a much greater correction capacity compared to the known codes used in communication networks. This method is the holographic coding method. When using it, the average speed of information transmission increases, the load on channels with retransmitted packets decreases, and freeing up channels will make it possible to do without additional frequency resources and an increase in the number of base stations. To ensure that the redundancy of the holographic code does not reduce the transmission speed in channels with good communication quality, it must be turned on only in those channels where a drop in speed of more than 10 times is recorded.

Universal problem of spectral characterization for element base of microwave photonic means from broad band electrooptic and optical electronic modulators and receivers to narrow band Bragg and Fabry-Perot filters is very actual. The presented modulating and forming devices contain, in a minimal structure, a special laser diode and two modulators, the first of which is calibrated (master) and has a significant impact on the accuracy of modulation and forming in second (functional), and ensuring the operating modes of both modulators affects the complexity of the devices structure. The last one element is photoreceiver with given characteristics as laser diode ones. The purpose of the work is to present developed devices for various implementation with a minimized structure and simple control, which allow achieving results similar to those obtained using complex multi-stage, two-port, dual, parallel, polarization divided Mach-Zehnder modulators, accompanied with acousto-optic and polarization modulators, all of which have become unavailable under the sanctions pressure. Their advantages can become more significant using microminiaturization technologies – combined microwave and photonic, photonic and quantum integrated circuits (PIC), developing in KNRTU-KAI and UUST, especially under the influence of external climatic factors. These aspects are discussed in the report using the examples of instantaneous frequencies measurements, broadband spectral characteristics of modulators and photoreceivers, quantum key distribution systems with frequency coding. Few words are said about sensor networks.

The paper considers a method for quantizing the phase of a vortex lens by the defined level which makes it possible to control the generation of diffraction orders (local foci) containing vortex phases. Two-level and three-level quantization examined in detail.

The paper describes an approach to the construction of microwave photonic vector analyzers that allow assessing the transfer and linear characteristics of optoelectronic, electro-optical and optical elements. The approach is based on the use of two- and three-frequency probing radiation generated through modulation conversion in an electro-optical Mach-Zehnder modulator.

Optoelectronic oscillator (OEO) output frequency stabilization in various use cases is urgent, especially for integrated photonics realizations. OEO environmental changes sensitivity limits the commercial use of this frequency generator type. In this article, we showed the application possibility of the tunable optical delay element for frequency stabilization. Also, we presented a mathematical model of the OEO with a tunable delay element for the output frequency control. We used Ansys Lumerical software for the mathematical model verification. The frequency tuning range is 2.6 GHz with a 50 MHz/ps frequency step.

Vortex beams, characterized by a spiral phase distribution and bearing orbital angular momentum, have unique properties that make them valuable for the research and practical applications. Such beams are used in optical communications, optical manipulation, including tweezers, super-diffraction limit imaging, mode-division multiplexing, and quantum coding. This work investigates the dependence of the radiation flux density of an emitted optical vortex beam depending on the emitting structure geometry. A micro-ring resonator with etched holes is used as a vortex beam emitter. In our study, optimizing the width of the ring waveguide leads up to 30% for the resonant wavelength 1563 nm increase in the power flow density. In order to analyze how the whispering gallery modes are distributed in the cross-section of the ring waveguide, we enlarged the width of the ring waveguide from 400 nm to 500 nm. This approach can be applied to radiating micro-ring resonators in various applications.

A nanophotonic resonator with high Q-factor and low mode volume is a promising system for creating optoelectronic devices on a chip and enhancing the light-matter interaction. In this work, the parameters of a silicon nitride nanophotonic resonator have been optimized to generate high-quality resonant states. The calculations were carried out using a deterministic method of achieving high Q-factor values.

In this paper, we propose module scheme of a quantum commutator for different photonic states based on combining photonic interface and polarization quantum memory. The Q-Commutator ensures the transformation and store of photonic states with reconfigurable time delay, which significantly facilitates the implementation of hybrid quantum networks. The interface module receiving photonic qubits with phase-frequency encoding transmits them to the input of memory module, converting them into polarization encoding. As a memory cell we use a polarization quantum memory consisting of a small number of high-quality WGM ring resonators capable of storing a wideband multi-frequency signal. The proposed configuration has low noise and can be used to build a quantum repeater and distributed sensor systems.

This study presents a model of a fully connected neural network (NN) implemented on elements of integrated photonics, including the software implementation of this architecture. The main purpose was to compare the results of two NNs, for this reason the average correlation coefficient was calculated, which amounted to 0.9904. This indicates a high degree of similarity and accuracy between the model's performance on PC and photonics elements.

The paper presents an ultrafast spectrum measurement method based on photonic time stretching technology. The working principle of the photonic time stretch enhanced recording scheme is discussed. This scheme, based on the direct detection, have disadvantages such as loss of information about the phase of the modulated signal, high harmonic distortions due to the non-linear characteristic of the output signal due to the squaring of the electric field by photodetector. To avoid these disadvantages, the coherent photonic time stretch enhanced recording scheme is discussed. Further, this time stretching technology was designed in the VPIphotonics Design Suite software environment. Finally, based on the simulation, a graph of measurement error was constructed. The maximum error of the scheme is 180 MHz at the frequency before 5 GHz. After 5 GHz, the frequency measurement error less than 100 MHz and after 10 GHz, the frequency measurement error does not exceed 50 MHz.

The demand for personal competencies in the Russian labor market has been analyzed for vacancies corresponding to the field of study "Information and Communication Technologies and Communication Systems," as well as the potential for their development in the educational process.