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A multiple quantum well (MQW) transistor vertical-cavity surface- emitting laser (T-VCSEL) is designed and numerically modeled. The impor- tant physical models and parameters are discussed and validated by modeling a conventional VCSEL and comparing the results with the experiment. The quantum capture/escape process is simulated using the quantum-trap model and shows a signicant eect on the electrical output of the T-VCSEL. The parameters extracted from the numerical simulation are imported into the an- alytic modeling to predict the frequency response and simulate the large-signal modulation up to 40 Gbps.

This paper investigates and enhances unmanned aerial vehicle (UAV) relay-assisted free-space optics (FSO) optical wireless communication (OWC) systems under the effects of pointing errors (PEs) and atmospheric turbulences (ATs). The incorporation of UAVs as buffer-aided moving relays in the conventional FSO (CFSO) relay-assisted systems is proposed for enhancing the performance of PEs through AT. Using M-PSK (phase shift keying) and M-QAM (quadrature amplitude modulation), the impact of PEs on transmission quality is evaluated in this work. We evaluate and optimize the symbol error rate, outage probability (OP), and signal-to-noise ratio (SNR) for the UAV-to-ground station-based FSO communications systems. The spatial diversity-based relay-assisted CFSO systems can enhance the performance of the UAV-UAV FSO links. In this paper, a new FSO (NFSO) channel model for the hovering UAV-FSO OWC fluctuations under the PEs, AT effects, jitter, deviation, receiving an error, and wind resistance effects are established. To improve the performance of hovering UAV-based FSO relay OWC systems. We reduce the influence of UAV-FSO OWC fluctuations under PEs and AT effects. By receiving incoherent signals at various locations, the spatial diversity-based relay-assisted NFSO systems can significantly increase the system's redundancy and enhance connection stability. Numerical results show that to achieve a bit-error-rate (BER) of $$\le 10^{ - 5}$$ ≤ 10 - 5 , the required SNR is ≥ 23 dB when the wind variance of the UAVs $$\sigma_{\alpha }^{2}$$ σ α 2 increases from 0 to 7 mrad with FSO link distance L = 2000 m. The required SNR is ≥ 25 dB when the wind variance $$\sigma_{\alpha }^{2}$$ σ α 2 is 1 mrad at an OP of $$10^{ - 6}$$ 10 - 6 . To obtain an average BER of $$10^{ - 6}$$ 10 - 6 , the SNR should be 16.23 dB, 17.64 dB, and 21.45 dB when $$\sigma_{\alpha }^{2}$$ σ α 2 is 0 mrad, 1 mrad, and 2 mrad, respectively. Using 8-PSK modulation without PEs requires 23.5 dB at BER of $$10^{ - 8}$$ 10 - 8 while 16-QAM without PEs requires 26.5 dB to maintain the same BER of $$10^{ - 8}$$ 10 - 8 . Compared with 16-QAM without PEs, the SNR gain of 8-PSK without PEs is 3 dB. The results show the relay-assisted UAV-FSO system with five stationary relays can achieve BER $$10^{ - 8}$$ 10 - 8 at 25 dB SNR in the ideal case and $$10^{ - 5}$$ 10 - 5 at 27 dB SNR with AT and PE at FSO length 1000 m. The results show the relay UAV-FSO system outperforms the CFSO at the BER and SNR performance. The effects of UAV’FSO s fluctuation increase when the UAV-FSO link length, $${\text{L}}_{{{\text{fso}}}}$$ L fso increases. The results of the weak turbulence achieve better SER compared with MT and ST. The obtained results show that decreasing $${\text{L}}_{{{\text{fso}}}}$$ L fso can compensate for the effects of UAV-FSO link fluctuation on the proposed system. Finally, we investigated the CFSO relay-assisted UAV-FSO system with aided NFSO-UAVs spatial diversity-based relay-based on NFSO OWC and revealed the benefits of the resulting hybrid architecture.

In this paper, we suppose an underwater optical wireless communication (UOWC) system, where the communication utilizes visible light communication for its advantages as wide spectrum, high data rate and high accuracy. The novelty of this paper is focused on improving the channel estimation between transmitter and receiver, where using Kalman Filter (KF) for channel estimation in UOWCs achieves the best results as compared to other traditional channel estimation methods. The scenario of this paper is summarized in transmitting data from transmitter to receiver via underwater harbor and coastal channels. Two channel models are utilized: weighted double gamma functions (WDGF) and a combination of exponential and arbitrary power function (CEAPF). The modulation technique used is optical orthogonal frequency division multiplexing with two kinds: direct current optical orthogonal frequency division multiplexing (DCO-OFDM) and asymmetrically clipping optical orthogonal frequency division multiplexing (ACO-OFDM). Three different techniques are used for channel estimation: Least Square (LS), minimum mean square error (MMSE), and KF. The simulation results reveal that the ACO-OFDM modulation technique with CEAPF channel modeling using KF achieves the lowest bit error rate (BER) compared to other channel estimation methods. The improvement percentage at BER = 10−1 is 13.3% for ACO-OFDM over DCO-OFDM with CEAPF in coastal water and is is 9.3% for WDGF. This indicates that CEAPF performs about 4% better than WDGF for ACO-OFDM than DCO-OFDM in terms of channel estimation.

This paper aims to improve the channel estimation (CE) in the indoor visible light communication system. The proposal of this paper deals with a system that depends on a comparison between Deep Neural Network (DNN), Yolo v3, and Kalman filter (KF) algorithm, for two optical modulation techniques; asymmetrically clipped optical-orthogonal frequency-division multiplexing (ACO-OFDM) and direct current optical-orthogonal frequency division multiplexing (DCO-OFDM). The CE can be evaluated by the error rates in the received bits, where increased error means a performance decrease of the system and vice versa. Receiving less errors at the receiver indicates improved CE and system performance. Hence, the main aim of our work is to decrease the error rate by using different estimators. Furthermore, we apply automatic hyper-parameter approach and Bayesian optimization, to Yolo v3 model to improve the system performance and reduce the positioning error. The metric parameter of bit error rate (BER) aims to determine the improvement ratio in different systems. The model in this paper is based on training with OFDM samples of signal with labels which are received and are corresponding to the signals of OFDM. At a BER = 10−3 with DCO-OFDM, the DNN outperforms KF with 1.7 dB (8.09%) at the bit energy per noise $$(E_{b} {/}N_{o} )$$ ( E b / N o ) axis. Also, for ACO-OFDM at BER = 10−3, the DNN achieves better results than KF by about 1.9 dB (11.8%) at the $$(E_{b} {/}N_{o} ){ }$$ ( E b / N o ) axis. For different values of M in QAM, the DNN outperforms KF for ACO-OFDM by average improvement of ~ 1.2 dB (~ 13%).

In this paper, core-shell nanoparticles are used to provide a transparent high-quality display. To realize this idea, Si-SiO2 core-shell nanoparticles have been used to achieve the most suitable nanoparticle composition for a transparent color display with high transparency and contrast. For color transparent monitor the superimposed QDs are used. There is a basic question for the realization of the proposed transparent monitor. What is the ratio of nanoparticles (ratio of three QDs) for three colors in the proposed monitor? In this paper, we are going to acknowledge this question. As it is clear, the scattering peaks for red, green, and blue are different because of the physics of the scattering that is wavelength-dependent. Thus, the optimum ratio for each color should be obtained. The numerical method of Finite-Difference Time-Domain is used to simulate and calculate the optical properties of the proposed transparent monitor. The effect of different combinations of nanoparticles to have the maximum dispersion at blue, green, and red wavelengths and the minimum absorption at other wavelengths has been investigated. Finally, the optimum ratio and arrangement of nanoparticles for all colors are reported and numerically evaluated.

Quantum key distribution uses the principle of quantum physics to realize unconditionally secure key distribution protocol. But this kind of security needs to be based on the authenticated classical channel. Although there are quantum key distribution protocols without classical channel, authentication is still needed. In the process of key distribution, authentication is not considered, which is also a problem of quantum key distribution protocol. In this paper, a quantum key distribution protocol with two-way authentication is proposed. Identity authentication is carried out at the same time of key distribution. If the identity authentication fails, the key distribution protocol cannot be carried out. If the key distribution protocol is aborted, the identity authentication is not successful. The conclusion of this paper is based on a central authentication system supported by symmetric encryption theory, which uses pseudo-random functions, multiple sets of quantum conjugate bases and Measurement-device-independent technology to simultaneously achieve two-way authentication and key distribution.

The increasing demand for bandwidth through modern applications and multimedia services has led to high-speed wireless communications. Optical wireless communications (OWC) encourages solutions that provide a higher data rate due to the large bandwidth available. In this paper, performance enhancement approaches are studied and simulated for visible light communication (VLC) as a case study. The orthogonal frequency division multiplexing (OFDM) systems are used to investigate Intensity modulation/direct detection (IM/DD) to improve the performance of VLC. The IM/DD in OWC requires positive real OFDM symbols, so there are many approaches to satisfy this requirement. This paper proposes a model of Asymmetrically Clipped DC-Biased Optical (ADO-OFDM) to use in OWC/VLC environment. The proposed system has avoided the use of the noise cancellation technology that is used in traditional ADO-OFDM. The results show that the ADO-OFDM has the best spectral efficiency than DC-biased optical (DCO-OFDM) and Asymmetrically clipped optical (ACO-OFDM). Also, it has better optical efficiency than DCO-OFDM with the equally overall bit error rate (BER) at the same signal-to-noise ratio. Hamming channel coding/decoding with different code lengths is applied in various optical OFDM schemes for BER improvements. Furthermore, we simulate and analyze these optical OFDM systems with many modulation orders.

Entanglement transmission is utilized widely in quantum communication. In this paper we establish a model, which characterizes the performance of entanglement state passing through the composite free space channel. This free space channel is compounded with atmosphere, sea surface and underwater channel. Based on the model, the entanglement photon pairs transmitted through composite channel are simulated. Simulation results show that the beam wandering, the incident angle of the beam on the sea surface, the concentration of chlorophyll in the seawater and other factors will lead to the degradation of the entanglement and these factors have a nonlinear relationship with transmittance. Moreover, the increase of the chlorophyll concentration is found to be a relatively heavy impact on the entanglement. In addition, expanding the aperture size of the receiving telescope will improve entanglement. The research of this paper has momentous meaning to the transmission of quantum entanglement in free space. What’s more, the results have an extremely vital reference value for quantum communications in diverse natural environments.

This paper presents the analytical inquisition of photonic entanglement generation circuit (PEGC) for non local Qubits designed using quantum dot within the optical micro-cavity, considering practical environment. It is established that the concurrence of the PEGC is considerably contingent on the interplay between spin of quantum dot and photon within the optical micro-cavity. The maximum concurrence obtained is 61.24 at \(g/k=.3\) and \({k}_{s}/k=0.1\) and 90.11 at \(g/k=4\) and \({k}_{s}/k=0.1\) with and without noisy environment, respectively. Different quantum cryptography-based protocols may be implemented using reported work.

Fourier domain mode locked (FDML) lasers are a class of frequency-swept lasers that are used to generate optical pulses with a wide sweep range, high repetition rate, and a low instantaneous bandwidth. They are commonly used in sensing and imaging applications, especially in optical coherence tomography. Ideally, the aspired features in the design of FDML lasers include a high coherence length, large sweep bandwidth, adjustable output power, and a high signal to noise ratio (SNR). However, the SNR of the output signal of FDML lasers is often lower than desired due to the presence of several irregularities in the output signal pattern, most notably because of the frequent occurrence of sharp power dips, also known as holes. These power dips originate due to the nonlinear gain dynamics of the semiconductor optical amplifier (SOA) that is employed in FDML lasers, while the occurrence frequency and strength of these dips are determined by the interaction of the FDML laser components, which involve the SOA, the tunable Fabry–Perot filter, and the optical delay fiber. Suppressing these power dips not only increases the output signal quality in terms of SNR, but also precludes the accumulation of phase offsets between subsequent roundtrips and facilitates convergence. As both current and future applications of FDML lasers are likely to require a higher signal power, in this paper, we are going to investigate the effect of self-phase modulation (SPM) in the optical fiber on dip formation and convergence. Since fiber nonlinearity, intracavity signal power, and fiber length all contribute to SPM, investigation of the effect of SPM on the formation of power-dips and operational convergence is critical. More importantly, the phase-mismatch that is caused by fiber-based SPM cannot be compensated easily in an FDML laser as in the case of chromatic dispersion, which necessitates a strategy for minimizing fiber-based SPM to ensure operational convergence and to secure a lower limit for the SNR of the output signal of FDML lasers.

In this paper, we present a novel method to design an ultra-small photonic integrated biosensor to detect cancerous cells. The proposed biosensor is based on the self-phase modulation in PhC-SOA, inducing a frequency shift on a pulse traveling through the device. The amount of the frequency chirp depends on the group velocity of the active medium waveguide being determined by the refractive index of the microfluidic infiltrating the holes around the waveguide. The refractive index of the microfluidic is also determined by the cell type that can be normal or cancerous. Since the refractive index of a cancerous cell is higher than that of a normal one, the group index of the waveguide and the output chirp will decrease. By measuring the amount of the output chirp, we can detect the cell type. The Simulation results showed that for a 0.02 change in the refractive index of the cell, a 3.71 nm central wavelength shift occurred for a 10-ps 71-mW gaussian pulse input with a central wavelength of 1533.53876 nm. In terms of the wavelength shift, the sensitivity and figure of merit are 185.5 and 530, respectively. To detect the cell type, we integrated a PhC channel drop filter to drop the chirped signal due to the cancerous cell infiltration. Designing an appropriate PhC-CDF leads to achieving an ultra-small cancerous detection cell biosensor with more than 97% precision.

In this paper, the functional variable method is used to obtain new optical soliton solutions for the perturbed stochastic nonlinear Schrödinger equation with generalized anti-cubic nonlinearity and multiplicative white noise. Using some transformations, new rational, Jacobi elliptic, Weierstrass, and hyperbolic stochastic solutions are obtained. Several optical soliton solutions were proposed, including dark, bright, and compacton soliton solutions. Graphical presentations of the obtained optical soliton solutions are shown to illustrate some of its physical parameters.

The fifth generation (5G) wireless communication system is considered a promising and recent research. Massive Multiple-Input Multiple-Output (MIMO) system has an influential role in improving game-changing enhancements in area throughput and energy efficiency (EE). EE refers to one of the easiest and most cost-effective ways to combat climate change, reduce energy costs for consumers, and improve the competitiveness of businesses. Deep Learning (DL) can significantly improve area throughput and EE. It plays a crucial role in the 5G wireless communication systems. Optical systems are not far from this system, which include the optical components which serve more accurately.To assess the overall power usage in up-link and down-link communications, a power dissipated model is introduced. The proposed model incorporates the overall power used by the base station (BS) power amplifier and circuit components as well as single antenna user equipment (UE). In this paper, EE and power consumption of massive MIMO systems are calculated based on Convolutional Neural Network hybrid with Long Short-Term Memory cell (CNNLSTM). This model is proposed to overcome the high complexity and over fitting by replacing the inner dense connections with convolution layers resulting in improved model performance. There are different linear processing schemes applied for detection and precoding, as Minimum Mean Squared Error (MMSE), Zero-Forcing (ZF), and Maximum Ratio Transmission/Maximum Ratio Combining (MRT/MRC). These schemes are applied to train our proposed CNNLSTM.It is observed the results are improved by 12.8% when using ZF (perfect CSI) and the system outperforms other schemes by 10%, 10.44% and 12.05% when using MRT, ZF (imperfect CSI), and MMSE, respectively, for the EE performance. The obtained results also reveal that an improvement of 7.5% is achieved when using MRT. It outperforms other schemes by 6.5%, 5% and 5%, respectively, when using ZF (perfect CSI), ZF (imperfect CSI), and MMSE for average power consumption per antenna using the CNNLSTM model. When using MRT, an improvement of 7.5% is achieved in the area throughput performance, and it outperformed the other schemes, ZF (perfect CSI), ZF (imperfect CSI) and MMSE, by 5.2%, 5% and 5.2%, respectively.

Quantum Dot Infrared Photodetector (QDIP) is one of the promising candidates for infrared photodetection due to its controllable heterojunction bandgap and sensitivity to normal incident radiation. It is expected to be superior to infrared photodetectors of mature technologies such as Mercury Cadmium Telluride (HgCdTe) or a quantum well infrared photodetector. In the presented paper, we have developed a theoretical model for the dark current in truncated conical QDIP as the truncated conical shaped QD structure is more appropriate to describe the fabricated dots. The dark current model is based on the drift diffusion model solving the main governing Poisson’s and continuity equations. In this model, the carrier mobility is calculated by solving time-dependent Boltzmann transport equation in the photodetector material with embedded truncated conical QDs using finite difference technique. The results of the developed model have been compared with the dark current characteristics with published experimental results of Indium Arsenide/Gallium Arsenide (InAs/GaAs) truncated QDIP. The effects of QD volume, QD aspect ratio and QD density and the operating temperature on the dark current characteristics have also been investigated.

This paper introduces a novel underwater (UW) optical communication system that utilizes optical code division multiple access transmission technique using the permutation vector code. Three scenarios of water are considered, pure sea (PS), clear ocean (CL), and coastal ocean (CO). The performance is evaluated analytically in terms of bit error rate (BER), received power, signal to noise ratio for different UW links and data rates. The results show that the shortest UW range is achieved in the case of CO, achieving the highest extinction ratio compared to CL and PS. Considering a BER below the forward error correction (FEC) limit of 3 × $${10}^{-3}$$ 10 - 3 , the maximum UW ranges reached are 21 m for PS, 12 m for CL, and 8 m for CO at 3 Gbps with 20 dBm transmitted power. The propagation range could be increased when the transmitted power is increased to 25 dBm, achieving the ranges of 31 m, 18 m, and 9 m, for PS, CL, and CO, respectively.

In this paper, a novel design of photonic crystal fiber (PCF) biosensor based on surface plasmon resonance (SPR) is introduced and analyzed for cancer cell detection. The full vectorial finite element method (FVFEM) is used throughout the numerical analysis of the suggested biosensor. The reported PCF has a V-shaped surface that is coated with ZrN as a plasmonic material. A coupling occurs between the core guided mode and surface plasmon mode SPM which depends on the studied analyte. Such a coupling is improved by using the suggested V-shape geometry which increases the sensor sensitivity.The geometrical parameters are optimized to achieve high sensor sensitivity. The proposed biosensor has high optical sensitivity of 6214.28, 3800, and 5008.33 nm/RIU, for quasi-transverse magnetic (TM), and 6000 nm/RIU, 4400 nm/RIU, and 5333.3 nm/RIU, for quasi-transverse magnetic (TE), for breast, basal, and cervical cancer cells, respectively. The reported optical sensor can pave the way for efficient and simple technique for cancer detection with low cost and high sensitivity instead of surgical and chemical techniques.

The fiber optic link is one of the main segments of up-to-date telecommunication systems. Developing low cost, ultra reliable systems with very low latency for massive machine to machine and enhanced broadband mobile networks is a hot research topic. Motivated by this we investigated the polarization multiplexing technique applicable in fiber optic links because it can be used for increasing the transmission capacity. In the present paper a novel approach, the double polarization multiplex method is investigated. In that case the crosstalk between two polarization states is one of the main issues. As a result of crosstalk, the two channels composed by double polarization can disturb each other significantly. Crosstalk can appear due to any imperfection in the fiber and in the optical circuitry of the transmitter and receiver. In this paper, we propose a new method for reducing the effect of crosstalk even in the case of high-speed long-distance transmission. The applicability of the new concept is validated by experiments. A bit error rate better than 10−6 has been achieved over a 7 km long fiber carrying 12 Gbit/s NRZ modulation. That result is significantly better than the already published experimental data using 2, 5 Gbit/s bit rate. The cross polarization discrimination is also improved by 10–15 dB.

The paper presents the design, operation, and proof of principle realisation and validation of a relatively cheap fibre optic strain sensor based on two fibre Bragg grating (FBG) elements with different spectral responses. Its performance is compared with the measurement capabilities of a FBG-based sensor that uses an optical interrogator.

This paper suggestsproposes a high-gain reconfigurable polarization antenna using a metasurface polarizaer. The metasurface polarizer is a rectangular array that consists of similar 25 unit-cell elements. Each metamaterial (MM) unit-cell element consists of a circular copper patch attached to two copper arrow-shaped strips installed at its circumference. The circular patch and two arrows are installed between a rectangular superstrate at the top and a rectangular substrate at the bottom, which is backed with a perfect electric conductor with a relative permittivity of εsub = 3.38. The MM characteristics are obtained in a wide range of frequencies from 1.4 to 2.1 THz. The metasurface polarizer array is installed at an optimized height of 25 μm under a linear polarized dipole antenna that operates at 1.81 THz with a bandwidth (BW) of 0.2 THz from 1.75 to 1.95 THz (11.05%, − 10 dB BW) and gain of 2.27 dBi. The incident-plane wave from the antenna can be converted into a reconfigurable left- or right-hand circular polarization according to the directions of the arrow of the MM unit-cell element. Moreover, the operating − 10-dB BW of the dipole antenna increases to 30.93%, and the gain is enhanced to 6.18 dBi at the same operating frequency. A reconfigurable polarization conversion for the dipole antenna can be obtained over wide 3-dB axial ratio BW from 1.45 to 1.95 THz (33.3% BW).

In this paper, reconfigurable chessboard coding plasma-based dielectric resonator structure for radar cross section reduction is investigated. The radar cross section (RCS) reduction is essential in military applications. The metallic conductor surface is covered with plasma-based dielectric resonator (DRA) unit-cells arranged in chessboard configuration. The plasma DRA unit-cell consists of concentric cylindrical ring filled with ionized plasma placed over FR4 dielectric substrate. The plasma ionization voltage values are tuned to reflect the electromagnetic wave with phase shift of 180° and equal amplitudes. The phase 0° state represents the logic “0” while the phase 180° state represents the logic “1”. The chessboard arrangement consists of super-cells with 0/1 logic states. Different sizes of uniform super-cells 3 × 3, 4 × 4, 6 × 6, and 12 × 12 unit-cells are investigated for maximum RCS reduction. The scattered beams are directed to (± 30°, 180° ± 30°), (± 25°, 180° ± 25°), (± 20°, 180° ± 20°), (± 15°, 180° ± 15°) and (± 10°, 180° ± 10°) for 3 × 3, 4 × 4, 6 × 6, 8 × 8, and 12 × 12 uniform super-cells, respectively. The RCS is reduced over a wide angle range reduction with − 18 dBm2 at the broadside direction and below − 32 dBm2 over the angular range from − 90° to 90° according to the super-cell size. The non-uniform allocation of unit-cells in the super-cell chessboard arrangement is investigated. The RCS reduction bandwidth extended from 8.5 to 9.65 GHz. The scattered beam produces null in the broadside direction with wideband RCS reduction. The proposed structures are simulated using CST-MWS electromagnetic simulator.

We examine the three-component coupled nonlinear Schrodinger equation that is used for the propagation of pulses to the nonlinear optical fiber. Multi-component NLSE equations have gained popularity because they can be used to demonstrate a vast array of complex observable systems as well as more kinetic patterns of localized wave solutions. The solutions are obtained by using the generalized exponential rational function method, a relatively new integration tool. We extract various optical solitons in different forms. Moreover, exponential, periodic solutions and solutions of the hyperbolic type are guaranteed. In addition to providing previously extracted solutions, the used approach also extracts new exact solutions and is beneficial for elucidating nonlinear partial differential equations. The graphs of different shapes are sketched for the attained solutions and some physical properties- are raised. The reported solutions in this work are new as they are compared to earlier similar studies. The results of this paper show that the used method is effective at improving the nonlinear dynamical behavior of a system. The findings show that the computational approach taken is successful, simple, and applicable even to complicated phenomena.

Transfer learning appears to be a potential method for transferring information from general to specialized activities. Unfortunately, experimenting using various transfer learning models does not yield good results. In this paper, we propose the utilization of the Hough transform (HT) to improve modulation format recognition. HT is utilized to estimate points on constellation diagrams patterns with perspective projection. The HT algorithm extracts the raw image feature lines. The feature edges are then translated into Hough space, where line segments are found. The Hough transform is used to project a constellation diagram in another location and extract features from it. Constellation diagrams for eight different modulation formats (2/4/8/16 - PSK and 8/16/32/64 - QAM) are obtained at optical signal-to-noise ratios (OSNRs) ranging from 5 to 30 dB. This model is based on classification, and transfer learning. The obtained results indicate that, even at low OSNR values, the suggested system is capable of blindly recognizing the wireless optical modulation format with a classification accuracy of up to 99%.

In this paper, a novel design of superlens based on photonic bandgap structure for high resolution point spread function (PSF) is reported at a wavelength of 3 μm. The lens is able to generate a non-diffraction Bessel beam with a number of focusing points with variant resolution limits. The optimized structure provides high resolution in both lateral and axial directions. The maximum achieved lateral resolution of PSF is down to ~ 0.27λ with corresponding axial resolution down to ~ 0.57λ attaining a FOM, the inverse of the product of both resolution limits, of ~ 6.49. Meanwhile, the maximum axial resolution is down to ~ 0.4λ with corresponding lateral resolution down to ~ 0.33λ with a FOM of ~ 7.34. In addition, the proposed design is able to generate a focusing point extended in space up to ~ 0.98 µm with a sub-diffraction lateral resolution down to ~ 0.47λ. Furthermore, the reported superlens demonstrates a sub-diffraction focusing in lateral direction along the range the bandgap wavelengths (from 2.4 to 3.6 µm) showing a significant increase of focal depth when decreasing the operating wavelength. Remarkably, a high focal depth up to ~ 1.77 µm is achieved at the operating wavelength of 2.6 µm. The suggested design has a tremendous potential in 3D biological imaging and biosensing applications.

Several applications depend on the localization technique in underwater visible light communication (UVLC) systems, as military, petroleum, and diving fields. Recent research aims to develop the localization system by different methods to obtain the optimum position of the receiver. In this paper, we use Kalman Filter (KF) algorithm with average Received Signal Strength (RSS) technique using optimization. Optimized Deep Learning Models (DLMs) are utilized to improve the system performance, including such as ResNet50V2, InceptionResNetV2, SSD, and RetinaNet. Two channel modeling Weighted Double Gamma Function (WDGF) with a Combination Exponential Arbitrary Power Function (CEAPF) are used for sea water to enhance the UVLC localization system. The obtained results show that using CEAPF channel modeling with ResNetV2 strategy achieves the best accuracy of the localization for different methods. Also, the ResNetV2 outperforms other strategies for using RSS average technique. The RSS with KF and DLM achieves a higher accuracy with ResNetV2 than InceptionResNetV2, RetinaNet and SSD. Using WDGF achieves accuracy less than that in CEAPF where for using KF with average RSS method. Applying the RSS with KF with CEAPF channel modeling improves the performance than using WDGF. We use an automatic hyper-parameter (HP) approach to the Bayesian optimization models ResNet50V2, InceptionResNetV2, SSD, and RetinaNet. The ResNet50V2 based on average RSS technique hybrid with KF in CEAPF channel model achieves 99.99% accuracy, 99.99% area under the curve (AUC), 99.98% precision, 99.89% F1-score, 0.099 RMSE and 0.43 s testing time.

This paper investigates a space-time modulated digital metamaterial array (DMA) based on reconfigurable plasma ionization. The DMA consists of 8 × 8 unit-cell elements with total dimensions of 120 × 120 × 3.2 mm3. Each unit-cell consists of a ring container filled with argon gas and is backed with a grounded dielectric substrate. The argon gas is ionized into a plasma state through metallic electrodes. The logic state of the unit cell is controlled via the changing of the plasma frequency, $${\omega }_{p}.$$ ω p . The value of $${\omega }_{p}=6\times {10}^{11}\mathrm{ rad}/\mathrm{sec}$$ ω p = 6 × 10 11 rad / sec represents logic “0”, and $${\omega }_{p}=8\times {10}^{11} \mathrm{rad}/\mathrm{sec}$$ ω p = 8 × 10 11 rad / sec represents logic “bit 1”. The periodic time switching of the plasma ionization controls the radiation at the fundamental and harmonic frequencies. The on-time instants and on-time durations control the number of radiated beams, their directions, amplitudes, and side-lobe levels. Different time-switching sequences are investigated for beam steering, dual-sum beams, broadside beams, end-fire beams, multi-beams, and fan-shaped beams for wireless communications applications. The DMA was investigated under different switching sequences for phase-modulation and amplitude-modulation schemes. A full-wave simulation CST Microwave Studio simulator is used to analyze the proposed DMA and the results are compared with ideal point sources array excited with the same switching sequences.

Hyperspectral image (HSI) classification plays an important role in a wide range of remote sensing applications in military and civilian fields. During past decades, significant efforts have been made on developing datasets and introducing novel approaches to promote HSI classification, such that promising classification performance has been achieved. However, existing datasets generally pose following issues, including the limited categories and annotated samples, the lack of sample diversity, as well as the low spatial resolution. These limitations severely restrict the development and evaluation of data-driven models, especially deep neural network-based ones. In recent years, advances in imaging spectroscopy provide us the opportunity to obtain the hyperspectral image data with high spectral and spatial resolution, therefore, in this paper, we contribute a large-scale benchmark dataset for conducting hyperspectral image classification to address issues raised by existing datasets, noted as ShanDongFeiCheng (SDFC). The proposed SDFC is characterized by 1) the large-scale annotated samples with diverse categories; 2) the high spatial resolution; and 3) the high intra-class variance yet relatively low inter-class variance, making the HSI classification task much more challenging on it. We evaluated 10 classic traditional and deep neural network-based models on SDFC, of which the results can be regarded as useful baselines for further experiments. Moreover, given the state-of-the-art performance of SpectralNet, we selected it as the representation method, and evaluated it across datasets to analyze the difference effects on the classification model induced by different datasets. The comprehensive review and analysis of representative classification models on both existing and proposed datasets demonstrate the advantages and challenges of our proposed dataset, and provide promising perspectives for future HSI classification studies.

The microwave photonic vector modulator (MPVM) sometimes shows an unmodulated carrier peak, which appears in the modulated signal. This peak results from an incorrect bias value or a Mach-Zehnder modulator (MZM) bias drift over time, which in turn leads to an imbalance in the I/Q signals. This paper describes a mathematical model of an MPVM output by showing the unmodulated carrier peak behavior. It also discusses a constellation imbalance resulting from this non-modulated peak. To control this non-modulated carrier peak and restore the constellation balance, an automatic bias control (ABC) is proposed and simulated through a co-simulation technique. Unlike previous methods, this ABC is based on the analysis of the I/Q signals to generate voltage steps for the photonic modulator bias. The I/Q signals were recovered through a direct-conversion receiver, and an algorithm was developed to analyze the I/Q amplitude and phase imbalance. Consequently, the photonic modulator bias is continuously monitored by analyzing the resulting modulated microwave signal. In this way, its operation is transparent under MZM bias variations or extinction ratio (ER) imperfection since only the I/Q and microwave signals are considered in the algorithm implementation. ABC is validated through a co-simulation technique using low and high-order modulation formats such as QPSK, 64QAM, and 256QAM.

In this paper, we consider the Sharma-Tasso-Olver-Like equation (STOLE) describing the dynamical behaviour of nonlinear dispersive waves in inhomogeneous medium. By using the Hirota bilinear method, some new type of solitons like breather-wave, kink solitary wave and rogue wave, one-, two- and new three-wave solutions to the STOLE have been determined. These results are achieved and verifed by using the Maple software. The obtained results are new from the existing results. For the further explanation of these solutions, diferent kinds of graphs are also drawn. These solitons suggest that this method is efective, straight forward and reliable as compare to other methods.

The aim of this paper is to analyse a planar optical waveguide with Kerr-type nonlinear cladding and a thin linear overlayer separating the cladding and the guiding core. The results of numerical calculations show that the bistable behaviour of the nonlinear waveguides can be easily controlled by changing the parameters of this additional layer. The analysis is based on the self-consistent iteration procedure which provides relevant dispersion characteristics limited to physically stable solutions.

As detection of cancer and diabetes diseases has captured a great attention in the field of biosensing, many ways were introduced to detect these diseases with high accuracy. This paper presents a novel use of zinc selenide (ZnSe) semiconductor material to enhance the sensitivity of a conventional Ag-based surface plasmon resonance biosensor. The proposed sensor structure is simple (BK7 prism/Ag/ZnSe), cost-effective, and easy to design and fabricate. The sensor is tested in the detection of different cancerous cells in human blood, showing an excellent sensitivity of 359$$^\circ$$ ∘ /RIU. In addiion, it is tested to detect various glucose levels in human urine, and it provides a very high performance with a sensitivity of 366.6$$^\circ$$ ∘ /RIU, which is 70% better than that of a similar reported work. Thus, the proposed biosensor is capable efficiently to detect various kinds of cancer cells and different glucose concentrations in urine.

Quantum Dash (QDash) SOAs are of interest as an alternative to quantum dot SOAs, since they have some dot-like properties and are easier to fabricate such as to operate in the 1550 nm region, albeit with longer gain recovery times in the range of hundreds of picoseconds. QDash-SOAs are promising core component is optical subsystems for applications in next generation coherent communications and optical signal processing, which often involve pulse amplification. It is of interest to measure both the dynamic power, phase and associated frequency chirp and thereby the spectrum of typical QDash-SOA amplified pulses. Non-linear measurement techniques are appropriate for pulsewidths less than 5 ps but have low sensitivity for wider pulsewidths often encountered in practice. This paper describes the use of a modified linear pulse characterization technique to measure the dynamic power and phase of a 20 GHz repetition rate QDash-SOA amplified 19 ps pulsewidth pulse train, from which the chirp and energy spectrum is calculated. The amplified pulses can exhibit a complex structure that is strongly dependent on the amplifier gain and the input pulse shape and energy.

Filterbank multicarrier (FBMC) is an effective method for modulation over massive multiple-input multiple-output (MIMO) channels in the future fifth generation wireless networks. This multicarrier technique provides high spectral efficiency, and it is resilient against synchronization errors compared to the well-known orthogonal frequency division multiplexing technique. This paper introduces a new technique, that combines the Code-division multiple-access (CDMA) and cosine modulated filter banks, a specific class of FBMC, to massive MIMO communication systems. In the proposed technique, the data symbols are transmitted on different sub-bands and also, they are spread in each sub-band by CDMA code. The proposed technique reduces the interference between data symbols, which consequently improves bit-error-rate (BER) performance. Simulation results show that the overall BER performance of the proposed multicarrier transmission technique is significantly enhanced. The results obtained show that as the number of base station antennas increases, different channel distortions are averaged out, thus BER decreases (in average by 10–2) for the same signal-to-noise ratio.

Nowadays, transmitting and receiving data with high speed and a high level of security are the main demands. So, a new model of spectral amplitude coding optical code division multiple access (SAC-OCDMA) is suggested in this paper, based on a free space optical (FSO) communication system using coherent sources. Three different codes: enhanced double weight (EDW), modified double weight (MDW) and multi-diagonal (MD) codes are assigned to our proposed model with the direct detection (DD) technique. Furthermore, the model is simulated under different weather conditions including clear air (CA), light mist (LM), very light fog, and light fog (LF). The system performance is evaluated through its bit error rate (BER), Q-factor, received power, and signal to noise ratio (SNR). Moreover, classification of the information received by the three different SAC-OCDMA using three different codes (EDW, MDW, and MD) is still challenging. So, two different machine learning (ML) algorithms are used, in this study, to classify the data received using the different codes. Detecting which code is received at the receiver end is important in order to reduce code error detection. Two algorithms: K-Nearest Neighbor (KNN) and Support Vector Machine (SVM) are adopted to classify different codes used for data transmission under four different weather conditions. The ML input dataset consists of the obtained simulation results, including Q-factor, BER, and SNR. Each feature is to be normalized before using ML. The obtained results show that the performance of the proposed FSO model achieved the longest propagation range under CA weather conditions, 7 km, while the shortest is under LF, which is 0.98 km. This is due to the attenuation of fog that causes signal degradation. The FSO system that uses EDW gives the best result under different weather conditions, while the system that uses MD code gives the worst performance. Also, the highest power is achieved when the EDW code is used at 5.5 km. The EDW has a received power of − 21.58 dBm, while the received power is − 22.04 dBm and − 23.8 dBm for MDW and MD codes, respectively. As for classification between the received information coming from three different codes under different weather conditions, both algorithms, KNN and SVM, achieve promising results in most cases. They showed more than 97% of classification accuracy under CA, LM, and LF weather conditions.

In this paper, we propose a dispersion compensation model to minimize the chromatic dispersion to enhance system performance. The proposed model is based on applying the duobinary modulation scheme on 4-stages of cascaded identical apodized uniform fiber Bragg grating. Different apodization functions are tested to determine the one that provides the best performance. The proposed model is connected in three different connection schemes: pre, post and symmetrical, to get the best connection. To evaluate the performance of the proposed system, a comparative study is conducted using non-return to zero (NRZ) and modified duobinary (MDB) modulation schemes. For evaluation, a 10 Gbps WDM link is simulated at a distance of 100 km under a set of predefined operating parameters. Optisystem 17.0 is used for simulation and evaluation. Both quality factor (Q-factor) and bit error rate (BER) are used as performance indices. All cases of NRZ modulation scheme do not meet the minimum operational requirements in terms of Q-factor and BER. Only in the case of MDB modulation scheme, the symmetrical compensation with tanh apodization meets the minimum operational requirements with a Q-factor of 6.39 and BER of 8.44 × 10–11. The proposed model achieves better results as compared to the other modulation schemes: a maximum Q-factor values of 8.964 and a BER of 1.3 × 10–19 with tanh apodization in the pre-compensation scheme. As compared to related work, the system performance achieves ~ 99% improvement.

In this paper, we present a tanh apodized FBG as a dispersion compensator in optical fiber communication systems. This grating is integrated as a hybrid system of four cascaded apodized FBGs with soliton transmission technique. This enhances the linewidth of the light source to get the most out of transmission per-channel bit rate of 9.687 Tbps at a temperature of 20 °C, a relative refractive index difference of 0.002, a Germania doping ratio of 0.2, and a signal wavelength of 1.65 µm.

Objective: This paper theoretically studies a hybrid optomechanical system embedded with two coupled quantum dots (CQDs) and a third-order Kerr nonlinear medium inside the cavity. The optical bistability and absorption spectrum are analyzed for the proposed system. Methods: From the Hamiltonian which describes the proposed system, a set of quantum Langevin equations are derived. Using these equations of motion, the steady-state mean field analysis is done which gives the phenomena of optical bistability. The performance of the optical switch is also analyzed in terms of gain and switching ratio. Further, the absorption spectrum of the system is derived and analyzed from the fluctuation dynamics. Results: The optical bistability has the potential to design tunable all-optical switches. The absorption spectra display peculiar characteristics of negative absorption (transparency dip). The transparency dips are found to be strongly dependent on the frequency of the mechanical resonator. The results of our investigation reveal that the proposed system can be used as an optical switch and has numerous other applications in quantum communication systems.

For several years, the fields of new technologies have been experiencing a real boom. The use of the terahertz band is an appropriate solution to meet the requirements of these technology. However, this technology has special requirements among which its antennas must have high bandwidth of few THz and achieve high gain for high productivity. In this paper, we will focus on the design and analysis of an antenna for THz technology. The antenna structure proposed in this work has better performance in terms of bandwidth and gain. In fact, multiples slots were added to the antenna to enhance the antenna’s bandwidth. in addition, to enhance the antenna performance in terms of gain and protect the antenna feed line against environmental jeopardies a thin layer as superstrate is used. The suggested antenna covers a wide − 10dB bandwidth from 0.9 THz to 17.3 THz with a peak gain of 12.8 dBi. Moreover, a VSWR less than 2 at the operating band is obtained. Furthermore, the suggested antenna has circular polarized radiations with an axial ration (AR) less than 3 dB over a wide band 13.6THz-17.3THz which mean that the proposed antenna is well suited for application where the transmitter and receiver are moving which is the most case for wireless system. Thus, the suggested THz antenna could be a successful choice for terahertz application like future high-speed short-range indoor wireless communication, explosive detections, arms detection, medical imaging, pharmaceutical analysis, and material characterization in the THz regime industrial inspections.

This paper suggests a high gain polarization converter using a graphene-based metamaterial array. The graphene-based metamaterial polarization converter is a rectangular array that consists of 20 periodic unit-cell elements. Each graphene-based metamaterial unit-cell element consists of a rectangular patch with four triangular-shaped graphene parts at its four corners. The rectangular patch with the four graphene parts are placed over a rectangular substrate backed with a perfect electric conductor (PEC) and has a relative permittivity of εsub = 3.38. The metamaterial characteristics of the proposed graphene-based metamaterial unit-cell element are obtained over a wide range of frequencies of 0.7 THz ranging from 1.5 THz to 2.2 THz. The graphene-based metamaterial array is placed over a linear polarized slot antenna that operates at 1.8 THz with a maximum gain of 5.5 dBi. The linearly polarized wave that radiated from the slot antenna can be converted into a reconfigurable right-handed circular polarization (RHCP) or Left-handed circular polarization (LHCP) according to the biasing states of the graphene parts. Moreover, the operating -10 dB B.W of the slot antenna is increased to 22.2%, and the gain is enhanced to 8 dBi at the same operating frequency. A reconfigurable polarization conversion for the slot antenna can be obtained over a wide 3dB axial ratio (AR) B.W from 1.75 THz to 1.92 THz (20% 3dB B. W).

As third-generation solar cells, dye-sensitized solar cells (DSSCs) can show bifacial harvesting capabilities by utilizing transparent conducting oxides as a counter electrode. Herein, the electrolyte is considered a critical layer from the optical perspective. In this paper, an attempt to estimate the optical properties of Iodine-based electrolytes, typically used in dye-sensitized solar cells, is demonstrated. The refractive index for electrolyte as an effective medium is calculated to be 1.4535 ± 0.005 for an effective thin film of 33.4 ± 0.5 μm thickness, using the near-infrared Fabry–Perot resonances. The extinction (absorption and scattering) and dispersion spectra for the prepared electrolyte were fitted using Lorentz–Dude (LD) model. Finally, the utility of the extracted optical parameters was examined through a finite difference time domain solver, Massachusetts Institute for Technology Electromagnetic Equation Propagation. The simulated optical transmission spectrum perfectly agreed with the measured spectrum with less than 0.1% root–mean–square error. The demonstrated attempt to accurately estimate the refractive index of electrolyte used in DSSCs fabrication may impacted theoreticians who are interested with the optoelectronic modelling of such electrochemical cells, as well as those dealing with optoelectronic devices informatics.

The weakly nonlinear wave propagation that occurs in the presence of magnetic felds, in which energy is concentrated in a narrow band of wave-numbers in a dispersive and dissipative fuid. The main objective of this paper is to analyze the (2 + 1)−dimensional elliptic nonlinear Schrodinger equation under the infuence of three diferent fractional operators. The generalized fractional soliton solutions and propagation of magnetohydrodynamics fuid in sort of solition will be visualized. The Conformable, 훽 and M-truncated fractional operator applied to classical evolution Schrodinger equation. In order to get the analytical closed form solution, one of the generalized approach new extended direct algebraic method is utilized. The fractional nonlinear elliptic Schrodinger equation is developed in three diferent fractional sense. The similarity transformation technique converted the controlling fractional system to ordinary diferential equations. The fractional analytical solutions such as, plane solution, mixed hyperbolic solution, periodic and mixed periodic solutions, mixed trigonometric solution, trigonometric solution, shock solution, mixed shock singular solution, mixed singular solution, complex solitary shock solution, singular solution and shock wave solutions are obtained. The graphical 2-D and 3-D representation of the results is shown to express the propagation of fuid with the magnetic feld by assuming the appropriate values of the involved parameters. The graphical performance of the obtained solution at various settings of parametric values and fractional order reveals new perspectives and fascinating model phenomena. The attained outcomes have signifcant applications and have opened up innovative development areas for research across numerous scientifc felds.

In this paper, we have presented an efficient original architecture of all-optical 2×4 photonic crystal decoder based on non-linear ring resonators. The fundamental structure is a square lattice of 2D GaAs rods, operating around the wavelength 1.55 µm. The proposed decoder is composed of a combiner with three input ports, where the port E is used for excitation and A1, A2 are the control ports, and an optical switch with four output ports, and it is a nonlinear DMEX. For the creation of a switch at the wavelength of 1.55 µm, we used nonlinear chalcogenide glass rods with a nonlinear Kerr coefficient equal to 9×10-17 m2/w. The switching intensity and structure size are 1 Kw /µm2, 27.12 µm × 17.96 µm, respectively. The contrast ratio is about 8.7. The maximum crosstalk and insertion losses are calculated to be about -22.1 and -4.5 dB. The maximum and minimum power levels for logic states 0 and 1 are 0.5P0 and 0.37P0 where P0 is the input power. The finite element method was used to perform the necessary calculations.

In this paper all optical ultra compact 4:2 encoder is proposed and designed using two dimensional photonic crystals. The proposed structure has silicon rods of refractive index of 3.4 embedded in air host by creating line defects in hexagonal lattice platform. PWE method is used to determine the photonic band gaps and structure is analyzed using FDTD method. Further, the proposed 4:2 encoder is operated at 1550 nm and it provides a high contrast ratio of 9.25dB and foot print of the structure is 119.34 μm2. Hence it is highly advisable for photonic integrated circuits and optical signal processing.

In this paper, we analyze a combination based on a hybrid triple hop terrestrial free-space optical (FSO), a fiber optic cable (FOC), and an underwater optical wireless communication (UOWC) link for providing high-speed optical connectivity between onshore and submerge systems. UOWC, scattering, absorption, and turbulence severely degrade the reliability and transmission rate of the UOWC link. In our manuscript, a bend-insensitive intermediate FOC link and a spatial diversity (SD) are exploited to improve the error performance of UOWC links, which involves the deployment of multiple input single outputs (MISO). For this purpose, different transmission signaling schemes, such as pulse position modulation (PPM) with spatial modulation (SM) and on–off keying (OOK) with repetition coding (RC), are employed to evaluate the system performance in terms of average bit error rate (ABER). The behavior of the entire system is obtained by applying a decode-and-forward (DF), where we consider log-normal channels for FSO and UOWC. The path loss and turbulence are obtained using intensity modulation and direct detection schemes. To obtain performance results, Monte Carlo-based statistical simulation method is applied to validate the analytical ABER performance of the system. The achieved results reveal that MISO-OOK-RC has superior ABER performance as compared to MISO-PPM-SM in higher signal-to-noise ratio (SNR) conditions with different underwater turbulence strengths.

A novel architecture with full-duplex direct communications(FDDC) between any two ONUs for optical access network is proposed in this paper. By designing combination switch(CS) ingeniously, the architecture is finished to realize FDDC between any two ONUs in wavelength division multiplexing passive optical networks(WDM-PONs). By utilizing interconnected optical fibers between ONUs, the network has achieved three-level protections(feeder optical fiber protection, distributed optical fiber protection and interconnected optical fiber protection). By constructing expansion module(EM), the network can be flexibly expanded and optimized, and the CapEx and OpEx of network can be greatly reduced. Finally, by the simulation and analysis, the effectiveness of the proposed architecture is demonstrated.

The Method of Lines (MoL) in combination with impedance-/admittance and field transformation (IAFT) is used to analyze electromagnetic waves. The used cases are wave-guiding structures in microwave technology and optics. The core of the theory is the solution of generalized transmission line equations (GTL). In the case of complex structures, a combination with finite differences (FD) can be used. The quality of this solution essentially depends on the effectiveness of the used interpolation of the differences. The individual steps of the FD are permanently linked to the steps of the fully vectorial impedance-/admittance and/or field transformation, so standard libraries cannot be used. Two approaches based on the linear and quadratic interpolation were built into the impedance-/admittance and field transformation in the past. However, the degree of improvement due to one or another kind of interpolation depends on the concrete behavior of the solution sought. In the case of complex structures, choosing the appropriate type of interpolation should be an effective aid. In this paper, an extension of the family of built-in methods is proposed - with the possibility of being able to build any known numerical method from the class of one-step or multi-step methods into the GTL solution. These can be higher-order methods, including fast explicit methods, or particularly stable implicit methods. The transmission matrices for the impedance-/admittance and field transformation serve as the building site. To illustrate the procedure, some different methods are integrated into the GTL solution. The accuracy of the solutions is tested on selected complex structures and compared with each other and with existing solutions. It is shown that the optimal choice of method and the quality of the solution can depend on concrete structures. Keywords: Method of lines, generalized transmission line equations, impedance/admittance transformation, waveguide structures, finite differences, finite differences with second order accuracy.

In this paper, a new framework is presented for indoor visible light communication (VLC) system, based on Yolo v3, EfficientNetB3, and DenseNet121 deep learning (DL) models, as well as an optimization strategy. The proposed framework consists of two steps: data collecting and DL model training. To start, data is acquired using MATLAB and Kalman Filtering (KF) with averaging approaches. Second, the received signal strength (RSS) is employed as the DL models input, with the Cartesian coordinates as the DL models output. The averaging RSS approach combined with KF algorithm are used in the suggested framework. This work introduces the impacts of Non-Line-of-Sight (NLoS) for initial reflection and Line-of-Sight (LoS) based on the three mentioned DL models. Furthermore, we used Bayesian optimization and automatic hyper-parameter (HP) optimization to increase system efficiency and to reduce positioning error in DL models. The obtained results show that the models outperform existing the HP-RSS-KF-LoS-DL models in terms of localization error when compared to traditional RSS signal-based localization techniques. Many performance indicators are considered to evaluate the proposed framework resiliency, including accuracy (ACC), area under the curve (AUC), sensitivity (Se), and precision (Pr), as well as F1-score, root mean square error (RMSE), training, and testing time. The DL models are generated and trained using Python software on a Kaggle Notebook GPU cloud (2 CPU cores and 13 GB RAM). The achieved results are: 99.99% ACC, 99.98% AUC, 98.88% Se, 98.98% Pr, 99.97% F1-score, 0.112 cm RMSE, and 0.29 s testing time. The proposed system could be easily deployed for autonomous applications, based on the analysis of the experimental data. Several applications can be used depending on enhancing the localization of VLC system in military systems, underwater systems, and indoor systems like hospitals, hotels, libraries and malls.

The challenge of tracking unmanned aerial vehicles (UAVs) is arising out of increasing their market and spread usage in many applications. Miscuing UAVs can lead to potential threats as they are considered an essential part of national security. One of the major issues in communication with UAVs is the enormous amount of data generated by UAVs that requires a high data rate link, making the free space optics (FSO) communication, with very high bandwidth, an appropriate choice. Consequently, current developments in UAVs have provided new horizons for establishing UAV-based FSO links. However, FSO is a narrow line of sight (LoS) technology that is highly affected by the misalignment between the transmitter and receiver. So, tracking mechanisms are of vital importance when considering UAV-based FSO communication systems. This paper addresses coarse to fine pointing, acquisition, and tracking (PAT) approaches and the recently developed tracking approaches to establish a reliable link for communication. Also, the various approaches are discussed and compared for precise alignment between the ground station and its associated UAV, highlighting their advantages and limitations. Current challenges and future research directions are addressed and integrated by combining different ideas.

In this paper, we consider the Sharma-Tasso-Olver-Like equation (STOLE) describing the dynamical behaviour of nonlinear dispersive waves in inhomogeneous medium. By using the Hirota bilinear method, some new type of solitons like breather-wave, kink solitary wave and rogue wave, one-, two- and new three-wave solutions to the STOLE have been determined. These results are achieved and verifed by using the Maple software. The obtained results are new from the existing results. For the further explanation of these solutions, diferent kinds of graphs are also drawn. These solitons suggest that this method is efective, straight forward and reliable as compare to other methods.

In communication networks that span large geographical regions, transfer of bulk data is often costly and hard to manage. One prominent reason for that is bandwidth contention among long-lasting flows, and between long-lasting and short-lived ones on inter-datacenter links. Delaying the transfer of bulk data to off-peak hours by temporarily storing transfer at edge of the network can help reduce bandwidth contention during peak hours, and improve overall bandwidth utilization and network utility. Although extensive research has been conducted on its use, to date no model has been developed to quantify the performance of storage assisted bulk transfers across multiple congested links. This research gap has limited our understanding of the operation of storage assisted transfer under different network conditions. In this paper, we model bulk data transfer in inter-datacenter optical networks with edge storage, and derive closed-form equations for bulk data transfer on inter-DC links that exhibit diurnal traffic patterns and varying peak hours. Our study reveals that when the data transfer requests arrive uniformly in a day, the probability of a successful transfer increases linearly with the time data is allowed to wait in edge storage. Our study also shows that this probability decreases linearly with β + D, where β and D are the durations of background traffic peak and size of data transfers, respectively, when the network is moderately loaded. And, the benefit of storage will barely increase when the allowed waiting time goes beyond β + D.

This paper aims to improve the channel estimation (CE) in the indoor visible light communication (VLC) system. We propose a system that depends on a comparison between Deep Neural Networks (DNN) and Kalman Filter (KF) algorithm for two optical modulation techniques; asymmetrically clipped optical-orthogonal frequency-division multiplexing (ACO-OFDM) and direct current optical-orthogonal frequency division multiplexing (DCO-OFDM). The channel estimation can be evaluated by changing the rate of errors in the received bits, where increased error means a performance decrease of the system and vice versa. Receiving less errors at the receiver indicates improved channel estimation and system performance. Thus, the main aim of our proposal is decreasing the error rate by using different estimators. Using the simulation results with the metric parameter of bit error rate (BER) aims to determine the improvement ratio between different systems. The proposed model is trained with OFDM signal samples with labels, where the labels represent the received signal after applying OFDM travelling across the medium. At a BER = 10–3 with DCO-OFDM, the DNN outperforms KF with 1.6 dB (7.6%) at the bit energy per noise $$({{\varvec{E}}}_{{\varvec{b}}}/{{\varvec{N}}}_{{\varvec{o}}})$$ ( E b / N o ) axis. Also, for ACO-OFDM at BER = 10–3, the DNN achieves better results than KF by about 1.3 dB (8.12%) at the $$({{\varvec{E}}}_{{\varvec{b}}}/{{\varvec{N}}}_{{\varvec{o}}}).$$ ( E b / N o ) . At different values of M in QAM, the DNN outperforms KF for ACO-OFDM by average improvement of ~ 1 dB (~ 11.5%).