Journal of Optics and Photonics Research
Journal of Optics and Photonics Research (JOPR) is an international, peer-reviewed journal that publishes research on advanced photonic devices and systems, with a focus on intelligent modeling, design, optimization, and manufacturing. JOPR particularly encourages submissions that bridge these domains, highlighting both theoretical advances and practical innovations that drive next-generation photonic science and engineering. The journal is a Gold Open Access journal, online readers don't have to pay any fee. The journal is currently free to the authors, and all Article Processing Charges (APCs) are waived until 31 March 2026.
Observable Effects and Peculiarities of the Low-Energy Quantum Gravity
The existence of a background of ultra-strongly interacting gravitons is a key postulate of the author's low-energy gravity model. Side effects of the model due to photons interacting with this background may be important for cosmology, and their observation would be essential to support the model. The most important such effect is the quantum redshift mechanism, which may constitute an alternative to the generally accepted mechanism associated with the expansion of the universe. The model should have a weakening of the light flux due to a change in the number of photons, which replaces the influence of dark energy. Scattered photons may form a new background that can be detected by deep space missions. Some important predictions of the model are tested using observational data sets of Supernovae Ia (SNe Ia), compact quasars, and Lyman-alpha emitters. The article shows that the linear function H(z) of the model satisfactorily describes the results of measurements of the Hubble parameter. Using a trial function for the weakening parameter, the possibility of a different interpretation of the Hubble tension is illustrated. The increasing angular diameter distance of this model is fitted to a set of 120 measurements of the angular sizes of compact quasars with redshifts of 0.46–2.76 with independent calibration of their linear sizes. Attention is drawn to the possibility of a false interpretation of changes in the measured sizes of Lyman-alpha emitters observed by the James Webb Space Telescope in the redshift range of 3–7 as evolutionary effects in the ΛCDM model, since these changes can be due to the increasing angular diameter distance of this model. Received: 14 August 2025 | Revised: 10 October 2025 | Accepted: 1 January 2026 Conflicts of Interest The author declares that he has no conflicts of interest to this work. Data Availability Statement The data that support the findings of this study are openly available at https://doi.org/10.1007/s41114-022-00040-z, reference number [9]; https://doi.org/10.1088/0004-637X/746/1/85, reference number [19]; https://doi.org/10.1051/0004-6361/201730551, reference number [25]; and https://doi.org/10.48550/ARXIV.2508.05052, reference number [26]. Author Contribution Statement Michael A. Ivanov: Conceptualization, Methodology, Validation, Formal analysis, Investigation, Resources, Writing – original draft, Writing – review & editing, Visualization.
Copyright (c) 2026 Author https://creativecommons.org/licenses/by/4.0/
Evaluation and Characterization of the Optical Properties of NBR Rubber/N220 Granular Carbon Black Composites
This study investigates the optical and dielectric properties of nitrile butadiene rubber (NBR) reinforced with varying concentrations of N220 carbon black (CB). Ultraviolet (UV)–visible spectroscopy, in the range of 200–800 nm, was used. The optical spectrum showed a high absorption peak at approximately 220 nm, indicating that the material is suitable as a strong absorber of ultraviolet radiation. The direct optical band gap decreases slightly from 5.55 eV to 5.34 eV as CB content increases. The Urbach energy values, around 1.5 eV, suggest the formation of structural disorder and band tail states induced by CB–rubber interfacial interactions. The optical parameters such as extinction coefficient and refractive index exhibit characteristic variations around 220 nm, corresponding to strong absorption and high photon–carrier coupling. Dispersion behavior, interpreted through the Wemple–DiDomenico and Sellmeier models, reveals consistent variations in the effective oscillator energy, dispersion energy, and oscillator length strength. Dielectric analysis demonstrates that both the static and high-frequency dielectric constants are sensitive to CB loading, while the real part of the dielectric constant dominates over the imaginary component across the spectrum. Generally, the optical and dielectric findings demonstrate that the incorporation of N220 CB substantially modifies the energy band structure, optical dispersion, and charge carrier dynamics of NBR composites. These characteristics suggest their promising potential for optoelectronic and UV-sensing applications, where tunable optical absorption and dielectric response are critical. Received: 24 August 2025 | Revised: 10 November 2025 | Accepted: 23 December 2025 Conflicts of Interest The authors declare that they have no conflicts of interest to this work. Data Availability Statement Data are available from the corresponding author upon reasonable request. Author Contribution Statement K. Alfaramawi: Conceptualization, Formal analysis, Resources, Writing – review & editing. S. Abboudy: Formal analysis, Resources, Data curation, Writing – review & editing, Visualization, Supervision, Project administration. L. Abulnasr: Formal analysis, Investigation, Data curation, Writing – review & editing. S. Ebrahim: Investigation, Writing – review & editing. Ahlam K. Yousif: Methodology, Data curation, Writing – original draft.
Copyright (c) 2026 Authors https://creativecommons.org/licenses/by/4.0/
Advances in Gain Control Techniques for Bismuth-Doped Fiber Amplifier
With the explosive growth of global data traffic, extending communication bandwidth is one of the important methods to alleviate the pressure on communication capacity. As the core device of an optical fiber communication system, the bandwidth extension of the optical amplifier is an indispensable research focus. Bismuth-doped fiber amplifier (BDFA) has been widely studied because of its unique broadband luminescence characteristics. In wavelength division multiplexing systems, the signal power fluctuates as the signal goes up and down, and the network is reconstructed. This results in a gain variation of the BDFA, which deteriorates the transmission system performance. The introduction and application of gain control technology can solve this problem well. In addition, the endogenous pump generated by the gain control structure can be combined with the characteristics of bismuth-doped fiber to achieve low-cost and efficient broadband amplification. The combination of these two technologies provides inspiration for the development and application of a broadband amplifier. Received: 20 August 2025 | Revised: 13 October 2025 | Accepted: 18 December 2025 Conflicts of Interest The authors declare that they have no conflicts of interest to this work. Data Availability Statement The data that support the findings of this study are openly available in Forc-Photonics at https://www.forc-photonics.ru/en/fibers_and_cables/Bi_doped_fibers/. Author Contribution Statement Lihong Wang: Methodology, Formal analysis, Investigation, Writing – original draft, Visualization. Ge Wu: Methodology, Investigation, Writing – original draft, Visualization. Yidan Zhao: Validation, Investigation, Writing – review & editing. Jingjing Zheng: Conceptualization, Writing – original draft, Writing – review & editing, Project administration, Funding acquisition. Li Pei: Resources, Supervision. Tigang Ning: Supervision.
On the Influence of Gravity on the Deviation of the Direction of Light Propagation and Gravitational Time Slowdown
It has been established that the change in the direction of light propagation near massive astronomical bodies, such as the Sun, occurs due to the refraction of light in the cosmic environment. The role of the gravitational field is exclusively to increase the density of the cosmic environment as it approaches a massive body. The gravitational field has no direct effect on the light beam or photons. The incompatibility of the energy of gravitational processes with the idea of the interaction of space-time with objects of physical reality, including massive bodies and photons, has been established. Space-time is not an object of physical reality. It has been established that due to the decrease in the optical density of the cosmic environment as it moves away from a massive body, a gravitational red shift occurs. The idea of gravitational time dilation is devoid of physical (common) sense. It is not time that slows down. It is the physical processes that occur with material objects that slow down. Received: 2 July 2025 | Revised: 27 August 2025 | Accepted: 10 October 2025 Conflicts of Interest The author declares that he has no conflicts of interest to this work. Data Availability Statement Data sharing is not applicable to this article as no new data were created or analyzed in this study. Author Contribution Statement Igor P. Popov: Conceptualization, Methodology, Software, Validation, Formal analysis, Investigation, Resources, Data curation, Writing – original draft, Writing – review & editing, Visualization, Supervision, Project administration.
Copyright (c) 2025 Author https://creativecommons.org/licenses/by/4.0/
Features of Restoration of Orientation of Nematic Liquid Crystals After Pulse Shift
The aim is to study the processes of restoring the orientation of nematic liquid crystals (LCs) after a pulse shift. A sample of 4-octyl-4'-cyanobiphenyl was examined. The thickness of the LC layers ranged from 35 to 105 microns. The research methods included an experimental study of the effect of a mechanical shear pulse on thin layers of homeotropically oriented LCs (the Foner method) and theoretical modeling based on the Eriksen–Leslie equations. The experiment was carried out on a multilayer cell. Changes in the orientation of molecules were studied using optical imaging and recording of electrical signals. The obtained results showed a significant change in the temporal dynamics of light transmission and the angles of rotation of the director with a change in the amplitude and duration of the pulse. The main results showed that director relaxation occurs exponentially, and nonlinear effects such as the formation of domain structures and orientation waves were observed at amplitudes from 200 to 350 microns. At the same time, the relaxation time decreases rapidly. The proposed theory made it possible to explain the observed effects and calculate the relaxation time spectra. A satisfactory agreement was found between the theoretical and experimental relaxation time. The results obtained are important for improving the performance of LC-based devices such as displacement sensors, as well as understanding the fundamental mechanisms of the functioning of LC materials. Received: 10 July 2025 | Revised: 4 September 2025 | Accepted: 26 September 2025 Conflicts of Interest The authors declare that they have no conflicts of interest to this work. Data Availability Statement Data are available from the corresponding author upon reasonable request. Author Contribution Statement Olga Denisova: Conceptualization, Methodology, Validation, Formal analysis, Investigation, Resources, Data curation, Writing – original draft, Writing – review & editing. Yaroslava Abramishvili: Formal analysis, Investigation, Writing – original draft, Visualization.
orientation relaxation in liquid crystals
Copyright (c) 2025 Authors https://creativecommons.org/licenses/by/4.0/
First-Principles Study of the Structural, Electronic, and Optical Properties of NaTaO3
This study applies first-principles density functional theory calculations to systematically analyze the structural, electronic, and optical behaviors of the NaTaO3 perovskite. Different structures were evaluated for the studied material. The computations were performed using the full-potential linearized augmented plane wave approach together with local orbitals. In order to incorporate exchange–correlation effects, we applied the generalized gradient approximation (GGA) method, which is known to underestimate the bandgap value. To address this limitation, the Tran-Blaha modified Becke–Johnson exchange potential approximation is utilized for enhanced accuracy. The study provides a description of the bulk modulus and pressure derivative of orthorhombic NaTaO3 (Pbnm), as well as its density of states and electronic band structure. The structural parameters and stability derived from our calculations are in good agreement with both previous theoretical studies and available experimental data. Electronic structure analysis indicates that the material behaves as a semiconductor, exhibiting direct bandgaps of 3.15 eV using the Tran-Blaha modified Becke–Johnson (TB-mBJ) approach and 2.75 eV within the GGA framework. NaTaO3 exhibits an increase in its bandgap, accompanied by an improvement in physical properties within the TB-mBJ. We present a detailed discussion of the material’s optical characteristics. The findings related to its electronic and optical properties indicate strong potential for optoelectronic applications within the visible and ultraviolet spectral ranges. Received: 7 August 2025 | Revised: 13 October 2025 | Accepted: 20 November 2025 Conflicts of Interest The authors declare that they have no conflicts of interest to this work. Data Availability Statement Data are available from the corresponding author upon reasonable request. Author Contribution Statement Saadi Berri: Conceptualization, Methodology, Software, Validation, Formal analysis, Investigation, Writing – original draft, Writing – review & editing, Visualization, Supervision, Project administration. Nadir Bouarissa: Validation, Formal analysis, Writing – review & editing.
The Transformative Role of Biophotonics in Rapid, Real-Time, and in Situ Studies of Microbial Structure, Cellular Processes, and Interactions
Photonics and optical technologies provide powerful, noninvasive means to study microorganisms, including those that remain unculturable, by detecting light signals arising from specific structural and biochemical features. These include intrinsic chromophores such as aromatic amino acids, nicotinamide adenine dinucleotide hydride, and flavins; spectral signatures of functional groups in proteins, lipids, and nucleic acids; refractive index contrasts from cell walls and organelles; and scattering patterns shaped by microbial morphology. This review synthesizes current advances in applying optical and photonic methods to microbial research, with the explicit aim of showing how these tools enable in situ, real-time characterization of microbial structure, metabolic state, behavior, and interactions. We overview high-resolution imaging modalities (confocal, multiphoton, and super-resolution microscopy) for visualizing morphology and dynamics, spectroscopic techniques (Raman, surface-enhanced Raman scattering, Fourier transform infrared spectroscopy, fluorescence) for label-free molecular fingerprinting, and biosensors (fiber-optic, plasmonic, lab-on-chip) for rapid detection. We also examine light-based manipulation strategies (optogenetics, optical tweezers, laser ablation) that allow precise control of microbial processes and discuss emerging integrations with artificial intelligence analytics, quantum sensing, and space-adapted photonics. By linking the physical principles of signal generation to microbial targets, we highlight how photonics is transforming microbial ecology, diagnostics, and biotechnology and identify the technical challenges driving the development of next-generation optical tools. Received: 1 August 2025 | Revised: 20 October 2025 | Accepted: 28 November 2025 Conflicts of Interest The authors declare that they have no conflicts of interest to this work. Data Availability Statement Data sharing is not applicable to this article as no new data were created or analyzed in this study. Author Contribution Statement Abdul Rafay Rafiq: Conceptualization, Methodology, Software, Validation, Formal analysis, Investigation, Resources, Data curation, Writing – original draft, Writing – review & editing, Visualization, Supervision, Project administration. Muhammad Abdullah Farooq: Conceptualization, Methodology, Software, Formal analysis, Investigation, Data curation, Writing – original draft, Writing – review & editing, Visualization. Hamza Tariq: Conceptualization, Methodology, Software, Formal analysis, Investigation, Data curation, Writing – original draft, Writing – review & editing, Visualization. Ahsan Raza: Conceptualization, Methodology, Software, Formal analysis, Investigation, Data curation, Writing – original draft, Writing – review & editing, Visualization. Zeeshan Zafar Iqbal: Conceptualization, Methodology, Software, Formal analysis, Investigation, Data curation, Writing – original draft, Writing – review & editing, Visualization.
BOL and EOL OSNR Margins in 10,000 km Pb/s DWDM Unregenerated All-Optical Lightwave Transmission Systems in the 2000 nm Band
We report the calculation of beginning-of-life and end-of-life (EOL) optical signal-to-noise ratio (OSNR) margins in designs of 10,000 km terrestrial and subsea Pb/s capacity all-optical (without O-E-O regeneration) dense wavelength division multiplexed lightwave systems in the 2000 nm band. Our margin analysis follows the OSNR budget tables originally designed for 1550 nm subsea lightwave transmission systems employing erbium-doped fiber amplifiers, as adapted for novel hybrid Tm-Ho-doped fiber amplifiers and hollow core fibers designed to operate in the 2000 nm region off the spectrum. Our analysis shows that ideal simulated losses of ≤ 0.0325 dB/km at 2000 nm in the novel hollow core transmission fibers are required for successful EOL system operation in the terrestrial lightwave system design, when assuming that the effective deployed loss = ideal loss + 0.030 dB/km. We discuss the implications of this analysis in the context of terminal tolerances, manufacturing and environmental impairments, Q-factor time variations, customer margins, and the anticipated aging behavior of the novel 2000 nm hollow core transmission fiber. Received: 15 May 2025 | Revised: 29 July 2025 | Accepted: 28 August 2025 Conflicts of Interest The author declares that he has no conflicts of interest to this work. Data Availability Statement Data for the 700 mW 1190 nm fiber-coupled PM-packaged pump diode are openly available at https://www.innolume.com/fabry-perot-laser-diodes/fiber-coupled-single-mode-laser-diode-at-1195nm-5/. Other data are available from the corresponding author upon reasonable request. Author Contribution Statement Robert E. Tench: Conceptualization, Methodology, Software, Validation, Formal analysis, Investigation, Resources, Data curation, Writing – original draft, Writing – review & editing, Visualization, Supervision, Project administration, Funding acquisition.
Remaining Life Estimation of Power Towers Using Strain Sensor Data and LSTM Sequence to Sequence Models
This study investigates the effectiveness of embedding fiber Bragg grating (FBG) sensors in power transmission towers to assess the remaining service life of the structures following impacts from strong winds and hurricanes. FBG sensors monitor the structural integrity of the tower using online measurement of strain variations at critical structural points. The novelty of this work lies in employing a compact long short-term memory (LSTM) framework to estimate the remaining useful lifetime (RUL) from real-time FBG sensor data under both stable and fluctuating wind conditions. To estimate RUL of the tower, LSTM neural network has been implemented, providing predictive insights for proactive maintenance and risk mitigation. A prototype transmission tower was built and experimentally evaluated in a wind tunnel to assess the effectiveness and performance of the proposed RUL model. To simulate different hurricane categories, the experiment was conducted across wind speeds between 0 and 150 mph. FBG sensors installed at critical locations continuously captured real-time strain data, which was transmitted via a low-power micro FBG interrogator to a computer for input into the RUL prediction model. The proposed three-layer LSTM converges rapidly, reducing training and validation loss by nearly two orders of magnitude within 40 epochs, and achieves robust RUL predictions with an average bias of about 50 s on the test set. To quantify structural health, a mathematical health indicator was formulated based on the observed strain responses. The FBG sensors demonstrated high effectiveness in accurately detecting strain variations and monitoring the tower's dynamic behavior under extreme wind loads. The findings support the implementation of condition-based maintenance strategies, enhance safety assessments, and enable early failure detection. This approach not only improves operational reliability but also facilitates timely intervention and maintenance during critical events. Received: 26 June 2025 | Revised: 12 September 2025 | Accepted: 11 November 2025 Conflicts of Interest The authors declare that they have no conflicts of interest to this work. Data Availability Statement Data are available from the corresponding author upon reasonable request. Author Contribution Statement Yu Shi: Methodology, software, formal analysis, data curation, writing – original draft, writing – review & editing, visualization, supervision, and project administration. Abolghassem Zabihollah: Conceptualization, methodology, software, validation, investigation, resources, data curation, writing – original draft, writing – review & editing, visualization, supervision, and project administration. Yao-Chi Yu: Methodology, software, formal analysis, data curation, and writing – original draft. Arunima Pathak: Investigation, writing – original draft, and visualization. Oluwaseyi Oyetunji: Investigation.
Performance Analysis of RSA Encrypted Secure Free-Space Optical Communication Link Under Adverse Atmospheric Conditions Implemented on a Testbed
The increasing interest in the field of free-space optical communication (FSOC) can be attributed to the rising demand for an alternate communication system that can replace the existing communication systems. FSOC ranges from a few meters of indoor communication to a few kilometers of terrestrial range to satellite communication. The challenges posed vary in different scenarios. For indoors, major challenges are the artificial light sources, and for outdoors, it is the atmospheric channel-related concerns, such as fog, smoke, wind flow, and the turbulence of the channel. These adverse atmospheric conditions will degrade the link performance. On the other hand, the demand for secure communication links from the physical layer to the network layer is ever-increasing. In this paper, we have conducted a simulation study for various modulation techniques in different atmospheric conditions and have demonstrated the integration of a Rivest–Shamir–Adleman (RSA) encrypted link that offers security along with various digital modulation schemes. We have designed a lab-level setup for FSOC and developed various testbeds to simulate adverse atmospheric conditions. We tested FSOC link performance by measuring the bit error rate with various modulation schemes, that is, OOK (NRZ, RZ), PPM, and DPIM formats, along with RSA on the testbed. Received: 28 April 2025 | Revised: 24 June 2025 | Accepted: 2 September 2025 Conflicts of Interest The authors declare that they have no conflicts of interest to this work. Data Availability Statement Data are available from the corresponding author upon reasonable request. Author Contribution Statement Dhanush Devappa B C: Conceptualization, Methodology, Software, Formal analysis, Investigation, Data curation, Writing – original draft, Writing – review & editing, Visualization. Chandani Kashyap: Validation, Investigation, Data curation. Shreyas Jain: Validation, Formal analysis, Data curation, Writing – review & editing. Soumit Banerjee: Methodology. Appala Venkata Ramana Murthy: Conceptualization, Resources, Data curation, Writing – original draft, Writing – review & editing, Visualization, Supervision, Project administration.
Redshift of Quantum-Particle Plasmon Stemming from Thermal-Induced Quantum Size Effects: Numerical Modeling and Experimental Evidence
Work is reported on thermal-induced redshifts of quantum particle plasmon. The redshifts are predicted to be caused indirectly by the quantum size effects. The particles are enlarged when temperature increases, and consequently, quantum size effects modify the plasmon but not the band structure. It has been modeled for metallic quantum particles. The results are also instructive to other quantum systems, such as complex molecules. Every electron inside the quantum particle is taken into account. Tiny quantum size effects are harvested, and the redshift becomes significant. What is shifted is the so-called small particle plasmon frequency, which stems from collective intraband transitions of electrons. Interband transitions are excluded from the plasmonics. Therefore, the band structure is intact from the onset. Experimental observation is also reported for the spectral redshift. Faujasite zeolites were synthesized. Optical spectroscopy has been carried out, and the resulting spectra showed a significant redshift with the increase in temperature. The experimental observation provides early phenomenological evidence for the spectral redshift predicted by our theoretical model calculations. Received: 18 April 2025 | Revised: 13 June 2025 | Accepted: 23 June 2025 Conflicts of Interest The authors declare that they have no conflicts of interest to this work. Data Availability Statement Data sharing is not applicable to this article as no new data were created or analyzed in this study. Author Contribution Statement Mufei Xiao: Conceptualization, Methodology, Software, Validation, Formal analysis, Investigation, Resources, Data curation, Writing – original draft, Writing – review & editing, Visualization, Supervision, Project administration, Funding acquisition. Constanza Koop-Santa: Validation, Formal analysis, Investigation, Resources, Data curation. Nikifor Rakov: Validation, Formal analysis, Investigation, Resources, Data curation.
Optical Antireflective Layered and Nanoporous Metamaterials for Optoelectronic Devices
This paper presents an overview of new ideas for creating antireflective coatings for protective glasses of optoelectronic devices based on layered and matrix metamaterials with extended functionality. Attention is drawn to such important types of metamaterials as layered porous and polymer composite nanomaterials. For layered antireflective nanostructures, distinctive optical properties of coatings achieved by controlling the composition and thickness of the layers are highlighted. Composites of silicon and titanium dioxide are considered the main materials of multilayer coatings. For single-layer coatings, attention is paid to polymer matrix composite nanomaterials based on polymethyl methacrylate with the inclusion of silver nanoparticles. Metaglasses (glass plates with a two-layer deposition of silver films) or membranes made of porous anodic aluminum oxide with a thin gold film are proposed to be used as electrically conductive transparent optical elements. The article discusses the technology of creating antireflective coatings and their optical properties. At the same time, among many known technological methods for creating antireflective coatings on glass substrates, special attention is paid to sol-gel technology as technically simple and having wide functional capabilities. The optical properties of the coatings were assessed by their spectral-optical characteristics of reflection and transmission in the range of 300–1000 nm. Received: 11 April 2025 | Revised: 5 September 2025 | Accepted: 28 September 2025 Conflicts of Interest The authors declare that they have no conflicts of interest to this work. Data Availability Statement Data sharing is not applicable to this article as no new data were created or analyzed in this study. Author Contribution Statement Nickolay M. Ushakov: Writing – original draft, Writing – review & editing, Visualization, Supervision, Project administration. I. D. Kosobudskiy: Validation, Formal analysis. M. Yu. Vasilkov: Investigation, Resources.
Study on the Aging of Sauce-Flavored Baijiu Based on Light Irradiation
Aging is a crucial process that enhances the quality of Chinese Baijiu production. This paper investigates the aging of sauce-flavored Baijiu through light irradiation. LED light sources with central wavelengths of 365, 395, and 455 nm are employed to age Baijiu samples. The total acid content is determined by titration, while the total ester content is obtained through saponification. Aged Baijiu samples are subjected to sensory evaluation, and their aroma profiles are analyzed using an electronic nose. The total acid and total ester content in the aged Baijiu samples meets the first-grade Baijiu standards established by national regulations. Principal component analysis of the electronic nose data indicates that the flavor profile of the aged samples closely resembles that of Maotai, a renowned sauce-flavored Baijiu. The experimental results demonstrate that irradiation with light at a central wavelength of 395 nm for 2 weeks represents an optimal aging solution, which may be beneficial for the aging of sauce-flavored Baijiu. Received: 9 April 2025 | Revised: 18 July 2025 | Accepted: 10 September 2025 Conflicts of Interest The authors declare that they have no conflicts of interest to this work. Data Availability Statement Data are available from the corresponding author upon reasonable request. Author Contribution Statement Xiang Gao: Conceptualization, Methodology, Validation, Investigation, Data curation, Writing – original draft, Visualization. Ri Zeng Tao: Conceptualization, Methodology, Validation, Investigation, Data curation, Writing – original draft, Visualization. Chun Feng Guo: Validation, Resources, Writing – review & editing, Supervision. Qi Fei Zhu: Software, Formal analysis, Investigation, Visualization. Bobo Yang: Resources, Writing – review & editing, Supervision. Jun Zou: Resources, Writing – review & editing, Supervision, Project administration, Funding acquisition.
High Coupling Efficiency Silicon-Based Colloidal Quantum Dot Electroluminescent Devices with Ag Reflectors
On-chip silicon photonic chips are critical in various applications including chip-to-chip communication, sensing, and near-eye display technologies, but they all face significant challenges in efficiently coupling light sources onto the chip. This study introduces a design adopting colloidal quantum dot light-emitting diode (QLED) as an on-chip light source coupled with optimized Ag reflectors below and within the SiN waveguide. The inclined Ag reflector was positioned directly below the QLED within the GaN waveguide with an optimal angle of 45° and 100 nm thickness, along with a planar Ag reflector 500 nm below the waveguide with 200 nm thickness. Numerical simulation results indicate that at a distance of 50 μm from the QLED center, the average coupling efficiency of the device is 9.76%, which is 2.58 times higher than the counterpart without the Ag reflector. These findings demonstrate a significant improvement in coupling efficiency, suggesting a promising approach for future on-chip light source designs. Received: 11 March 2025 | Revised: 14 May 2025 | Accepted: 29 July 2025 Conflicts of Interest The authors declare that they have no conflicts of interest to this work. Data Availability Statement Data are available from the corresponding author upon reasonable request. Author Contribution Statement Jiajun Zhu: Validation, Formal analysis, Investigation, Data curation, Writing – original draft, Writing – review & editing, Visualization. Yuxuan Ye: Software, Validation, Data curation, Writing – original draft, Writing – review & editing. Fankai Zheng: Software, Validation, Investigation. Yilan Zhang: Writing – review & editing, Visualization. Zhiyang Lu: Software, Writing – review & editing. Hechun Zhang: Data curation, Writing – review & editing. Sifan Chen: Writing – review & editing, Supervision. Jiongwen Fang: Writing – review & editing. Yunji Yi: Methodology, Resources, Writing – review & editing, Supervision. Kai Wang: Methodology, Resources, Writing – review & editing, Supervision. Dan Wu: Conceptualization, Methodology, Resources, Writing – review & editing, Supervision, Project administration, Funding acquisition.
Comparative Analysis of Corneal and Lens Doses in Nuclear Medicine and Impact of Lead Eyeglasses: A Monte Carlo Simulation Approach
Research on eye lens dosimetry for radiation workers has increased after the 2012 International Commission on Radiological Protection 118 update on eye lens dose limits, while corneal dosimetry has remained underexplored due to historical focus and measurement challenges. This study employed a high-resolution digital eye phantom in Monte Carlo simulations to estimate corneal and lens doses for nuclear medicine staff, with and without lead glasses. Using the Monte Carlo code GATE (Geant4 Application for Tomographic Emission) (version 9.0), based on the GEANT4 toolkit (version 10.6), we estimated doses from primary and scattered radiation emitted by common radionuclides (F18, I131, Tc99m) under varying lead glass shielding thicknesses (0–0.75 mm). The simulations demonstrated that across all radionuclides, the dose to the cornea was consistently higher than the dose to the lens. Moreover, the ratio of corneal to lens dose increased with thicker lead glasses, reflecting a greater relative dose reduction to the lens. These findings indicate that while thicker lead glasses enhance lens protection, they reduce corneal exposure less effectively, thereby raising the cornea-to-lens dose ratio. Although protective eyewear remains important, its practicality may be limited by diminishing returns in shielding effectiveness and potential discomfort. Overall, this work highlights the necessity of considering both corneal and lens dosimetry to optimize occupational eye protection strategies in nuclear medicine. Received: 29 March 2025 | Revised: 8 September 2025 | Accepted: 17 December 2025 Conflicts of Interest The authors declare that they have no conflicts of interest to this work. Data Availability Statement Data sharing is not applicable to this article as no new data were created or analyzed in this study. Author Contribution Statement Zahra Akbari Khanaposhtani: Conceptualization, Methodology, Software, Formal analysis, Investigation, Data curation, Writing – original draft, Visualization. Hossein Rajabi: Conceptualization, Methodology, Validation, Resources, Writing – review & editing, Supervision, Project administration.
Spectral Limit of the Optical Behavior Between Film and Substrate for a Fluorine-Doped Tin Oxide (FTO) Transparent Conductive Layer
The optical constants of a fluorine-doped tin oxide (FTO) transparent conductive layer (of 400 nm thickness), deposited over a glass (G) substrate, were determined from the collimated transmittance (T) and reflectance (R) optical measurements of a bilayer FTOG sample in the solar wavelength range (from 250 nm to 2500 nm). The three-extinction matching requirement (3εMR) phenomenon was used as a feedback system to validate the accuracy of the optical constants results, obtained by fitting to the collimated T and R solutions of the four-flux model (4FM). The same extinction coefficients (ε) were observed than the obtained when computing light fluxes at the interfaces and substituting into the 4FM collimated differential equations (CDE). The compression of the wavelength of the incident light inside G and FTO layers was validated by computing ε from optical constants. Despite a layer is considered a thin film when its thickness is lower than the wavelength of incident light beam, and a substrate when higher, the 3εMR allowed to determine the spectral limit of the FTO layer behavior, as a substrate and as a film, at 1200 nm (instead of at 400 nm, i.e., three times higher). FTO layer behaves as a substrate, for the shorter wavelength range of the solar spectrum (SWRSS), and as a film, for the longer wavelength range of the solar spectrum (LWRSS). The thickness gradients of the forward and backward (for&back) collimated light fluxes were determined at the glass substrate of the G and FTOG samples and for the SWRSS of the FTO as a substrate layer. Then, for the LWRSS, the thickness gradients for the complex magnitude and phase (Bode plots) of for&back electric fields of the FTO film layer have been spectrally determined and represented by means of imaginary versus real parts (Nyquist plots) depending on wavelength. Received: 12 February 2025 | Revised: 9 May 2025 | Accepted: 29 May 2025 Conflicts of Interest The author declares that he has no conflicts of interest to this work. Data Availability Statement Data sharing is not applicable to this article as no new data were created or analyzed in this study. Author Contribution Statement David Barrios-Puerto: Conceptualization, Methodology, Software, Validation, Formal analysis, Investigation, Resources, Data curation, Writing – original draft, Writing – review & editing, Visualization, Supervision, Project administration.
GaN Lattice Damage and GaN-HEMT Metrology by Cameraless T-Ray Imaging and Time-Domain Spectroscopy
Gallium nitride (GaN) film grown on a silicon substrate has been investigated for high electric field-induced lattice damage via cameraless terahertz (T-ray) imaging technique. In addition, T-ray time-domain spectroscopy (TDS) has been conducted on the same GaN film as a function of depth via nondestructive and noncontact pump-probe technique. This is termed as the deep-level TDS. Further, a pair of GaN high electron mobility transistor (HEMT) dies has been imaged at the channel area where the deep-level TDS has also been conducted. A pristine die has been compared with a similar die that was irradiated with mild nuclear radiation. The channel width measured via T-ray metrology of both dies matches those determined from the optical microscope images. However, T-ray deep-level spectral analysis of both dies reveals that the pristine die's channel structure remains unaffected up to 5.5 THz up to a depth of 3 μm while that of the irradiated die's channel structure's performance is shrunk to 4.2 THz to the same depth of 3 μm. Details of data and analysis have been discussed. The technique may be deployed to other similar systems and devices. Received: 23 December 2024 | Revised: 27 February 2025 | Accepted: 19 March 2025 Conflicts of Interest The author declares that he has no conflicts of interest to this work. Data Availability Statement Data are available on request from the corresponding author upon reasonable request. Author Contribution Statement Anis Rahman: Conceptualization, Methodology, Validation, Formal analysis, Investigation, Resources, Data curation, Writing – original draft, Writing – review & editing, Visualization, Project administration.
Photobiomodulation with Low-Level Laser Therapy to Treat Rheumatoid Arthritis: Experimental and Clinical Evidence
Rheumatoid arthritis (RA) is a chronic autoimmune inflammatory disease that primarily affects the joints and can cause severe deformities, progressive destruction of joint structures, and significant functional impact. Although several mechanisms are known, the etiology is multifactorial and three times more women than men are affected. In addition to the joints, the disease can affect other systems, causing manifestations such as fatigue, fever, cardiovascular and nephrological changes, which together reduce patients' quality of life. Despite therapeutic advances with immunomodulatory and biological drugs, there are still many limitations, such as adverse effects and insufficient control of disease progression. In this scenario, photobiomodulation (PBM) using low-intensity lasers or LEDs has emerged as a promising complementary therapeutic approach due to its ability to modulate inflammatory processes, relieve pain, and stimulate tissue repair, all in a safe and non-invasive manner. This study aims to evaluate the effects of PBM in the treatment of RA based on a systematic review of the literature, examining the physical aspects of the technique, the pathophysiological mechanisms of RA in humans and in experimental models, and the clinical and experimental evidence related to the efficacy of PBM. The results indicate that PBM works by reducing oxidative stress and promoting tissue regeneration, with significant benefits in controlling inflammation and pain. Recent technological advances in the field of PBM, including more precise and adaptable devices, strengthen its potential as an effective complementary therapy, but challenges remain in terms of standardization of application parameters and clinical validation. Received: 24 January 2025 | Revised: 19 May 2025 | Accepted: 25 June 2025 Conflicts of Interest The authors declare that they have no conflicts of interest to this work. Data Availability Statement Data sharing is not applicable to this article as no new data were created or analyzed in this study. Author Contribution Statement Sabrina Zanchetta Lanza: Methodology, Investigation, Writing – original draft, Writing – review & editing, Visualization, Funding acquisition. Gaspar de Jesus Lopes Filho: Methodology, Writing – review & editing, Supervision, Project administration. Fernando Russo Costa do Bomfim: Conceptualization, Methodology, Validation, Investigation, Writing – original draft, Writing – review & editing, Supervision, Project administration, Funding acquisition.
Mini-review on Synthesis and Characterization of Metal/Silver Iodides Nanostructures and Their Applications to Optical Sensors
Currently, metal/silver iodide (AgI) nanomaterials are considered one of the most promising material candidates for future optical sensor applications because of their inherent optical, electronic, and photoactive properties. The integration of AgI is beneficial because it has a wide bandgap of about 2.8–3.0 eV, a high refractive index, and a high light absorption in the ultraviolet-visible region that improves the sensor's performance. With the incorporation of metal nanoparticles such as silver (Ag) and gold (Au), AgI possesses photochromic characteristics, plasmonic behavior, and surface-enhanced Raman spectroscopy as well as localized surface plasmon resonance properties, which offer higher sensitivity for real-time and label-free sensing. These nanocomposites are analyzed by gas sensing, sensing application of biology, sensing of pH, sensing of environmental pollution, and the application of optical imaging, where receptor-colorable properties enhance quantities of analyte especially in a high noise background. However, there are some drawbacks to their synthesis and application. The major limitations include instability of the environment, difficulties in reproduction when synthesizing, and challenges in mass production. Specifically, future work will involve investigating new approaches to creating layers of protection, solid-state stabilizers, and low-cost synthesis techniques for the purpose of enhanced stability and scalability. Besides, the scope of their uses in diagnostics, environment monitoring, and biomedical imaging will assure a steady position of metal/AgI nanocomposites as the materials for enhanced optical detection in the creation of future high-performance sensing systems. Received: 17 January 2025 | Revised: 9 April 2025 | Accepted: 5 August 2025 Conflicts of Interest The authors declare that they have no conflicts of interest to this work. Data Availability Statement Data are available from the corresponding author upon reasonable request. Author Contribution Statement Nazia Nusrat: Conceptualization, Investigation, Writing – original draft. Humaira Aslam: Methodology, Validation, Investigation, Writing – review & editing. Ali Umar: Methodology, Formal analysis, Visualization. Jehanzaib Sohail: Software, Formal analysis, Data curation, Visualization. Aman Ullah: Methodology, Software. Shumaila Ayuab: Validation, Writing – original draft. Ayesha Siddiq: Investigation, Data curation. Shehla Honey: Conceptualization, Resources, Writing – review & editing, Supervision, Project administration. Misbah Ullah Khan: Conceptualization, Resources, Writing – review & editing, Supervision, Project administration.
Dependence of the Electromagnetic Radiation Transmission Coefficient of Liquid Crystal π – Cells in the Terahertz Range
In this article, a modified Abeles technique is proposed for calculating the energy transmission coefficient of electromagnetic radiation of a liquid crystal modulator operating on the basis of a π-cell. The proposed technique has an accuracy of modeling the characteristics of the liquid crystal modulator comparable to known analogs. The results of computer modeling allow us to draw the following practical conclusions. The effect of changing the design parameters on the transmission coefficient of the liquid crystal modulator increases with a decrease in the wavelength of the electromagnetic range within the range from 16 μm to 1 μm. The maximum effect on the transmission coefficient of the liquid crystal modulator in the short-wave part of electromagnetic radiation is exerted by the thickness of the electrode layer, while there is no such dependence in the long-wave part of this radiation. The thickness of the orienting layer of the liquid crystal modulator has the same effect on its transmission coefficient as the thickness of the electrode layer, but with a smaller amplitude. The control voltage of the liquid crystal modulator has a significant effect on its transmission coefficient of electromagnetic radiation for short wavelengths and almost does not affect it in the long-wave region of electromagnetic radiation. Received: 14 January 2025 | Revised: 13 March 2025 | Accepted: 18 April 2025 Conflicts of Interest The authors declare that they have no conflicts of interest to this work. Data Availability Statement Data are available from the corresponding author upon reasonable request. Author Contribution Statement Anfal Fadhil Ahmed Mulamahawsh: Validation, Formal analysis, Investigation, Writing – original draft, Visualization. G. V. Simonenko: Conceptualization, Methodology, Software, Validation, Formal analysis, Data curation, Writing – review & editing, Visualization, Supervision, Project administration.
Increasing the Capacity in NG-PON Using QPSK, 4-QAM, and 8-QAM Modulation Formats
This work demonstrates the potential of a dual-polarized multilevel modulation format with coherent detection (CD) to maximize the spectral efficiency to meet the demand of the next-generation passive optical network (NG-PON). Maximizing capacity and spectral efficiency in NG-PON networks is particularly crucial for improving high-speed internet access, bridging the digital divide, and enabling new services and opportunities in rural and underserved areas, ultimately contributing to their socio-economic development. The proposed NG-PON system based on a higher modulation format can support 64 subscribers accessing the medium simultaneously at a 10 Gb/s data rate. The power splitting network was investigated using the Virtual Photonics Incorporation simulation tool. In this paper, we optimize the downstream transmission of the 1550.1 nm channel over 20 km standard single-mode fiber using Quadrature Phase Shift Keying and Quadrature Amplitude Modulation (4-QAM and 8-QAM) formats. A digital signal processing system was employed to mitigate fiber dispersion and losses. The modulation format of 8-QAM was discovered to maximize the spectral efficiency of the carrier. From the bit error rates analysis, an aggregate transmission capacity of 3.84 Tbps was achieved for 64 users using the 8-QAM format. The findings showed that CD with higher modulation formats improved receiver sensitivity by more than 7 dB to –22.69 dBm, compared to direct detection reported in the literature. This enhancement increases the capacity of optical networks. The study also provides an analytical perspective on high-capacity NG-PON systems utilizing advanced modulation techniques for diverse users. Received: 6 January 2025 | Revised: 15 July 2025 | Accepted: 3 November 2025 Conflicts of Interest The authors declare that they have no conflicts of interest to this work. Data Availability Statement Data sharing is not applicable to this article as no new data were created or analyzed in this study. Author Contribution Statement Henry C. Cherutoi: Conceptualization, Methodology, Software, Validation, Formal analysis, Investigation, Data curation, Writing – original draft, Writing – review & editing, Visualization, Project administration. Dismas K. Choge: Conceptualization, Validation, Investigation, Resources, Data curation, Writing – review & editing, Supervision, Project administration, Funding acquisition. David W. Waswa: Conceptualization, Validation, Investigation, Resources, Data curation, Writing – review & editing, Supervision, Project administration, Funding acquisition.
Nano-Engineering Versatile Core-Shell Nanoplatforms for Tuning Enhanced Opto-electronic Matter Interactions
In this communication, it is presented the concept of optics based on Core-shell architectures controlling the nanoscale and beyond. It is demonstrated how these types of architectures can be designed, from prototyping to synthesis, using colloidal and laser-based techniques. This particular nanoarchitecture was presented as a fundamental structure that can be tuned as needed through the use of various materials, enabling control over size, shape, and topological features. Then, the impact of Core-shell nanoarchitecture to tune photon and electron matter interactions to enhance physics and chemistry with perspectives of non-classical light generation is shown. Therefore, fundamental wet chemistry to advanced nano-optics studies by the use of Core-shell nanoplatforms is discussed. In this regard, varied phenomena such as enhanced and amplified approaches are presented. Enhanced based techniques such as metal-enhanced fluorescence (MEF), phosphorescence (MEP), enhanced quantum phenomena (EQ), and amplified signaling are of interest. In this context, the control of nanoarchitecture should be accurately controlled to place the different optical components. Optical active materials are varied to tune photon matter interactions accompanied by the generation of new modes of energies. These emerging non-classical light pathways involve strong electromagnetic field interactions, which significantly influence the electronic and optical properties of all participating materials. Moreover, photonics pathways could be modified to stabilize the excited state, increase quantum yields, and improve performances. In this context, the tuning of high-intense electromagnetic fields related with plasmonics and pseudo-electromagnetics from other semiconductors such as carbon-based materials was presented. Thus, targeted enhanced nano-emitters are presented and highlighted in this article; however, further discussion towards enhanced optics is discussed. In this manner, highlights from the nanoscale to far-field optical studies and applications are opened. So, Core-shell nanoarchitectures are presented as important optical nanoplatforms with high impact within varied optical set-ups. Received: 30 December 2024 | Revised: 21 February 2025 | Accepted: 26 March 2025 Conflicts of Interest The author declares that he has no conflicts of interest to this work. Data Availability Statement Data are available from the corresponding author upon reasonable request. Author Contribution Statement A. Guillermo Bracamonte: Conceptualization, Methodology, Software, Validation, Formal analysis, Investigation, Resources, Data curation, Writing – original draft, Writing – review & editing, Visualization, Supervision, Project administration, Funding acquisition.
Sustainable Nanoparticle Synthesis Using Tinospora cordifolia (Giloy) Leaves Extracts: Evaluation of Antimicrobial Efficacy Against MultiDrug Resistant Bacteria and Optical Features
Sustainable synthesis, also known as environmentally benign synthesis, of nanoparticles, presents an energy and resource-efficient approach for the development of nanoparticles to advanced materials with considerable biomedical potential. This study focuses on the synthesis of zinc oxide (ZnO) nanoparticles using Tinospora cordifolia (Giloy) leaves, aqueous extract as a natural strengthening and stabilizing and natural reducing agent. The bioactive compounds present in the leaves extract facilitated the reduction of zinc ions (Zn2+) to ZnO nanoparticles under optimized reaction conditions. For the characterization of nanoparticles, analytical tools were used like UV-Vis spectroscopy and X-ray diffraction (XRD) to determine the size of nanoparticles, their morphology, and crystalline structure. Green-synthesized ZnO nanoparticle's optical properties and their energy band gap were evaluated, which revealed an energy band gap of approximately 3.12 eV, which suggests their efficiency for photocatalytic and biomedical applications. The antimicrobial potential of the green-synthesized ZnO nanoparticles was assessed against a pathogen associated with waterborne infections which is Aeromonas hydrophila, showcasing multidrug-resistant (MDR) activity. The nanoparticles exhibited significant biocidal activity, with a zone of inhibition that is directly correlated to the size of nanoparticles and their concentration. The effectiveness of antimicrobial activity is attributed to the unique physicochemical properties of the ZnO nanoparticles, including a high surface area and size-dependent reactivity, which increases their interaction with bacterial cell membranes. This study brings to light the potential of Tinospora cordifolia-mediated green synthesis of ZnO which is a renewable and competent method for producing biofunctional ZnO nanoparticles. The encouraging antimicrobial activity, coupled with their tunable optical properties, positions these nanoparticles as valuable agents in combating multidrug-resistant bacteria, with further applications in nanomedicine, biosensing, and environmental remediation technologies. Received: 20 December 2024 | Revised: 26 March 2025 | Accepted: 16 April 2025 Conflicts of Interest The authors declare that they have no conflicts of interest to this work. Data Availability Statement The data sharing is not applicable to this article as no new data were created or analyzed in this study. Author Contribution Statement Jyoti Jaglan: Conceptualization, Methodology, Writing – review & editing, Supervision. Anshu Jaglan: Methodology, Validation, Investigation, Writing – review & editing, Project administration. Bajinder Singh: Formal analysis, Resources. Harsh Jaglan: Software, Formal analysis, Resources, Data curation, Visualization. Preeti Jaglan: Validation, Investigation. Savita Jaglan: Investigation, Writing – original draft. Monika Barala: Conceptualization, Writing – original draft, Visualization, Project administration.
Optical Antenna of Complex Molecule: Simulation of Anisotropic Global Dipole
Work is reported on optical antennas of complex molecules. Optical antennas of a nanometric particle are widely considered for light relays in various on-chip applications. An appealing candidate for an optical antenna is a complex molecule, for example, a huge cell containing a few hundred atoms. The optical properties, such as the radiation patterns, of the antennas may be optimized. The optimization includes the design and synthesis of the contents and structures of the molecule, such as the participating atoms and their positions. A convenient method to simulate the antenna is to solve the local field at the sites of atoms, self-consistently. A revolutionary proposal is to treat the molecule as a single dipole. Therefore, the molecule can be treated as a dipole in further simulations, and the degree of the isotropic property becomes visualizable. An isotropic radiator has an angular dependence, and a global dipole is a collective radiator. In the present work, we show that by making use of the density function theory one can calculate the global band caps. Based on the calculated density of states distribution, one obtains various optical parameters of the global dipole, including the polarizability of the dipole. Our attention is concentrated on the degree of anisotropy of the dipole, as it modifies dramatically the radiation pattern of the antenna. Received: 5 December 2024 | Revised: 12 February 2025 | Accepted: 26 February 2025 Conflicts of Interest The authors declare that they have no conflicts of interest to this work. Data Availability Statement Data sharing is not applicable to this article as no new data were created or analyzed in this study. Author Contribution Statement Mufei Xiao: Conceptualization, Methodology, Software, Formal analysis, Investigation, Resources, Data curation, Writing – original draft, Writing – review & editing, Visualization, Supervision, Project administration, Funding acquisition. Hyrum Contreras-Jimenez: Data curation, Writing – original draft, Writing – review & editing, Visualization, Funding acquisition. Jessica Méndez-Velarde: Data curation, Writing – original draft, Writing – review & editing, Visualization, Funding acquisition. Roberto Núnez-González: Validation, Data curation, Writing – original draft, Writing – review & editing, Visualization, Funding acquisition. Joel Antúnez-García: Validation, Data curation, Writing – original draft, Writing – review & editing, Visualization, Funding acquisition. Fabian N. Murrieta-Rico: Data curation, Writing – original draft, Writing – review & editing, Visualization, Funding acquisition. Constanza Koop-Santa: Data curation, Writing – original draft, Writing – review & editing, Visualization, Funding acquisition. Armando Reyes-Serrato: Data curation, Writing – original draft, Writing – review & editing, Visualization, Funding acquisition. Vitalii Petranovskii: Data curation, Writing – original draft, Writing – review & editing, Visualization, Funding acquisition. Nikifor Rakov: Data curation, Writing – original draft, Writing – review & editing, Visualization, Funding acquisition.
Deep Learning Model-Based Adaptive Power Transfer in FSO Communications
In bidirectional atmospheric channel transmission with channel reciprocity, the correlation between two transmission channel turbulence noises is high, and different techniques can be used to extract channel state information (CSI) in forward transmission, and adaptive power techniques can be used to inhibit turbulence effects in reverse transmission to improve the performance of free-space optical (FSO) systems. In atmospheric FSO communication systems, the scintillation response from turbulence effects increases the bit error rate (BER) of the communication system and reduces the system performance. In this paper, we propose two different adaptive power transmission (APT) techniques, namely gated recurrent unit (GRU)-based APT with cascading LPF and recurrent neural network (RNN)-based APT with cascading LPF, which utilizes the CSI of the channel for adaptive transmission to reduce BER. The proposed adaptive power transfer technique can improve the BER performance of the system and effectively mitigate the scintillation effect caused by atmospheric turbulence on the FSO communication system. A bidirectional atmospheric channel with different turbulence intensities is constructed in the simulation software, different background noises are added to change the channel reciprocity, the effect of reciprocity on the signal transmission is investigated, and the performance of different deep learning models in bidirectional channels. The future development of the technique is promising. According to the simulation results, APT technology based on deep learning achieves a lower bound that stabilizes at 10−4 ∼10−5 in turbulent channels under high signal-to-noise ratio conditions. Specifically, the LPF-RNN-APT technology excels due to its lightweight structure and parameter efficiency, delivering outstanding performance in strongly symmetric channels. Received: 30 November 2024 | Revised: 24 March 2025 | Accepted: 18 June 2025 Conflicts of Interest The authors declare that they have no conflicts of interest to this work. Data Availability Statement Data are available on request from the corresponding author upon reasonable request. Author Contribution Statement Wen-Yao Liu: Investigation, Resources, Data curation, Writing – original draft, Visualization. Yan-Qing Hong: Conceptualization, Methodology, Validation, Formal analysis, Writing – review & editing, Supervision, Project administration. Xu Liu: Software, Validation, Resources. Xue-Heng Chen: Data curation, Writing – review & editing. Peng-Fei Lv: Formal analysis, Writing – review & editing.
Deep Learning and LPF-Based Decision Technique in Free-Space Optical Communication Links
This study proposes a threshold decision technology to compensate for the turbulence effect in free-space optical (FSO) communication links, which integrates deep learning (DL) with a low-pass filter (LPF) to enhance system performance. Firstly, we introduce DL model of fully connected neural network (FCNN) for the sake of adaptive threshold decision (ATD) capability improvement. Then, in the cascaded LPF and FCNN approach, in order to improve the accuracy of channel state information (CSI) signal acquired from LPF, FCNN model is deployed behind LPF with a fixed cut-off frequency set for different turbulence channel degrees and data rates. For the adaptive cut-off frequency scheme of FCNN-based LPF technology, we utilize the FCNN model to determine the cut-off frequency value of LPF according to the estimated turbulence channel characteristics, enabling flexible variation of cut-off frequency values across diverse turbulence channel degrees and data rates. Finally, we conducted simulations to evaluate this technology. Simulation results demonstrate that FCNN-based adaptive cut-off frequency LPF technology outperforms LPF-based ATD with a fixed cut-off frequency, the FCNN-based ATD, and our proposed cascaded LPF and FCNN approach. Furthermore, its performance is approximate to theoretical ATD with comprehensive CSI knowledge. Therefore, the proposed method is a promising solution to compensate turbulence effect in FSO links. Received: 27 November 2024 | Revised: 18 March 2025 | Accepted: 11 June 2025 Conflicts of Interest The authors declare that they have no conflicts of interest to this work. Data Availability Statement Data are available from the corresponding author upon reasonable request. Author Contribution Statement Yan Gao: Writing – original draft. Yan-Qing Hong: Conceptualization, Methodology, Software, Validation, Formal analysis, Investigation, Resources, Data curation, Visualization, Supervision, Project administration, Funding acquisition. Chao-Yue Zhai: Writing – original draft, Writing – review & editing. Xiao-Xue Ren: Writing – review & editing.
Ultra-sensitive Photonic Crystal Fiber Based Refractive Index Sensor for Efficient Alcohol Detection at Near Infrared Region
This paper describes the development and evaluation of an ultra-sensitive modified circular photonic crystal fiber (MC-PCF) sensor for efficient alcohol detection. Operating at 850 nm, the sensor has exceptional relative sensitivity and low confinement losses, making it suitable for a wide range of practical applications. The MC-PCF sensor was developed using COMSOL Multiphysics and a finite element method to improve light-matter interaction by increasing sensitivity and precision. Performance metrics such as relative sensitivity, confinement loss, and nonlinear coefficients were assessed for various alcohols (methanol, ethanol, propanol, butanol, and pentanol). The sensor has impressive relative sensitivity values: 95.51% for methanol, 97.2% for ethanol, 97.85% for propanol, 98.69% for butanol, and 99.4% for pentanol. The confinement losses are 2.345 × 10−9, 1.022 × 10−9, 8.656 × 10−10, 1.821 × 10−9, and 3.097 × 10−9 dB/m, respectively. Methanol, ethanol, propanol, butanol, and pentanol have nonlinear coefficients of 78.95, 75, 73.69, 73.03, and 72.54 W−1km−1, respectively. The numerical apertures for the MC-PCF sensor at an 850 nm operating wavelength are 0.2599 for methanol, 0.2566 for ethanol, and 0.2567 for propanol, butanol, and pentanol. The optimized design of the MC-PCF sensor significantly improves light-matter interaction, resulting in high precision and rapid response when detecting changes in alcohol concentration. This makes the proposed sensor a strong and dependable solution for industrial quality control, medical diagnostics, and environmental monitoring. In summary, the MC-PCF sensor's outstanding sensitivity and low confinement loss at the near-infrared region demonstrate its potential for effective alcohol detection across various fields. Received: 26 November 2024 | Revised: 24 February 2025 | Accepted: 21 May 2025 Conflicts of Interest The authors declare that they have no conflicts of interest to this work. Data Availability Statement Data are available from the corresponding author upon reasonable request. Author Contribution Statement Amit Halder: Conceptualization, Methodology, Investigation, Writing – original draft, Writing – review & editing, Visualization. Md Riyad Tanshen: Software, Validation, Formal analysis, Resources, Data curation, Project administration. Md Mushfiqur Rahman Neidhe: Investigation, Data curation, Writing – review & editing, Visualization. Md Mohsin: Methodology, Formal analysis, Supervision.
modified circular photonic crystal fiber
Based on the modern idea that a photon is a stable, indivisible particle, it is necessary to abandon the generally accepted idea that in the elementary act of Raman scattering of light, a photon splits into two particles. Such a rejection and the transition to a four-photon scheme of the elementary act with the participation of an axion make it possible to preserve the integrity of the photons involved in the elementary act of Raman scattering. The laser beam interacts with vibrations of atoms in molecules, with electrons in atoms, and with phonons or other excitations in the medium under study, as a result of which frequency components appear in the radiation spectrum at the output of the medium under study, shifted relative to the laser frequency toward high or low values. Raman scattering of light is the inelastic scattering of optical radiation in the medium under study, accompanied by a noticeable change in the frequency of radiation. Unlike Rayleigh scattering, which occurs when the refractive indices of the medium and the pumping radiation coincide in phase, in Raman scattering, spectral lines appear in the spectrum of scattered radiation that are not present in the spectrum of primary (exciting) light. Raman scattering of light can be observed in various media: liquids, semiconductors, and gases. It is noteworthy that with the advent of lasers, spontaneous Raman scattering has been supplemented by forced scattering, which allows for a clear result. Using the example of laser radiation scattering in a cell with atomic potassium vapor, it is shown that axions participate in the process of Raman scattering of light. Received: 26 November 2024 | Revised: 29 July 2025 | Accepted: 28 August 2025 Conflicts of Interest The author declares that he has no conflicts of interest to this work. Data Availability Statement The data that support the findings of this study are openly available at https://journalofscience.org/index.php/GJSFR/article/view/102768, reference number [5]. Author Contribution Statement Valeriy Evgenievich Ogluzdin: Conceptualization, Methodology, Software, Validation, Formal analysis, Investigation, Resources, Data curation, Writing – original draft, Writing – review & editing, Visualization, Supervision, Project administration.
An Innovative Measurement Protocol for Determining the True Glass Transition Temperature of Chalcogenide Glasses by Differential Scanning Calorimetry
The glass transition temperature, Tg, is one of the most important physical attributes of a glass. The value of Tg often defines how a glass is made and used and dramatically impacts the electrical, mechanical, optical, and transport properties of the material. Despite its importance, the manner in which the thermal equilibrium temperature value for Tg is defined and measured in the chalcogenide glass community varies widely among researchers and practitioners leading to confusion about the term and misrepresentation of the property. Unique to this glass community, the measurement instrument of choice is the Differential Scanning Calorimeter. Countless variations in practice, coupled with incorrect equations which have been passed down unchallenged for more than 55 years, have yielded hundreds of peer-reviewed research papers and dozens of undergraduate and graduate theses. We review representative research and apply equations recently corrected by members of our team to reveal how a novel mathematical extrapolation technique to a "zero" heating rate limit provides an innovative analytical technique which will determine what we call the "true" glass transition temperature Tg(0) of a chalcogenide glass composition at isothermal equilibrium. Received: 18 November 2024 | Revised: 3 January 2025 | Accepted: 13 February 2025 Conflicts of Interest The authors declare that they have no conflicts of interest to this work. Data Availability Statement Data are available from the corresponding author upon reasonable request. Author Contribution Statement Thomas J. Loretz: Conceptualization, Methodology, Software, Validation, Formal analysis, Data curation, Writing – original draft, Writing – review & editing, Visualization, Project administration. Rashi Sharma: Investigation, Resources, Writing – review & editing. Anna Zachariou: Investigation, Resources. Richard A. Loretz: Validation, Formal analysis, Data curation, Writing – review & editing, Visualization. Myungkoo Kang: Investigation, Writing – review & editing. Kathleen A. Richardson: Conceptualization, Validation, Writing – review & editing, Supervision, Project administration, Funding acquisition.
Performance Evaluation of Underwater Optical Communication System Using Numerical and Physical Modeling
Underwater optical wireless communication (UOWC) is gaining significance beyond security and defense, extending to applications such as underwater exploration, surveillance, and vehicle networking. Optical communication offers advantages like higher data rates, compact system size, and easier deployment on small underwater remotely operated vehicles than acoustic methods. However, UOWC faces challenges due to the dynamic underwater environment, including turbidity and salinity variations, which impact performance. This paper investigates the feasibility of UOWC using commercially available components such as avalanche photodiodes, light-emitting diodes (LEDs), and laser diodes. The effectiveness of the communication link is evaluated through numerical modeling and validated using an experimental setup. Key performance metrics, including bit error rate, are analyzed to assess different modulation schemes and their impact on communication efficiency. Baseband modulation and forward error correction techniques are explored to enhance reliability. By combining theoretical analysis with practical implementation using a UOWC testbed, this work provides valuable insights into system performance under varying environmental conditions, contributing to the advancement of UOWC technology for real-world applications. Received: 30 October 2024 | Revised: 19 March 2025 | Accepted: 24 June 2025 Conflicts of Interest The authors declare that they have no conflicts of interest to this work. Data Availability Statement Data are available from the corresponding author upon reasonable request. Author Contribution Statement Dhanush Devappa B C: Methodology, Software, Investigation, Data curation, Writing – original draft, Writing – review & editing, Visualization. Kalyani Pawar: Validation, Investigation. Shreyas Jain: Formal analysis, Writing – review & editing. Appala Venkata Ramana Murthy: Conceptualization, Resources, Writing – review & editing, Visualization, Supervision, Project administration, Funding acquisition.
underwater optical wireless communication