This study introduces a compact monopole antenna designed for near-field breast tumor detection within the 915 MHz ISM band. By integrating rectangular slots along the antenna’s non-radiating edges, the design achieves a 59% size reduction, resulting in a compact footprint of 0.4λg × 0.27λg.. To enhance its performance, a partially reflective surface (PRS) is added beneath the antenna, significantly boosting gain from 1.86 dBi to 5.3 dBi, while maintaining high radiation efficiency between 95% and 99% across the 907–920 MHz range. A key feature of this study was its S-parameter analysis using a realistic three-dimensional breast phantom composed of both adipose and fibroglandular tissues. This study shows that the antenna’s reflection coefficients are sensitive to tumor size, enabling the detection of structural variations in breast tissue. Furthermore, the electromagnetic behaviour of the antenna was modelled to assess the how power is transmitted and reflected through different breast layers, with and without the PRS. Specific absorption rate (SAR) analysis confirmed that the sensor operates safely at power levels up to 215 mW. The experimental results closely aligned with simulations, confirming the antenna’s reliability and effectiveness in detecting early-stage breast cancer by identifying tumors of varying sizes in both adipose and fibroglandular tissue environments.

In this work, a heterostructure photodetector that uses few-layer graphene (FLG) is proposed for ultra-fast near-infrared (NIR) optoelectronic applications. The device has a vertically stacked FLG/InSb/AlSb structure, built on an n-type GaAs substrate. In this configuration, the FLG acts as a high-mobility conductive contact, thereby facilitating efficient carrier transport, while the narrow bandgap InSb layer serves as the primary light-absorbing region for NIR radiation. Furthermore, the AlSb layer acts as a barrier that improves carrier confinement and promotes charge separation at the heterojunction interface. When exposed to NIR illumination, the electron-hole pairs are mainly produced in the InSb absorption layer, which are then separated by the built-in electric field, resulting in effective photocurrent generation. The high carrier mobility and ballistic transport properties of FLG contribute to rapid carrier collection and improved photoresponse. The device's performance is evaluated by employing Silvaco ATLAS TCAD simulation software. The proposed graphene-based heterostructure photodetector exhibits stable current-voltage characteristics under illumination, improved photocurrent density with a photocurrent-to-dark current density ratio of 1010, responsivity of 0.53 A/W, detectivity of 2.4 × 1016 cmHz1/2/W, and ultrafast response characteristics with a rise (fall) time of 0.51 (0.54) ns. Moreover, machine learning regression models, such as Random Forest, Extra Trees, XGBoost, and CatBoost, are used on the simulated dataset to learn how device parameters affect key performance metrics. This makes it possible to accurately predict and efficiently optimize the characteristics of photodetectors at a lower computational cost. These results demonstrate the potential of the proposed heterostructure for high-speed and high-sensitivity NIR applications, such as optical communication, environmental monitoring, and infrared imaging systems.

Contemporary advances in the spatial-temporal modulation of electromagnetic wavefields have fundamentally reshaped optical beam-shaping paradigms, positioning structured light as a pivotal enabler of next-generation photonic architectures and catalysing transformative developments in nanoscale optics, ultra-sensitive sensing, computational imaging, and high-bandwidth optical communications. Within this evolving landscape, structured-light engineering has unlocked unprecedented control over modal excitation and propagation dynamics in fiber-optic platforms. Nevertheless, despite these advances, most fiber-optic sensing schemes still rely on conventional Gaussian-beam illumination, which is inherently limited in its capacity to preferentially couple energy into higher-order guided modes, resulting in reduced evanescent-field extension and weaker interaction with the surrounding medium. Motivated by this fundamental shortcoming, the present work unveils what we believe to be a novel waveguide-based refractive index sensing system by launching a Laguerre higher-order cosh-Gaussian beam (LHOChGB), whose non-trivial spatial structure enables preferential coupling of higher-order guided modes within a uncladded multimode fiber, thereby enhancing the evanescent field localization and strengthening the guided-mode interaction with the external medium. Furthermore, our study was corroborated by using the beam propagation simulations based on the finite-difference method in OptiBPM to characterize the propagation dynamics of the LHOChGB within the sensor structure. Such rigorous analysis unequivocally demonstrates an impressive peak absolute sensitivity of 33.72 dB/RIU, representing an approximate 10.6-fold enhancement over the conventional Gaussian-excited sensor, which typically yields a sensitivity of 3.18 dB/RIU. Therefore, this incipient genre of structured optical field propels innovative trajectories in the field of optical sensing and exhibits substantial potential for multifaceted physico-chemical and biosensing applications.

The emergence of structured light as a controllable photonic entity has transformed the manipulation of electromagnetic fields, facilitating advanced light-matter interactions that critically enhance the operational efficiency of diverse fiber-optic sensors. Within this emergent framework, the Airy-Bessel beam, characterized by its non-diffracting propagation and self-healing dynamics, stands as a paradigmatically superior candidate for fiber-based refractive-index measurements. In this investigation, we employed the Airy-Bessel excitation within a decladded multimode fiber to transcend the inherent constraints of conventional Gaussian illumination, whose efficacy is typically curtailed by shallow evanescent-field penetration and diminished mode-medium interaction. By tailoring the excitation conditions, higher-order guided modes are efficiently stimulated, thereby amplifying the evanescent-wave contribution and enabling a superior refractive index sensitivity. The proposed sensor architecture was validated using full-vector beam propagation method (BPM) numerical modeling performed in OptiBPM (v13.1.3, Optiwave Inc.), allowing a comprehensive analysis of Airy-Bessel beam evolution within the sensing structure. The sensor demonstrates absolute sensitivities of 1502.96 dB/RIU and 1878.72 dB/RIU for sensing lengths of 20 cm and 25 cm, respectively, with corresponding detection resolutions of 6.65 × 10−6 RIU and 5.32 × 10−6 RIU. These results affirm a notable advancement over Gaussian beam configurations and highlight that structured-beam excitation enables scalable sensing without the need for geometric alterations such as tapering, side-polishing, U-bending, surface-functionalized designs, etc. Therefore, the proposed sensing method furnishes a potent pathway for futuristic fiber-optic sensing across chemical, biomedical, and environmental domains where ultralow refractive index detection is imperative.

The emergence of structured optical waveforms as precisely engineered photonic frameworks has remarkably propelled the mastery of electromagnetic field distributions, thereby fortifying the light-matter interaction essential for high-performance fiber-optic sensing. In this work, a Tricomi-Gauss beam, characterized by its propagation-invariant behavior, is employed as the excitation source within a decladded multimode fiber to overcome the inherent limitations of conventional Gaussian illumination, which is typically constrained by limited evanescent-field penetration and weaker modal-medium interaction. The key novelty lies in leveraging a Tricomi-Gauss beam to enable selective higher-order mode excitation in a decladded multimode fiber without requiring any structural modification to the waveguide dimensions, thereby augmenting the modal-field interaction with the sensing medium, which leads to intensified evanescent-field strength and enhanced sensitivity to refractive-index variations. This novel sensing configuration is rigorously analyzed using a beam propagation method implemented in OptiBPM, with particular emphasis on modal evolution across the sensing region. Our proposed sensor manifests an exceptional peak absolute sensitivity of 3352.10 dB/RIU, accompanied by a notably refined detection resolution of 2.98×10−6RIU. Therefore, these observations demonstrate the pronounced superiority of the proposed sensor over the Gaussian-based excitation methodology and affirm that structured beam engineering enables coherent, systematic sensitivity amplification without structural intervention in the fiber, making it suitable for next-generation high-performance refractometric sensing applications.

Detection of low-concentration and diluted target analytes within specific hotspot regions is essential for ultrasensitive surface-enhanced Raman spectroscopy (SERS) analysis. However, achieving high reproducibility and sensitivity for SERS substrates remains a significant challenge. In this study, we present the fabrication of Ag nanoparticles (AgNPs) assemblies on a cylindrical plasmonic copper (Cu) rod substrate, using a drop-casting method to construct colloidal-based droplet-SERS platforms. Systematic optimization of droplet volume, analyte-to-nanoparticle ratio, and reaction conditions revealed the ideal parameters for performance enhancement. The cylindrical substrate exhibits sufficient hydrophobicity, confining the analyte to the tip of the SERS surface and preventing aqueous sample spreading, a common limitation in conventional substrates. This design enabled the analysis of samples as small as 4 μL, without requiring a drying step. Additionally, aligning the cylindrical substrates into a 3D-printed holder facilitated the production of an array for high-throughput analysis of aqueous samples. This strategy demonstrated outstanding SERS performance, with a relative standard deviation of 8.6% and substrate reusability. Under optimized conditions, Rhodamine B, a carcinogenic dye, was detected at a low threshold of 10–9 M (1 nM) in aqueous and real-world samples, including cotton candy without spiking. This application highlights the potential of this method for food safety analysis by addressing critical concerns regarding toxic contaminants, particularly those that pose health risks to children, who are the primary consumers of these products.

The rapid expansion of Internet of Things (IoT) applications has driven advancements in networking technologies such as low-power wide-area networks (LPWANs) to extend coverage and enhance the lifespan of IoT devices (IoDs). However, real-world IoT networks are typically heterogeneous, comprising static and dynamic IoDs leading to variations in network topology. These fluctuations cause challenges such as increased data latency and energy imbalances, which hinder efficient information flow. To overcome these issues, this article presents a novel approach that integrates small-world characteristics (SWCs), inspired by social network theory, into heterogeneous LPWANs using reinforcement learning (RL). Specifically, the Q-learning technique is used to introduce new long-range links into the network, enhancing connectivity and optimizing performance. Different conventional networks with varying numbers of mobile nodes are studied in this work followed by their subsequent transformation to small-world versions. The performance of the networks is optimized in terms of energy efficiency and latency in data routing. It is observed that irrespective of the network (conventional or small-world), the performance is better if the number of static nodes is greater. Furthermore, independent of the degree of dynamicity, the SW-LPWAN is more energy-efficient and has lower transmission delay than the corresponding conventional network. Numerically, SWLPWANs achieve up to 14.6% faster data transmission speeds, supporting 19.7% more active IoDs, and maintaining 15.5% higher residual energy compared with conventional networks.

Recent advancements in the spatiotemporal engineering of electromagnetic wavefronts have redefined contemporary beam-shaping paradigms, solidifying their role as foundational elements in emergent photonic architectures and precipitating breakthroughs in nanoscale optical physics, hypersensitive metrology, computational imaging, optical sensing, and terabit-scale optical communications. Building upon this technological inflection point, the present investigation delineates a meticulously architected fiber-optic refractometric platform predicated on Airy-vortex beam excitation as distinguished by its intrinsic orbital angular momentum and transversely self-accelerating intensity profile. The principal novelty of the proposed sensing scheme resides in harnessing an Airy-vortex beam, whose unique spatial topology affords highly efficient and selective excitation of higher-order modes within a decladded multimode fiber, thereby augmenting evanescent-field confinement at the fiber-medium boundary. Furthermore, our study was supported by full-vector Beam propagation method (BPM) simulations in OptiBPM (v13.1.3), enabling detailed examination of Airy-vortex beam dynamics across the sensor geometry. The comprehensive beam propagation analysis establishes a peak sensitivity of 2808.49 dB/RIU with the refractive index resolution as fine as 3.56 × 10⁻⁶ RIU, surpassing the Gaussian-mode analogues by a conspicuous margin. Thus, this unique blend of diffraction resilience and structured phase topology inherent to the Airy-vortex beam renders this architecture a compelling platform for high-resolution, real-time refractometric sensing across various chemical, environmental, and biomedical regimes.

A novel integrated optic microring resonator (MR) and MR based force sensor is reported. The microring’s and bus waveguide’s width, and coupling gap of MR are optimized using Finite-Difference-Time-Domain (FDTD) Method. This optimized MR provides large FSR and high Q-factor. The optimized IOMR is used as an optical sensing element in force sensor. MR is integrated into the micro cantilever beam (MCB) of the force sensors. The radius and thickness of MR are considered as 5 μm radius and 220 nm respectively, and length, width and thickness of MCB is considered as 75 μm, 15 μm and 300 nm respectively. The working principle behind the sensor is principle of photo-elastic effect. The effective refractive index of the sensor changes when a force is applied to the sensing element, which leads to a resonant wavelength shift of MR output characteristics. A shift in resonant wavelength is detected as a function of the applied force. The Finite-Element Method is used to analyze the sensor’s stress, and the FDTD method is used to analyze MR’s field propagation. The optimized MR provides an FSR of 22.29 nm. The sensitivity of the force sensor is 5 pm per 1μN and Q-factor is 18,241. The sensor range is from 0 to 1 μN. The optimized MR can be used for different sensing applications such as force, pressure, acceleration sensing, biosensing, etc.

The widespread presence of plastic contamination in the environment presents a severe threat to human and animal health. This study introduces a toluene dispersion strategy for detecting microplastics of different sizes using surface-enhanced Raman spectroscopy (SERS). The evaporation-induced self-assembly (EISA) method was employed to prepare SERS substrates by incubating silver nanoparticles (AgNPs) of ∼40-60 nm with a microplastic solution containing polystyrene (250 μm, 2.1 mm), polypropylene (10-50 μm), and polyvinyl chloride (1-5 μm). SEM images and Raman spectroscopy confirmed the uniform decoration of AgNPs on filter paper substrates, with a relative standard deviation (RSD) of 8.22%. Thiophenol was used as a Raman reporter to monitor surface changes, showing a strong correlation (R2 = 0.986-0.995) between its SERS signal and microplastic concentration in aqueous and real samples. This is the first time a toluene dispersion strategy has been integrated with EISA to achieve highly sensitive microplastic detection, reaching a limit of 0.001 mg mL−1. The method was validated in real-world matrices, including lake water and salt samples, in the presence of interferents such as organic pollutants, inorganic ions, colloids, bio-organisms, and bisphenol A. This approach enables rapid detection of diverse microplastics in complex environmental samples.

This paper introduces a two-port millimeter wave multiple input multiple output (MIMO) antenna designed with a compact area of 75 × 50 mm2. The proposed antenna comprises a cavity-backed substrate integrated waveguide (SIW), which results in improved performance. It provides a minimum isolation of 41 dB across the operating frequency band, ensuring maximum port decoupling. The envelope correlation coefficient (ECC) is well within the acceptable threshold over the operational bandwidth, supporting efficient MIMO operation. The proposed antenna resonates at 28 GHz and has a gain of 9.4193 dBi, making it a suitable option for millimeter wave communication systems in the n257 band, which is used for 5G applications.

This study conducts a technical comparison of monopole antenna-based sensors for near-field breast tumor detection at two resonant frequencies: 2 GHz and 915 MHz. The 2 GHz antenna configuration initially provides a gain of 2.13 dBi, which is significantly enhanced to 6.9 dBi by integrating a Partially Reflective Surface (PRS) comprising a 4 × 4 array of unit cells. However, due to limited penetration at this higher frequency, tumor detection is largely confined to the superficial adipose layer. To improve diagnostic depth and sensitivity, an alternative antenna is designed to operate at 915 MHz, achieving a baseline gain of 1. 8 6 dB i. The integration of a 5 × 5 PRS array further elevates the gain to 5.3 dBi. The increased aperture and improved directivity at this frequency support enhanced near-field sensing performance. S-parameter evaluation using a multilayer heterogeneous breast phantom demonstrates that the 9 1 5 MHz design facilitates the detection of tumors in both adipose and fibroglandular tissue layers. These findings highlight the superiority of lower-frequency antennas, especially when combined with PRS structures, for achieving deeper tissue penetration and improved sensitivity in breast tumor detection scenarios.

Persistent organic pollutants (POPs) pose significant environmental and biological risks due to their stability and bioaccumulation in the food chain, often facilitated by contamination from sewage water. Monitoring POPs is crucial for assessing their detrimental environmental impacts and preventing related health issues. Conventional analytical techniques for detecting POPs typically require labeling, energy-intensive, and cost-effective equipment, can be time-consuming, and may alter the properties of analytes. In this study, we demonstrate a label-free biosensing approach utilizing spoof surface plasmon polaritons (SSPP) for the rapid and sensitive detection of commonly encountered POPs (including textile and paper dyes, worn-out antibiotics, and herbicides) in sewage water. Inspired by plasmonic, our results show that SSPP biosensors exhibit excellent sensitivity and selectivity for POPs in sewage water samples as small as 0.634 mL. Additionally, we validate the performance of our biosensors using real-time sewage water samples spiked with widely prevalent and harmful POPs, showcasing their practical utility in complex environmental matrices. This study underscores the potential of SSPP-based biosensing as a powerful tool for the label-free detection of POPs in sewage water, offering a rapid, sensitive, and cost-effective solution for monitoring environmental pollutants. Our findings contribute to water quality assessment efforts and the development of effective pollution mitigation strategies.

It is important in the rising demands to have efficient anomaly detection in camera surveillance systems for improving public safety in a complex environment. Most of the available methods usually fail to capture the long-term temporal dependencies and spatial correlations, especially in dynamic multi-camera settings. Also, many traditional methods rely heavily on large labeled datasets, generalizing poorly when encountering unseen anomalies in the process. We introduce a new framework to address such challenges by incorporating state-of-the-art deep learning models that improve temporal and spatial context modeling. We combine RNNs with GATs to model long-term dependencies across cameras effectively distributed over space. The Transformer-Augmented RNN allows for a better way than standard RNNs through self-attention mechanisms to improve robust temporal modeling. We employ a Multimodal Variational Autoencoder-MVAE that fuses video, audio, and motion sensor information in a manner resistant to noise and missing samples. To address the challenge of having a few labeled anomalies, we apply the Prototypical Networks to perform few-shot learning and enable generalization based on a few examples. Then, a Spatiotemporal Autoencoder is adopted to realize unsupervised anomaly detection by learning normal behavior patterns and deviations from them as anomalies. The methods proposed here yield significant improvements of about 10% to 15% in precision, recall, and F1-scores over traditional models. Further, the generalization capability of the framework to unseen anomalies, up to a gain of + 20% on novel event detection, represents a major advancement for real-world surveillance systems.

Elastic optical networks enhance the flexibility of bandwidth distribution and making it precise, enables optimal use of the spectrum. The routing and spectrum problem (RSA) in spectrum-sliced elastic optical networks is addressed by a unique technique of spectrum allocation that uses Gaussian distributions. The routing algorithms used include balanced load spectrum allocation and shortest path spectrum reuse. The results show that using a Gaussian distribution method to distribute spectrum provides less blocking probability. For a 6-node and 14-node NSFNET topology networks with static traffic demands, the blocking probability of the algorithm is studied. The blocking probability for the proposed distributions is obtained and compared with the gold-fit algorithm and first-fit, exact-fit algorithms. The proposed algorithm shows the least blocking probability of 0.0125 for 150 cumulative average demand when compared to other algorithms.

A Spoof surface plasmon polariton (SSPP) sensor is developed to identify honey samples by adding different concentrations levels of sugar (glucose and fructose). The SSPP-based sensor is integrated with a microfluidic reservoir to discriminate honey samples. The change in the resonating frequency shift with changed percentages of fructose and glucose levels of honey samples shows the performance of the SSPP sensor. This innovative approach presents a non-destructive, non-intrusive, label-free, rapid, and real-time methodology for analysing honey samples. The sensor exhibits exceptional sensitivity in detecting subtle differences in the dielectric constants of diverse samples. We systematically investigate the impact of distinct geometrical parameters on the sensor's performance, focusing on optimizing its characteristics. A distinctive pentagon-shaped unit cell (UC) for the SSPP construction is thoroughly explored, revealing its unique performance and sensing capabilities. We construct a multilayer SSPP microwave structure with a pentagon unit cell to create a functional sensing platform for honey samples. The transient solver is used for computational analysis. Our results indicate a remarkable sensitivity of 1522 MHz/epsilon unit, with a correlation coefficient (R2) of 0.9367, for discerning between different dielectric samples ranging from 1 to 5 for normal pentagon unit cells. Additionally, for vertex-based pentagon unit cells, the sensor demonstrates a sensitivity of 1105 MHz/epsilon unit, with an R2 of 0.9524, when applied dielectric constants within the range of 1–5. These simulation outcomes highlight the viability of the suggested SSPP-inspired sensor as a promising solution for monitoring applied dielectric quality and characterizing the honey sample's dielectric constants. This integrated approach showcases the potential to revolutionize quality assessment within the realm of honey production and diverse materials through its advanced sensing capabilities.

The paper presents a Multiple-input- multiple-output (MIMO) antenna with four ports, designed on an 80 × 80 mm2 substrate. The antenna utilizes an Eighth-mode substrate integrated waveguide (EMSIW) circular cavity-backed structure, with narrow half-wavelength linear slots to suppress mutual coupling between the elements. This design provides a minimum isolation of 27 dB over the operational frequency band. The antennas are arranged at 90° angles to each other, are linearly polarized, and offer polarization diversity, further improving isolation. This orthogonal design creates overall system performance by lowering the potential of signal deterioration owing to multipath propagation. The Envelope Correlation Coefficient (ECC) is within the acceptable threshold across the operating band, confirming better diversity performance. The antenna operates at 3.5 GHz, with a gain of 1.39 dBi, making it suitable for 5G use cases, particularly in small-cell deployments for modern wireless communication systems where space and performance are major constraints.

A novel photonic crystal based hexagonal ring resonator (HRR) based 5-channel DWDM demultiplexer, its design and analysis is reported. The wavelength controlling of each channel is achieved by fine tuning of radius of special hole of HRR. Each channel of DWDM demultiplexer is designed with a PC-HRR consists of a special hole, which is incorporated in between hexagonal contour and input waveguide. And the radius of the special hole of each HRR varies from 95 to 115 nm with a variation of 5 nm. These five different HRR are connected serially by input-waveguide, which is used to couple the light. The air-holes on a silicon slab configuration is used in the device design. The resolved wavelength of this filter is in 1535–1539 nm range, where Erbium-Doped-Amplifier can be used. An average channel coupling-efficiency is 72.4% and channel cross talk is -18.31 dB reported. Photonic band gap of the device is computed by Plane-Wave-Expansion method. EM field analysis of this device is carried out by Finite-Difference-Time-Domain method.

Biosensing through bodily fluids (especially through blood) is gaining attention due to their preciseness and broad range of detection. Various point-of-care diagnostic methods based on different sensing techniques are emerging rapidly. However, the future lies in simple and rapid detection technologies with a wide range of applications. Here, we designed a sensor based on microwave spoof surface plasmon polaritons (SSPPs) for sensing biological fluids. A novel octagon-shaped unit cell for the SSPP structure is fully explored in terms of its behavior and sensing capabilities. The SSPP microwave structure with a microfluidic reservoir is built as a multilayer arrangement based on the proposed unit cell to serve as a sensing platform for various bodily fluids. We first evaluated the sensing feature of the designed sensor using various sugar solutions. We further demonstrated the biosensing capacity of the sensor by testing the blood phantom samples, which are prepared with different sugar concentrations. The sensor shows good sensitivity, and the corresponding sensing performance is experimentally validated with the distinguishable resonance frequency shift of 1.202 GHz on average per blood phantom sample. Our analysis revealed that this SSPP-based sensor is a good candidate for biosensing of bodily fluids. This biosensing capability of the sensor may be further extended to other bodily fluids and, thus, offers nondestructive, noninvasive, label-free, rapid, and real-time biosensing.

This study investigates the use of spoof surface plasmon polaritons (SSPPs) as an effective feeding mechanism for antennas functioning within the extremely high-frequency (EHF) range. A novel method is proposed for feeding a dielectric rod antenna with SSPPs, featuring a simple design made from FR-4 material with a relative permittivity of 4.3. In contrast to traditional tapered dielectric rod antennas and their feeding configurations, this design shows promise for achieving a gain of up to 16.85 dBi with an antenna length of 7.6 λ0. By carefully optimizing the design, impedance matching and directional radiation characteristics were obtained at 7.3 GHz. Simulations were conducted using CST Microwave Studio to validate and evaluate the design’s performance. The enhanced gain, improved impedance bandwidth, and use of cost-effective materials such as FR-4 present a compelling case for adopting this design in future wireless communication technologies. Additionally, the remote sensing properties of the feeder can be utilized for concealed object detection, material characterization, and the analysis of the spectral properties of materials.

The studies concerning solar cell technology has consistently been captivating and inspiring, largely because of its environmentally friendly and sustainable characteristics. The outstanding electronic, optical, mechanical, and electrical characteristics of perovskite materials make them crucial for the development of the photovoltaic industry. In order to model the mixed cation Rb0.05Cs0.1FA0.85PbI3 perovskite solar cells, the SCAPS-1D tool was used. The main feature of RbCsFAPbI3 perovskite is its remarkable stability, and wide bandgap. Rubidium (Rb) and cesium (Cs) cations improve the optoelectronic characteristics of the material, resulting in less non-radiative recombination and improved charge transfer. In this work, the effects of different hole transport layers (CuSCN, CuSbS2,Cu2O) and back metal contacts (Ag, Fe, C-Cu, Au, Ni, Pt) on solar cell performance were investigated. The maximum efficiency of the solar cell has been achieved by studying various parameters like temperature, series resistance, shunt resistance, defect density, and absorber layer thickness. With FF = 84.12%, Jsc = 24.52 mA cm−2, Voc = 1.19 V, and the configuration of FTO/TiO2/RbCsFAPbI3/Cu2O/Au, the optimised device obtains a PCE of 24.64%. The impressive enhancements in performance parameters observed in the structure of the device make it highly suitable for applications in solar energy harvesting systems.

We explore the concept of spoof surface plasmon polaritons (SSPPs) as a means to confine plasmons on the surface of a tiny metallic structure. We focus on introducing an efficient transition design that confines the SSPP wave along a corrugated metallic strip with metal acting as a ground material. To achieve this, a unique unit cell specifically designed for waveguiding purposes was analyzed. The dispersion characteristics of this design were presented, demonstrating its potential for SSPP waveguiding applications. By varying the groove height from h1 to h7 (ranging from 0.5 to 3.5 mm), the SSPP waveguide was developed and analyzed its spectral characteristics through corresponding S parameters. Furthermore, the effects of altering the corrugated groove width from 1 to 2 mm was investigated. This variation is shown to have a linear impact on the gain, with a maximum gain of 7.71 dBi observed.

This research work describes, a novel integrated optic serially coupled micro racetrack-ring resonator (SCRR) based pressure sensor. Racetrack-ring resonators of radius 5μm and 4μm are chosen to create the Vernier-effect. The resonators are optimized for large FSR and high Q-factor by Finite-Difference-Time-Domain (FDTD) Method. The resonators are coupled serially between input–output waveguides to design a SCRR. The SCRR is used as a sensing element and integrated on silicon diaphragm. The sensor follows the Photo-elastic effect principle. When the pressure is applied on sensing element, there is a change in the effective refractive-index of sensor and leads to a shift in the super resonant wavelength. The shift is proportional to an applied pressure. So, the change in applied pressure is observed as a resonant-wavelength shift. The stress analysis of sensor is examined by Finite-Element-Method, and the field propagation of SCRR is examined using the FDTD-method. This sensor provides, high sensitivity of 1.04 nm per 100 kPa and Q-factor of 14084. The sensor range is 0 to 300 kPa.

A novel narrowband dielectric-based spoof localized plasmon polariton (DSLPP) with plasmonic waveguide sensor has been developed for biosensing applications. This sensor exhibits a narrowband response with good sensitivity and high-quality factor, characterized by resonances at 6.1 GHz and 8.2 GHz. The designed plasmonic sensor consists of coplanar waveguide (CPW) and plasmonic waveguide with a sandwiched resonator (SR). With the integration of plasmon waveguide and SR, a fundamental mode with high quality factor and multiple higher order modes are observed from the transmission coefficient spectrum. The proposed sensor is versatile and can be employed for detecting various diseases, including cancer and malaria, as well as for analyzing edible oils and other chemicals. Key advantages of this sensor include its simple design, tunability, narrow sensitive bandwidth, and high sensitivity. Moreover, it achieves very high-quality factor (Q) values for band I it is 1105.86 and band II, 1177.69, good sensitivity for band I it is 58 MHz/∈r and for band II it is 114 MHz/∈r, with the linearity R2 = 0.9786, 0.9873 respectively, making it an excellent candidate for precise and reliable detection in diverse biosensing and chemical sensing applications.

This study presents the design and analysis of a 5-channel dense wavelength division multiplexing (DWDM) demultiplexer based on a photonic crystal (PC) hexagonal ring resonator (HRR). By varying the radius of a unique hole inside each HRR, the novel method enables exact wavelength control. The apparatus is ideal for applications using Erbium-Doped Fiber Amplifiers (EDFAs) and operates in the wavelength range of 1535 to 1539 nm. With a maximum channel crosstalk of - 15.39 dB and an average channel coupling efficiency of 72.4%, the study shows good signal separation performance. The Plane-Wave Expansion (PWE) approach is used to determine the device's photonic band gap (PBG), and the Finite-Difference time domain (FDTD) method is used to analyze the electromagnetic (EM) field. This research contributes to the advancement of integrated optical components, showcasing the potential of PC-based devices in enhancing the capacity and efficiency of optical communication systems.

This work explores the potential of spoof surface plasmon polaritons (SSPPs) for effectively feeding high-frequency antennas operating in the extremely high-frequency (EHF) range. An innovative approach is introduced in this study to utilize SSPP to feed a dielectric rod antenna. The design incorporates a straightforward dielectric rod antenna fabricated using FR-4 material with a relative permittivity of 4.3. Compared to conventional tapered dielectric rod antennas and their corresponding feeding configurations, this design presents the potential benefit of achieving an improved gain of up to 16.85 dBi using a specific antenna length of 7.6λ0. Through careful design optimization, we achieved impedance matching and directional radiation characteristics at a frequency of 7.3 GHz. To validate our design and assess its performance, we conducted simulations using the CST Microwave Studio. This study aims to demonstrate the effectiveness and practicality of the proposed dielectric rod antenna with an SSPP feed.

In this paper, we introduce an innovative, extremely sensitive microwave sensor that is based on Spoof Surface Plasmon Polariton (SSPP) like propagation and has an integrated chamber for liquid samples. By examining the impacts of variations in geometrical parameters on sensor responses, sensor performance is optimized for the ultra-sensitive identification of tiny dielectric constant in liquid specimens. When the sensor is loaded with a different sample, the variation in the resonance frequency is subsequently acquired. The findings show that the sensor has a high sensitivity 1055 MHz/epsilon unit and good linearity R2 = 0.927. The proposed sensor is a strong contender for the identification of minute variations in the dielectric constant of various samples.

Design and analysis of spoof surface plasmon polariton waveguide is presented in this work. The novel structure exhibits an improved gain of 6.973dBi with an increment of 0.83dBi compared to the existing designs.

In this work an 8-channel DWDM demultiplexer is proposed with multiple designs and numerical analysis. Photonic crystal ring resonators of airholes on a 220 nm thick silicon slab are used as wavelength selective elements. Demultiplexers of three different designs are considered and their characteristics are analyzed. For all the three designs, the resolved wavelengths are in the range of 1530–1540 nm, where Erbium Doped Fiber Amplifiers are applicable. For the optimized device, the average coupling efficiency, cross talk are found to be 70.4% and − 16.76 dB, respectively. Maximum and minimum coupling efficiencies of 79% and 56% are achieved. Photonic bandgap computation is performed by using plane wave expansion method and spectral characteristics are obtained by applying 3D finite difference time domain method.

Design and analysis of spoof surface plasmon polariton waveguide is presented in this work. The novel structure exhibits an improved gain of 6.973dBi with an increment of 0.83dBi compared to the existing designs.

A novel DWDM device based on Silicon Photonic Crystal (PC) slab is proposed. Hexagonal ring resonators are used for channel dropping purpose. Channel dropping is achieved by fine tuning of lattice constant inside the ring resonators. The device is designed in such a way that the demultiplexed wavelengths are in C band of electromagnetic spectrum where EDFA is applicable. An average channel spacing of 0.8 nm is obtained and the maximum cross talk between the adjacent channels is found to be a fraction of 0.07 of the applied input intensity. The coupling efficiency of the input power to the channels is observed to be 60%. Approximate footprint of the device is found to be 475 µm2.

A micro/nanofabrication feasible compact photonic crystal (PC) ring-resonator-based channel drop filter has been designed and analyzed for operation in C and L bands of communication window. The four-channel demultiplexer consists of ring resonators of holes in two-dimensional PC slab. The proposed assembly design of dense wavelength division multiplexing setup is shown to achieve optimal quality factor, without altering the lattice parameters or resonator size or inclusion of scattering holes. Transmission characteristics are analyzed using the three-dimensional finite-difference time-domain simulation approach. The radiation loss of the ring resonator was minimized by forced cancelation of radiation fields by fine-Tuning the air holes inside the ring resonator. An average cross talk of-34 dB has been achieved between the adjacent channels maintaining an average quality factor of 5000. Demultiplexing is achieved by engineering only the air holes inside the ring, which makes it a simple and tolerant design from the fabrication perspective. Also, the device footprint of 500 μm2 on silicon on insulator platform makes it easy to fabricate the device using e-beam lithography technique.

We present a silicon 2.5D Photonic crystal based CWDM (Coarse Wavelength Division Multiplexer) design, suitable for fabrication by lithography techniques. Particularly, a 3-channel, near-infrared wavelength range CWDM design has been achieved, with the wavelength spacing in accordance with ITU-T G.694.2 standards, i.e. 20 nm. A hexagonal lattice of holes-in-slab has been used for the design with a L-type drop waveguide. Plane wave expansion and FDTD methods were employed for the design.

In this paper theoretical investigation of photonic crystal based force sensor is presented. Photonic crystal ring resonator design is optimized for the improvement of quality factor considering the fabrication feasibility. For the optimized configuration a high quality factor of 15500 is obtained and it is found that it remains constant over the desired force range. The minimum detectable force is found to be 9 nN for 0.1 nm wavelength resolution. A high sensitivity of 11 nm/μN is obtained in the studied force range.

In this paper a 2D Photonic Crystal array in SOI platform having hexagonal periodicity with a ring defect incorporated along with two bus waveguides is conceptualized and realized for various applications of optical communication, sensing etc. The ring structure filters out a resonant wavelength from the spectrum carried to it through the line defect where the resonated peak is determined by the effective ring radius. The hexagonal architecture enables more coupling length than an ideal ring structure which helps in better intensity accumulation. The resonant peak exhibited at 1554nm in simulation, which is observed in the optical characterization at 1543nm. This is attributed to the fabrication tolerance.

A photonic crystal-based force sensor to measure forces in the wide range 100 nN-10 μN is proposed here. An optimized photonic crystal resonator integrated on top of a Si/SiO2 bilayer cantilever, is used as the sensing device. A sensitivity of 0.1 nm for a force of 100 nN is obtained with a high-quality factor of 10,000. The sensor characteristics in the force ranges 0-1 μN and 0-10 μN are also presented here. Linear wavelength shift and constant quality factor are observed in the entire studied force range.

A Photonic Crystal ring resonator based force sensor is proposed. The device consists of Photonic crystal slab integrated on top of a 220nm thick silicon cantilever and is capable of sensing forces as small as 10nN. The sensitivity is derived as 8.33nN for a wavelength resolution of 0.1nm with a high quality factor of 16000.

A design is proposed to enhance the quality factor of a photonic crystal ring resonator. A super defect is employed inside the ring resonator, which consists of variation of hole dimensions inside the ring resonator in such a way that the radiation field components of the resonant nanocavity are forced to get cancelled in order to reduce radiation loss. After this forced cancellation, the improved Q factor is calculated as 18,000. This photonic crystal ring resonator can be used for sensing applications like force sensing, pressure sensing, biochemical sensing, and communication applications like demultiplexing.

A force sensor is designed, which consists of a Photonic Crystal (PC) ring resonator integrated on top of a 220nm thick Silicon microcantilever. The quality factor(Q) of the resonator is improved by fine tuning the size of holes inside the hexagonal ring resonator. This force sensor with high Q PC ring resonator is subjected to Finite Element Method (FEM) simulations under various forces below 1microNewton and it is found that Q remains constant for all the forces in the studied range. Since the sensor offers high Q value, it can be used to sense forces in the range of nano Newton. In this work, we have presented the force sensing characteristics of the device in the range of 0 to 1microNewton, 0.2microNewton to 0.3microNewton with increment of 10nN. The force sensitivity of the device is derived as 9.33nN for a wavelength resolution of 0.1nm. The improvement in Q of PC device is explained by using field distribution in the momentum space of the PC.

In this paper the case of a typical line defect in 2D Photonic crystal is analyzed. The 2D photonic crystals are of dielectric rods in air in square and triangular lattice configurations. This line defect serves as waveguide with a pair of modes having opposite dispersion characteristics. © 2012 IEEE.