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In this study, we present a novel design for a photonic crystal fiber (PCF) biosensor utilizing a quadruple silica channel configuration, specifically engineered for highly sensitive external sensing through surface plasmon resonance (SPR). In order to take advantage of the interaction between the surface plasmon polariton (SPP) and core-guided modes within the fiber, the silica channels are carefully positioned to generate an H-shaped PCF. The suggested sensor is designed and completely characterized by the finite element method-based COMSOL Multiphysics program, taking into account the refractive index (RI) variation in the analyte channels. A noticeably performance is achieved with a maximum wavelength sensitivity (WS) of 20,000 nm/RIU and amplitude sensitivity (AS) of - 1367.62 R I U - 1 in the wide RI range of 1.33 to 1.41. The proposed research aids in the early identification of certain cancer cells. Due to the variation in RI between cancer-affected and normal cell samples, the resonance wavelength of cancer-affected cell samples differs from their normal cell samples. The study demonstrates the sensor's specific sensitivities, AS of - 792.8853, - 422.7596, and - 985.2674 R I U - 1 and WS of 5000, 4000, and 7857.14 nm/RIU for HeLa, Basal, and MDA-MB-231 cell lines, respectively. The proposed SPR sensor is a strong contender in a variety of refractive index detection applications due to its high sensing performance and fabrication viability that is evident in this study. [ABSTRACT FROM AUTHOR]

Vibrio cholera (V.C.) is currently one of the most hazardous bacteria since it can lead to hepatitis, diarrhea, vomiting, and typhoid. The various methodologies include time-consuming steps that take several hours before the test report is accessible. Therefore, creating a quick and reliable technique to identify V.C. is essential. The detection of V.C. is proposed in this study using a unique bio-photonic detector that employs Surface Plasmon Resonance (SPR) structure and layers of silver (Ag), silicon (Si), and graphene (G). The reflectance spectrum properties are inspected by the transfer matrix technique. To optimize the efficiency of the bio-photonic sensor, the effects of changing the type of prism and layer thicknesses are thoroughly examined. The proposed detector achieves an extremely great sensitivity of 307.81 Deg./RIU as the structure has Ag (50 nm), Si (3 nm), and the G monolayer, which is not obtained in many previous studies in this sector. The suggested detector also facilitates designing for industry using low-cost product nanofabrication methods due to its low cost, customizable design and straightforward structure. Based on these benefits, the suggested detector candidate is a practical and effective device for detecting V.C. in water, and it may also be used for any biological sample. The optical device designed based on the proposed sensor can be used for detecting V.C and used in biomedical applications. [ABSTRACT FROM AUTHOR]

This work determines the optimization of 2D TiO2-noble metal thin film for its applications in photocatalysis and SPR (surface plasmon resonance) biosensing. The impact of noble metal thickness fixed on TiO2 is checked by using RF module in COMSOL Multiphysics. In this work, an optimal slit width of 400 nm is obtained, at which the absorption of light is enhanced due to the enhanced light matter interaction. Near- and far-field analysis is done to attain the optimized parameters. The optimized parameters are used for the photocatalytic degradation rates of organic pollutants like tetracycline (TC), methylene blue (MB), and phenol (Ph). The study examines the role of Ag layer thickness in photocatalysis. Experimental data align with simulations, indicating that a 160-nm Ag layer maximizes the degradation rate at 0.00692 per minute. This thickness optimizes charge transfer and amplifies surface plasmon resonance effects, crucial for efficient pollutant breakdown. Moreover, the SPR biosensor has been analyzed for the detection of bacteria in various liquid analytes. The maximum value of sensitivity is obtained as 2000 nm per refractive index unit (RIU), outperforming current SPR biosensors. The linear behavior between the variables confirms the biosensor's precision in bacterial detection. This study contributes valuable insights into the design of TiO2-noble metal gratings for organic pollutant degradation and biosensor applications. [ABSTRACT FROM AUTHOR]

An anti-resonant fiber (ARF) surface plasmon resonance (SPR) dual-parameter sensor is designed for simultaneous detection of the magnetic field and temperature. Both sides of the fiber core in the sensor are filled with gold nanowires and gold dielectrics, respectively, to excite SPR. The center air hole in the ARF is filled with a magnetic fluid (MF) which responds to the magnetic field and temperature, and the temperature measurement is carried out by putting polydimethylsiloxane (PDMS) outside the gold nanowires. Analysis by the finite element method reveals maximum first and second resonance peak sensitivities of 300 pm/Oe and 500 pm/Oe, respectively, when the magnetic field is between 50 and 130 Oe. The maximum wavelength sensitivity of the second resonance peak is 10.8 nm/°C in the temperature range of 20–30 °C. Temperature cross-sensitization due to the magnetohydrothermo-optical effects is overcome by building and demodulating the sensing matrix. This new sensor design is very promising in fields such as industrial automation, military application, and geological exploration. [ABSTRACT FROM AUTHOR]

This paper presents a photonic crystal fiber (PCF)-based surface plasmon resonance (SPR) sensor designed to achieve precise malaria detection in blood samples. The sensor's innovative architecture incorporates carefully optimized layers of plasmonic materials, including gold and TiO2, to attain sensitivity and specificity. Extensive assessment of this sensor's performance has been carried out through rigorous finite element analysis using COMSOL Multiphysics v5.6. The sensor's configuration features a gold-coated PCF with a thin analyte layer, enabling the external detection of malaria parasites within blood samples. The air-hole configuration of the PCF sensor resembles the shape of a "barred spiral galaxy". It has undergone comprehensive testing across various stages of infected blood cells (ring, trophozoite, schizont), as well as normal red blood cells, each with their distinct refractive indices (RI). Through meticulous adjustments to the sensor's geometric parameters, remarkable wavelength sensitivity of 17,857.14 nm/RIU and amplitude sensitivity of 442.92 RIU−1 have been achieved for the ring phase, 10,210.53 nm/RIU and 392.72 RIU−1 for the trophozoite phase, and 8758.62 nm/RIU and 352.86 RIU−1 for the schizont phase. The numerical investigation also shows that the sensor possesses a low confinement loss of 50.25 dB/cm, 34.97 dB/cm, 28.74 dB/cm, and 25.47 dB/cm for normal RBC, ring phase RBC, trophozoite phase RBC, and schizont phase RBC, respectively. The results confirm the potential of the proposed sensor to detect malaria compared to existing methods. Hence, this sensor holds significant promise for advancing malaria detection and monitoring in blood samples, potentially leading to improved diagnostic and management strategies for this disease. [ABSTRACT FROM AUTHOR]

We propose a numerical investigation of a sensor for acetone monitoring in exhaled breath and exhaled breath condensate (EBC) using the surface plasmon resonance principle. For the theoretical analysis, we use the Kretschmann-Raether (K-R) setup and the Fresnel multilayer model. Four figures of merit, i.e., resonance angle (RA), minimum reflectance at resonance (MRR), full width at half maximum (FWHM), and sensitivity, are used for performance assessments. As the first step, we evaluate the performance of the sensor for various plasmonic metals and substrates. Results for emulations of exhaled breath indicated polycarbonate as the most suitable substrate for the scenario. For the exhaled breath condensate case, PMMA is deemed the optimal choice. Subsequently, we evaluate the effects of adding polyaniline (PANI), graphene, or chitosan as a chemisorption binding layer for the selective sensing of acetone. Our findings suggest that these materials are not able to improve SPR figures when using refractive indexes that emulate the exhaled breath scenario. For the exhaled breath condensate case, chitosan and graphene are able to improve the sensitivity of the sensor, achieving competitive values. Chitosan generates sensitivities of 246 ∘ /RIU, 216 ∘ /RIU, and 150 ∘ /RIU in associations with gold, copper, and silver, respectively. Graphene stands as a second option by improving sensitivities of gold up to 210 ∘ /RIU and silver up to 150 ∘ /RIU. [ABSTRACT FROM AUTHOR]

In this paper, we present a tetragonal cluster-based photonic crystal fiber (PCF) surface plasmon resonance (SPR) sensor with high wavelength sensitivity (WS). Indium tin oxide (ITO), as a dielectric material with adjustable photoelectric properties and low loss in the infrared range, is used in this sensor. The central rectangular air hole is used to construct an asymmetric structure which enables the sensor work in y and x polarization. We optimized the structural parameters of the sensor and the result shows that the sensor has high WS of 31,500 nm/RIU and 31,000 nm/RIU, wavelength resolution of 3.17 × 10−6 RIU and 3.23 × 10−6 RIU, maximum AS of 141.0 RIU−1 and 148 RIU−1, the refractive index (RI) detection range of 1.32–1.42 for y and x polarization, respectively. The sensor shows great potential in the detection of plasma, ethanol, and silicone oil. [ABSTRACT FROM AUTHOR]

A surface plasmon resonance (SPR) biosensor based on dual-side polished photonic crystal fiber (PCF) has been presented in this paper. An external gold (Au) coating was used as a plasmonic material to detect changes in an analyte refractive index (RI). Sensor's structural parameters were optimized for better performance. The proposed sensor's simulation was conducted using the finite element method (FEM). Analytes within the RI range of 1.30 to 1.40 were used to develop a sensor. The numerical results are expected to have a wavelength sensitivity (WS) of 9400 nm/RIU and amplitude sensitivity (AS) of 27.27 RIU−1, respectively, and a spectral wavelength resolution of 1.063 × 10−5. Furthermore, it is expected to obtain maximum loss of 161,270 dB/m for a Y-polarization (Y-P) odd mode with an analyte RI = 1.37. We obtained an extinction ratio of − 321.54 dB for the polarization filter effect, which is considered to be good. This structure has the advantages of being easy to fabricate, affordable, and expected to show better sensitivity than many other sensors. It assumes to detect a wide range of analytes, making it suitable for organic chemical sensing, pharmaceutical inspection, and biosensor applications. [ABSTRACT FROM AUTHOR]

The surface plasmon resonance (SPR) sensor with better sensitivity and gas detection capabilities is reported in this paper. It is based on a hybrid layer of silver (Ag)/magnesium oxide (MgO)/silicon (Si). For numerical analysis, the finite element technique (FEM) was employed. The attenuated total reflection (ATR) approach has been used for diagnosing various types of hazardous gas. The increase in the refractive index of various hazardous gases, ranging from 1.327 to 1.38 for four different types of gas, caused the resonance angle to shift. The obtained sensitivities were 86.12 deg/RIU, 164.54 deg/RIU, 199.59 deg/RIU, and 253.68 deg/RIU, respectively, for cyanogen, phosgene, ethanol, and propane gas. Additionally, the values of the detection accuracy (DA), the figure of merits (FoM), and full-width at half-maximum (FWHM), which are 0.17 deg−1, 43.30 RIU−1, and 5.86 deg, respectively, were also obtained. The proposed structure's distribution of the electric field propagation under resonant conditions was also depicted. Further tests were done to see how the thickness of the Ag and other layers affected the overall sensitivity sensor for the four different gas types. The proposed layered Ag/MgO/Si arrangement had the highest overall sensitivity in distinguishing propane gas from other hazardous gases. [ABSTRACT FROM AUTHOR]

This study reports an investigation on the detection of one of the essential branched-chain amino acids (AA) named leucine. The detection is done by using two different configurations of surface plasmon resonance (SPR) sensors, such as Probe1 (silver/graphene oxide (GO)/leucine dehydrogenase/leucine) and Probe2 (gold/GO/leucine dehydrogenase/leucine). The transfer matrix method (TMM) is used to analyze the performance of the sensors. The analysis of both the sensor probes is done in the presence of RI ranging from 1.3373 to 1.3425. The detected RI range is considered at two different temperatures of 298.15 K and 308.15 K which corresponds to lower and normal human body temperatures. The results show that the maximum sensitivity of Probe1 and Probe2 is 261.54°/RIU and 192.31°/RIU, respectively, attained at 308.15 K. Additionally, the quality factor, detection accuracy (DA), and full-wave half maximum (FWHM) of Probe1 and Probe2 at 308.15 K are 33.97, 0.04, 7.70, and 119.45, 0.16, 1.63, respectively. Furthermore, the field confinement in metallic layers is studied by using two-dimensional Opti-FDTD software. [ABSTRACT FROM AUTHOR]

In this study, silver nanoparticles have been synthesized using green synthesis from Echium amoenum Fisch. &C.A.Mey. extract. The extract of this flower was used to reduction of silver nitrate solution and stabilization of formed silver nanoparticles. The extract of this flower contains different anthocyanin compounds, polyphenols, and vegetable stearic fatty acids that can contribute in reduction and stabilization of silver nanoparticles. Characterization of the nanoparticles was performed using X-ray diffraction method (XRD), dynamic light scattering (DLS), UV–Visible spectrum, and open aperture Z-scan method. The measurements showed that stable nanoparticles with an average size of about 54 nm were synthesized and the use of this extract was successful. Adding a few droplets of the extract to the nano-colloid made the peak of localized surface plasmon resonance (LSPR) clearer. Also, the trend of absorption spectrum changes with the addition of droplets and their nonlinear absorption changes were investigated. Nonlinear optical measurements also showed that silver nanoparticles synthesized by this method exhibit reversed saturation absorption which is due to multi-photon absorption and electrostriction effects. This green synthesis method can lead to the synthesis of stable and high-performance silver nanoparticles with high potential in electro-optic devices and can be considered as an environmentally friendly and low-cost synthesize method. [ABSTRACT FROM AUTHOR]

In our current study, silver (Ag) as a noble metal and tantalum diselenide (TaSe2) material are used in the proposed SPR biosensor to detect the chikungunya virus. To increase the sensitivity of the Ag-based SPR biosensor, TaSe2 is used. We have discussed various refractive indices of the analytes normal plasma (1.350), infected plasma (1.330), normal platelets (1.390), and infected platelets (1.380), as well as sensitivity, detection accuracy (DA), and figure of merit (FoM) maximum performance parameters for proposed sensors. For early detection of the chikungunya virus, we designed a structure comprised of Ag and TaSe2. CsF-coupled prisms are combined with an Ag layer in the proposed sensor. TaSe2 layers have been optimized for superior performance by optimizing the thickness of the Ag layer. An SPR sensor with Kretschmann configuration at a wavelength of 633 nm has a sensitivity of 167.31°/RIU and 371.27°/RIU for plasma and platelets, respectively, at minimum reflectance (Rmin) value. We achieved the maximum sensitivity of 387°/RIU with a TaSe2 layer thickness of 0.75 nm and an optimized Ag layer thickness. [ABSTRACT FROM AUTHOR]

In this paper, we propose a cavity-coupled perfect absorber (CCPA) consisting of a bottom gold layer, a SiO2 layer, and multilayer MIM (metal–insulator-metal) nanowires. By coupling the Fabry-Pérot (F-P) cavity mode with the magnetic plasmons (MPs) resonance mode in multilayer MIM structure, the MPs resonance in the multilayer MIM structure is enhanced and leads to increased absorption of the structure. By designing and optimizing the parameters, near-perfect absorption in the mid-infrared wavelengths can be achieved. The positions of the two absorption peaks can be adjusted by changing the width of the nanowires and the thickness of the SiO2 layer, resulting in the formant excitation at any position in the mid-infrared. The full-width at half-maximum (FWHM) of the short-wave peak is only 0.076 µm, and the FWHM of the long-wave peak is only 0.46 µm. The long-wave absorption peak maintains high efficiency and stability even at large incident angles, exhibiting "omnidirectional" characteristics. The tunable mid-infrared emission peak can be matched to the characteristic spectra of gases, making it suitable for infrared radiation sources in gas detection. [ABSTRACT FROM AUTHOR]

This research article proposes a periodically elliptical graphene metamaterial array-based wavelength-tunable absorber. The recent identification of graphene represents a substantial advancement in the field of plasmon-based electronics, which includes design, fabrication, wave distribution, inherent adaptability, and affordable prototyping. The finite difference time domain (FDTD) method is used to study the effects of different parameters. This article shows an apparent absorption peak with maximum absorption of 49.6% occurs at 55.12 µm compared to the existing metamaterial absorber. By extending the ellipse's major axis, increasing the X polarization of the incidence angle within a specific range, and enhancing graphene's chemical potential, the absorption rate of elliptical graphene arrays will be increased. Furthermore, to accurately evaluate the sensing capabilities of the structure, we model the spectra under varying refractive indexes in the environment, resulting in a design with a sensitivity (S) of up to 15,169 nm/RIU and a figure of merit (FOM) value. This research makes it easier to design environmental monitors, biosensors, and optoelectronic devices based on graphene. [ABSTRACT FROM AUTHOR]

The synthesis and characterization of Au nanoparticles produced from Punica granatum L. leaves (PGL) grown in Trabzon province of Turkey were investigated in this study. After the pomegranate leaves were collected, they were dried under suitable conditions and divided into small pieces, and Supercritical Fluid Extraction (SFE) was applied to obtain the extract. The SFE was performed at a pressure of 200 bar, 50 °C for a period of 2.5 h using ethanol modifier at 0.5 mL/min flow rate in this procedure. Twenty milliliters of 0.5 mM HAuCl4.3H2O solution was mixed in the microwave device with different volumes of the prepared aqueous solution (0.1 mL and 0.2 mL). After the mixture was exposed to microwaves for 1 to 30 min at a power of 90 W, Au nanoparticles were synthesized. Au nanoparticles produced utilizing green chemistry principles were characterized by UV–Vis, TEM, FTIR, XRD, and Zeta-sizer. The surface plasmon resonance absorption (SPR) spectra were measured using the UV–visible technique to determine the ideal conditions. The TEM images showed that the PGL-AuNPs had a mean size of 23.510 ± 7.009 nm, with sizes ranging from 14.188 to 42.508 nm, and a shape that was triangular, spherical, or elliptical. The reflection peaks appear at 38.21, 44.40, 64.61, and 77.59 corresponding to lattice planes (111), (200), (220), and (311), respectively. The average size of the synthesized gold nanoparticles is 23.24 nm. The Au nanoparticles have an average particle size of 50.76 ± 1101 nm in aqueous medium, a zeta potential of −14.8 ± 0.4 mV, and the polydispersity index for gold nanoparticles is 0.45 ± 0.011, indicating a moderately level of polydispersity. AuNP production was best achieved at 0.5 mM concentration in 0.1 mL pomegranate (P. granatum L.) leaves extract volume. The process utilized for producing the gold nanoparticles allowed for their stability for 2–2.5 months. [ABSTRACT FROM AUTHOR]

In this work, a high performance surface plasmon resonance (SPR) fiber sensor based on metallic elliptical nanohole and circular nanodisk binary array has been theoretically designed and investigated. The binary array structure is integrated on the end facet of optical fiber to excite SPR and generate three optical resonance dips in reflection spectra in the near-infrared region. The first resonance dip not only fits the characteristics of narrow linewidth, but also has the advantages of high peak-to-dip signal ratio and sensitivity. When the external environment changes in the refractive index (RI) range of 1.33 ~ 1.40, a high RI sensitivity of 669 nm/RIU, a narrow FWHM of 5.8 nm, and a high FOM value of 115.3 are yielded simultaneously for the first dip. Compared to unitary nanostructure arrays, the composite plasmonic structure of nanodisk and elliptical nanohole array demonstrated here can generate SPR modes with sharper spectral feature which is crucial to high sensitivity and precision detection technology. These features make our proposed plasmonic fiber tip sensor highly promising in terms of high-performance biosensing applications. [ABSTRACT FROM AUTHOR]

In this study, silver nanoparticles (Ag NPs) dispersed in deionized water (DW) are prepared using the Nd:YAG laser ablation method. Transmission electron microscopy (TEM) results were used to investigate the shape and particle size of Ag NPs. The spherical shape and size of about 30 nm are characterized. X-ray diffraction (XRD) analysis shows a good crystallinity of Ag NPs and distinguished peaks at 38° without any impurities. The optical properties of Ag NPs were studied by a UV–visible spectrophotometer, and the surface plasmon resonance was observed at an excitation wavelength of about 402 nm and a direct band gap of about 2.25 eV. The results of the inhibitory activity against Lactobacillus and Streptococcus mutans bacteria indicated areas of high inhibition. The highest inhibition zone was 19 mm at the stock concentration. The anticancer properties of Ag NPs were studied with multi-concentration; the small particle size of Ag NPs led to the killing of about 70% of the MCF-7 line; and the inhibitory concentration (IC50) of Ag NPs was about 93.55 µg/mL−1. [ABSTRACT FROM AUTHOR]

Throughout history, societies have harnessed renewable energy sources driven by technological advancements and external factors, resulting in the emergence of hydropower, wind turbines, and solar PV, often bolstered by supportive policies and agreements. In the current research, the cylinder-inspired resonator solar absorber (CIRSA) structure has been introduced in optical science. This innovative design, functioning at the nanoscale, achieves exceptional wideband absorption from 200 to 700 nm, a challenge given Earth's limited wavelength spectrum. Impressively, it attains a 98.71% solar energy absorptance within this range, with notable peaks at 490 nm (98.99%) and 500 nm (98.71%) in the solar thermal wavelength band, maintaining high absorption across angles from 0 to 80° for both TE and TM polarizations. Moreover, this cylinder-inspired solar thermal energy absorber effectively minimizes solar energy losses and ensures a high Air Mass Index (AM 1.5), although a significant reduction in AM 1.5 is observed beyond 700 nm. As a part of this world-breaking research project, a cylinder-inspired gold resonator is also introduced. It includes a Gallium-Arsenide (GaAs) substrate and chromium (Cr) ground. It led to the development of efficient solar heaters for air and water systems, opening up significant opportunities for solar energy harvesting. [ABSTRACT FROM AUTHOR]

A novel design of an optical biosensor based on surface plasmon resonance using tin selenide (SnSe) and graphene is presented. Including biological solutions, the performance of the obtained biosensor over a wide range of refractive index variations is promising. It is designed such that its key parameters are optimized to detect different cancerous cells with high selectivity and sensing ability. The design and analysis of the sensor have been carried out by implementing a finite element method–based simulation platform. The results revealed that the designed sensor can provide a sensitivity of 121.0 deg.RIU−1, 134.2 deg.RIU−1, 142.9 deg.RIU−1, 143.6 deg.RIU−1, and 72.2 deg.RIU−1 for sensing skin, cervical, blood, adrenal gland, and breast cancerous cells respectively with maximum quality factor of 408 RIU−1 and a detection accuracy of 5.71. The results obtained using the proposed model of the SPR biosensor are promising. It could be a potential candidate for several sensing applications such as detecting different types of cancer disease in the early stages. Such detection is anticipated to save the lives of cancer patients. Comparing our results to work published recently, we were able to achieve an enhanced angular sensitivity (S) ranging from 72 to 143.6 deg.RIU−1, a detection accuracy (DA) ranging from 2.66 to 5.71, and a quality factor (QF) ranging from 190 to 408 RIU−1. [ABSTRACT FROM AUTHOR]

This study introduces a novel biosensor utilizing silver (Ag)–dielectric–black phosphorus (BP) as the foundation to analyze the surface plasmon resonance (SPR) system for alcohol detection for the first time. Silver (Ag) is employed as a metallic layer in the Kretschmann configuration of the proposed sensor to induce the generation of surface plasmons. The present study employs dielectric materials, namely lithium titanate (LiTiO3), potassium tantalite (KTaO3), bismuth silicon oxide (BSO), and zinc selenide (ZnSe), to safeguard the Ag material from oxidation. Additionally, 2D material of BP is used to augment the detecting capacity of the sensor. This study focuses on the detection of ethyl alcohol (ethanol) and propanol alcohol. To analyze the sensor's performance, the transfer matrix method is used with the help of angular interrogation technique. The proposed sensor performance is significantly enhanced by achieving a maximum sensitivity of 277.63°⁄RIU, a detection accuracy of 4.37, and a quality factor of 97.06 RIU - 1 for the optimized sensor design. Hence, the sensor has significant utility in the field of biological applications. [ABSTRACT FROM AUTHOR]

In this article, we have introduced an innovative sensor configuration employing a metasurface encompassing three rectangles configured into a star-shaped structure and multiple square-graphene elements—for accurate blood analysis. The suggested sensor architecture, characterized by its hierarchical structural configuration, offers several advantages crucial for accurate and reliable detection of target biomolecules. The star-shaped pattern, meticulously constructed with specific dimensions, significantly increases the surface area exposed to target compounds, thereby enhancing sensor sensitivity. Forensic science is at the core of investigations into crimes. It is undoubtedly crucial to modern legal structures. It is a constantly growing field that is always looking for new ways to increase the level of accuracy, sensitivity, and effectiveness of evidence examination. Terahertz (THz) spectra have recently developed as a sophisticated method with incredible potential in every aspect of forensics. A critical component of this endeavor is the development of THz sensors capable of detecting hemoglobin, a crucial protein in the evaluation of blood. The proposed sensor displays a remarkable level of sensitivity, with a maximum value of 300 GHzRIU−1 and a detection limit of 1.013 RIU−1. Moreover, the sensor demonstrates its capacity to detect subtle variations through its resolutions and Figure of Merit (FOM), quantified respectively as 0.268 and 1.796 RIU−1. [ABSTRACT FROM AUTHOR]

To satisfy the marking demand for microwave absorbing devices, we design an ultra-broadband nearly perfect absorber. The proposed absorber demonstrates absorption band from long to very long-wavelength ranges (15.7–37.9 µm). An average absorption efficiency of 95.16% and a satisfactory absorption bandwidth of 19.2 µm are achieved. The absorption with high absorptivity and large bandwidth is achieved through combined propagating surface plasmon (PSP) resonances in two directions and localized surface plasmon (LSP) resonances. By simulating and calculating the absorptivity, we demonstrate that the absorber possesses the properties of polarization independence and incident angle insensitivity. When the incident angle reaches 60°, the device still maintains a high absorptivity. Finally, the manufacturing process is illustrated, using radio frequency sputtering with dual guns or an E-beam. Compared with other related microwave absorbers, the proposed absorber balances the contradiction between absorption bandwidth and average absorption. We have strong confidence that the absorber has tremendous applications in many areas, such as infrared thermal emitters, imaging, and photodetectors. [ABSTRACT FROM AUTHOR]

A long-range surface plasmon biosensor (LRSPR) using the 2S2G/Teflon/Au MXene/Sensing medium (SM) is proposed for improve the imaging sensitivity. Here, the MXene layer is used to improve imaging sensitivity and protect against unwanted oxidation of Au layer. MXene having formula is Ti3C2Tx layered materials with hydrophilic nature, better stability, good conductivity and large surface area. The proposed LRSPR uses the high adsorption efficiency and high resolution. Numerically investigate the imaging sensitivity compared to the conventional surface plasmon sensor (cSPR) as well as systematic layer of proposed LRSPR sensor. The maximum imaging sensitivity of 10,465/RIU at 1.35 based RI of plasma sensing medium is achieved. The maximum electric field normalized at the interface between the Teflon-Au layer in the proposed sensor and the Au/MXene layer in the cSPR sensor. For the proposed LRSPR sensor, the penetration depth (PD) of the field into the sensing medium of 611.7 nm and 806.13 nm is obtained at Au-SM and MXene-SM interface for the sensing medium of 1.337 and 1.350. In addition, the figure of merit (FoM) as 193/RIU and 275.6/RIU is exhibited for the same sensing medium. [ABSTRACT FROM AUTHOR]

An innovative photonic crystal fiber (PCF) biosensor using surface plasmon resonance (SPR) to diagnose six distinct kinds of cancers (skin cancer, cervical cancer, adrenal gland cancer, blood cancer, and breast cancer types 1 and 2) in cells is demonstrated here and incorporates with two microchannels and a bimetallic configuration. The numerical analysis utilizes the finite element method (FEM) combined with perfectly matched layers (PML). The plasmonic material employed in the biosensor is gold (Au), and a supportive material, titanium dioxide (TiO2), is combined with Au. By combining these two materials, the sensor's performance is improved. The numerical calculations indicate that breast cancer type 2 has the highest wavelength sensitivity (24,285.71 nm/RIU) and amplitude sensitivity (3959 RIU−1). The rest of the cancer cells' wavelength sensitivities are 11,000.00 nm/RIU (skin cancer), 13,333.33 nm/RIU (cervical cancer), 15,000.00 nm/RIU (blood cancer), 17,142.85 nm/RIU (adrenal gland cancer), and 21,428.57 nm/RIU (breast cancer type 1). This advanced biosensor has several uses in biological sensing and medical technology, and it has the potential to revolutionize cancer identification and medical diagnosis. [ABSTRACT FROM AUTHOR]

The traditional and modified structures are simulated by the finite element method (FEM). In the modified structure, ten well-known add layers with complex refractive indexes (MgF2, SiO2, ITO, Si, ZnO, PLZT, GaAs, LNO, PZT, and TiN) are proposed over a thin film of gold metal. Due to the addition of the add layer, the stability of the proposed structure increases and also manipulates the performance parameters of the considered structure. Therefore, we investigated theoretically that the reflectance spectrum is a function of the incidence angle, and surface plasmon waves at the resonance angle were obtained. From the reflectance spectra, we obtained the maximum shift, i.e., 2.369° in Si, and the minimum shift, i.e., 1.484° for MgF2, from the considered add layer. Moreover, the full beam width is minimum, i.e., 5.1140°; the figure of merit is high, i.e., 27.109 a.u./RIU; detection accuracy is maximum, i.e., 0.292; and the quality factor is also high, i.e., 27.563 RIU−1 for the traditional SPR sensor among all considered structure. In addition, if we keep the complex refractive index (n + ik) of considered add layer remain constant and varying the thickness of considered add layer then the resonance angle shifts towards right angle, minimum reflectance value shift upwards, width of reflectance curve becomes broader, and penetration depth decreases. After that, the same observation is found if we keep thickness and imaginary part of complex refractive index remain constant but only real part of complex refractive index increases of considered add layer. But, when we keep the thickness of add layer and real part of complex refractive index remain constant and varying the imaginary part complex refractive index of the considered add layer then the resonance angle shifts towards right angle, minimum reflectance value decreases, and penetration depth (PD) value increases. After that, we calculated the performance parameters, i.e., field intensity at different interfaces (metal-sensing medium (M-S), metal-dielectric (M-D), and dielectric-sensing medium (D-S)), shift in resonance angle (∆θr), full beam width (FBW), sensitivity (S), detection accuracy (DA), quality factor (Q), figure of merit (FoM), and penetration depth (PD) for all the considered structures. From the obtained result, we have observed that the PD is maximum for MgF2, i.e., 2.96 nm, and minimum for GaAs, i.e., 0.26 nm, among all the structures considered. This comparative study will help to choose an add layer with a complex refractive index over a metal thin film in a SPR sensor for the detection of analytes or molecules present in the sensing medium. [ABSTRACT FROM AUTHOR]

This manuscript presents a Kretschmann configured long-range surface plasmon resonance (LRSPR) imaging sensor (structure: 2S2G prism-MgF2-Ag-PtSe2-BlueP/MoS2-SM) demonstrating ultrahigh imaging sensitivity, SImg. (23,250 RIU−1); detection accuracy, DA (50 Deg.−1); angular figure of merit, FoMAng. (1930.87 RIU−1); imaging figure of merit, FoMImg. (1,162,500 Deg.−1 RIU−1); and better penetration depth, PD (1129.4 nm), for sensing of biomolecules. The MATLAB and COMSOL simulation software are used for numerical analysis of the results. The effect of different dielectric buffer layers, DBLs (MgF2, LiF, Cytop & Teflon), and Ag/Au thin metal films on sensor performance has been substantiated to find the best suited DBL and metal film. The use of PtSe2 leads to further enhance sensor performance due to its high carrier mobility, tunable bandgap, chemical stability, and immunity to toxicity. Heterostructure of BlueP/MoS2 plays an important role in attachment of biomolecules due to larger surface area and higher optical adsorption efficiency (5%), quantum confinement effect of MoS2. Furthermore, heterostructure of BlueP/MoS2 leads to improve the sensor performance parameters due to high charge carrier transfer efficiency. Overall, larger PD of proposed LRSPR sensor is suitable to detect larger size biomolecules. Hence, the proposed sensor performance paves a way for its efficient use in field of biological molecule sensing. [ABSTRACT FROM AUTHOR]

Our research focuses on the development of a surface-plasmon sensor that uses a stationary surface plasmon, referred to as a "nonpropagating mode." This mode is observed when light is incident perpendicularly on a surface-plasmon sensor based on a metal diffraction grating. We performed a comprehensive analysis of the behavior of the surface-plasmon resonances within this nonpropagating mode, employing the rigorous coupled-wave analysis method. Using electron-beam lithography, sputtering, and a lift-off process, we fabricated such a surface-plasmon sensor and evaluated its optical properties rigorously. By combining simulations and experiments, we successfully utilized the nonpropagating mode to detect a liquid medium with a refractive index of 1.70. Simulations show that the nonpropagating mode arises due to a Fano resonance; i.e., to a resonant interaction between a localized surface plasmon generated at the edge of a metal grating strip during normal incidence and a propagating surface plasmon that occurs at the boundary between the metal diffraction grating and the measurement medium. The present results provide useful information for the advancement of surface-plasmon sensing technologies. [ABSTRACT FROM AUTHOR]

In this article, a surface plasmon resonance (SPR)-based refractive index sensor is proposed for the detection of colorectal cancer (CRC). The prism-based configuration has been employed to excite the surface plasmons (SPs). The structure of the proposed sensor consists of an Al–Cu bimetallic layer on the BK7 prism. To ensure contact between the metallic layer and the prism, an adhesive layer of TiO2 is used. Graphene layer is used above the bimetallic layer to improve its stability. In order to detect CRC, the healthy and infected tissues are utilized as the analyte media. The numerical simulations of the sensor have been performed using the transfer matrix method. The sensitivity, quality factor, and figure of merit (FOM) are the parameters that determine the performance of the proposed sensor, where FOM includes full width at half maxima (FWHM) and dip strength of the SPR curve. The number of graphene layers and thicknesses of the Al, Cu, and TiO2 layers have been optimized to achieve better performance of the sensor. The effect of incident angle on the performance of the sensor has also been studied. It has been found that a smaller incident angle gives better performance. The maximum value of the sensitivity, quality factor, and FOM obtained are 13,842.1 nm/RIU, 410.95 RIU−1, and 0.92, respectively. The proposed sensor would be a promising candidate for biosensing and medical diagnostics. [ABSTRACT FROM AUTHOR]

Tropical diseases present significant challenges to global health, particularly in resource-limited regions. Early and accurate detection of these diseases is vital for effective management and control. In recent years, metallic-based LSPR sensors have emerged as promising diagnostic tools for sensitive and rapid detection of tropical diseases. This comprehensive review aims to provide an in-depth analysis of the current state of research on metallic-based LSPR sensors for the detection of various tropical diseases. In this study, we focused on the connection between neglected tropical diseases (NTDs) and its risk using metallic-based LSPR sensors to identify potential inflammatory biomarkers. We conducted a literature search using PubMed, Web of Science, and Google Scholar. Only published materials written in English were considered, resulting in the identification of ∼ 220 articles. After a comprehensive evaluation, we selected 35 relevant ones. Our analysis revealed 35 links to neglected tropical diseases, providing valuable insights into their relationship using metallic-based LSPR sensors. Moreover, we explore the potential of metallic-based LSPR sensors in point-of-care testing and their integration with emerging technologies such as microfluidics and smartphone-based diagnostics. This review underscores the need for continued research efforts to develop affordable, sensitive, and user-friendly metallic-based LSPR sensors for early detection and surveillance of tropical diseases. [ABSTRACT FROM AUTHOR]

In this work, an efficient optical sensor is proposed for the sensitive detection of various pollutants in water. The suggested optical sensor is based on an indium fluoride (InF3) glass fabricated as a D-shaped optical fiber. The polished surface of the D-shaped fiber is coated with a gold grating to induce the surface plasmon resonance (SPR). The SPR depends on the optical properties of the polluted water analyte in physical contact with the grating. The proposed optical SPR fiber sensor operates within the mid-infrared (MIR) range (3000–4500 nm) to detect any slight change in the water refractive index (RI) due to any pollutants. The full vectorial finite element method (FVFEM) is utilized to calculate the modal properties of the reported sensor. High sensor sensitivity of 17,834 nm/RIU (refractive index units) is achieved for the detection of dissolution of nitric acid (HNO3) in water at a concentration of 14% v/v (volume/volume). Additionally, the reported sensor detects the dissolution of hydrogen peroxide (H2O2) in water investigated at concentrations of 15% v/v and 30% v/v, with sensitivities of 12,308 nm/RIU and 17,143 nm/RIU, respectively. Further, suspending polystyrene beads of diameter 0.1 μm in the water at a concentration of 10% v/v gives a maximum sensitivity of 5333 nm/RIU. Therefore, the proposed sensor provides a promising approach for the detection of water pollutants in the MIR wavelength regime, rather than the weaker response in the near infrared. [ABSTRACT FROM AUTHOR]

The present work focuses on the detection of dengue virus using a proposed copper (Cu) and black phosphorus (BP)–based SPR sensor. This proposed sensor is capable of detecting normal and infected blood samples containing plasma, platelets and hemoglobin. We studied the performance parameter at optimized Cu layer thickness of the proposed sensor by calculating that the maximum sensitivity is 150.55°/RIU, 226.73°/RIU and 295.58°/RIU at Rmin values with 57 nm, 57 nm and 51 nm thickness of Cu layer for the detection of plasma, platelet and hemoglobin in the blood sample of dengue malaria. The properties of BP combined with the unique plasmonic properties of SPR sensors can result in enhanced interactions between surface plasmons and incident light. These results are intended for improved sensitivity and remarkable figure of merit (FoM). We also calculated the electric field and penetration depth (PD) for the same sample. In this study, the normal and infected blood samples are successfully examined for the performance parameters for the plasma, platelets and hemoglobin. [ABSTRACT FROM AUTHOR]

This review presents the theory, configurations, and various applications of plasmonics in a variety of surface plasmon–based devices. It describes how light waves travel along the surface where metals and dielectrics meet, revealing the detailed reasons behind the phenomenon. Here, we have used the well-known Drude optical model, a widely accepted theoretical approach, to figure out how different materials behave by considering atoms as tiny vibrating dipoles. In this review, we have thoroughly looked at many aspects, all wrapped up in the concept of complex dielectric functions. We used Maxwell's equations customized for simple, non-magnetic materials to derive the above mentioned model, with the goal of helping to better grasp how surface plasmon polaritons are generated. In this research, we have organized the conditions needed for momentum matching by applying particular boundary conditions. Along with, we presented different techniques required for the generation of surface plasmon polaritons. We studied how metal and dielectric materials work together, by making comparisons to different optical devices along the way. Our main focus on the subject highlights the significant possibilities that this theory and research offers to various plasmonic applications. [ABSTRACT FROM AUTHOR]

This manuscript presents a Kretschmann configured long-range surface plasmon resonance (LRSPR) imaging sensor (structure: 2S2G prism-MgF2-Ag-PtSe2-BlueP/MoS2-SM) demonstrating ultrahigh imaging sensitivity, SImg. (23,250 RIU−1); detection accuracy, DA (50 Deg.−1); angular figure of merit, FoMAng. (1930.87 RIU−1); imaging figure of merit, FoMImg. (1,162,500 Deg.−1 RIU−1); and better penetration depth, PD (1129.4 nm), for sensing of biomolecules. The MATLAB and COMSOL simulation software are used for numerical analysis of the results. The effect of different dielectric buffer layers, DBLs (MgF2, LiF, Cytop & Teflon), and Ag/Au thin metal films on sensor performance has been substantiated to find the best suited DBL and metal film. The use of PtSe2 leads to further enhance sensor performance due to its high carrier mobility, tunable bandgap, chemical stability, and immunity to toxicity. Heterostructure of BlueP/MoS2 plays an important role in attachment of biomolecules due to larger surface area and higher optical adsorption efficiency (5%), quantum confinement effect of MoS2. Furthermore, heterostructure of BlueP/MoS2 leads to improve the sensor performance parameters due to high charge carrier transfer efficiency. Overall, larger PD of proposed LRSPR sensor is suitable to detect larger size biomolecules. Hence, the proposed sensor performance paves a way for its efficient use in field of biological molecule sensing. [ABSTRACT FROM AUTHOR]

In this research, we proposed and numerically investigated a D-shaped dual-core photonic crystal fiber (PCF) refractive index (RI) sensor based on surface plasmon resonance (SPR), and a plasma material indium tin oxide (ITO) is deposited on the polished surface of a D-shaped PCF to produce the SPR effect. The proposed PCF sensor incorporates a dual-core structure and innovatively introduces an elliptical air hole, which increases the coupling of the SPR effect, resulting in a notable improvement in sensor performance. This enhancement enables the sensor to efficiently detect variations in the RI of the analyte. Utilizing the finite element method (FEM), we analyzed the influencing characteristics of sensor performance, meticulously investigating and optimizing various structural parameters. In the RI sensing range spanning from 1.18 to 1.33, the designed PCF sensor exhibits an outstanding maximum wavelength sensitivity of 29,300 nm/RIU, along with the highest achievable amplitude sensitivity of 261.01 RIU−1. Upon analyzing the light signal modulated by the sensor, the findings unequivocally demonstrate that the proposed sensor displays outstanding sensitivity to changes in the analyte's RI via the SPR effect. This responsiveness enables effective and precise real-time detection. The proposed sensor is characterized by exceptional sensing performance, strong economic feasibility, and low manufacturing intricacy. Consequently, the proposed sensor can be used to detect medical oxygen, anesthetics, methane gas, glucose, fluorine-containing organics, etc., and it holds a diverse array of promising applications spanning industrial detection, biochemical analysis, and medical diagnostics. [ABSTRACT FROM AUTHOR]

The opto-thermal properties of Au- and Ag-coated core–shell hybrid nanoparticles (NPs) have been thoroughly investigated by using the PyMieLab V1.0 simulation tool based on electrodynamics modelling. We, specifically, investigated the plasmonic resonance tunability and spatial temperature profiles of Au- and Ag-coated composed hybrid core–shell nanospheres as optimized combinations of alloy core (viz. Au0.25Ag0.75, Au0.25Cu0.75, Au0.75Al0.25, Ag0.75Cu0.25 and Ag0.75Al0.25) immersed in the local water (n = 1.33) media. In the present core–shell nanostructure configuration, the alloy core radius (r ) has been changed from 5 to 50 nm (with 5-nm step-size) and shell thickness, t = 5 , and 10 nm is kept the same with varying core radii. The localized surface plasmon resonance (LSPR) of Au- and Ag-coated optimized alloys composed of hybrid core–shell nanospheres is tuned between 238–545 nm and 347–531 nm, respectively, and lies under the ultraviolet–visible segment of the electromagnetic band. The temperature recorded at the surface of core–shell NPs (i.e. alloy core@gold/silver shell) lies between the range of 0.20 and 2.38 °C (for Au-coated alloys) and 0.64–2.44 °C (for Ag-coated alloy) with different core/shell size ratios. The present results are of paramount importance for using these alloy core–plasmonic shell NPs in several types of thermoplasmonic applications. [ABSTRACT FROM AUTHOR]

Surface plasmon resonance (SPR) technology–based biosensors, including photonic crystal fiber (PCF-SPR) biosensors, have been investigated for their potential in cancer detection. The biosensors can detect biomolecules in a label-free and real-time manner, which results in high sensitivity and specificity. This article provides a comprehensive analysis of the current and future trends in PCF-SPR biosensors for cancer detection. The study commences by presenting the fundamental principles of SPR and PCF-SPR biosensors, highlighting their comparative benefits over conventional biosensors. Recent studies utilizing PCF-SPR biosensors for cancer detection are reviewed, focusing on detecting cancer biomarkers and cancer cells in bodily fluids. The study examines the challenges and limitations of PCF-SPR biosensors in cancer detection, including the requirement for enhanced sensitivity and selectivity. Additionally, the review emphasizes the need for further research to address these limitations. Furthermore, the article explores potential avenues for advancing PCF-SPR biosensors in the realm of cancer detection. The research explores the utilization of novel sensing materials and their properties, different performance parameters. The findings of the review suggest that PCF-SPR biosensors hold great potential for detecting cancer and could be further developed and applied in clinical applications. [ABSTRACT FROM AUTHOR]

In this paper, we propose and numerically characterize the optical characteristics of a dual eccentric-core D-shaped photonic crystal fiber (PCF) surface plasmon resonance (SPR) refractive index (RI) sensor. The dual eccentric-core structure can leak more power to plasma film to excite SPR phenomenon than conventional structures. We investigate the influences induce by diameter of air holes, distance between air holes and thickness of gold film. The results show that our sensor has the wavelength sensitivities (WS) of 44,000 nm/RIU for odd mode and 39,000 nm/RIU for even mode. Moreover, the sensor has the detection range of RI from 1.00 to 1.37, the maximum figure-of-merit (FOM) of 325/RIU, maximum resolution of 2.27 × 10−6 RIU for analyte RI change of 0.1 nm, and the minimum full-width at half-maximum (FWHM) of 56 nm. The sensor has wide application prospects in methane, blood plasma, and methanol detecting. [ABSTRACT FROM AUTHOR]

The proposed work exhibits the novel Kretschmann (K)-surface plasmon resonance (SPR) sensor structure based on the cobalt and 2D material MXene (Ti3C2Tx). The performance of a silver (Ag)-cobalt (Co) (bimetallic)-based SPR sensor is numerically investigated by the transfer matrix method (TMM) for the analysis of light propagation through the proposed layers. Additionally, the electric field intensity and penetration depth (PD) are analyzed by the finite element method (FEM) using COMSOL Multiphysics. The cobalt confirms the large magneto-optical activity suitable for plasmonics. The optimization of the Ag-Co metals and MXene thickness enhances the sensitivity of the proposed sensor with the minimum reflectance (Rmin). Two-dimensional (2D) material of MXene enhances the sensitivity and protects the bimetals (Ag-Co) from oxidation. The highest sensitivity of 272.38°/RIU is achieved with the proposed sensor, and it is convenient in the medical and life science field to detect biomolecules. [ABSTRACT FROM AUTHOR]

An ultrahigh sensitivity surface plasmon resonance sensor based on double-side polished photonic crystal fiber is designed, and the gold film with a zigzag cross section is used as the plasmonic material. We study the refractive index sensing characteristics of the proposed sensor by numerical simulation. The results show that compared with the flat gold film structure, the zigzag gold film structure effectively improves the sensing performance, and the sensitivity and resolution of the sensor are significantly enhanced. The maximum wavelength sensitivity and resolution of the proposed sensor can reach 20,000 nm/RIU and 5.00 × 10−6 RIU, respectively. The working wavelength range of the sensor is between 590 and 1200 nm, and the refractive index range that can be used for detection is 1.350 RIU-1.400 RIU. This can be applied to precise detection of extracellular vesicles, breast cancer cell, and red blood cells. The proposed sensor has significant advantages such as stable structure, ultrahigh sensitivity, fast response, small size, and saving noble metal. It has great application potential in biomedical testing and medical equipment. [ABSTRACT FROM AUTHOR]

In this demonstrated design, we built a perfect solar absorber, with three appropriate layers of base (tungsten) layer, substrate (aluminum), layer, and gold resonator in a cross-design. The absorption result of the demonstrated cross-design can be identified in three sections by dividing the whole wavelength range (2800 nm) into two sections the first 1400-nm bandwidth range (starting from 0.2 to 1.6 µm), and the second part of 1400 nm (between 1.6 and 3 µm) respectively. With the support of the adding graphene layer by developing the top and middle layer, the absorption percentage can be increased to 91% for the overall range of 0.2 and 3 µm. The developed cross-design absorption rate is above 90% at an overall bandwidth of 2800 nm. For the first half section of the 1400-nm bandwidth (0.2–1.6 µm), the absorption amount is observed more than 90%, and at the rest half of the overall wavelength (1.6–3 µm), the solar radiation is greater than 95%. To highlight the variation in absorption situations, the peak four wavelengths (micrometers) are picked up such as λ1 = 0.33, λ2 = 1.23, λ3 = 2.24, and λ4 = 2.6 respectively. In this developed cross-solar design, the absorber can be explored in the four spectra of ultraviolet (UV) region, violet (V), and near and middle infrared regions (NIR and MIR). The creation of the cross-design in many steps, and it can be also expressed with the AM 1.5 situation. To indicate the absorption value variations for this cross design, various parameter sections of the ground layer parameter, cross design length, and substrate length can be distinguished in four different peak wavelengths. The electric potential value changes and the color distinguished of the electric field progression of the cross-design can be also extinguished. Transverse electric value and magnetic (TE and TM) variations in four different peak wavelengths can be demonstrated by varying degrees from 0 to 50. Finally, the proposed cross-design absorption value can be compared with the other published design in a table with the respective sections of absorption percentage, bandwidth range, angle variation, and polarization sensitivity respectively. [ABSTRACT FROM AUTHOR]

We studied the effect of core-semiconductor radius, Au-shell thickness, graphene chemical potential, and graphene layers on the plasmonic resonance under quasi-static approximation. The core quantum dots used in the study are CdS, CdSe, ZnTe, and C u 2 O . The core-semiconductors are coated with Au and then wrapped with graphene. We compared the absorbance peaks position, the width of the absorbance peaks (FWHM), and the enhancement of the peak intensity of each core-bishell nanoparticles. We considered three fixed radii of the core semiconductors; r 1 = 20 , 30, and 35 nm. For each radius, the thickness of the Au varied from 1 to 15 nm, and μ varied from 1.0 to 1.6 eV. For all samples, the first resonance peaks are found in the visible region or in near-infrared region depending on the value of the chemical potential and the second peaks found in the infrared or near-infrared region. The effect of the graphene layers is also studied. From the four samples, C u 2 O @ A u @ g r a p h e n e has better absorbance/extinction cross-section, with relatively large values of d for each value of μ and r 1 . CdSAu@graphene has least absorption cross-section intensity that occurs relatively at small thickness of Au. The overall combined effect of the four parameters is enhanced absorption/extinction surface plasmon resonance peaks accompanied by blue shift of the graphene resonance. The obtained results can be used in medical applications that require sensitive imaging, therapy, and as a sensor. [ABSTRACT FROM AUTHOR]

A highly sensitive D-shaped microfluidic channel (MFC) incorporated in a single-mode fiber (SMF) equipped with a tungsten trioxide ( W O 3 ) layer coated with gold (Au) or silver (Ag) on the base of the MFC is designed and investigated utilizing a finite element method (FEM) to obtain the sensing performance of the optical fiber surface plasmon resonance (SPR) structure. The proposed sensor is appropriate for both bimetallic layers and analytes. With the sizeable cladding diameter of SMF, the fluidic channel size can be changed following demand, making fabrication more accessible and applicable. The hollow D-section above the core deposited a bimetallic structure of silver (Ag) or gold (Au) as plasmonic materials, followed by a tungsten trioxide ( W O 3 ) nanolayer. This optical fiber biochemical monitors the changes in the refractive index (RI) by measuring the transmission spectral shifts of the fiber at their resonance wavelengths. The W O 3 layer protects the plasmonic material from oxidation and effectively enhances the surface plasmon wave (SPW) while interacting with free electrons. Upon achieving the optimum structural parameters, the numerical investigation results showed that the maximum wavelength sensitivity of 6.0 μ m//RIU and 5.0 μ m//RIU for Au/ W O 3 and Ag/ W O 3 were obtained, with the coefficient of performance of 50.12 R I U - 1 and 134.84 R I U - 1 , respectively, for ultra-wide sensing ranges from 1.28 to 1.38. Also, the simulation outcomes revealed that the tungsten trioxide-coated with Ag or Au layers significantly enhanced the sensor. Finally, the numerical results of this study showed that the proposed sensor has substantial possibilities for large sensing RI applications such as biology and chemistry analytes, and it is also valid for other lower RI analyte sensing requirements as a consequence of its features such as high sensitivity, simple design, cost-effective design, and promising linear sensing performance. [ABSTRACT FROM AUTHOR]

In this paper, a refractive index (RI) sensor is presented on the basis of the surface plasmon resonance (SPR) effect of double-ring hollow-core anti-resonant fiber (DR-HC-ARF), which has great sensitivity and wide detection range. In the design, the DR-HC-ARF consists of 12 silica tubes in two layers inside and outside, with the X-forward inner silica tube filled with gold wire. The simulation results indicated that the achievable maximum sensitivity, minimum resolution, and largest figure of merit of the DR-HC-ARF sensor filled with gold wire are −20600 nm/RIU, 4.85 × 10−6 RIU, and 615.79 RIU−1, respectively, when measuring using the confinement loss approach. The maximum sensitivity, minimum resolution, and largest birefringence of the DR-HC-ARF sensor filled with gold wire are −21200 nm/RIU, 4.71 × 10−6 RIU, and 2.38 × 10−4, respectively, for the birefringence analysis approach. The ultrahigh RI sensitivity of DR-HC-ARF sensor filled with gold wire paves a promising way on the applications in the field of biochemical detection. [ABSTRACT FROM AUTHOR]

We proposed the numerical studies and machine learning prediction for the multilayered Borophene-GST-silica-Ag-based refractive index sensor for the 1.3–1.5 µm wavelength range. The top layers of the proposed sensor incorporate Ag gratings. The proposed structure utilizes a mode based on surface plasmonic resonance, which has been created using a finite element model through computational analysis. Resonance is observed across a range of refractive index values from 1 to 2.5, which primarily aligns with the refractive indices of key biomolecules such as haemoglobin, saliva, urine, and cancerous cells. The proposed structure has also been investigated for the different physical parameters such as material height, grating space, the incident wave's wide incident angle, and the GST material's phase. We demonstrate the modulation of reflectance values in response to varying phases of the GST material (amorphous and crystalline), which can be controlled through external temperature changes. The distribution of the electric and magnetic fields of the structure is also provided in order to examine the field distribution across the grating and other layers of material. This sensor offers a wide angle of stability (0 to 80°) for the respective resonating points. An artificial neural network is employed to analyze the simulated data and make predictions regarding the behaviour of the structure. We have found the R2 = 0.97 for the proposed artificial neural network (ANN) model. The ANN model of this structure also presented the values of mean square error (MSE), mean absolute error (MAE), and root mean square error (RMSE) for different epoch values. Results shown in this research can help to sense the wide range of biomolecule samples whose refractive index ranges from 1 to 2.5. The wide wavelength range makes this device applicable for developing wideband infrared biosensors. [ABSTRACT FROM AUTHOR]

In this paper, a triple-band absorber based on a rectangular split ring resonator and cross-shape graphene structure is achieved. The proposed absorber can achieve perfect absorption at 3.61 THz, 4.61 THz, and 5.86 THz, with absorption efficiency of about 97.8%, 99.3%, and 98.6% at the three peaks. Results show that the perfect absorption effect is originated from the surface plasmon resonance (SPR) of graphene metamaterial. An equivalent circuit model is presented, reveals the absorption peak, and absorption efficiency are related to the resistor of graphene. The absorption peaks can be independently tuned by changing the geometrical sizes, structure period, and A l 2 O 3 thickness. We also study the influences of the incident angle, polarization angle, chemical potential, and scattering rate on the absorption spectrum. Moreover, the proposed structure can be applied as an excellent refractive index sensor, the maximum sensitivities of the three peaks are 0.86 THz/RIU, 1.01THz/RIU, and 1.27 THz/RIU, and the FOM is 10 R I U - 1 , 10.1 R I U - 1 , and 10.3 R I U - 1 , respectively. Other important sensing parameters including Quality factor, detection limit, detection range, detection accuracy, sound-to-noise ratio, and sensor resolution are also calculated. Therefore, the proposed graphene-based structure can be applied to multiple absorption switches, near-infrared modulators, sensors, and other fields. [ABSTRACT FROM AUTHOR]

High-efficiency integrated photodetectors can assist in future high-speed communication devices for achieving high responsivity characteristics. In this paper, we designed and optimized a graphene/GaAs heterojunction photodetector based on ellipse wall grating-nanowire (EWG-NW) structure. We evaluated the optical and electrical performance of the photodetector between 400 and 800 nm by COMSOL. Compared with graphene/GaAs heterojunction photodetector based on plain structure, our device exhibits enhanced responsivity performance within the visible spectrum at 0 bias voltage. The maximum photocurrent responsivity of 514 mA/W (increased by 56%) and detectivity of 1.16 × 1011 Jones (increased by 41%) are achieved at 725 nm. The mechanism of improvement originates from surface plasmon resonance-enhanced electromagnetic field excited by elliptical wall gratings and metal nanowires in graphene/GaAs heterostructures, thus significantly enhancing carrier separation and transfer. We also analyzed the influence of structural parameter on the absorptivity. The result indicates that the performance of our photodetector can be significantly improved by our design of the plasma structure, which provides a potential scheme for the application of plasma structure optoelectronic devices. [ABSTRACT FROM AUTHOR]

There are many ways to boost the optical absorption efficiency of photovoltaic devices. It has been observed that the plasmonic effect is an efficient technique to increase the incident light collection and improve carrier dynamic control. Here, we made some modifications in the electron transport layer (ETL) and hole transport layer (HTL) of perovskite solar cells (PSCs). The hollow spheres of TiO2 nanoparticles (NP) of different sizes were incorporated in the ETL, and carbon nanoparticles were added to the HTL of the PSCs. Finite element method (FEM) was used to determine the UV–Vis absorption and bandgap energy results under AM 1.5 solar spectrum. General-purpose photovoltaic device model (GPVDM) and COMSOL Multiphysics version 5.3 are the software tools used in the analysis. Here, we introduced gold nanoparticles along with dielectric material (TiO2) of different geometries in the absorber layer of PSCs to investigate the optical absorption and bandgap energy of the PSC structure. For the monolayer structure, we have achieved a power conversion efficiency (PCE) of 24.23%, which is 2.54% higher than the bilayer structure of a Perovskite solar cell. In the absorber layer, we have also used a core@shell structure with metal as core and dielectric nanoparticles TiO2 and SiO2 as shell materials. The optical absorption in both Au@TiO2/Au@SiO2 core–shell and without plasmonic NP TiO2/SiO2 is 10.82% and 4.11%, respectively. These findings suggested that by using the plasmonic NPs the charge separation has been enhanced. Additionally, this study offers a very sophisticated method for enhancing the performance of overall photovoltaic devices. [ABSTRACT FROM AUTHOR]

Early in history, societies utilize renewable energy sources in response to technical developments and external factors, which resulted in the development of hydropower, wind turbines, and solar PV, as well as their support through policies and agreements. The double ring covered disk resonator solar absorber (DRCDRSA) structures are examined over the spectral range of wavelength 0.2 µm to 2.5 µm (UV-FIR) with the help of finite element method (FEM) in this study. This design achieved effective solar absorption, surpassing 99% over the 0.46 µm band, 95% over 2.05 µm wideband, and 90% over the entire observed spectral range, with an overall average absorbance of 96.38%. In addition, the maximum absorbance is 99.9% with three pick values at the wavelengths of 0.34 µm, 1.35 µm, and 1.51 µm. This research includes a parameter optimization as well as the electric field strength and magnetic field intensity distribution over a three-dimensional solar absorber construction. The structure's angle-polarization study shows it is polarization independent, handles diverse angles, and maintains even absorption up to 60° across all wavelengths. This study explores effective solar heaters for air and water systems, offering promising prospects for maximizing solar energy utilization. [ABSTRACT FROM AUTHOR]

In this study, we propose a wide-angle broadband solar absorber based on multilayer etched toroidal structure. It is composed of a top layer Ti, W, and Si3N4 multilayer material, a silica insulator, and a Ti substrate. The average absorption from visible to mid-infrared wavelengths is 94.2%. The absorption bandwidth above 90% absorption is 3092 nm, and the peak absorption is 99.9%. The absorber achieves a perfect collection of incident solar energy caused by the combination of the local surface plasma resonance at the top layer of this absorber and the propagating plasma resonance in the lower insulator layer. The results are verified by applying impedance matching theory. Then, the effects of different structural geometrical parameters, polarization angles, and TE and TM incidence angles on the absorption are discussed. In addition, this absorber captures solar energy across the entire solar spectrum. Finally, we demonstrate that the absorber has a solar thermal conversion efficiency of more than 90% in the temperature range of 100–900 °C. This absorber has good application prospects in the fields of solar absorbers, solar thermal photovoltaic devices, and solar thermal electronic devices. [ABSTRACT FROM AUTHOR]