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This study presents the design and analysis of a novel surface plasmon resonance sensor based on D-type photonic crystal fiber. The analyte channel in the sensor comprises an open ring with a thin gold film deposited on the channel, inducing the surface plasmon resonance effect to enhance the resonance effect and improve the spectral sensitivity of the sensor. The proposed design eliminates the need to introduce liquid into the analyte channel. Upon inserting the sensor into the vessel, the analyte automatically flows into the liquid channel. Simulations illustrate the capability of the proposed sensor to detect low refractive indices spanning from 1. 1 5 to 1. 2 6 , exhibiting a remarkable spectral sensitivity of up to 9000 nm/RIU. The surface plasmon resonance sensor presented in this study emerges as a competitive candidate for applications requiring low refractive index detection. It is all because of its promising sensing results, wide refractive index sensing range, and simple, compact fiber design. [ABSTRACT FROM AUTHOR]

Biopolymer electrolytes based on methyl cellulose (MC) and sodium bromide(NaBr) have been prepared through solvent casting technique. Both the concentrations of MC and NaBr are varied. The prepared biopolymer electrolytes have been subjected to AC impedance and UV-Vis spectroscopic techniques. The ionic conductivity reached a maximum value of 4.84 × 10−8 Scm−1 for 0.8 g of MC and 0.2 g of NaBr. UV studies revealed that low direct and indirect band gaps have been observed for the maximum ionic conducting sample. Other optical parameters, such as refractive index, extinction coefficient, skin depth, and optical conductivity, have been estimated. The single-oscillator energy (Eo) and dispersion energy (Ed) for all the prepared biopolymer electrolyte samples were calculated with the help of Wemple and DiDomenico single oscillator model. The higher-order non-linear susceptibility values were also calculated. Polymer electrolytes are found to be suitable for optical and electronic devices. [ABSTRACT FROM AUTHOR]

We explore the effect of crystallographic anisotropy on the optical properties of high-quality β-Ga2O3 thin films by conducting experimental measurements and theoretical simulations. High resolution x-ray diffraction measurements confirm the high-quality and the single crystalline quality, ruling out the effect of defects for all films. Raman spectra reveal the presence of anisotropy, as evident from a stronger B g (2) mode related to GaIO4 chain libration in (100) orientation. Conversely, a stronger A g (10) mode corresponding to tetrahedral bonds is evident in the (010) orientation, while it is suppressed in the (100) orientation. Low-temperature photoluminescence spectra indicate the presence of intrinsic impurity-related emissions in the ultraviolet and blue regions for all films. An anisotropic bandgap is observed, wherein the lowest bandgap value is related to the (010) oriented sample. Spectroscopic ellipsometry measurements confirm different refractive indices and extinction coefficient values depending on crystallographic orientation, which are in good agreement with the theoretical values obtained by density functional theory, confirming the anisotropic characteristics. The theoretical calculations of charge density show that the strength of covalent bonding depends on the β-Ga2O3 orientation, while experimental findings demonstrate that as the covalent bonding character increases, the film bandgap and the refractive index decrease. The anisotropy of β-Ga2O3 with respect to the crystal orientation leads to variations in the extinction coefficient, refractive index, and bandgap energy. [ABSTRACT FROM AUTHOR]

Reentry vehicles in near space used to suffer from communication blackout, which is led by the plasma sheath enveloping the whole reentry vehicle. Terahertz (THz) communication is believed to be a potential solution to mitigate the communication blackout effectively. Previous studies have investigated the attenuation characteristics of THz signals in plasma sheaths. However, the offset of THz signal transmission direction by the plasma sheath has rarely been a concern. In this study, the auto-evolution of the plasma sheath is taken into account. The consequent evolution of the refraction index distribution of the plasma sheath is investigated. It is found that the plasma sheath acts as a gradient index lens to the propagating THz signals. The lens structure keeps evolving due to the evolution of the plasma sheath itself. The main mechanism that dominates the evolution of the lens structure is the convection of electrons. By analyzing the offset of the transmission direction yielded by the lens structure, it is suggested that the onboard THz antenna could be installed close to the bottom of the vehicle in order to stabilize the transmission direction of THz signals in an evolving plasma sheath. [ABSTRACT FROM AUTHOR]

A series of mixed glass formers (MGF) with varying compositions denoted as (79-x)B2O3-xTeO2-20Li2O-0.5Ho2O3-0.5Yb2O3 (x = 0–50 mol%) were prepared using the melt-quenching technique. This aim of this study was to examine the effect of combining glass formers TeO2 and B2O3 on the structural, DC conductivity, elastic, and optical properties of the glass system. XRD measurements confirmed the amorphous nature of the glass samples. Structural analysis revealed a rivalry between the TeO2 and B2O3 formers. It was observed that the bridging oxygen (BO) indicated by the BO4 functional group decreases gradually at x ≥ 40 mol%, implying that non-bridging oxygen (NBO) units, denoted by BO3, become dominant beyond 40 mol%. The variation in DC conductivity showed a non-linear behaviour upon addition of TeO2, with the conductivity increasing to a maximum value at x = 30 mol% before decreasing at x > 30 mol%. Interestingly, the conductivity showed a slight decline at x = 40 mol%, possibly resisting a decrease due to the mixed glass former effect (MGFE). Elastic moduli such as CL, Ke and Y exhibited a non-linear decrease between 10 ≤ x ≤ 30 mol% and reached a lowest value for x = 40 mol%, which coincided with the maximum of DC conductivity attributed to MGFE. Quantitative analysis of ultrasonic data, utilizing bulk compression and ring deformation models, revealed that the Kbc/Ke value is maximum at x = 40 mol%, implying a reduction in ring deformation within the MGFE region. UV–Vis spectroscopy demonstrated that with increasing TeO2 content, Eopt and Eopt' decreased except for x = 40 mol%. The refractive index, n also increased except at x = 40 mol%. The alternating dominance of BO and NBO in the MGFE region led to this conclusion. [ABSTRACT FROM AUTHOR]

Herein, we report the extraction of natural pigment curcumin from curcuma longa and their linear and third-order nonlinear optical (NLO) characteristics. The characterization techniques viz., UV–Visible absorption, FT-IR, Micro Raman and Gas Chromatography Mass Spectrum (GC–MS) are used to study the spectral characteristics of curcumin. Third-order NLO features of curcumin are studied using Z‒scan technique with a semiconductor diode laser working at 405 nm wavelength. The natural pigment exhibits negative nonlinear index of refraction resulting from self-defocusing and positive coefficient of absorption is the consequence of reverse saturable absorption (RSA). The order of nonlinear index of refraction (n2) and nonlinear coefficient of absorption (β) is measured to be 10−7 cm2/W and 10−2 cm/W, respectively. Third-order NLO susceptibility (χ(3)) and second-order hyperpolarizability (γ) of curcumin is measured to be 2.73 × 10‒7 esu and 1.67 × 10‒31 esu, respectively. A low optical limiting (OL) threshold of 0.71 mW is observed in the extracted pigment. The experimental results are supplemented by quantum mechanical calculations of the NLO parameters. The overall result finding is that curcumin extracted from curcuma longa has the potential to be novel optical candidates for photonics and optoelectronics applications. [ABSTRACT FROM AUTHOR]

Antireflection surfaces are widely used in optical devices (such as vehicle display, solar cells, and architectural glass) to reduce the reflection and increase transmittance. Plasma etching shows great potential in making subwavelength antireflection structures for its advantage of scalable, low‐cost, and applicable in flexible substrates. Here, we demonstrate an antireflection nanostructure by O2 plasma etching on poly (ethylene terephthalate) (PET) substrate without additional corrosive gas species or antireflective coatings. Nanopores on the surface were formed due to the different etching rates of the organic region and silica region of the surface. The solar weighted average transmittance was improved from 91.6% to 94.8% for single‐side treated PET with silica antiblocking layer. The transmission increment was attributed to the gradient refractive index of the nanostructured surface due to the elimination of step discontinuity in refractive index. The result shows a highly efficient, eco‐friendly, solvent‐free, economical, and sputtering target‐free method for reducing the reflection and increasing the transmittance of the substrates. [ABSTRACT FROM AUTHOR]

An investigation on a single mode optical fiber sensor-based surface plasmon resonance was carried out in this work. A titanium dioxide (TiO2) coated gold Nano-column (Au) are deposited on the proposed sensor and theoretically analyzed using COMSOL Muliphysics software 5.3. Presence of TiO2 over the Au Nano-column can improve the sensitivity of the sensor and tune the resonance peak of transmission spectrum from visible region to near-infrared region. The size effect of TiO2 nanoparticles on the sensor performance is studied. The optimum parameters of such as Au size and separation width between the Au Nano-column have been selected to enhance the performance of the sensor. In comparison, the sensor with TiO2 over Au Nano-column is significantly improve the sensitivity and develop the sensor performance. The greater sensitivity of 5243.76 nm/RIU (refractive index unit) is obtained of sensor with TiO2 over Au Nano-column when the external refractive index of analyte is varying from 1.33 to 1.39, while sensitivity of the sensor coated with Au Nano-column is obtained to be 4643.17 nm/RIU for the same analyte range. Above results can be used to predict the best parameters values of the sensor that corresponding to the greatest sensitivities of detection and finally opening new study in the field of gas sensors. [ABSTRACT FROM AUTHOR]

Spatio-temporal particulate matter (PM) measurements are critical to understanding emission profiles to develop effective mitigation strategies. However, high-resolution spatio-temporal measurements using research-grade instruments are cost-prohibitive, making low-cost sensors (LCS) a promising alternative. LCS measures particle light scattering intensity (Isc) and converts it to mass and number concentrations. Such measurements are influenced by particles' physico-optical properties, which make LCS appropriate for measuring PM with similar properties to those used for calibration. This work evaluates the performance of an LCS (PurpleAir) against reference instruments (SMPS + APS) during cooking experiments performed in a test house where PM0.3/PM10 as high as 90% was observed. LCS demonstrated better correlations (R2) for PM1 (0.98–1), PM2.5 (0.96–1), and PM10 (0.88–1) compared to coarser size bins, i.e., PM1–2.5 (0.04–0.99) and PM2.5–10 (0.02–0.93). Measurements from different cooking activities show different linear fits. Isc calculated using size-resolved measurements of reference instruments also had different linear fits with corresponding mass concentrations, even after assuming the same refractive index for all cases, highlighting the dependence of size distribution on LCS measurements. On average, sub-300 nm particles accounted for up to 75 ± 18% of the total Isc. Such dominance of sub-300 nm particles leads to size misclassification by LCS, whose algorithm assumes the inability to measure sub-300 nm particles. Moreover, the Isc calculated using the size distribution reported by LCS is considerably lower than that of reference instruments. This mismatch can be attributed to truncated angle error and positioning of particles in the sensing zone relative to the photodiode. Copyright © 2024 American Association for Aerosol Research [ABSTRACT FROM AUTHOR]

In the present work, the polyvinyl alcohol (PVA) matrix was reinforced with various contents of Nd2O3 nanoparticles (from 1 to 3.8 wt%) to form PVA-Nd2O3 nanocomposite films via the casting technique. The PVA-Nd2O3 films were characterized by X-ray diffraction (XRD), Raman, Fourier transform infrared (FTIR), scanning electron microscope (SEM), and energy dispersive X-ray (EDX) techniques. The XRD analysis revealed the presence of Nd2O3 in the nanoscale and the presence of Nd(OH)3 due to the adsorption of water vapor from the air. The Nd2O3 additive to the PVA matrix causes an alternation in the PVA structure, which appears in the change in the PVA characteristic peak. Raman analysis of the PVA-Nd2O3 films showed the presence of Ag and E1g modes and bands at 470 and 750 cm− 1 produced by the Nd-O-H deformation brought on by OH-rotation. The PVA film showed a decrease in film transparency and an increase in absorbance with the addition of Nd2O3 nanoparticles to the matrix. Moreover, there was a decline in the PVA bandgap energy from 5.43 eV to 3.32 eV for the undoped PVA film and doped with 3.8 wt.%Nd2O3, respectively. The addition of Nd2O3 to the PVA matrix improved other optical characteristics such as optical basicity, electronegativity, metallization criteria, and linear refractive index. The obtained PVA-Nd2O3 films are candidate options for electronic and photonic applications. [ABSTRACT FROM AUTHOR]

Hybrid polymer nanocomposites (HPNC) with improved optical and magneto-dielectric properties are an exciting class of materials from economic and industrial points of view. In the present work, CoFe magnetic nanoparticles (NPs), and HPNC based on a polyethylene oxide (PEO)/polymethyl methacrylate (PMMA) matrix were synthesized by simple and cost-effective chemical methods. The NPs morphology, HPNC structure, and film surface were investigated using FE-scan electron microscopy, X-ray diffraction, and Fourier transform-infrared techniques. The PEO/PMMA blend exhibits 39% crystallinity, which is reduced upon 1.0 wt% CoFe NPs addition. The uniformly distributed CoFe NPs resulted in a reduction in the FTIR absorption band’s intensity. The optical spectra displayed the high transmittance of the blend matrix and CoFe/PEO/PMMA. The influence of CoFe content on the Urbach energy, refractive index, and carrier concentration is reported. The optical band gap ( E g ) was evaluated by two different methods and was found to decrease from 5.0 to 4.5 eV. The dielectric spectroscopy was studied in at frequencies of 1 × 102–5 × 106 Hz, and temperatures in the range of 30–110 °C. The real (imaginary) dielectric constant, modulus, and the correlation between the dielectric constant and dc conductivity were studied. The blend’s ac conductivity was 4.14 × 10–4 S/m, which increased to 6.91 × 10–4 S/m upon 1.0 wt% CoFe NPs doping. The enhancement in the structural, optical parameters and dielectric features, and the ac and dc conductivities, make CoFe/PEO/PMMA HPNC the best candidate for advanced optoelectronics, photonic devices, and microcapacitors. [ABSTRACT FROM AUTHOR]

Adsorption-based plasmonic refractometric biosensors have a great potential for applications in environmental protection, medicine and industry, as they are highly sensitive detectors of a broad range of biological analytes. Their response is determined by the temporal change of the effective refractive index (RI) of the sensing area caused by biomolecules adsorption. Many biomolecules undergo a structural transformation upon a contact with the sensing surface, causing a change in their affinity towards adsorption sites. Different forms of molecules also have different RI, which affects the sensing area effective RI. Adsorption leads to depletion of biomolecules from the sample, affecting the instantaneous rate of change of the number of adsorbed molecules, and thus also the effective RI change. Therefore, it is necessary to investigate the influence of these phenomena on the sensor response. In this work, we derive the first mathematical model that describes the change in the effective RI of the sensing area by taking into account reversible adsorption, structural transformation of adsorbed biomolecules, and sample depletion. We then use that model to analyze influences of these processes on the RI change by studying an exemplary protein adsorption. The results have shown the significant influence of these processes on the sensing area effective RI, and thus on the sensor time response, particularly when extremely low biomolecule concentrations are to be detected. The use of the presented model prevents erroneous interpretation of measurement results in ultrasensitive plasmonic biosensors, which may occur if using models that do not take into account structural transformation and analyte depletion. [ABSTRACT FROM AUTHOR]

This article presented a sensing method for detecting SARS-CoV-2 based on refractive index (RI). The approach utilizes the established nanogap terahertz metamaterial unit cell design as a biosensor. The underlying idea is that the SARS-CoV-2 virus can be treated as a nanoparticle, falling within the 30–100 nm diameter range. Therefore, it can be detected using established and dependable photonics methods. Notably, the SARS-CoV-2 virus family exhibits a negative RI between − 0.96 and − 1. Absorption coefficient (α ) is 226,615.2 cm−1, absorption rate is 97% and sensitivity (S) is 330 nm / RIU . The analysis shows a minimal deviation in absorption and resonant frequency when varying the thickness of the dielectric clad from 30 to 100 nm. This stability makes it a suitable outcome for sensing SARS-CoV-2. [ABSTRACT FROM AUTHOR]

In this paper, a novel D-shaped photonic crystal fiber (PCF) refractive index (RI) sensor based on surface plasmon resonance (SPR) effect is proposed. By introducing a smiley-faced hole and Ag-TiO2 composite micro-grating, the high RI sensing performances can be realized. With finite element method, the propagation characteristics of the proposed D-shaped SPR-PCF RI sensor are numerically investigated. The simulation results show that the average wavelength sensitivity (WS) is 5400 nm/RIU, and the maximum WS can reach 15,500 nm/RIU in the RI range from 1.30 to 1.39. Besides, the proposed D-shaped SPR-PCF RI sensor can obtain the maximum resolution (R) of 4.95 × 10−5RIU and the maximum figure of merit (FOM) of 423.78 RIU−1, respectively. It is believed that the proposed SPR-PCF RI sensor has potential applications in the fields of environmental monitoring, biomedical analysis, and food safety management. [ABSTRACT FROM AUTHOR]

Early identification of Mycobacterium strains that cause TB (Tuberculosis) is crucial in preventing tuberculosis illness. Conventional medical diagnostics, such as PPD (tuberculin skin tests) tests and antibody-assisted tests, have low sensitivity, extensive processing times, and complex post-test procedures. These problems minimize its potential and drive innovation in tuberculosis diagnosis. Biosensors have simplified the identification of illnesses by reducing the time between sample and results. This paper proposes a circular ring-shaped refractive index sensor for the identification of the four different types of mycobacterium tuberculosis cells. This sensor has achieved the highest sensitivity of 1500 nm/RIU for all four types of tb cells by analyzing the different parameters like substrate height, resonator height, radius of the circle, length of the substrate, and width of the circle resonator. It covers the wavelength range of 2000 nm to 2050 nm. The highest value of the quality factor has been observed is 40,280 for TBC2 (Tuberculosis cell 2, specific type of tuberculosis) and the highest value of the figure of merit has been observed is 30,000 for TBC2 compared to normal cells. The best response for the DL (Detection limit) has been observed at 0.000005 for TBC2. [ABSTRACT FROM AUTHOR]

In this article, a surface plasmon resonance (SPR) sensor based on photonic crystal fiber (PCF) is simulated and analyzed by finite element method (FEM). Gold and titanium oxide (TiO2) are used as plasmonic layers. The TiO2 layer is placed under the gold layer to increase the sensitivity of this sensor. The sensor's top and bottom surfaces are polished, and the plasmonic layer is placed on both these surfaces. Unlike sensors with typical external circular coating, less plasmonic material is used. Additionally, unlike internal coating sensors, there is no issue of partial air holes coating and achieving a uniform thickness of the plasmonic layer. Also using two plasmonic levels can expand the range of refractive index (RI) detection. The sensor's structure creates birefringence, allowing complete coupling between the core mode and both plasmonic layers. This results in more reliable detection ability. By optimizing the dimensions and arrangement of air holes and the sensor's structure, the ability to detect unknown analytes in the ultra-wide range of refractive index of 1.21–1.41 with the maximum wavelength sensitivity (WS) of 61,000 nm / RIU , the maximum amplitude sensitivity (AS) of 1294.29 RIU - 1 , the maximum figure of merit (FOM) of 657.14 RIU - 1 and the sensor resolution (SR) of 4.35 × 10–6 RIU have been obtained. This sensor operates in the visible to near-infrared wavelength range. During its design, feasibility in construction was taken into consideration, along with reducing the complexity and multiplicity of structural parameters. As a result, the sensor delivers excellent performance in detection parameters and is a suitable option for RI detection applications like organic chemicals and biosensing. [ABSTRACT FROM AUTHOR]

In this paper, we analyzed the structural and optical properties of quaternary semiconductor Cu2ZnSnSe4 (CZTSe) thin film. For this purpose, the structural properties of CZTSe thin film were analyzed using X-ray diffraction (XRD) and transmission electron microscopy (TEM). CZTSe nanocrystals (NCs) were formed in the kesterite phase and with good crystallinity. Optical characterization of thin film was investigated using spectroscopic measurements. Optical parameters of CZTSe film coated using the spin coating technique were determined by UV-Vis-NIR spectroscopy. The refractive index, extinction coefficient, and dielectric constant of the thin film were calculated using transmittance and reflectance data. Moreover, dispersion parameters such as oscillator energy, and dispersion energy were obtained by the Wemple DiDomenico model. For CZTSe film in the visible wavelength region, the transmission has values of 70–75%. The thin film of CZTSe has a direct band gap of 1.4 eV which is suitable for absorbed layer for solar cell. [ABSTRACT FROM AUTHOR]

A highly sensitive and simple structure side-polished micro-structured fiber (MOF) refractive index (RI) sensor based on surface plasmon resonance is proposed and studied by the finite element method. The gold nanofilm used to stimulate plasmons is directly deposited on the inner wall of the open-loop channel of a MOF consisting of an arrangement of six cladding air-holes. The sample analyte is arranged on the outer surface of the optical fiber to improve the utilization rate of the sensor and reduce the tediousness of operation. Meanwhile, in order to increase the leakage intensity of evanescent field, three large air-holes were introduced near the fiber core. Research has shown that the proposed sensor can achieve sensing detection in the range of 1.19–1.37 RI. The maximum sensitivity in the x-polarized direction can reach 12,500 nm/RIU, and its corresponding resolution is 3.64 × 10–5 RIU. Moreover, it has a high linear response of 0.9944 within the RI detection range of 1.19–1.33. Obviously, the proposed sensor has a simple structure, wide RI detection range, and high sensitivity, which can make it widely used in biomedical and analytical chemistry. [ABSTRACT FROM AUTHOR]

This paper presents the design and analysis of a temperature sensor that utilizes an optical filter consisting of an elliptical-shaped photonic crystal ring resonator (E-PhCRR) in a two-dimensional configuration. The basic structure comprises silicon (Si) rods immersed in the air (disconnected structure) arranged in a triangular lattice. The newly designed structure's photonic band gap (PBG) was calculated using the plane wave expansion (PWE) method, and the temperature sensor was modeled and studied using the finite difference time domain (FDTD). The temperature change causes a redshift in the resonance wavelength due to the subsequent change in refractive index. The temperature was systematically adjusted within the range of 0 °C to 50 °C, leading to a discernible change in the resonant wavelength by 5.2 nm, shifting it from 1682.59 nm to 1687.79 nm. The elliptical shape of the photonic crystal ring resonator provided us with significant flexibility to attain improved outcomes. Specifically, we achieved a quality factor of 316200, a temperature sensitivity of 103.92 pm/°C, and a refractive index sensitivity of 443 nm/RIU. Furthermore, we were able to acquire a detection limit of 5.12 × 10 - 9 RIU while maintaining a compact size of 116.5 μ m 2 . [ABSTRACT FROM AUTHOR]

In this work, we use symbolic computation and ansatz function schemes, to investigate the soliton solutions for the nonlinear Schrödinger equation (NLSE) along with Kudryashov's quintuple self-phase modulation system (KQSPMS) including dual-form of nonlocal nonlinearity (DFNLN). We initially determine the ordinary differential (OD) form for this model through a variable transformation. Then we introduce numerous new dynamical soliton types: the M-shaped rational soliton, the M-shaped interaction between one and two stripe solitons, the periodic cross-M-shaped rational (PCMR) soliton, the periodic cross-kink (PCK) soliton, multi-waves, and the homoclinic breather soliton. Secondly, we determine the partial differential (PD) form for this model through a variable transformation. Moreover, a lump soliton, a periodic wave, a rogue wave, a lump interaction with a periodic and kink wave, and three different types of breather soliton will obtain. We'll demonstrate these solutions' unique structure and extremely interesting interaction behavior. We'll also use graphs (3-D and contour plots) to discuss the dynamics of the results after setting the parameters to the proper values. [ABSTRACT FROM AUTHOR]

A hollow-core photonic crystal fiber based Refractive Index sensor in the terahertz frequency regime for bio-sensing application is proposed in this paper. Refractive index variation is used for the identification of different analytes with refractive indices ranging from n = 1.35 to 1.39. Zeonex is chosen as the fiber material. The proposed photonic crystal fiber (PCF) sensor features a solitary rectangular core enclosed by an arrangement of 16 rectangular air holes within the cladding area with different heights and widths. Simulation and numerical analysis are conducted using Finite Element Method-based based Comsol Multiphysics Software. The proposed PCF sensor exhibits relative sensitivity of 98.8%, an Effective Mode Area of 1.06 × 10−7 m2 with a very low confinement loss of 7.751 × 10–14 dB/cm are achieved at a frequency of 1.4 THz for an analyte of refractive index 1.39 in X Polarization direction of electric field. Moreover, birefringence, non-linearity, effective refractive index and power fraction are also analyzed. Further simple PCF structure based on rectangle ensures that fabrication is feasible with current fabrication techniques.Please check and confirm that the authors and their respective affiliations have been correctly identified and amend if necessary.I have checked the authors name and affiliations and found its correct.Kindly check and confirm whether the corresponding author and corresponding mail ID is correctly identified.I have checked about corresponding authors name and email id. I found it correct. [ABSTRACT FROM AUTHOR]

In this study, novel Li2ZnSnS4 (LZSS4) thin films have been manufactured using the inexpensive spray pyrolysis system. The study of the X-ray diffraction (XRD) of the LZSS4 films demonstrated that these LZSS4 samples have crystalline structures with monoclinic phases. The elemental analysis of the LZSS4 samples refers to the presence of Li, Zn, Sn, and S in the LZSS4 samples. Their ratio is near 2:1:1:4. Meanwhile, the linear optical study of the LZSS4 samples indicates that the LZSS4 samples have a direct energy gap (Eg), and the growth of thickness led to a decrease in the Eg values from 1.73 eV to 1.48 eV. Conversely, the refractive index of the LZSS4 samples increases from 2.56 to 4.18 by raising the thickness of the investigated samples. Moreover, the Wemple-Didomenico single oscillator model was applied to compute the dispersion parameters of the LZSS4 samples. It was found that the dispersion energy, Ed, improved from 15.87 to 17.26 eV, and the oscillator energy, Eo, dropped from 6.44 to 4.91 eV by raising the thickness from 261 to 486 nm. Also, the study of the optoelectrical and nonlinear optical parameters refers to enhancing the non-linear refractive index (n2), optical resistivity (), optical carrier concentration (), relaxation time (τ), and optical mobility (). [ABSTRACT FROM AUTHOR]

In this article, the modified extended direct algebraic method is applied for the perturbed highly dispersive nonlinear Schrödinger equation with conformable fractional derivative and sextic-power law refractive index. Various types of solutions are extracted such as bright solitons, dark solitons, combo bright-dark solitons, singular solitons, singular periodic wave solutions, exponential wave solutions and rational solutions. The impact of the fractional derivative is illustrated graphically using examples of some of the retrieved solutions with various values of fractional order. [ABSTRACT FROM AUTHOR]

Digital Light Processing (DLP) technology can achieve high-precision and high-efficiency molding of complex and irregularly shaped ceramic components. However, silicon nitride ceramics have high light absorption and large refractive index, leading to poor slurry curable performance and difficulty in molding. This study concentrates on the particle gradation of silicon nitride powder, investigating how varying proportions affect slurry rheology properties, curing properties, and the performance of the sintered body. When the ratio of fine/coarse powder was 7:3, the silicon nitride slurry with a solid content of 45 vol% had a viscosity of 5.4 Pa·s at a shear rate of 30 s−1, a solidification thickness of 42 μm (288 mJ/cm2). The sintered body obtained the flexural strength of 679 MPa, with increases of 26.92% compared to the single coarse powder sample. Additionally, a complex shaped silicon nitride impeller suitable for high-temperature melt transport was successfully fabricated using DLP technology. [ABSTRACT FROM AUTHOR]

• Observation of Multiple layer structures (Temperature Sheets) around the tropopause region and lower stratosphere. • Strong hydrostatic stability responsible for the intensity gradient in the radio refractive index. • Temperature sheets in the troposphere have significant implications for weather and atmospheric stability. • Higher-order spectral analysis has been applied to the atmospheric signals to detect the nonlinearities associated with the temperature sheets near the tropopause region. • Large shear region shows the temperature variation, which results in temperature sheet formation near the tropopause region. Temperature sheets have been observed in the lower stratosphere up to 20 km, with strong (positive) temperature gradients within very thin layers. These were observed from vertical profiles obtained from the Stratosphere and Troposphere (ST) radar located in Kolkata. The sheets tend to occur in groups and contribute to the regions of high static stability, inhibiting vertical air motion. Several experiments were carried out to understand the backscattering mechanism of the Very High Frequency (VHF) radar. Many experiments have reported the multiple layered structures at and around the tropopause regions, especially in the lower stratosphere, it is well established that these layered structures are due to presence of strong negative and positive temperature gradients, which is called as temperature sheets. In order to understand the nonlinearities associated with temperature sheets, Higher-order spectral analysis has been carried out on backscattered signals received from the Mesosphere Stratosphere and Troposphere (MST) radar. This approach allowed for a more detailed examination of the nonlinearities associated with temperature sheets. Therefore, this study proposes a new way of distinctly identifying temperature sheets and the process associated with them using Nonlinear Index based measurements. [ABSTRACT FROM AUTHOR]

A novel all optical JK Flip Flop design is presented based on 2cDimension photonic crystals (PhC). The overall size of the designed JK flip flop is 80 μm × 40 μm of 2cDimension square lattice photonic crystals with a refractive index equal to 3.4 placed in air. The band gab is equal (a/λ) = 0.321 to (a/λ) = 0.441 corresponding to the wavelength range 1550 nm< λ <1560 nm. The lattice constant ’a’ of the structure is equal to 630 nm. The design of optical JK flip flop is based on the nonlinear 3x3 and 9x9 photonic crystal ring resonator. The proposed J-K flip flop has been designed, analysed, and time dependent simulation results are standing on the finite difference time domain (FDTDc) and Plane Wave Expansion (PWEc) methods to confirm its operation and feasibility. [ABSTRACT FROM AUTHOR]

The flow field of a hydrocyclone was investigated using both computational fluid dynamics (CFD) and particle image velocimetry (PIV). A refractive index matching method was employed to improve the precision of the PIV measurements. The CFD results are in good agreement with PIV measurements. Detailed analysis reveals significant axial asymmetry in the velocity components, with the radial velocity component exhibiting notable disparities. This observation is supported by quantitative data comparing different sections of the hydrocyclone. It is further found that the asymmetry might be mainly attributed to the secondary vortexes with the single inlet of the hydrocyclone. And the secondary vortexes, superimposed on the primary flow rather than existing on its own, spiral downwards from near the inlet towards the underflow orifice. It is hypothesized that specific boundary effects and pressure gradients play a pivotal role in the formation of secondary flows. This assumption is grounded on both theoretical considerations and empirical observations, suggesting that these factors significantly influence the flow dynamics within the hydrocyclone. The insights gained from our measurement methodology and enhanced understanding of secondary flows within hydrocyclones are not only poised to serve as valuable references for fellow researchers but also have the potential to inform the design and operational optimization of hydrocyclones for improved efficiency and performance. [ABSTRACT FROM AUTHOR]

Physical properties of mantle minerals are essential for comprehensive geodynamic modeling. High-pressure experiments allow measurements of physical properties but fundamental insights into their evolution with pressure are often experimentally inaccessible. Here we report the first in situ experimental determination of the optical refractive index, its wavelength-dispersion, and optical absorption coefficient of ferropericlase up to ~140 GPa at room temperature. All these properties change gradually in dominantly high-spin (below ~50 GPa) and low-spin (above ~80 GPa) ferropericlase. However, in the mixed-spin state (i.e., significant presence of both high- and low-spin iron), the index dispersion and the absorption coefficient decrease by a factor of three and ~30%, respectively. These anomalies suggest that charge transport by small polaron is reduced in mixed-spin ferropericlase, providing fundamental insights into the factor-of-three lower electrical conductivity of ferropericlase at ~50–70 GPa. [ABSTRACT FROM AUTHOR]

In the present work, the density, speed of sound, and refractive index of binary mixtures of propiophenone (PP) with 3-amino-1-propanol (AP), propylamine (PA), or isobutanol (IB) were measured over whole composition range at temperatures 298.15 to 308.15 K and ambient pressure (0.1 MPa). From these experimental data the excess molar volume, V m E , excess isoentropic compressibility, κ S E , and excess refractive index, n D E , were calculated. The calculated excess molar properties were correlated by Redlich–Kister equation, and their coefficients and standard deviations were calculated. The results show that the V m E values of PP + AP are positive in the entire composition range and at all temperatures, while the V m E values of PP + PA and PP + IB mixtures are negative over whole composition range and at all temperatures. The obtained V m E values were also correlated by Prigogine–Flory–Patterson (PFP) theory which show good agreement between experimental and predicted data. [ABSTRACT FROM AUTHOR]

Currently, coating with anti-reflective materials is an attractive approach to improve the quality of screen-based displays. In this study, mesoporous silica particles were systematically synthesized as a function of surfactant (i.e., CTAC-cetyltrimethylammonium chloride) concentration to serve as main coating fillers possessing low refractive indices. Precisely changing the amount of the CTAC surfactant, silica sol with an average diameter of 50 nm exhibits distinctively different specific surface areas, pore size, and pore volume. Prior to the preparation of final coating solutions containing these silica particle fillers, the percentage of solid content was optimized on a glass slide. The use of 50 wt% solid content exhibited the highest transmittance of light. Among various content levels of silica sol, the use of 3.5 wt% of silica particles in the solid content displayed the highest transmittance (i.e., best anti-reflectiveness). Under the almost identical coating layers prepared with the fixed amount of silica particles possessing different surface areas, pore size, and pore volume, it appears that the largest pore volume played the most important role in improving the anti-reflective properties. Experimentally understanding the key feature of low-refractive filler materials under the optimized conditions could provide a clear view to develop highly effective anti-reflective materials for various display applications. [ABSTRACT FROM AUTHOR]

Label-free optical biosensors, such as interferometers, can provide a comparable limit of detection to widely used enzyme-linked immunosorbent assays while minimizing the number of steps and reducing false positives/negatives. In 2020, the authors reported on a novel optofluidic Young interferometer (YI) that could provide real-time spatial information on refractive index changes occurring along the length of the sensor and reference channels. Herein, we exploit these features of the YI to study interactions of biomolecules with recognition elements immobilized in selected regions of agarose gel in the sensor channel. We show that the YI is well suited for the biosensing of an exemplar biomolecule, streptavidin, in the absence and presence of the bovine serum albumin interferent. Equally, we couple the YI with electrokinetic transport to reduce the time needed for biosensing. [ABSTRACT FROM AUTHOR]

A model for the refractive index dispersion of garnets was developed by extension of a model for garnet refractive indices at 589 nm wavelength. The cation and anion polarizabilities in garnets were determined as a function of wavelength from dispersion data, and fit to Sellmeier relations. Dispersion predictions were compared to measurements of refractive index between 400 and 5500 nm for 35 garnet compositions. The median prediction error was 0.5% with a maximum error < 4.4%. Sources of error and applications of the predictive method are discussed. [ABSTRACT FROM AUTHOR]

Optical biosensors are optical technologies that evaluate changes in the refractive index as they monitor non‐covalent molecular interactions in real time. These make use of unsophisticated, label‐free analytical approaches, which do not require dyes to produce a visible signal. In this study, the efficiency of localized surface plasmon resonance (LSPR) biosensor in detecting a single nucleotide mismatch in deoxyribonucleic acid is examined. The detection is based on the hybridization of a target DNA at 100 ng μL−1 with a complementary biotinylated probe as well as a partially complementary biotinylated with one nucleotide mismatch probe on a gold‐coated surface. Both probes are used at a concentration of 0.1 μm. The LSPR exhibited sensitivity by differentiating sample M+ from sample C+ through varying transmission intensities of 0.28 and 0.26 μA, respectively. Based on these findings, this approach demonstrates a great potential due to its ability to distinguish samples that differ with a single base pair, and its efficiency will be explored in the development of a point‐of‐care device as a simpler and cost‐effective approach for detection of various biologically and medically significant mutations such as antimicrobial resistance mutations. More work is underway to determine the robustness of the LSPR biosensor using the biotin–neutravidin approach. [ABSTRACT FROM AUTHOR]

We propose and analyze numerically new approaches to force the laser emission from VCSELs in a well-defined linear polarization independent of the existing phase and amplitude anisotropies by using dielectric columnar thin-film (CTF) layers in the distributed Bragg reflector (DBR). In one approach, we have demonstrated CTF-VCSELs with top DBR consisting of two alternating CTF layers grown in orthogonally oriented planes and with high and low refractive index for one linear polarization while having the same value of the refractive index value for the orthogonal linear polarization. Such CTF-VCSELs have large dichroism of the mirror losses for two orthogonal linear polarizations. We have also shown DBR designs with parallel columnar orientations of the two CTF dielectric materials. In a second approach, we implement only one CTF layer in the dielectric DBR chosen in such a way that only one linearly polarized longitudinal mode is resonant in the CTF-VCSEL while light with the orthogonally oriented linear polarization is out of resonance and thus cannot lase. Simple estimation of the polarization mode suppression ratio for the different exemplary designs of CTF-VCSELs based on T i O 2 and T a O 2 dielectric CTFs results in values as high as 80 dB, which compares favorably to the existing alternative approaches. [ABSTRACT FROM AUTHOR]

We demonstrate fast writing of strong fiber Bragg grating (FBG) without hydrogen loading using 343 nm femtosecond pulses of only 7 μ J energy at 60 kHz repetition rates and a two-mask interferometer. The beam was focused to a 30–50 μ m diameter along the fiber axis, greatly enhancing the peak power while avoiding damage to the masks. A refractive index modulation of more than 10 − 3 could be obtained in less than one minute exposure. To avoid the observed strong temperature gradient observed in the SMF-28 fiber, a galvo scanner was used to rapidly move the beam back and forth laterally up to 1 mm. FBG were written in SMF-28, as well as 20/400 μ m fiber. In the latter fiber, better heat dissipation allowed us to write the FBG with the standard phase mask scanning technique, and a 0.28 mm Gaussian apodized FBG could be written. [ABSTRACT FROM AUTHOR]

We present a comparison between interband cascade lasers (ICLs) with a six-stage active region emitting at 5 μm with AlSb/InAs superlattice claddings and with bulk A l 0.85 G a 0.15 A s 0.07 S b 0.93 claddings. Utilizing bulk AlGaAsSb claddings with their lower refractive index compared to the more commonly used AlSb/InAs superlattice claddings, the mode-confinement in the active region increases by 14.4% resulting in an improvement of the lasing threshold current density. For broad area laser and under pulsed excitation, the ICL with AlGaAsSb claddings shows a lower threshold current density of J t h = 396 A / c m 2 compared to J t h = 521 A / c m 2 of the ICL with superlattice claddings. Additionally, a higher characteristic temperature was obtained for the ICL with bulk claddings. Emission in pulsed operation is observed up to 65 °C. [ABSTRACT FROM AUTHOR]

Magnesium is a rising alternative plasmonic metal that is potentially cheaper, more biocompatible, and less lossy in the ultraviolet-blue region of the visible spectrum than the commonly used gold and silver. Recent studies of colloidal magnesium nanoparticles demonstrated the plasmonic resonances of a variety of faceted shapes. However, applications such as refractive index sensing benefit from well-defined arrays, which have been developed for all other plasmonic metals. Here, we implement nanosphere lithography to fabricate metallic magnesium arrays that display attractive plasmonic properties. The deposition process was found to be highly vulnerable to oxidation, recrystallization, kinetic energy of the metal vapor, and substrate properties. The resulting structures obtained with 350, 500, and 750 nm hexagonally packed nanosphere masks exhibit the hallmark light–matter interactions of plasmonic metals, including strong extinction and resonance energy dependence on feature size, further securing Mg's place as an alternative plasmonic metal. [ABSTRACT FROM AUTHOR]

To realize nanoscale manufacturing based on laser direct writing technology, objective lenses with high numerical apertures immersed in water or oil are necessary. The use of liquid medium restricts its application in semiconductors. Achieving nanoscale features on silicon by laser direct writing in a low refractive index medium has been a challenge. In this work, a microsphere assisted femtosecond laser far-field induced dewetting approach is proposed. A reduction in the full-width at half-maximum of the focused light spot is realized by modulating tightly focused light through microspheres and achieving a minimum feature size of 9 nm on silicon in ambient air with energy smaller than the ablation threshold. Theoretical analysis and numerical simulation of laser processing are performed based on a two-temperature model. Furthermore, we explored the potential of femtosecond laser-induced dewetting in nanolithography and demonstrated its ability to achieve an arbitrary structure on silicon. Our work enables laser-based far-field sub-10-nm feature etching on a large-scale, providing a novel avenue for nanoscale silicon manufacturing. [ABSTRACT FROM AUTHOR]

Modulating extracellular matrix (ECM) elasticity with fibrillar collagen offers great potential for regenerative medicine, drug discovery, and disease modeling by replicating in vivo mechanical signals. This enhances the understanding of cellular responses and fosters therapeutic innovation. However, precise ECM elasticity measurements are still lacking. This study couples time-resolved Brillouin spectroscopy and pulsed laser-induced Scholte wave generation. We measure how collagen fibrillation affects sound velocity and refractive index. These insights are advancing tissue engineering and cellular biomechanics. [ABSTRACT FROM AUTHOR]

α-RuCl3, a narrow-band Mott insulator with a large work function, offers intriguing potential as a quantum material or as a charge acceptor for electrical contacts in van der Waals devices. In this work, we perform a systematic study of the optical reflection contrast of α-RuCl3 nanoflakes on oxidized silicon wafers and estimate the accuracy of this imaging technique to assess the crystal thickness. Via spectroscopic micro-ellipsometry measurements, we characterize the wavelength-dependent complex refractive index of α-RuCl3 nanoflakes of varying thickness in the visible and near-infrared. Building on these results, we simulate the optical contrast of α-RuCl3 nanoflakes with thicknesses below 100 nm on SiO2/Si substrates under different illumination conditions. We compare the simulated optical contrast with experimental values extracted from optical microscopy images and obtain good agreement. Finally, we show that optical contrast imaging allows us to retrieve the thickness of the RuCl3 nanoflakes exfoliated on an oxidized silicon substrate with a mean deviation of −0.2 nm for thicknesses below 100 nm with a standard deviation of only 1 nm. Our results demonstrate that optical contrast can be used as a non-invasive, fast, and reliable technique to estimate the α-RuCl3 thickness. [ABSTRACT FROM AUTHOR]

The recent comment on our previously published article questioned the novelty and computational efficiency of our work. Here we respond by restating the novelty and scientific value of our work as well as showing why the specific alternative methods stated in the comment are unlikely to outperform the methods we compare for metasurface applications involving high refractive index particles near high refractive index substrates. [ABSTRACT FROM AUTHOR]

This work investigates the inverse coupled radiation–conduction problem for estimating thermophysical parameters and source terms by an improved grey wolf optimization (GWO). The transient coupled radiation–conduction heat transfer problem in participating slab media is solved by the finite volume method. The radiative intensities on both boundaries are adopted as known measurement information in the inverse model. To overcome the disadvantages of the original GWO algorithm, an improved grey wolf algorithm (IGWO) is developed by introducing the weight strategy and nonlinear factors. Three benchmark functions are adopted to prove that the IGWO has a faster convergence speed and higher estimation accuracy than the original one. The IGWO is applied to inverse the thermophysical parameters and source terms based on the coupled radiation–conduction model; the results indicate that the IGWO is accurate and effective for estimating refractive index, absorption coefficient, and source terms. [ABSTRACT FROM AUTHOR]

The pseudo ab initio ability is based on density function theory (DFT), use of generalized gradient approximation (GGA). In this work we use the Siesta code for the first time in studying this specific FeNi3 and FeNi2Pt alloys and its fcc phase which enabled us to find the structural and optical properties of FeNi3 and FeNi2Pt alloys in its fcc cubic crystal structure. Obtained results showed that the structural properties of the cubic phase structure have lattice constants very close to what was previously found in theoretical and experimental studies, and all the optical properties calculated such as absorption coefficient, reflectivity, refractive index, and the imaginary part of the dielectric constant, show that the FeNi3 and FeNi2Pt alloys They are two electrical conductors, whose valence band is completely overlapped with the conduction band. Through the optical results, it was found that we can use them in the infrared and visible region applications, and this type of work was studied in this research for the first time. [ABSTRACT FROM AUTHOR]

An all optical Gray to BCD converters will be proposed and designed based on photonic crystals. The proposed structure is composed of one XOR gate and a buffer. The final structure consists of 6 optical waveguides and two nonlinear ring resonators. The nonlinear defects are made of doped glass with the Kerr coefficient of 10−14 m2/W. The rest of the structure was made of Si rods with the refractive index of 3.46. The maximum rise time for the proposed structure is 1 ps. [ABSTRACT FROM AUTHOR]

In this study, we determined the refractive index of the air at different pressures and temperatures using a home-built Mach–Zehnder interferometer. The pressure and temperature were controlled using a home-built gas flow system and a temperature controller. A He–Ne laser operating at wavelengths of 632.8 nm was used to illuminate the Mach–Zehnder interferometer to obtain interference fringes. The changes in the number of fringes that crosses the field of view were exploited to calculate the variation in the refractive index with temperature and pressure. Some refractive index-dependent physical constants such as the thermo-optical constant (refractive index temperature coefficient dn/dT), dielectric constant, molar refractivity, and molecular polarizability were calculated for the air at different temperatures and pressure. In the pressure (66–80 cmHg) and temperature (303–338 K) range, the refractive index, dielectric constant, molar refractivity, and molecular polarizability of the air were found to vary between 1.000189 ± 0.000006–1.000281 ± 0.000007, 1.000379 ± 0.000010–1.000562 ± 0.000014, 4.03396 ± 0.13693–4.42908 ± 0.10860 cm3/mol, and 2.01 ± 0.07 × 10–29–2.21 ± 0.05 × 10–29 m3, respectively. [ABSTRACT FROM AUTHOR]

The surge in the incidence of skin cancer caused by UV exposure in Yemen served as the impetus for the current study. Fixed volumes and concentrations of both propolis aqueous extract and zinc salt solution were reacted to form zinc oxide (ZnO) nanoparticles at various temperatures (25, 35, 50, 65, 75, and 90 °C) and at a constant pH. The characteristics of the nanostructure and the degree of deformation that took place inside the nanoparticles were determined (for example, microstrain, stacking fault, surface stress, porosity, etc.). The optical parameters that affect the estimation of the blocking ultraviolet radiation parameters, such as the absorption coefficient, extinction coefficient, skin depth, refractive index, energy gap, Urbach energy, and optical conductivity, were calculated. The best results obtained in blocking ultraviolet radiation (A and B) were 81% and 75% for the sample that was prepared at 75 °C, respectively. Based on scientific methodology, empirical data, and exact equations, the results were interpreted within the nanoscale structure. [ABSTRACT FROM AUTHOR]

In this paper, we propose an absorber with adjustable single-layer graphene multi-band perfect absorption, which has the advantages of simple structure, polarization insensitivity, tunability, multi-band absorption, and high sensitivity. The device can achieve four perfect absorption peaks at the same time, and the absorption rate of all absorption peaks is above 99%. The absorption effect of the absorber can be efficiently adjusted and controlled by adjusting the geometric parameters of the single-layer graphene array and the thickness of the dielectric layer. In addition, by changing the strength of the applied magnetic field, the Fermi level, and the relaxation rate of graphene, the absorption of the device can be dynamically adjusted, and high absorption can be maintained in the range of 0°–70° wide incidence angle. Finally, considering the potential sensing applications of the device, we measured maximum sensitivity (S) of 3.06 THz/RIU and a maximum figure of merit (FOM) of 54.6 when exposed to different ambient refractive indices, suggesting that the device can be used as a refractive index sensor. These results show that this study provides a new idea for the design of the tunable multi-band perfect metamaterial absorber based on graphene, which has great application value in many fields and provides a new reference for future research. [ABSTRACT FROM AUTHOR]

Background and Objectives: To compare the biometry of eyes obtained with two swept-source optical coherence tomography-based biometers—Argos (A), using an individual refractive index, and IOLMaster 700 (IM), using an equivalent refractive index—for all structures. Materials and Methods: The biometry of 105 eyes of 105 patients before cataracts were analyzed in this study. Parameters such as axial length (AL), anterior chamber depth (ACD), and lens thickness (LT) were compared from both devices. According to the axial length measurements, patients were divided into three groups, as follows: group 1—short eyes (AL < 22.5 mm), group 2—average eyes (22.5 ≤ AL ≤ 26.0 mm), and group 3—long eyes (AL > 26.0 mm). Results: The correlation coefficiency among all compared parameters varies from R = 0.92 to R = 1.00, indicating excellent reliability of IM and A. A statistical significance in axial length was indicated in the group of short eyes (n = 26)—mean AL (A) 21.90 mm (±0.59 mm) vs. AL (IM) 21.8 mm ± (0.61 mm) (p < 0.001)—and in the group of long eyes (n = 5)—mean AL (A) 27.95 mm (±2.62 mm) vs. mean AL (IM) 28.10 mm (±2.64) (p < 0.05). In the group of average eyes (n = 74), outcomes were similar—mean AL (A) 23.56 mm (±0.70 mm) vs. mean AL (IM) 23,56 mm (±0.71 mm) (p > 0.05). The anterior chamber depth measurements were higher when obtained with Argos than with IOLMaster 700—mean ACD (A) 3.06 mm (±0.48 mm) vs. mean ACD (IM) 2.92 mm (±0.46) p < 0.001. There was no statistical significance in mean LT—mean LT (A) 4.75 mm (±0.46 mm) vs. mean LT (IM) 4.72 mm (±0.44 mm) (p = 0.054). The biometry of one eye with dense cataracts could be measured only with Argos, using the Enhanced Retinal Visualization mode. Conclusions: Axial length measurements from both devices were different in the groups of short and long eyes, but were comparable in the group of average eyes. The anterior chamber depth values obtained with Argos were higher than the measurements acquired with IOLMaster 700. These differences may be particularly important when selecting IOLs for patients with extreme AL values. [ABSTRACT FROM AUTHOR]

Abstract Fiber optic localized surface plasmon resonance (LSPR) sensors have become an effective tool in refractive index (RI) detection for biomedical applications because of their high sensitivity. However, using conventional optical fiber has caused limitations in implanting the sensor in the body. This research presents the design and construction of a new type of polymer-based LSPR sensors to address this issue. Also, finite element method (FEM) is used to design the sensor and test it theoretically. The proposed polymer optical fiber (POF) based on citrate is biocompatible, flexible, and degradable, with a rate of 22% and 27 over 12 days. The step RI structure utilizes two polymers for light transmission: poly (octamethylene maleate citrate) (POMC) as the core and poly (octamethylene citrate) (POC) as the cladding. The POF core and cladding diameters and lengths are 700 µm, 1400 µm, and 7 cm, respectively. The coupling efficiency of light to the POF was enhanced using a microsphere fiber optic tip. The obtained results show that the light coupling efficiency increased to 77.8%. Plasma surface treatment was used to immobilize gold nanoparticles (AuNPs) on the tip of the POF, as a LSPR-POF sensor. Adsorption kinetics was measured based on the pseudo-first-order model to determine the efficiency of immobilizing AuNPs, in which the adsorption rate constant (k) was obtained be 8.6 × 10–3 min−1. The RI sensitivity of the sensor in the range from 1.3332 to 1.3604 RIU was obtained as 7778%/RIU, and the sensitivity was enhanced ~ 5 times to the previous RI POF sensors. These results are in good agreement with theory and computer simulation. It promises a highly sensitive and label-free detection biosensor for point-of-care applications such as neurosciences.

Abstract Surface plasmon resonance (SPR) sensors are based on photon-excited surface charge density oscillations confined at metal-dielectric interfaces, which makes them highly sensitive to biological or chemical molecular bindings to functional metallic surfaces. Metal nanostructures further concentrate surface plasmons into a smaller area than the diffraction limit, thus strengthening photon-sample interactions. However, plasmonic sensors based on intensity detection provide limited resolution with long acquisition time owing to their high vulnerability to environmental and instrumental noises. Here, we demonstrate fast and precise detection of noble gas dynamics at single molecular resolution via frequency-comb-referenced plasmonic phase spectroscopy. The photon-sample interaction was enhanced by a factor of 3,852 than the physical sample thickness owing to plasmon resonance and thermophoresis-assisted optical confinement effects. By utilizing a sharp plasmonic phase slope and a high heterodyne information carrier, a small atomic-density modulation was clearly resolved at 5 Hz with a resolution of 0.06 Ar atoms per nano-hole (in 10–11 RIU) in Allan deviation at 0.2 s; a faster motion up to 200 Hz was clearly resolved. This fast and precise sensing technique can enable the in-depth analysis of fast fluid dynamics with the utmost resolution for a better understanding of biomedical, chemical, and physical events and interactions.