Refractive Loss Research Articles

Investigation of structural, electronic, mechanical, optical and hydrogen storage properties of cobalt-based hydride-perovskites XCoH3 (X = In, Mn, Sr, Sn, Cd) for hydrogen storage application

In the current study, the physical and hydrogen storage properties of XCoH3 (X = In, Mn, Sr, Sn, Cd) are studied by using first principles calculations. The bandgap and lattice parameters of the studied materials match well with the previous studies involving cobalt-based hydride perovskites. All the compounds are found stable and possess metallic behavior with zero band gap. All the materials are found ductile except MnCoH3 and SrCoH3 which have brittle nature. The Bulk, Shear, and Youngs modulus suggest that CdCoH3 is harder than the other materials. The anisotropic factor suggests that all the materials possess anisotropic nature. The absorption coefficient shows that SrCoH3 is briskly in absorbing the incident photons. The reflectivity shows that SnCoH3 is an effective material for bouncing back the incident radiations. The other optical parameters such as refractive index, extinction coefficient, dielectric function, conductivity and loss function are also investigated in detail. The gravimetric hydrogen storage is found 1.71%, 2.59%, 2.03%, 1.68%, and 1.74 wt% for InCoH3, MnCoH3, SrCoH3, SnCoH3 and CdCoH3, respectively. Due to the higher gravimetric ratio, MnCoH3 is suggested as the most favorable material for storing hydrogen.

A first principle investigations for electronic, optical and mechanical response of novel Ba2AgIO6 perovskite

The double perovskite compound, Ba2AgIO6 has been studied through density functional theory to explore its mechanical, electronic, and optical properties. To examine the mechanical stability of the compound, elastic constants, Young’s modulus, bulk modulus and shear modulus have been computed. The computed electronic properties show the direct band gap semiconducting nature of the studied perovskite compound. The optical properties of Ba2AgIO6 are interpreted with the help of energy dependent dielectric tensor, absorption, reflection, refraction, and energy loss spectra. From the present study it is found that Ba2AgIO6 is suitable for the various photovoltaic and optoelectronic applications.

Harnessing Evanescent Waves in UV-Irradiated TiO2-Coated Quartz Optical Fibers Improves Pollutant Degradation in Water

Coupling TiO2-coated quartz optical fibers (TiO2-QOFs) with LEDs shows potential in degrading organics in water. Conventional TiO2-QOFs with thick and compact coatings are inefficient to degrade organic pollutants due to refraction losses. The research focuses on manipulating coating strategies to increase the generation of evanescent waves, which react more efficiently with the coated TiO2, which shows a crystal structure at anatase/rutile of 85/15. Through the use of dip-coating methods, TiO2 can be effectively deposited on quartz optical fibers, leveraging the principle of electrostatic attraction. By decreasing TiO2 dip-coating concentrations from 200 to 10 mg/L, dip-coating duration from 2 to 0.5 h, and coating cycles from 3 to 1, TiO2 patchiness on quartz fibers was reduced by 50–60%, enhancing the formation of more interspaces between the fiber surfaces and the coatings, which in turn allowed over 90% of evanescent waves in the TiO2-QOFs. The evanescent wave-dominated TiO2-QOFs irradiated by 275 nm UV-LED exhibited methylene blue degradation rate constants at around 0.03 h−1 and quantum yields greater than unity, indicating a highly efficient interaction between the evanescent wave and the surface coatings. These findings offer significant insights into optimizing the utilization of evanescent waves in TiO2-QOFs for pollutant degradation by regulating the coating structures.

Study of optoelectronic, thermoelectric, mechanical, and thermodynamic properties of Cs2NaTlX6 (X = Cl, Br, I) for energy harvesting

The inorganic double perovskites are remarkable materials for renewable energy which can be realized through solar cells and thermoelectric generators. Here, we have comprehensively elaborated the stability, mechanical, thermodynamic, optical and transport characteristics. The formation energy is computed to ensure thermodynamic validity and the tolerance factor is assessed for structural existence. The elastic constants satisfied the Born criteria and mechanical stability. Naviera's velocities have been used to study the Debye temperature and directional lattice conductivity. Modifying the band gap from 3.1 to 0.58 eV by halide ions (Cl to I) probes the distinct optoelectronic characteristics. Absorption bands, dispersion of light energy, refraction, and optical loss explain the optical characteristics. In addition, the above thermoelectric factors like conductivities, Seebeck effect, and performance are studied in the temperature range of 100–600 K. Large figure of merit and extremely low lattice vibration at room temperature indicate their significance for thermoelectric devices.

Optical and optoelectronic properties of (Ge2S8)100-xTex thin films for IR optical device fabrication

A detailed study of the optical and optoelectronic properties of (Ge2S8)100-xTex thin films for optical device fabrication is described in the present paper. Thin films of melt-quenched chalcogenide samples were deposited, on ultrasonically cleaned glass substrates, employing thermal evaporation technique. Transmission spectra were used to calculate the refractive index (n) and extinction coefficients (k). The refractive index increases from 2.187 to 2.329 by adding Te = 0 to 12. Dispersion parameters are evaluated using the WDD single oscillator model. The dielectric parameters real (εr) and imaginary (εi), electric modulus (M) and dielectric loss (tan δ) are used to evaluate the relaxation process in different compositions of (Ge2S8)100-xTex thin films. To further grasp the importance of amorphous chalcogenide compositions, we compute their optical conductivity (σ*op), electronic polarizability (αp), plasma frequency (ωp), metallization parameter (M), and refraction losses (RL) in optical devices. The dependency of Te content on the nonlinear refractive index (n2) and third-order susceptibility (χ(3)) is also calculated by an empirical formula, and it is found that the value of n2 increases from 11.938 × 10−12 to 20.615 × 10−12 esu, and the value of χ(3) rises from 6.8 × 10−13 to 12.472×10−13 esu with the addition of denser and higher atomic radius elements Te in the Ge-S system. The overall composition of Ge17.6S70.4Te12 is suitable as all-optical parameters show the maximum values that can be used for optical device purposes.

Detection of Virus SARS-CoV-2 Using a Surface Plasmon Resonance Device Based on BiFeO3-Graphene Layers.

Coronavirus disease (COVID-19) pandemic outbreak is being investigated by severe respirational syndrome coronavirus-2 (SARS-CoV-2) as a global health issue. It is crucial to propose sensitive and rapid coronavirus detectors. Herein, we propose a biosensor based on surface plasmon resonance (SPRE) for the detection of SARS-CoV-2 virus. To achieve improved sensitivity, a BiFeO3 layer is inserted between a metal (Ag) thin film and a graphene layer in the proposed SPRE device so that it has the structure BK7 prism/ Ag/ BiFeO3/ graphene/ analyte. It has been demonstrated that a small variation in the refractive index of the analyte can cause a considerable shift in the resonance angle caused by the remarkable dielectric properties of the BiFeO3 layer, which include a high index of refraction and low loss. The proposed device has shown an extremely high sensitivity of 293 deg/RIU by optimizing the thicknesses of Ag, BiFeO3, and the number of graphene sheets. The proposed SPRE-based sensor is encouraging for use in various sectors of biosensing because of its high sensitivity.

Tissue-Like 3D Standard and Protocols for Microscope Quality Management.

This article outlines a global study conducted by the Association of Biomedical Resource Facilities (ABRF) Light Microscopy Research Group (LMRG). The results present a novel 3D tissue-like biologically relevant standard sample that is affordable and straightforward to prepare. Detailed sample preparation, instrument-specific image acquisition protocols and image analysis methods are presented and made available to the community. The standard consists of sub-resolution and large well characterized relative intensity fluorescence microspheres embedded in a 120 µm thick 3D gel with a refractive index of 1.365. The standard allows the evaluation of several properties as a function of depth. These include the following: 1) microscope resolution with automated analysis of the point-spread function (PSF), 2) automated signal-to-noise ratio analysis, 3) calibration and correction of fluorescence intensity loss, and 4) quantitative relative intensity. Results demonstrate expected refractive index mismatch dependent losses in intensity and resolution with depth, but the relative intensities of different objects at similar depths are maintained. This is a robust standard showing reproducible results across laboratories, microscope manufacturers and objective lens types (e.g., magnification, immersion medium). Thus, these tools will be valuable for the global community to benchmark fluorescence microscopes and will contribute to improved scientific rigor and reproducibility.

Structural, optical and radiation shielding parameters of sodium aluminium borate glasses modified with chromium oxide

Samples of nominal composition xCr2O3. (60-x)B2O3.5Al2O3.35Na2O: x = 0 (Cr0), 0.1 (Cr0.1), 0.2 (Cr0.2), 0.4 (Cr0.4), 0.6 (Cr0.6), 0.8 (Cr0.8), and 1 (Cr1) mol% were prepared via the traditional melt quenching route. Structural FTIR absorption spectra of the prepared glasses reveal distinct absorption bands which are characteristic of both triangular BO3 and tetrahedral BO4 groups within their varying wavenumber vibrational sites. The dopant chromium ions are observed to have no distinct variations on the FTIR spectra because of low dopant percent. Optical absorption characterization indicates that the undoped glass shows only UV absorption which is related to originating from unavoidable trace ferric ions present as impurities in the used chemicals. The Cr2O3-doped glasses reveal additional UV absorption at about 370-385 nm correlated with the hexavalent state of chromium, producing this distinct charge transfer band. Additionally, two visible bands are identified at about 420-400 nm and 580-640 nm originating from trivalent chromium ions with distorted octahedral coordination. Optical parameters including band gap, refractive index, molar refraction, and reflection losses were calculated together with optical dielectric properties, electronic and molar polarizability. In terms of radiation shielding capacity, increasing Cr2O3 mol% of the sample encoded Cr1 that possessed the highest mass (μm) and linear (μ) attenuation coefficients, but the lowest half value layer (HVL) at low and high incident photon energy, results showed that Cr1 can be used in optical and radiation shielding safety.

Cubic to pseudo-cubic tetragonal phase transformation with Mg, Ca, and Be doping and its impact on optoelectronic, elastic and mechanical properties of SrHfO3

The structural, optoelectronic, elastic and mechanical properties of pure, Ca-, Mg-, and Be-doped SrHfO3 have been computed with CASTEP code based on density functional theory. The structure of SrHfO3 remains cubic with 1.40% doping concentration of Ca, Mg and Be whereas it is altered in pseudo-cubic tetragonal at the doping concentration of 4.22% and 7.04%. Reduction in the electronic band gap is observed in all the doping concentrations. For detailed explanation of electronic band gap reduction density of states (DOS), partial DOS and elemental partial DOS have also been computed. DOS plays a very meaningful role in understanding the behavior of band gap at different doping. The impact of dopants on the optical properties of pure SrHfO3 indicates the increment in refractive index (n), absorption (I), Loss function (L) and extinction coefficient (k) as well. For both cubic and tetragonal structures our compound shows mechanical stability in all doping percentages of Ca, Mg and Be other than the 1.40% of Mg and Be for cubic geometry. Over and above that to examine the mechanical properties of material like ductility and brittleness we have also computed the different characteristics such as Bulk modulus (B), Shear modulus (G), G/B ratio, Cauchy Pressure (CP) and Anisotropic factor (A). Interestingly, the material is purely ductile on all concentrations of Ca, Mg, and Be and shows brittleness only at the doping concentration of 1.40% of Ca.

The effect of substituting Cobalt into graphene-like InAs on its optical properties: A DFT study

ObjectiveInvestigating the effect of substituting Cobalt (Co) on the optical properties of graphene-like InAs has been carried out. MethodsCalculations were performed by the full potential linear augmented plane wave (FP-LAPW) approach in the density functional theory framework with the computational Wien2k. ResultThe results were compared with the optical properties of graphene-like InAs including the imaginary and real part of the dielectric function, the refractive index, optical conductivity, absorption coefficients, loss function, and extinction coefficients. Also, the energy gap, the static refractive index, and the plasmonic frequency were by using the roots of dielectric function and maximum electron loss function. Finally, it was revealed that adding impurity decreased the energy gap and increased refractive index.

Vacancy defects transform zinc tellurite glass from insulator to semiconductor: A first-principles prediction

The effect of vacancy defects on the zinc tellurite glass (ZnTeO3) was investigated by performing density functional theory using GGA-PBESOL functional and norm-conserving pseudopotential. The effect of the inclusion of Hubbard-U correction for only Ud, Zn state or Up, O state or both states was investigated to obtain the experimental band gap. The lattice parameters, band structure, and density of states of ZnTeO3 were predicted. The value of Up, O has a significant impact on the band gap (Egap) value of ZnTeO3. Our calculated Egap exactly agrees with the experimental value (4.1 eV). The Egap values of the vacancies were significantly decreased as compared to the perfect structure. The Egap values of the Zn-vacancy and Te-vacancy were 2.5 eV and 2.0 eV, respectively. Three kinds of O vacancies were studied and their Egap values ranged from 2.2 eV to 2.5 eV. The vacancy defects changed the insulating character of ZnTeO3 to semiconductor behavior, which may have promising applications. The vacancies stability follows the order of perfect crystal > O-vacancy > Zn-vacancy > Te-vacancy, i.e., based on their cohesive energies. The formation energies were calculated and indicated that the spontaneous formation of the vacancies is impossible; however, the formation of the O-vacancy was determined to be the most probable, followed by Zn-vacancy and then Te-vacancy under specific conditions. The optical properties (refractive index, reflectivity, dielectric function, optical conductivity, and loss function) and thermodynamic properties of zinc ZnTeO3 and its vacancy defects were predicted.

Optical Properties and Gamma Radiation Shielding Capability of Transparent Barium Borosilicate Glass Composite

In this study, both radiation shielding capability and optical properties of prepared SiO2-ZnO-Na2CO3-H3BO3-BaCO3 glass composite with different concentrations of barium carbonate (0–30 mol%) have been studied. Gamma attenuation properties, such as the mass attenuation coefficient (MAC), mean free path (MFP), and exposure build-up factor (EBF), are experimentally and theoretically investigated. The detected XRD patterns for the prepared glass composites confirm their amorphous nature. It is evident from the obtained data that all tested parameters, such as mass density, molar volume, refractive index, dielectric constant, refraction loss (%), and molar refraction, have been increased as BaCO3 mol% increased. At the same time, the results of the optical bandgap show a gradual decrease with increasing barium concentration. It was also found that the mass attenuation coefficients increased with BaCO3 concentration from 0.078 at zero mol% BaCO3 to 0.083 cm2/g at 30 mol%. Moreover, the half-value layer (HVL) and the exposure build-up factor (EBF) up to 40 mfp penetration depth were investigated in addition to the effective atomic number (Zeff) and the corresponding equivalent atomic number (Zeq) at the energy range of 0.015–15 MeV. The produced glass composite might be considered for many shielding applications based on the obtained results that require a transparent shielding material.

Numerical modeling of an integrated non-volatile reflector switch and mode converter switch based on a low loss phase change material (Sb2Se3) in SiN platforms

Programmable integrated photonics is an emerging research field due to its range of applications, from data processing to computing. Phase change materials (PCMs) on waveguides provide enormous flexibility for programmable integrated photonics. These materials show a large contrast in the optical properties (such as refractive index and optical loss) between the two stable states (i.e., amorphous to crystalline) of the PCM. These states are reversible and reproducible with an external stimuli which could be optical, thermal or electrical. Their non-volatile behavior allows PCMs to serve as an active layer for programmable photonics. In this work, we investigate hybrid device architectures utilizing the non-volatile properties of PCMs for integrated programmable photonics in a Si3N4 platform. FDTD modeling was carried out to design two configurations of non-volatile reconfigurable switches: (1) A non-volatile reconfigurable reflector switch consisting of a photonic crystal (PhC) slab waveguide and having a thin layer of Sb2Se3 on top of the waveguide and (2) 1×2 mode converter switch. In the case of a non-volatile reconfigurable reflector switch, the reflectivity of the waveguides is controlled by shifting the mode-gap of the photonic crystal slab waveguide by changing the phase of the PCM. It has applications as a reconfigurable reflective filter in the optical communication system and on-chip smart Bragg mirror. Non-volatile broadband directional switches provide a new paradigm for designing programmable multifunctional nanophotonics, which works in the same way as electronic field-programmable gate arrays. A 1×2 mode converter switch — based on Sb2Se3 as a clad layer on a coupling waveguide of a directional coupler — is proposed. The optical switches proposed in this paper offer very low optical insertion loss (∼ 0.5 dB), low coupling length (∼ 12 µm), broadband operation (∼ 80 nm), small cross talk (∼ 16 dB), and zero static power consumption.

Express method for measuring the refractive index of transparent fibres

An express method for measuring the refractive index, which is one of the main optical parameters of transparent fibres, is suggested. The method uses focusing properties of a cylindrical lens, which such a fibre is. The possibility to accurately measure such characteristics of optical fibres as the shell and core diameters, numerical aperture, refractive index profile, loss, and dispersion is equally important for fibre manufacturers and designers of optical communication systems who should choose the fibre that meets their requirements best. Almost all measurement methods use the refraction of light rays at the interface between the media. To do this, one should make samples of given shape and size, which are individual for each measuring instrument. The suggested method takes into account the fact that when light strikes upon a refractive cylinder (glass rod, fibreglass), the focusing occurs perpendicular to its axis with a focal region where light rays converge. Behind this region, the rays diverge again. The position of the focal region is determined by the refractive index of the cylinder. It can be inside the cylinder, outside it, or on the surface of the cylinder. During the observation of the fibre using a microscope, one can see that the light, which has passed through the fibre, forms a bright band on its backside against a dark background. The bandwidth depends on the refractive index of the fibre. The calculations using the methods of geometric optics were carried out. These methods may be applied over a wide range of fibre diameters. Using strict formulas of diffraction theory, the distribution of radiation energy in the fibre and its vicinity was calculated. A digital analysis of the resulting pattern was carried out. The results of the analysis coincided with the results obtained using the methods of geometric optics. An algorithm for determining the refractive index was worked out. The measurements of the refractive indices of artificial and natural fibres like fibreglass, webs and human hair (blonde-haired person, brown-haired person, grey hair) were provided.

Refraction, diffraction and energy losses studies using Arduino and Raspberry Pi

The major purpose of this paper is to present laboratory measurements for a physics foundation course that meet the needs of the physics department. Furthermore, for obvious reasons, measures should be low-cost. Arduino and Raspberry Pi are low cost and open-source platforms that include both hardware and software that can be beneficial in a physics laboratory. Because of its inexpensive cost, wide range of sensors and transducers, ease of use, and open nature, they are the optimal tool for engaging students in active and cooperative learning. Measurements based on mentioned platforms related to refraction and diffraction processes, as well as to hysteresis losses measurement, are presented.

First-principles investigation of structural, electronic, optical, and mechanical properties of Na-based fluoro-perovskites NaXF3: (X = Ni, Co, Be, Ba)

Several structural, electrical, optical and mechanical properties for the cubic sodium-based fluoro-perovskite NaXF3 (X = Ni, Co, Be, Ba) were investigated employing density functional theory (DFT) within generalized gradient approximation (GGA) and local density approximation (LDA). According to the computations like an electronic group formation, electrical charge density includes electronic states, NaNiF3 and NaBeF3 give the indirect energy bandgap while NaCoF3 shows metallic behavior, and however, NaBaF3 gives the direct bandgap. NaNiF3 and NaBaF3 are semiconductors, NaCoF3 is a conductor while NaBeF3 has insulating behavior. Optical constants like refractive index, absorption coefficient, reflectivity and loss function were determined by employing both real and imagined portions in dielectric work. An imaginary component from its dielectric function was used to determine various transitions between bands. These compounds NaXF3 have a mixture of ionic and covalent bonding characteristics. The greater bulk modulus from elastic characteristics and B/G ratio, suggest that such compounds were highly strong but ductile. In the future, such findings will present theoretical guidance for experimental studies and industrial applications of NaXF3 (X = Ni, Co, Be, Ba) compounds.

U-Bent Plastic Optical Fiber Sensor for Iron in Iron Supplements

In this paper, we have designed a U-bent fiber optic sensor based on evanescent wave absorption for iron detection and quantification in the iron tablet. A detailed investigation of the impact of the bend-induced material deformation on the refractive index losses, numerical aperture, light propagation inside core and absorption coefficient has been presented. The experiment results of the developed sensor demonstrate the sensor sensitivity as 0.0316 O. D/ppm with a linear regression coefficient (R <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> ) of 98.1%.

Study of lead-free vacancy ordered double perovskites Cs2TeX6 (X = Cl, Br, I) for solar cells, and renewable energy

Herein, the electronic, optical, mechanical, and transport properties of a double perovskites Cs2TeX6 (X = Cl, Br, I) are explored with the focus on solar cell and thermoelectric applications by the density functional theory (DFT). The feasibility of structural, thermodynamic, and elastic stabilities is arbitrated by a tolerance factor, formation energy, and elastic constant, respectively. Further, the Poisson and Pugh’s ratio display the ductile behavior of studied compounds. From the electronic properties analysis, it is revealed that the bandgap decreases by changing Cl with Br, and I from 2.67 eV to 2.52 eV and 1.73 eV, respectively which in results tune the optical properties from visible to infrared region. The shifting of maximum absorption from visible to infrared region makes them promising materials for solar cell and remote sensing devices. Moreover, various optical parameters including refractive index, reflectivity, and optical loss were also reported. Additionally, the transport characteristics were analyzed by electrical, thermal conductivities, and figure of merit (ZT) versus temperature and chemical potential effect. The ZT increases from Cl to I substitution. At the end, the thermodynamic behavior studied by specific heat capacity, Debye temperature and Hall coefficient was presented. All these characteristics have demonstrated that our studied materials are excellent choice for probing solar cell and renewable energy applications.

Bessel-Beam Interferometry for Turbidity With Refractive Index, Attenuation Coefficient, and Loss

This letter demonstrates a quasi-Bessel beam optical interferometry and fast Fourier transform (FFT) to estimate turbidity of liquid samples in terms of the refractive index (RI), optical attenuation coefficient, and loss. The device comprises a broadband superluminescent diode (SLD) source and a packaged deep-seated optical fiber negative axicon (DSNA) probe connected to the SLD source guiding light to the liquid sample trapped in between DSNA probe head and a glass slide. It generates a low-coherence interference spectrum as recorded in a spectrometer via an optical circulator. The FFT of the said spectrum gives power spectrum corresponding to the respective interfaces of the trapped sample. The power spectrum is used wisely to estimate turbidity in terms of RI, optical attenuation, and optical loss. The design is able to measure as low as 5 NTU (nephelometric turbidity units). This sensing platform may be useful in environmental protection, pharma, and processing industries.

Step-etched U-bent silica fiber optic probes – Design and optimum geometry for refractive index sensing

This study presents a ray-optics based model for the multimode U-bent silica fiber optic refractive index (RI) sensor probes, followed by a detailed experimental investigation to identify the optimum fiber core (d) and bend diameter (D), and the optimal bend ratio (D/d). U-bent probes with different geometries (d = 200, 400 and 600 µm; D = 1.0, 1.5, 2.0, and 2.5 mm) were fabricated and evaluated for their RI sensitivity in terms of refractive losses. Among the bend ratios between 1.7 and 12.5, the U-bent probes with a bend ratio between 3 and 5 exhibit a higher RI sensitivity for a given core diameter. Among the twelve different geometries tested, U-bent probes with 600 µm core and ~2.5 mm bend diameter demonstrate the highest RI sensitivity of ~6 ∆A/RIU, measured as a change in absorbance (∆A) per refractive index unit (RIU). Further investigations to improve light-medium interactions by wet chemical step-etching of the silica fiber core show a gradual improvement in the RI sensitivity until a etched waist diameter of 200 µm, followed by an abrupt drop. At least a two-fold improvement in the RI sensitivity was observed. A compact LED-photodetector based dip-type handheld refractometer was realized as a proof-of-the-concept to demonstrate the feasibility of using these etched probes in reusable or disposable form for RI based analytical applications.