Refractive Index Dispersion Research Articles

Bright solitons of the model with arbitrary refractive index and unrestricted dispersion

Objective:The generalized Schrödinger equation with arbitrary refractive index and unrestricted order is considered. The objective of this paper is to demonstrate the bright solitons of this mathematical model can be found by the same formula taking into account the order of nonlinear differential equation. Method:The algorithm of constructing optical solitons of the generalized nonlinear Schrödinger equation with unrestricted dispersion using the simplest equation method is presented and applied for finding of optical solitons. Results:The optical solitons of the generalized nonlinear Schrödinger equation of the twelfth order are found at three powers on nonlinearity. The application of the method for finding solution of the generalized Korteweg–de Vries equation with arbitrary power of nonlinearity and unrestricted dispersion is discussed.

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.

Effect of vacuum annealing on the optical properties of tungsten oxide films

• Annealing of WO 3– x films in vacuum initiates their coloration in blue. • Colored film absorption band is adequately described by the Breit-Wigner distribution. • Annealing temperature rise nonlinearly increases the absorption band intensity. • Decrease in the spectral line width is saturated when annealing temperature increases. • Asymptote of refractive index dispersion decreases in proportion to the temperature. In this work, the thermochromic properties of tungsten oxide films are studied. The goal of this work is to study the influence of vacuum annealing on optical properties of amorphous WO 3– x films deposited on silica glass substrates. These dependences of the absorption index were approximated using the Breit-Wigner distribution. An increase in the annealing temperature led to an increase in the intensity and a decrease in the width of the absorption band in the near infrared range of the film transmission spectrum. This changed the dispersion of absorption and refractive indices.

Optical performance of Tin doped Indium Oxide (ITO) thin films prepared by sol gel dip coating techniques using acrylamide route

At present various oxide of metal semiconductors play a significant role in the field of electronics. Most of the semiconductor devices exploit the special characteristics of the junction between a p-type and n-type semiconductor. These devices can be made extremely small in size and they are incredibly fast in their response. Generally metal have good reflectivity in the electromagnetic region of infrared and visible radiation. Indium oxide material doped with tin (ITO) is recently used in the substrate material for various applications, because it has special properties of low resistivity and high optical transmittance in the visible region. In this paper, we prepare ITO films with different tin concentration (5%, 10%, 15%, 20%, 30%, 40%, 50%, 60% and 70%) using acrylamide sol gel dip coated method and its results were reported. TCO materials have good electrical conductivity and optical transparency, and also it has n-type semiconductor with a band gap between 3.5 and 4.3 eV. An X-ray study indicates all the prepared samples had bixbyte structure. Optical behaviour of materials can be understood in the near infrared and visible spectrum. Some optical parameters of refractive index, extinction coefficient and dielectric constant of ITO films are calculated from the data received from the UV transmission studies. Using W-D model the dispersion of refractive index was calculated. The optical band gap, oscillator energy, dispersion energy and optical conductivity and N/m* ratio were estimated and this material is well suitable for dye sensitized solar cell and sensor application.

Correlation of optical parameters of pure and doped Ge17Sb8Se75-xErx chalcogenides films using transmission spectra

Six compositions of erbium (Er) doped Ge17Sb8Se75-xErx(x = 0, 0.2, 0.4, 0.6, 0.8, and 1.0) chalcogenide bulk have been synthesized by melt quenching technique. Further, systematic studies of chemical composition based optical parameters via Inverse synthesis methods have been carried out. Thin films of these chalcogenides have been deposited using thermal evaporation technique (∼10−4 Pa) on the microscopic glass substrate which are found to be amorphous. Transmission spectroscopy carried out in the range 400–2000 nm has been used as the signature of these compositions to calculate various optical parameters. Further, inverse synthesis method is used to estimate the refractive index (n), extinction coefficient (k), and thickness (d) of thin film. In the strong absorption region, absorption coefficient is calculated with the help of method suggested by Connel and Lewis. The systematic compositional dependency on Er doped has been established with refractive index and band gap of chalcogenide glasses. The refractive index dispersion is also discussed in terms of the single oscillator using the Wemple-Di Domenico model. The chemical composition dependent parameters such as dispersion energy, oscillator energy have been calculated to understand the order parameter.

Measurement of the absolute radius, refractive index, and dispersion of a long cylinder

Long cylinders, such as optical fibers, are some of the most widely used photonic devices. The radius and refractive index of these fibers are therefore fundamentally important parameters in determining their performance. We have developed a method to determine the absolute radius, refractive index, and chromatic dispersion of a long cylinder using only the resonance wavelengths of the whispering gallery modes around its circumference for two different polarizations. Since this method only requires the measurement of resonance wavelengths, it is non-destructive and it can be performed using standard equipment. As a proof-of-concept, we demonstrate the method on a 125µm optical fiber and an 80µm borosilicate capillary fiber with thick walls, obtaining values for the diameter and the refractive index with an accuracy of 2 nm and 2 × 10-5, respectively.

Temperature-dependent luminescence of intrinsic defects and excitons in nanocrystalline monoclinic Y2O3 films

This work presents a comprehensive study of the optical properties of Y2O3 film with a monoclinic structure obtained by magnetron sputtering on a silica glass substrate. The parameters of band energy structure and emission characteristics of the film were determined by absorption, transmission, and photoluminescence spectroscopy. The dispersion of refractive index was established and the values of transparency gaps for direct and indirect interband transitions were determined. Optically active intrinsic centers were identified as vacancy (F - centers) and interstitial type (Oi - centers) defects, which are characterized by distribution of radiative states over activation energy of emission quenching. Luminescence in the UV and visible spectral ranges is interpreted as triplet-singlet radiative transitions in self-trapped and bound excitons. The values of thermally activated barriers for flare up and quenching of exciton luminescence are determined, and the configuration-coordinate diagram is proposed.

Effect of temperature change on refractive index of an egg white and yolk: a preliminary study

In this article, the refractive index of an egg white and yolk depending on temperature in range 30 - 47 °C over 1550 nm was determined. The measurement head was constructed as fiber optic Fabry-Perot interferometer with interference between polished fiber end-face and aluminum weighing dish. The measurement setup has been made of an optical spectrum analyzer, a superluminescent diode with a central wevelength of 1550 nm, 2:1 fiber coupler and heat plate. Full Text: PDF ReferencesP. Magdelaine, "Egg and egg product production and consumption in Europe and the rest of the world, Improving the Safety and Quality of Eggs and Egg Products", Egg Chemistry, Production and Consumption, 3 (2011). CrossRef H. Kuang, F. Yang, Y. Zhang, T. Wang, and G. Chen, "The Impact of Egg Nutrient Composition and Its Consumption on Cholesterol Homeostasis", Cholesterol (2018). CrossRef J. Gienger, K. Smuda, R. Müller, M. Bär, and J. Neukammer, "Refractive index of human red blood cells between 290 nm and 1100 nm determined by optical extinction measurements", Sci. Rep. 9, 1 (2019). CrossRef P. Listewnik, M. Hirsch, P. Struk, M. Weber, M. Bechelany, and M. Jędrzejewska-Szczerska, "Preparation and Characterization of Microsphere ZnO ALD Coating Dedicated for the Fiber-Optic Refractive Index Sensor", Nanomaterials 9, 2 (2019) CrossRef Y. Wu, Y. Zhang, J. Wu, and P. Yuan, "Fiber-Optic Hybrid Structured Fabry-Perot Interferometer Based On Large Lateral Offset Splicing for Simultaneous Measurement of Strain and Temperature", J. Lightwave Technol., 35, 19 (2017). CrossRef M. Islam, M. Mahmood, M Lai, K. Lim, and H. Ahmad, "Chronology of Fabry-Perot Interferometer Fiber-Optic Sensors and Their Applications: A Review", Sensors 14, 4 (2014). CrossRef K. Karpienko, M. Wróbel, and M. Jędrzejewska-Szczerska, "Determination of refractive index dispersion using fiber-optic low coherence Fabry-Perot interferometer: implementation and validation", Opt. Eng. 53, 7 (2014). CrossRef M. Kosowska, D. Majchrowicz, K. Sankaran, M. Ficek, K. Haenen, and M. Szczerska, "Doped Nanocrystalline Diamond Films as Reflective Layers for Fiber-Optic Sensors of Refractive Index of Liquids", Materials 12, 13 (2019). CrossRef G. Xiao, A. Adnet, Z. Zhang, F. Sun, and C. Grover, "Monitoring changes in the refractive index of gases by means of a fiber optic Fabry-Perot interferometer sensor", Sensors and Actuators 118, 2 (2005). CrossRef

Structural, Optical, Mechanical and Antibacterial Properties of MgO/Poly(Vinyl Acetate)/Poly(Vinyl Chloride) Nanocomposites

Polymeric blends and nanocomposites with improved functional properties have attracted attention worldwide for industrial applications. For food packaging applications and carrying purposes, the materials to be used should have UV blocking ability, antibacterial activity, and good mechanical properties. In this study, polyvinyl acetate (PVAc)/polyvinyl chloride (PVC) blends with optimized properties and MgO/PVAc/PVC polymer nanocomposites (PNCs) were prepared by solution casting and evaporation. Fourier transform infrared (FTIR) spectroscopy confirmed the complexation and miscibility between PVAc and PVC and their interaction with MgO nanoparticles (NP). X-ray diffraction and HR-TEM analyses showed the phase purity of MgO NP with a crystallite size of ~ 18.8 nm and their dispersion in the amorphous regions of the blend without affecting the structure of each other. UV–vis-NIR spectroscopy revealed that the band gap of the blend can be tuned by changing the added ratio of each polymer, and loading MgO NP increased the semiconducting behavior of the blend. Various optical constants such as the refractive index, absorption index, and optical dispersion parameters have been evaluated. The blend composition and effects of MgO content on the stress–strain behavior were studied. The addition of MgO to the blend enhanced the tensile modulus and strength. However, there was a corresponding decline in toughness and elongation at break. These results reflect the reinforcing effect of MgO NP, which reduces the flexibility of the polymer chains. The antibacterial activities of MgO/PVAc/PVC PNCs against Staphylococcus aureus, Escherichia coli, and Candida albicans fungi are studied. The improvements in optical, mechanical, and anitmicrobial properties make these nanocomposites suitable for some optical devices and in food packaging applications.

Optical properties of LMBE grown c-axis oriented GaN thin films using Surface Plasmon Resonance technique

Present work reports the growth and optimisation of thin films of Gallium nitride (GaN) with preferred c-axis (0002) orientation on Si (111) substrate using the Laser Molecular Beam Epitaxy technique. For the development of optically efficient GaN thin film, the nitrogen gas flow during film deposition has been optimised and film properties are measured using the highly sensitive Surface Plasmon Resonance (SPR) technique in OTTO configuration. Structural, morphological and optical properties of the GaN thin films were studied using XRD, AFM, PL and FTIR spectroscopy. Varying the deposition gas flow from 1.3 sccm to 4 sccm led to a decrease in refractive index values from 2.77 to 2.21. By using the SPR technique, the refractive index (n) dispersion of GaN thin films was also analysed with the incident radiated wavelength.

Radiative transfer simulations for in-situ particle size diagnostic in reactive, particle growing plasmas

When considering particles produced in reactive plasmas, their basic properties, such as refractive index and grain size often need to be known. They can be constrained both ex-situ, e.g. by microscopy, and in-situ by polarimetry, i.e. analyzing the polarization state of scattered light. Polarimetry has the advantage of temporal resolution and real-time measurement, but the analysis is often limited by the assumption of single scattering and thus optically thin dust clouds. This limits the investigation of the growth process typically to grain sizes smaller than about 200 nm. Using 3D polarized radiative transfer simulations, however, it is possible to consider multiple scattering and to analyze the properties of dense particle clouds. We study the impact of various properties of dust clouds on the scattering polarization, namely the optical depth of the cloud, the spatial density distribution of the particles, their refractive index as well as the particle size dispersion. We find that ambiguities can occur regarding optical depth and spatial density distribution as well as regarding refractive index and particle size dispersion. Determining the refractive index correctly is especially important as it has a strong impact on the derived particle sizes. With this knowledge, we are able to design an in-situ diagnostics strategy for the investigation of the particle growth process based on radiative transfer simulations which are used to model the polarization over the whole growth process. The application of this strategy allows us for the first time to analyze the polarization measured during a growth experiment in a reactive argon-acetylene plasma for particle radii up to 280 nm.

A wavelength calibration method for photoelastic-modulated Fourier transform spectrometers

PurposeAn interferogram is produced by modulating the difference between the extraordinary refractive index and the ordinary refractive index for photoelastic crystals in photoelastic-modulated Fourier transform spectrometers (PEM-FTs). Due to the influence of the refractive index dispersion characteristics on the maximum optical path difference of the interferogram, it is necessary to study wavelength calibration methods.Design/methodology/approachA wavelength calibration method for PEM-FTs was proposed based on the modulation principle of the photoelastic-modulated interferometer and the relationship between the maximum optical path difference and the refractive index difference. A 632.8 nm narrow-pulse laser was used as a reference source to measure the maximum optical path difference () of the interferogram, and the parameter was used to calculate the discrete frequency points in the frequency domain. To account for the influence of refractive index dispersion on the maximum optical path difference, the refractive index curve for the photoelastic crystal was used to adjust the discrete frequency coordinates.FindingsThe error in the reconstructed spectral frequency coordinates clearly decreased. The maximum relative error was 2.5%. A good solar absorption spectrum was obtained with a PEM-FT experimental platform and the wavelength calibration method.Originality/valueThe interferogram is produced by adjusting the difference between extraordinary refractive index and ordinary refractive index for the photoelastic crystal in the PEM-FTs. Given the wavelength dependence on the refractive indices, in view of the modulation principle of the photoelastic modulated interferometer, the relationship between the maximum optical path difference and the refractive index difference, the variation law of the refractive index of the photoelastic crystal and the process of spectral reconstruction is presented in this paper.

Dynamic Refractive Index-Matching for Adaptive Thermoresponsive Smart Windows.

Thermoresponsive smart windows (TRSWs) take great advantages in energy-efficient buildings and on-demand devices owing to their self-adaptiveness and external energy consumption-free nature. Currently used TRSWs largely rely on thermal-induced phase transitions in single-material systems, however, the intrinsic characteristics of which may not be suited for practical window utilization, such as poor luminous transparency and fixed critical temperature (Tc ). Herein, an adaptive TRSW based on dynamic refractive index (RI) matching between two phases is demonstrated, which is facilely fabricated by embedding ethylene glycol solution microdroplets into polydimethylsiloxane (PDMS) via a one-step emulsification approach, realizing a smart temperature response in PDMS. The TRSW presents high transparency (≈92%) and bidirectional transparency-temperature response (≈20% at 73°C, ≈40% at 8°C). Moreover, the RI dispersion generates a unique effect of wavelength selectivity with temperature. Notably, the effective optical-temperature response with variable Tc could be tuned over a wide range of 13-68°C by adjusting the EGS concentration. The proposed strategy with dynamic RI matching allows TRSW construction to extend beyond phase transitional materials and greatly broadens the applicable scope of TRSWs, which is promising in the fields of smart optical devices such as smart windows, anti-counterfeiting, optical switches, and optical selection.

Nonlinear optical response, theoretical efficiencies, and high photosensitivity of CH3NH3PbI3−xClx thin films for photonic applications

In this paper, we have investigated the nonlinear optical response and theoretical efficiency of CH3NH3PbI3−xClx thin films from the optical transmission and reflection measurements. The dispersion of the complex refractive index is evaluated using the Wemple–DiDomenico single oscillator model. The oscillator energy (E0) of CH3NH3PbI3−xClx follows by an empirical relationship with optical bandgap (Eg) as E0 ≈ 2.41 Eg for chemical dip coating, spray, and E0 ≈ 1.63 Eg for dipping deposited samples, respectively. The long wavelength refractive index, average oscillator wavelength, and oscillator strength are also determined using the Sellmeier oscillator equation. The estimated third-order nonlinear optical susceptibility is found to be the order of 10−12 esu. The incident photon and charge carrier interaction in CH3NH3PbI3−xClx is studied from the dielectric response of the samples. The charge carrier excitation is found higher at lower wavelength and experienced bulk excitation in volume while surface excitation on the surface region. The optical conductivity of CH3NH3PbI3−xClx is notably high, which leads to an increase in carrier transfer through the extrinsic halide perovskite material expedient for higher conversion efficiency. The highest theoretical efficiency of CH3NH3PbI3−xClx is estimated to be 17.4%, which is in excellent agreement with the experimental report. From photosensitivity study, it is confirmed that CH3NH3PbI3−xClx films are highly photosensitive. All these results comprehend that CH3NH3PbI3−xClx is a potential candidate for photonic applications.

Sub-bandgap refractive indexes and optical properties of Si-doped β-Ga2O3 semiconductor thin films

In this article, we present a theoretical study on the sub-bandgap refractive indexes and optical properties of Si-doped β-Ga2O3 thin films based on newly developed models. The measured sub-bandgap refractive indexes of β-Ga2O3 thin film are explained well with the new model, leading to the determination of an explicit analytical dispersion of refractive indexes for photon energy below an effective optical bandgap energy of 4.952 eV for the β-Ga2O3 thin film. Then, the oscillatory structures in long wavelength regions in experimental transmission spectra of Si-doped β-Ga2O3 thin films with different Si doping concentrations are quantitively interpreted utilizing the determined sub-bandgap refractive index dispersion. Meanwhile, effective optical bandgap values of Si-doped β-Ga2O3 thin films are further determined and are found to decrease with increasing the Si doping concentration as expectedly. In addition, the sub-bandgap absorption coefficients of Si-doped β-Ga2O3 thin film are calculated under the frame of the Franz–Keldysh mechanism due to the electric field effect of ionized Si impurities. The theoretical absorption coefficients agree with the available experimental data. These key parameters obtained in the present study may enrich the present understanding of the sub-bandgap refractive indexes and optical properties of impurity-doped β-Ga2O3 thin films.

S2-semipolar GaN grown by HVPE on a non-polar m-plane sapphire: Features of growth and structural, morphological, and optical properties

In our study, we have analysed the effect of a non-polar m-plane of sapphire substrate on the features of HVPE growth as well as the structural, morphological, optical properties, and Raman scattering of the grown single crystal GaN epitaxial film.We found that the chosen technological approach makes it possible to obtain samples of structurally high-quality semipolar gallium nitride with an S2 orientation (11‾22) on the m-sapphire. The S2 plane of (11‾22) GaN has a polar reversal of φ ∼ 75° relative to the non-polar (10‾10) m-plane of sapphire, as well as an azimuthal tilt. Under the selected conditions of epitaxial growth, the GaN film has the morphology of a stepped terrace formed during the growth of mesa-like crystal islands, and their coalescence determined the observed surface topography. Based on the data analysis obtained by complex structural-spectroscopic methods, the level of residual biaxial stresses and refractive index dispersion were determined, testifying to the high structural and optical quality of the epitaxial film of semipolar GaN. An analysis of Raman spectra revealed the presence of optical anisotropy depending on the polar angle when the heterostructure is rotated around the m axis of the sapphire substrate.Optimisation of the technological methodology may in future lead to a promising approach for the growth of quality GaN structures on large area m-sapphire substrates as optoelectronic devices based on these layers will have excellent characteristics.

Role of rubrene additive for reinforcing the structural, optical, and dispersion properties of polyvinyl alcohol films towards optoelectronic applications

A conventional casting method was used to produce promoted polyvinyl alcohol (PVA) films via rubrene additive. The 1.2 g of PVA dissolved in 120 ml of distilled water and doped with various concentrations (0, 0.1, 0.3 and 0.4 wt%) of rubrene dye. The influence of rubrene dopants on the structural properties of PVA was studied using FTIR and XRD techniques. The semicrystalline nature of the PVA polymer was established by the XRD pattern. FT-IR analysis shows changes in peaks intensities of PVA and their widths are expanded in the presence of rubrene dopants which indicates the interactions between the functional groups of PVA and the rubrene dopants. XRD patterns exhibit the existence of rubrene inside the PVA structure leads to form cross-linking which enhances the amorphous nature within the doped PVA samples. The optical characteristics were investigated using spectrophotometric measurements of transmittance T(λ), reflectance R(λ), and absorbance A(λ) in the spectral range of 200–2500 nm. The indirect and direct optical band-gap values of PVA films decreased from 5.15 eV and 5.69 eV to 3.63 eV and 4.50 eV as rubrene doping ratio was increased from 0 to 0.4 wt%, respectively. The refractive index dispersion region was explained using the single oscillator (Wemple–DiDomenico) model. The extracted values of dispersion energy (Ed), dielectric constant at infinite frequency (ε∞) and lattice dielectric constant (εL) of PVA/rubrene composite films increased from 0.74 eV, 1.31 and 1.35 to 5.35 eV, 3.47 and 4.35; respectively, whereas oscillator energy (Eo) decreased from 2.41eV to 2.17 eV as rubrene contents increased from 0 to 0.4 wt%, respectively. Indeed, these changes in values of dispersion parameters is evidence to the cross-linking bonds between the host polymer and the rubrene dopants. The improvement of optical properties of PVA/rubrene films demonstrates their applicability as eco-friendly packaging materials, particularly in flexible optoelectronic and microelectronic devices.

Stationary optical solitons with complex Ginzburg–Landau equation having nonlinear chromatic dispersion and Kudryashov's refractive index structures

This work obtains stationary optical solitons for complex Ginzburg–Landau equation that is structured with Kudryashov's self–phase modulation structures. The chromatic dispersion is also taken to be nonlinear. Six forms of nonlinear refractive index are considered. The adopted integration scheme is the generalized G′/G-expansion approach that yields solutions in terms of Jacobi's elliptic functions. The limiting approach, when applied with the modulus of ellipticity leads to the stationary optical solitons that finally emerge from the model.

Temperature-dependent refractive index and material dispersion of diamond

Temperature-dependent refractive index and material dispersion of diamond

Refractive index dispersion of BGa(As)P alloys in the near-infrared for III-V laser integration on silicon

BxGa(1−x)P and BxGa(1−x)AsyP(1−y) alloys are of potential interest in III-V heterostructures for integration with silicon. Waveguide design utilizing these alloys requires an understanding of the refractive index properties and their variation with composition. Refractive index dispersion was measured and modeled in the wavelength range of 827–2254 nm using spectroscopic ellipsometry at room temperature for samples with boron and arsenic fractions from 0% to 6.6% and 0% to 17%, respectively. The refractive index was found to increase with increasing boron composition as a result of strain due to lattice constant mismatch with the silicon substrate. For the arsenic-containing alloy, the refractive index was found to increase independently of strain. An empirical model based on the composition dependent variation of Cauchy dispersion function coefficients was developed for BGaAsP alloys lattice matched to silicon at the growth temperature. This model can be used to calculate the wavelength dependent refractive index of lattice matched boron and arsenic combinations for applications in semiconductor waveguides, an example of which is proposed. The results of this study are of interest more broadly for other III-V on silicon applications including photovoltaics and more generally in terms of the ellipsometric investigations of thin films on non-native substrates.