Sellmeier Dispersion Relation Research Articles

Thermal, Optical, and Emission Traits of SM3+-Ion-Doped Fluoride/Chloride/Oxide Glass for Red/Orange Laser Fiber Applications

This study examined spectroscopic, thermal, and other qualities, such as the lasing parameters, of Sm3+-doped glass with the composition 40P2O5–30ZnO–20LiCl–10BaF2. The ellipsometric data were used in a Sellmeier dispersion relation to estimate the refractive index values of the glasses investigated. The measured absorption spectra of the doped glass reveal the presence of various absorption bands assigned to transitions from the 6H5/2 ground state attributed to Sm3+-ion-excited states. We studied the decay of the 4G5/2 level of the Sm3+ ions in the doped glass by analyzing its absorption and emission fluorescence spectra. The Judd–Ofelt hypothesis allowed us to determine that the quantum efficiency of the 4G5/2–6H7/2 transition is high: 96% and 97% for glass doped with 4.05 × 1019 ions/cm−3 and 11 × 1019 ions/cm−3, respectively. Furthermore, this glass exhibits efficient red/orange enhanced spontaneous emission that matches the excitation band of the photosensitizer material used in medical applications.

Electrochemical synthesis of a novel hybrid nanocomposite based on Co3O4 nanoparticles embedded in PANI- camphor sulfonic Acid matrix for optoelectronic applications

In this study, we report on the preparation and characterization of Co3O4 nanoparticles (NPs) embedded in polyaniline-Camphor Sulfonic Acid (PANI-CSA) polymer matrix via electrochemical polymerization method. Developing conductive organic films with tunable optical properties are crucial for many novel optoelectronic applications. Thus, incorporation of metallic oxide nanoparticles (Co3O4 NPs) into polymer matrix (PANI-CSA) represents an alternative approach to address these desired features. As a result of careful optimization of several growth conditions, PANI-CSA/Co3O4 hybrid nanocomposites with high crystalline and homogeneous structures were successfully synthesized on ITO substrates. The impact of Co3O4 NPs concentrations on the structural and optical properties has been extensively investigated. A variety of structural and optical techniques, including FTIR, UV-VIS spectroscopy, and XRD, were employed to characterize the prepared hybrid nanocomposites. The initial findings and analysis reveal that the integration of Co3O4 NPs into PANI-CSA matrix have a trifunctional role in reducing π-polaron and Urbach energies (EU) whereas increasing π-π* band gaps. A further increase in NPs concentration up to 12 wt % results in continuous increase in the absorbance bands and absorption coefficients, indicating improved optical properties as compared to the control sample (PANI-CSA without NPs). The observed redshifts in absorbance band positions are attributed to narrowing of the optical band gap caused by interactions between PANI-CSA chains and Co3O4 NPs. FTIR spectra confirmed the exact chemical composition of PANI-CSA/Co3O4 nanocomposites, exhibiting broadened and less intense peaks compared to the control sample, indicating their interaction at the molecular levels. Additionally, XRD measurements indicate that no peaks of other phases were detected in all nanocomposites, demonstrating their purity and crystallinity. Finally, A single oscillator model by Wemple-DiDomenico (WDD) coupled with a Sellmeier dispersion relation based on one term has been utilized to model the typical electronic transition excitation energies, dispersion energies, optical conductivities, and many other optical desperation parameters for PANI-CSA and PANI-CSA/Co3O4 at various concentrations. For instance, in response to increased NPs content, linear optical susceptibility, third-order nonlinear optical susceptibility, and nonlinear refractive index decrease. In contrast, the ratio of free carriers to effective mass (N/m) increased from 4.73 × 1039 to 4.91 × 1039 m−3 kg−1 with increasing NPs concentration. Based on the observed results, these hybrid nanocomposites possess improved properties, indicating their potential use as active materials in a variety of novel optoelectronic applications.

First-principles investigation of optoelectronic properties of novel SnS2 with a cubic structure

Using the density functional theory (DFT), some of the electronic (density of states, energy band structure) and optical properties (dielectric function, refractive index, energy loss function) of the novel discovered SnS2 in the cubic structure, have been investigated. The calculations have been performed using the FP-LAPW method. The electronic results reveal that SnS2 in the cubic structure like to SnS2 in the trigonal structure is a semiconductor with an indirect band gap of 1.724 eV which the obtained band gap is in good agreement with experimental band gap of 1.7 eV–1.9 eV. In the optical properties, the real and imaginary parts of the dielectric function have been explored. The calculated optical band gap of 2.27 eV is close to the experimental optical band gap of SnS2 in the cubic structure. The plasmon energy of 19.60 eV has been calculated for this compound. A Sellmeier dispersion relation has been presented for the variation of the refractive index.

Microstructural and optical properties of high-quality Mg–Zn oxide thin films

The microstructural and optical properties of Mg–Zn oxide thin films deposited by aerosol assisted chemical vapor deposition onto fused silica substrates were studied as a function of the Mg concentration in the precursor solution, which was varied from 0 to 100 mol %. The thickness of all the samples was around 150 ± 20 nm. Scanning electron microscopy and grazing incidence x-ray diffraction were used for the analysis of the morphology, composition, and crystalline structure. Outcomes showed a gradual evolution of the microstructural and optical properties of the films as the Mg content increased. The systematic increase of the lattice parameter a, and the decrease of parameter c were observed with the increase of Mg concentration, nevertheless, the unit cell volume remained nearly constant, around 0.0471 ± 0.0007 nm3. Energy dispersive x-ray microanalysis results indicated that Mg /(Zn + Mg) atomic ratio (x) up to 0.59 was found for a single-phase hexagonal MgxZn1-xO film. This value is higher than most of the reported Mg content in wurtzite ZnO. At higher Mg loadings (>70 mol % in solution), the segregation of periclase MgO phases occurred. X-ray photoelectron spectroscopy confirmed the composition of selected Mg doped ZnO films and the substitution of Zn+2 by Mg+2 atoms. The Williamson-Hall analysis of diffracted peaks was employed to determine the micro-strain in the films, it was found ∈ = 0.2 ± 0.1 % with a slight tendency to decrease ∈ as x increases. For single-phase hexagonal MgxZn1-xO films, the computation of the dispersion relations of the optical constants was achieved using direct transmittance and near-normal absolute reflectance. For this objective, TFcalc software was used to fix the Sellmeier dispersion relation parameters by fitting the modeled transmittance and reflectance spectra of the stack film-substrate with corresponding experimental spectra. A detailed analysis of the optical band gap energy and its correlation with the microstructural characteristics of the films was performed, in particular with lattice parameters. The modification of optical band gap energy and lattice parameters with the inclusion of Mg in the wurtzite structure can be explained because the MgO4 unit has a compressed tetrahedral geometry with a much shorter height than those of ZnO4 tetrahedra, and due to the change in electronegativities and ionic radius between Mg and Zn, the bonding character becomes more ionic, and the increased localization of Zn 3d and O 2p orbitals. The optical band gap energy was tuned by changing the Mg content, from about 3.3 eV of undoped ZnO up to 4.3 eV of hexagonal MgxZn1−xO (x ~ 0.59). Moss relation was used to analyze the relationship of optical band gap energy and refractive index.

Characterization of the framework of Cu doped TiO2 layers: An insight into optical, electrical and photodiode parameters

The CuxTi1-xO2 films (x = 0.05, 0.10 and 0.15) with various Cu dopants were prepared by sol-gel spin coating technique on a glass substrate and Si wafer in order to determine their optical and photodiode behaviors. Surface topology of thin films was investigated by Atomic Force Microscopy. The optical properties and dispersion parameters have been calculated completely for the samples by using the single term Sellmeier dispersion relation and Wemple–DiDomenico single oscillator model. Photodiode properties were studied by current-voltage I−V characteristics of Al/n-Si/CuxTi1-xO2/Al at room temperature under various illumination intensities. According to the results, the devices have good rectifying, photoresponse and photodiode properties. The electrical behaviors were characterized also by C−V and G−V measurements for various frequencies. The capacitance–voltage–frequency C−V−f measurements indicate that the capacitance of the devices depends on voltage and frequency. The results confirm that the various Cu doped TiO2 devices are the good candidate for photodiode and photodetector applications.

Investigation of optical framework of chalcostibite nanocrystal thin films: An insight into refractive index dispersion, optical band gap and single-oscillator parameters

Herein, we report the synthesis of chalcostibite (CuSbS2) nanocrystals based on hot injection method and the characterization of CuSbS2 thin films by spin coating technique. The deposited films were subjected to the UV–Vis spectrophotometer, XRD, TEM and SAED for optical, structural, morphological and elemental analysis. XRD pattern showed that CuSbS2 nanocrystals have chalcostibite structures and SAED diffraction spots supported the XRD results. Different optical parameters like extinction coefficient, refractive index, real and imaginary parts of dielectric constant and surface and volume energy loss functions have been calculated applying single term Sellmeier dispersion relation and Wemple–DiDomenico single oscillator model. The obtained results are discussed in detail. The optical dispersion and dielectric properties of the CuSbS2 have been determined by the transmittance and reflectance modes in the range of 300–1600 nm. Thus, the CuSbS2 is transparent up to 40–45% in the visible range. The optical bandgap determined by the optical absorbance spectrum analysis showed that thin films possess direct bandgap of 1.86 eV. The calculated refractive index of thin film varies between 1.76 and 2.11 throughout the spectral region considered. The results presented here permit a better understanding of the properties of the chalcostibite nanocrystals which in turn result in the design of more efficient solar cells.

Investigation of structural, optical and dielectrical properties of Cu2WS4 thin film

Ternary I-Cu2WS4 were synthesized based on hot-injection process and their thin films are prepared by spin coating techniques at ambient temperature. The energy dispersive analysis of X-rays of the thin films confirmed that synthesized thin film is stoichiometric. Transmittance and reflectance have been used to determine the optical, dispersion and dielectric properties of the Cu2WS4 in the range of 200–2400 nm. The transparency of the Cu2WS4 is 40–45% in the visible range. Optical dispersion parameters have been calculated by using the single term Sellmeier dispersion relation and Wemple–DiDomenico single oscillator model. Several dispersion parameters were determined by the analysis of refractive index dispersion.Absorption coefficient (α), extinction coefficient ( $$k$$ ), the Urbach energy ( $${{E}_{U}}$$ ), real and imaginary parts of dielectric constant (e) and surface and volume energy loss function have been calculated. The optical bandgap determined by the optical absorbance spectrum analysis showed that thin films possess a direct bandgap of 1.74 eV.

Retrieval of optical constants of undoped amorphous selenium films from an analysis of their normal-incidence transmittance spectra using numeric PUMA method

The as-measured room-temperature normal-incidence transmittance–wavelength (T exp(λ) − λ) spectra of undoped amorphous selenium (a-Se) films, which were thermally deposited onto glass slides, exhibit well-resolved interference-fringe maxima and minima λ > λ c (≈630 nm), below which they fall rather sharply to zero transmittance. In the transparency and weak absorption region, the maxima transmittance is close to the substrate transmission, implying good uniformity of the a-Se films. The geometric thicknesses of the films and the spectral dependency of their optical constants n(λ) and κ(λ) were retrieved by analyzing the T exp(λ) − λ spectra by the PUMA method, based on the full T(λ)-formula for air-supported {uniform thin film/thick transparent substrate}-stacks, without the need for dispersion relations in prior and regardless of the number of interference fringes. The n(λ) − λ data of the transparency and weak absorption regions were found to fit the Wemple–DiDomenico and modified Sellmeier dispersion relations. The ω-dependency of the absorption coefficient α(ω) in the absorption-edge region has been analyzed in view of various interband transition models and was found to be nearly described by the linear power-law relation $$\alpha \hbar \omega \propto \hbar \omega - E_{\text{g}}$$ , with E g ≈ 2.2 eV over a broad spectral range.

Structural, optical dispersion and dielectric properties of novel chromium nickel organic crystalline semiconductors

A novel organic crystalline semiconductor, [Cr(DPPP)(DPPM)(Ni-ap)(CO)2] (Cr–Ni OSC) (6a), (DPPP=diphenylphosphino-propanone, DPPM=diphenylphosphino-methane and Ni-ap=nickel apyrazole ring) (6a) was synthesized. Structural characteristics of the Cr–Ni OSC complex have been investigated by IR, 1HNMR, 31P NMR, thermal analysis (TG/DTA), and XRD. Thermal analysis of Cr–Ni OSC implies that, the complex was thermally stable up to 218°C, and the melting point of it was 193°C. Two discrete regions of (44.46%, 128–421°C) and (41.15%, 600–823°C) by TG analysis of Cr–Ni OSC complex was determined. XRD crystal data of Cr–Ni OSC showed the formation of monoclinic (P21/n). Transmittance and reflectance have been used to determine the optical dispersion and dielectric properties of the Cr–Ni OSC complex in the range of 200–800nm. The transparency of the complex is 75–80% in the visible range. The optical and transport energy gaps were estimated as 1.87eV and 2.01eV respectively. Optical dispersion parameters have been calculated by using single term Sellmeier dispersion relation and Wemple–DiDomenico single oscillator model. Several dispersion parameters were determined by analysis of refractive index dispersion. The optical conductivity, surface and volume energy loss functions, and the electric modulus were also estimated from the optical dielectric constant analysis.

Optical dispersion and dielectric properties of rubrene organic semiconductor thin film

Rubrene thin film has been fabricated on a glass substrate by spin-coating at 300 K. The optical dispersion and dielectric properties of the film have been determined from the analysis of transmittance and reflectance measurements at normal incident of light between 200 and 700 nm. The optical transmittance of the film was estimated as of 80–85 % in the visible range. Optical absorption characteristics show that the absorption mechanism is due to the indirect transition. The transport and onset optical energy gaps were determined as 2.93 and 2.31 eV, respectively. Single term Sellmeier dispersion relation and Wemple–DiDomenico single oscillator model were used to determine the optical dispersion parameters. Several dispersion parameters such as lattice dielectric constant, optical dielectric constant at higher frequency, dispersion energy, oscillator energy, the ratio of carrier concentration to the effective mass, the average oscillator wavelength, and average oscillator strength were determined by analysis of refractive index dispersion. The loss factor, the electric modulus, the optical conductivity, the volume and surface energy loss functions, and the relaxation time were also evaluated from the optical dielectric constants analysis.

Spectral dispersion of linear optical properties for Sm2O3 doped B2O3–PbO–Al2O3 glasses

Glasses having composition (B2O3)25 (PbO)70 (Al2O3)5 (Sm2O3)x ,where x=0, 0.5, 1, 2, 3 and 5g were prepared using the normal melt quench technique. Spectral reflectance and transmittance at normal incidence of the glass samples are recorded with a spectrophotometer in the spectral range 220–2200nm. These measured values are introduced into analytical expressions to calculate the real and imaginary parts of the refractive indices. Wemple–DiDomenico single oscillator model and one-term Sellmeier dispersion relations are used to model the real refractive indices. Dispersion parameters such as: single oscillator energy, dispersion energy, lattice oscillating strength, average oscillator wavelength, average oscillator strength and Abbe's number are deduced and compared. Absorption dispersion parameters such as: Fermi energy, optical energy gap for direct and indirect transitions, Urbach energy and steepness parameter are calculated. Effects of doping Sm2O3 on these linear optical parameters are investigated and interpreted.

Optical properties of thermally evaporated Bi2Se3 thin films treated with AgNO3 solution

Bismuth selenide (Bi2Se3) thin films have been prepared onto clean glass substrates by the thermal evaporation technique. The deposited films were then immersed in silver nitrate solution for different periods of time, followed by annealing in Argon atmosphere at 473K for 1h, to obtain Ag/Bi2Se3 samples. The prepared films have been examined by X-ray and transmission electron microscopy for structural determination. The optical transmission and reflection spectra of the deposited films have been recorded within the wavelength range 400–2500nm. The variation of the optical parameters of the prepared films, such as refractive index, n, and the optical band gap, Eg as a function of the immersion duration times has been determined. The refractive index dispersion in the transmission and low absorption region is adequately described by the well-known Sellmeier dispersion relation, whereby the values of the oscillator strength, oscillator position, the high-frequency dielectric constant, ε∞ as well as the carrier concentration to the effective mass ratio, N/m* were calculated as a function of the immersion duration time.

Polarization properties of retroreflecting right-angle prisms

The cumulative retardance Delta(t) introduced between the p and the s orthogonal linear polarizations after two successive total internal reflections (TIRs) inside a right-angle prism at complementary angles phi and 90 degrees - phi is calculated as a function of phi and prism refractive index n. Quarter-wave retardation (QWR) is obtained on retroreflection with minimum angular sensitivity when n=(sqr rt 2+1)(1/2)=1.55377 and phi =45 degrees. A QWR prism made of N-BAK4 Schott glass (n=1.55377 at lambda=1303.5 nm) has good spectral response (<5 degrees retardance error) over the 0.5-2 microm visible and near-IR spectral range. A ZnS-coated right-angle Si prism achieves QWR with an error of < +/- 2.5 degrees in the 9-11 microm (CO(2) laser) IR spectral range. This device functions as a linear-to-circular polarization transformer and can be tuned to exact QWR at any desired wavelength (within a given range) by tilting the prism by a small angle around phi =45 degrees. A PbTe right-angle prism introduces near-half-wave retardation (near-HWR) with a < or =2% error over a broad (4< or =lambda< or =12.5 microm) IR spectral range. This device also has a wide field of view and its interesting polarization properties are discussed. A compact (aspect ratio of 2), in-line, HWR is described that uses a chevron dual Fresnel rhomb with four TIRs at the same angle phi =45 degrees. Finally, a useful algorithm is presented that transforms a three-term Sellmeier dispersion relation of a transparent optical material to an equivalent cubic equation that can be solved for the wavelengths at which the refractive index assumes any desired value.

Optical and electrical properties of GaSe thin films

GaSe thin films were deposited at room temperature onto glass substrate and carbon stub by thermal evaporation technique. The X-ray diffraction analysis showed that both as-deposited films and those vacuum annealed at 475 K for 1 h are amorphous in nature. The elemental analysis of thin films deposited onto carbon stub revealed that nearly stoichiometric films of Ga 0.98Se 1.02 could be deposited with a deposition rate of 1.8 nm/s. The optical transmittance and reflectance spectra of as-deposited films were recorded at normal light incident in the wavelength spectral range 600–3000 nm. The refractive index in the transmission and low absorption region is adequately described by Sellmeier dispersion relation. The mechanism of the optical absorption follows the rule of indirect optical transition and the corresponding energy was estimated. The I– V characteristics of MSM configuration system have indicated an ohmic behaviour with similar In electrodes. However, for Al/GaSe/In system non-ohmic behaviour was observed. The data of the forward branch were analyzed. The dc measurements were made on the as-deposited GaSe films in the temperature range 130–475 K. The obtained result revealed two distinct regions. The mechanisms of such region were analyzed.

Optical properties of ZnO related to the dc sputtering power

Zinc oxide thin films were sputter deposited on (100) silicon substrates at 250 ○C substrates temperature via reactive unbalanced dc magnetron process using pure zinc target and argon/oxygen gases. The influence of the applied dc sputtering power (between 100 to 250 Watts, step 50 Watts) on the optical properties of the grown films was systematically investigated by variable angle of incidence spectroscopic ellipsometry (VASE) technique. The refractive indices were found to follow the second-order Sellmeier dispersion relation. However, Cauchy-like dispersion model was formulated to account for the absorption tail and excitonic structure near the direct band gap. The optical properties such as refractive indices, extinction coefficients, optical band gaps, Urbach's energies, excitonic binding structure and absorption coefficients of the grown films were reported as a function of dc power in the photon energy range between 1.2 eV and 4.2 eV. The films were found to be polycrystalline with (002) preferred orientation.

Epitaxial growth and properties of Ga-doped ZnO films grown by pulsed laser deposition

Epitaxial films of gallium-doped zinc oxide (GZO) have been deposited on sapphire (0 0 0 1) substrates by pulsed laser deposition method. X-ray diffraction, photoluminescence (PL) and spectroscopic ellipsometry (SE) were used to characterize the films. It was found that the epitaxial growth of GZO films could be obtained for a substrate temperature at 400°C and the high quality epitaxial films were obtained at 500°C. The PL spectra of epitaxial GZO films showed a near band edge (NBE) emission peak and a broad orange deep-level emission peak. The NBE emission had a blue shift while the deep-level emission shifted to lower energy comparing with those of pure ZnO films. The refractive indices were obtained from the fitting of the SE data by Sellmeier dispersion relation.

Linear and nonlinear optical properties of ZnGeP2 crystal for infrared laser device applications: revisited.

Measurement of refractive indices in the spectral bands 9-11 microm and 1.32 microm from a cw CO2 laser and a Q-switched Nd:YAG laser, respectively, is reported in a ZnGeP2 crystal. A new set of Sellmeier dispersion relations has been derived from the measured refractive indices data in this crystal. Second-harmonic generation (SHG) of CO2 laser radiation in this crystal is also reported. It is also seen that the previously reported phase-matching data for others experiments in SHG and optical parametric devices is explained satisfactorily with this new set of Sellmeier dispersion relation.

Optical functions of InGaP/GaAs epitaxial layers from 0.01 to 5.5 eV

In0.49Ga0.51P films, both undoped and doped n- and p-type (up to 1018 cm-3), were grown lattice matched on GaAs substrates, with different miscut angles, by Metal-Organic Vapour Phase Epitaxy (MOVPE) at different temperatures. The shift of the fundamental gap E0, caused by “ordering effect” was measured as a function of temperature by photoluminescence. The complex refractive index = n + ik and the dielectric function = ɛ 1 + iɛ 2 at room temperature were determined from 0.01 to 5.5 eV by using complementary data from fast-Fourier-transform far-infrared (FFT-FIR), dispersive, and ellipsometric spectroscopies. The effect of the native oxide was accounted for and the self-consistency of the optical functions was checked in the framework of the Kramers-Kronig causality relations. In the restrahlen region the dielectric function was well fitted by classical Lorentz oscillators; in the transparent region below E0, the refractive index was modelled by a Sellmeier dispersion relation; in the interband region the dielectric function was well reproduced by analytical lineshapes associated to seven critical points. Thus parametrized analytical expressions were obtained for the optical functions all over the spectral range, without discontinuities, to be used in the modelling and characterization of multi-layer structures, also on opaque substrates.

Interferometric determination of gamma radiation effects on optical parameters of a GRIN optical fibre

Multiple-beam white-light interference fringes across an irradiated GRIN fibre, of length 2 cm and immersed in a liquid wedge interferometer that is followed by a grating spectrograph, are produced. These fringes are used to investigate the effect of gamma radiation, with different doses from 0.01 to 1 MGy, on the optical parameters of both the cladding (pure silica) and the core (germanium-doped silica) of the GRIN fibre. Optical parameters such as refractive index, refractive index difference, numerical aperture, V-number, index profile, chromatic dispersion and zero-dispersion wavelength are determined and studied. A two-term Sellmeier dispersion relation is adopted and fitted to the experimental data of the refractive index. Then, a dose-dependent Sellmeier formula is deduced to represent the effect of gamma radiation on different optical parameters.

Application of fringes of equal chromatic order for investigating the effect of temperature on optical parameters of a GRIN optical fibre

Multiple-beam white light interference fringes across a GRIN optical fibre immersed in a liquid wedge interferometer placed in front of a grating spectrograph are produced. They are used to investigate the effect of temperature on the optical fibre parameters of both the cladding (pure SiO2) and the core (GeO2-doped SiO2). A two-term Sellmeier dispersion relation is adopted and fitted to the experimental refractive index data. Then a temperature-dependent Sellmeier formula is deduced to study the effect of temperature on the refractive index of the fibre and its dispersion in addition to all of its optical parameters. These parameters are the average energy gap, the variation of the thermo-optic coefficient with photon energy, the refractive index difference, the numerical aperture, the normalized frequency (V-number), the number of modes, the material dispersion and the zero-dispersion wavelength.