Linear Optical Susceptibilities Research Articles

Impact of film thickness on the structural and linear/nonlinear optical properties in highly oriented Cs3Bi2I9 perovskite films

This study presents the successful preparation of highly oriented Cs3Bi2I9 films with different thicknesses using sol–gel spin-coating method. X-ray diffraction analysis confirmed a single hexagonal crystal phase with a high orientation along the <0 0 l> direction. The crystallite size in the range of 27 and 41 nm increase with increasing film thickness. The band gap energy ranged from 1.91 to 1.97 eV was found to decrease with increasing film thickness which was associated to the film relaxation with increasing film thickness. The refractive index, absorption index, complex dielectric coefficients, complex optical conductivity coefficients, and the ratio of free charge concentration also were found to increase with film thickness. The first-order linear optical susceptibility ranged from 0.22 to 0.38, the non-linear optical susceptibility χ(3) and the nonlinear refractive index parameters n(2) were respectively within the range of 0.4–3.77 × 10−12esu 0.96–7.97 × 10−11esu, the highest value of all the parameters was found in the visible region at 500 nm. These findings position Cs3Bi2I9 as highly promising material for optoelectronics.

Effects of Mn doping on the structural, linear and nonlinear optical properties of Gd2O3 nanoparticles

We report on the effects of Mn doping on the structural, linear, and nonlinear optical properties of Gd2-xMnxO3 nanoparticles (x = 0.00, 0.03, 0.05, and 0.10). The Gd2-xMnxO3 powders were prepared using sol-gel process. The x-ray diffraction technique shows that the Mn3+ doping results in a small decrease in lattice parameter and an increase in crystallite size. UV–visible measurements were carried out in the wavelength range of 200–800 nm. The direct optical band gap estimated using Tauc model decreases with increasing Mn content from 5.152 to 5.008 eV, while Urbach energy increases from 0.753 to 1.012 eV. Moreover, the insertion of Mn results in a significant enhancement in the optical parameters (refractive index, extinction coefficient, absorption coefficient, dielectric constants (ε', ε"), optical and electrical conductivity. The dispersion energy (Ed) increases from 24.13 to 30.1 eV, while the single oscillator energy (E0) declines lightly from 10.28 to 9.998 eV with the increase of Mn content. With Mn doping an enhancement in the static linear refractive index (n0) and high-frequency dielectric constant (ε∞) were also observed. Analysis of linear and nonlinear optical parameters shows that the presence of manganese enhanced the linear optical susceptibility (χ(1)), third-order non-linear susceptibility (χ(3)), and non-linear refractive index (n2). These optical results show the potential applications of Gd2-xMnxO3 nanoparticles (x = 0.00, 0.03, 0.05 and 0.10) in various optical devices.

The influence of La/Mg co-doping on the structure, linear and nonlinear optical properties of Fe2O3 nanoparticles for environmentally friendly applications

The structure and linear/nonlinear optical properties of iron oxide (Fe2O3) nanoparticles (NPs) films are examined for environmentally friendly applications. Undoped and La, Mg and La/Mg co-doped Fe2O3 NPs films were equipped using the spray pyrolysis procedure. The structural, morphological and optical properties of the films were characterized by X-ray diffractometer, FT-IR spectrophotometer, FE-SEM and UV–visible–NIR spectrophotometer. XRD analysis exposes that the samples possess a rhombohedral structure of α- Fe2O3 (hematite). Besides, the crystallite size of the undoped Fe2O3 NPs increases from 20.7 nm to 21.8 nm (La/Fe2O3), 23.0 nm (Mg/Fe2O3) and 24.4 nm (La + Mg/Fe2O3). The direct/indirect optical band gap of the undoped Fe2O3 film decreases from 2.47 eV/1.87 eV to 2.43 eV/1.72 eV (La/Fe2O3), 2.37 eV/1.65 eV (Mg/Fe2O3) and 2.31 eV/1.56 eV (La + Mg/Fe2O3). Moreover, the effect of La/Mg co-doping on the refractive index, extinction coefficient, dielectric constants, linear optical susceptibility (χ(1)), third-order nonlinear susceptibility (χ(3)) and nonlinear refractive index (n2) of Fe2O3 NPs have been explored. In instance, the real dielectric constant of the undoped Fe2O3 NPs decreases at 600 nm from 6.46 to 5.00 (La/Fe2O3), 3.80 (Mg/Fe2O3) and 3.17 (La + Mg/Fe2O3). The ability to tailor the linear/nonlinear optical properties of Fe2O3 NPs films upon La/Mg co-doping nominate them for uses in a lot of environmentally friendly applications.

Tailoring optoelectronic properties of InGaN-based quantum wells through electric field, indium content, and confinement shape: A theoretical investigation

This paper conducts a comprehensive theoretical examination of the electronic and optical responses, including linear and nonlinear optical responses, of an InGaN-based quantum well with a variable inverted parabolic confinement potential. This examination takes into account the effects of applied vertical electric fields, variable indium content, different confinement shapes, and sizes. The Schrödinger equation is solved numerically using the finite element method and the effective mass theory. The results indicate that both the electrical and optical properties of the system are highly influenced by these factors. Additionally, it is found that by carefully selecting these factors, the total optical absorption coefficient, total refractive index, and linear complex optical susceptibility of the system can be precisely controlled. This study makes a valuable theoretical contribution to the understanding of how electromagnetic radiation interacts with matter and can be applied to help explain the absorption and scattering properties of III-nitride materials, used in the active regions of various devices such as solar cells, photodetectors, and modulators, as well as in the design stages of them.

Excitonic spectra of monoclinic anthracene-like 2D model

The paper contains symmetry analysis and classification of the excitons (Frenkel excitons - FEs - and Charge Transfer Excitons - CTEs) in anthracene-like two-dimensional model taking into account the symmetry of the monoclinic axis, the inversion center and the glide plane. The symmetry permitted combinations of CTEs and their coupling with dipole active FEs are studied. These circumstances govern the excitonic spectra and their manifestation in linear absorption. Green functions method is applied to find linear optical susceptibilities and excitonic spectra with polarization along the monoclinic axis or perpendicular to it.

Structural and optical exploration of promising zinc (8-hydroxyquinoline) thin films for wide-scale optoelectronic applications

This research presents a detailed sequential study of the thickness effect on structural, morphological, and optical properties of vacuum thermally deposited zinc 8-hydroxyquinoline (ZnQ2) thin films. The FTIR results demonstrate that ZnQ2's molecular structure has a high degree of stabilization. On the other hand, the change in thickness affects the film's roughness. The film roughness decreases to 2.398 nm as the film thickness increase to 143 nm, and then roughness increases again at a thickness of 185 nm. The optical absorption features of the prepared films are explained. The optical energy gap has been calculated and found to be in the range of (2.79–2.87) eV. Furthermore, the refractive index dispersion has been analyzed. ZnQ2 thin film of thickness 87 nm achieved the highest linear optical susceptibility, nonlinear optical susceptibility, and nonlinear refractive index. The high peak located at photon energy 4.4 eV assures the validity of the material's proposal for optical switching applications. Besides, compared to many other organic complexes, ZnQ2 is a highly recommended candidate for efficient organic optoelectronic and optical switching applications.

Divulging the Potential of Sodium Carbide Thin Film for Semiconductor Applications

The work reported in this article is an attempt to introduce the least explored sodium carbide as a thin film and to explore its semiconducting behavior. The sodium carbide thin film deposited by the radio frequency sputtering technique is subjected to morphology, structure, and spectroscopic characterizations. The floral petal‐like morphology, understood from the field‐emission scanning electron microscopy and atomic force microscopy images, helps in enhancing interaction with the radiation that is revealed through the UV–visible absorption spectrum. X‐ray diffraction, photoelectron and Raman spectroscopic analyses confirm that the film is sodium carbide. The optical emission behavior of the sodium carbide thin film in the blue region is unveiled through the photoluminescence spectrum, power spectrum, color purity, and chromaticity diagram. Employing the refractive index and extinction coefficient values from the specular reflectance data, optical and electrical conductivities, nonlinear refractive index, linear and nonlinear optical susceptibility, dissipation factor, and surface and volume energy loss functions and their wavelength dependence due to interfacial polarization are investigated. The transfer matrix method is used to understand the spatial variation of the induced electric field and optical current density.

Investigating into physical properties of composites of polymer blends and cobalt chloride irradiated by gamma ray for optical devices development

The present work studies the influence of cobalt chloride (CoCl2) and γ-irradiation dose on the optical, thermal properties, and dynamic mechanical analysis (DMA) of different blends of (PVA/PEG /PVP). Different optical parameters were deduced before and after γ-irradiation with different doses (5, 10, and 15 kGy). The optical conductivity (σoptical) values for the prepared blends and composites indicate their importance for optical energy applications, especially after γ-irradiation. Modifying and enhancing the refractive index of γ-irradiated samples enables their use in various optical devices. Linear optical susceptibility (χ(1)) and the third nonlinear susceptibility (χ(3)) increased by decreasing the PVA amount in the blend and composites. Thermogravimetric analysis TGA confirmed that by adding CoCl2 to the hosting blends, the thermal oxidative degradation energy Ea became much higher than unirradiated samples. The DMA results show that the storage modulus was significantly improved after adding CoCl2 and after irradiating the samples by 5 and 10 kGy. Also, all the samples exhibited two relaxation temperatures and were greatly affected by adding the filler.

Tailoring Variations in the Microstructures, Linear/Nonlinear Optical, and Mechanical Properties of Dysprosium-Oxide-Reinforced Borate Glasses

Hybrid dysprosium-doped borate glassy samples [B-Gly/Dy]HDG (Borate Glass/Dysprosium)Hybrid Doped Glass were prepared in this study via the melt-quenching method. Its linear/nonlinear optical, photoluminescence, hardness indentation, and micro-creep properties were analyzed. The amorphous structure for all the prepared samples was confirmed from the XRD patterns. In addition, density functional theory (DFT), optimized by TD-DFT and Crystal Sleuth, was used to study the structure and crystallinity of the [B-Gly/Dy]HDG as isolated molecules and agreed with the peaks of experimental XRD patterns. Additionally, theoretical lattice types were studied using Polymorph, a content studio software, and orthorhombic Pc21b (29) and triclinic P-1 (2) structures were provided. Both mechanical and optical properties were responses to different concentrations of Dy2O3 in the glassy borate system. It was found that the length of indentation increases by increasing the load time, and the hardness decreases by increasing the load time. The stress exponent value also increased from 4.1 to 6.3. The indentation strain increases by increasing the load time. The direct optical band gap was evaluated using the Davis–Mott relation. Urbach energy and its connection to the disorder degree in materials were studied depending on the Dy2O3 concentration. The acquired optical parameters were also analyzed to determine the nonlinear refractive index as well as the linear and third-order nonlinear optical susceptibility of the investigated glass samples. The photoluminescence emission spectra were recorded, and their attributed transitions were studied. The mechanical studies showed that the hardness values increased by increasing Dy2O3 concentrations from 4160.54 to 5631.58 Mpa. The stress exponent value also increased from 4.1 to 6.3. Therefore, the higher value of stress exponent (S) is more resistant to indentation creep.

Complex dielectric, electric modulus, impedance, and optical conductivity of Sr3−x Pb x Fe2TeO9 (x = 1.50, 1.88 and 2.17)

Abstract Sr3−x Pb x Fe2TeO9 (x = 1.50, 1.88 and 2.17) were synthesized in polycrystalline form via the solid-state reaction route in air, and were studied at room temperature using powder X-ray diffraction and ultraviolet visible spectroscopy techniques. The crystal structures were resolved by the Rietveld refinement method; x = 1.50 and 1.88 adopt a tetragonal phase (space group I4/mmm) while x = 2.17 adopts a hexagonal phase (space group R 3 ̄ $\bar{3}$ m). The direct bandgap energy (E g) of ∼1.89 eV for (x = 1.50), ∼1.87 eV for (x = 1.88) and ∼1.74 eV for (x = 2.17) was estimated from the Tauc plots of (αhʋ)2 versus photon energy. The Urbach energy (E U) was determined from the plots of logarithmic absorption coefficient versus hυ. Plots of the incident photon energy dependence of optical parameters such as refractive index, extinction coefficient, real and imaginary parts of the dielectric function, dielectric loss, real and imaginary parts of the complex optical conductivity, linear and nonlinear optical susceptibilities, real and imaginary parts of the electric modulus, real and imaginary parts of the impedance were obtained by means of ultraviolet visible spectrophotometer experiments. Additionally, the estimated values of the single oscillator energy, dispersion energy, static refractive index and high-frequency dielectric constant were obtained from the linear portion of the (n 2 − 1)−1 versus (hυ)2 plots using the Wemple–DiDomenico model.

Hybrid quantum dot-graphene layers with improved optical properties in the terahertz spectrum region

Recently, it has been shown that the graphene plasmonic (GP) effect can enhance the optical properties of quantum dots (QDs) through the Purcell's effect. This can happen when the electromagnetic field is concentrated tightly in a region where the ground state (S-state) and the first excited state (P-state) of electron are present, and the S-to-P transition frequency falls onto the frequency of plasmonic resonance of graphene layers. Here, we use a hybrid composition of graphene layers, consisting of a disk and four L-shaped layers, and a QD aimed to enhance the linear and third-order optical susceptibilities of QD in the terahertz (THz)/far infrared (FIR) spectrum region. Unlike the previous works, where much more graphene layers were used, in this work, we use fewer layers beneath the wetting layer and with a noticeably simpler scheme, we achieve comparable results in transition dipole moments (TDMs) and optical properties. By changing the Fermi's energy of graphene, we could reach 90-fold enhancement for TDM and 8 × 10 3 - and 6 × 10 7 -fold enhancements, respectively, for linear and third-order susceptibilities. Our scheme can noticeably reduce the difficulties in fabricating hybrid graphene-QD systems. • Graphene flakes in nanodisk and L-shaped geometry have been placed in conic-shaped InAs/GaAS quantum dots (QDs). • The emission of QDs has been tuned with graphene plasmonic (GP). • With use of GP effect, S-to-P transition dipole moment (TDM) of QD has been enhanced 120 times. • Linear susceptibility of QD has been multiplied by a factor of 8 × 10 3 . • Third-order susceptibility of QD has been multiplied by a factor of 6 × 10 7 . • GP has been used as a passive method to enhance significantly the optical properties of QDs.

Linear and Nonlinear Optical Properties of a Doubly Clamped Suspended Monolayer Graphene Nanoribbon Nanoresonator

We studied the optical properties of a hybrid structure that was composed of a semiconductor quantum dot and a doubly clamped suspended graphene nanoribbon nanoresonator. We obtained analytical results for the linear and third-order optical susceptibilities of the hybrid system. The spectrum of the linear susceptibility exhibited a single resonance, and its position depended on the value of the on-resonance exciton energy and the exciton–nanoribbon resonator coupling strength coefficient; the amplitude of the resonance was independent of the values of these parameters. The third-order optical susceptibility spectrum exhibited a sharp resonance arising at low frequencies of the probe field, the position of which depended only on the frequency of the fundamental flexural phonon mode. It also presented a broader resonance arising at higher frequencies of the probe field, the position of which was determined both by the coupling strength coefficient and by the exciton frequency; its amplitude depended solely on the exciton–photon coupling strength.

Optical susceptibility of metal nanoparticle-double quantum dot hybrid system

This work is modeling the linear optical susceptibility of a double quantum dot (DQD)–metal nanoparticle (MNP) hybrid system using density matrix equations that consider the interaction between excitons and surface plasmons. The wetting layer (WL)-QD interaction is considered.The absorption of the hybrid DQD-MNP system increases by five times compared to the bare DQD system. The absorption peak is reducing in a similar ratio of increasing MNP radius. A Mollow triplet with asymmetric sidebands appears and decreases with increasing MNP radius, which is compatible with recent experimental evidence. The susceptibility peaks at resonance for a small distance between the hybrid MNP-DQD. The susceptibility is increased by one order for the DQD system compared to a single QD. A similar result is obtained under WL-QD detuning compared to the case of the probe between DQD states. Small DQDs give high absorption and dispersion, offering more shifts from resonance.

Modification of the structural, linear and nonlinear optical properties of zinc oxide thin films via barium and magnesium doping

In the current work, the structural, linear and nonlinear optical properties of zinc oxide thin films have been modified via barium/magnesium doping for modern optoelectronic applications. Ba/Mg-doped and undoped ZnO thin films were successfully prepared by the spray pyrolysis route. The surface morphology, structures' modification and structural parameters were explored using a field emission scanning electron microscope, FT-IR spectrophotometer and X-ray diffraction techniques, respectively. The XRD analysis shows that Ba/Mg-doped and undoped ZnO thin films possess a crystalline nature with a hexagonal wurtzite structure. The crystallite size of the undoped ZnO nanoparticles is 18.5 nm and varies to 21.4 nm (Ba:ZnO), 23.1 nm (Ba/Mg:ZnO) and 16.4 nm (Mg:ZnO). The optical properties (transmittance, absorbance and reflectance) were measured using a UV–visible spectrophotometer. The optical bandgap (Eg) of ZnO thin film decreases from 3.42 eV to 3.35 eV (Ba:ZnO), 3.25 eV (Ba/Mg:ZnO) and 3.31 eV (Mg:ZnO). The decrease in the Eg values of the doped ZnO films as compared with that of the undoped one is mainly attributed to the created defects and localized states in the bandgap of the host ZnO due to Ba/Mg-doping. Moreover, the major optical parameters (refractive index, distinction coefficient, dielectric constant) are also affected as a result of Ba/Mg-doping. Furthermore, a great effect of Ba/Mg-doping on the nonlinear optical constants (third-order optical susceptibility (χ(3)) and nonlinear refractive index (n2)) and first-order linear optical susceptibility (χ(1) is achieved. The obtained results show that the linear and nonlinear optical properties of ZnO film could be enhanced via Ba/Mg-doping for updated applications in multifunctional modern optoelectronics and high-speed communications.

Tailoring the linear and nonlinear optical characteristics of PVA/PVP polymeric blend using Co0.9Cu0.1S nanoparticles for optical and photonic applications

In this work, the linear and nonlinear optical characteristics of polyvinyl alcohol/polyvinyl pyrrolidone (PVA/PVP) polymeric blend have been tailored via Co0.9Cu0.1S nanoparticles (CCS NPs) incorporation. Plain PVA/PVP polymeric blend and different (0.1, 0.5, 1.0, 5.0 and 10.0) wt% of Co0.9Cu0.1S NPs polymeric nanocomposites (PNCs) were prepared by solution casting technique. The samples' surface morphology, structures’ variation, linear and nonlinear optical characteristics were explored using scanning electron microscopy, Fourier transform infrared (FT-IR) and UV–Vis–NIR spectrophotometry respectively. The FT-IR spectra analysis exposes the successful interaction and complexation of the CCS NPs with the host blend structure. The UV–Vis–NIR spectra analysis shows that the direct and indirect optical energy bandgap (Eg) of the host blend decreases from 5.15 eV to 4.94 eV–3.86 eV and 3.05 eV (10.0 wt% of CCS PNC) respectively. The Urbach energy of the plain blend increases from 0.41 eV to 1.18 eV (10.0 wt% of CCS PNC), which reveals the increase of the defects density due to CCS NPs incorporation. Also, the refractive index (n), dielectric constants (real εr and imaginary εi), optical conductivity, linear optical susceptibility (χ(1)), third-order nonlinear optical susceptibility (χ(3)) and nonlinear refractive index (n2) of the PVA/PVP blend are greatly enhanced due to CCS incorporation. The enhancement in the linear and nonlinear optical performance of the plain PVA/PVP blend via Co0.9Cu0.1S NPs incorporation nominates their applications in various optical and photonic devices.

Optical properties and novelty preparation PVA/PVP doping with Cu as surface plasmonic ions

This paper presents a low-cost microwave-assisted chemical reduction method to synthesize copper nanoparticles using sodium borohydride (NaBH4) and ascorbic acid as reducing and stabilizing agents. Furthermore, the preparation of copper-doped PVA and copper-doped PVA/PVP composite films was operated using a solution casting technique. Low-cost copper nanoparticles are considered to have a broad and weak surface plasmon resonance (SPR). With the help of scanning electron microscopy (SEM) and UV–vis near-infrared spectroscopy (UV–VIS–NIR), the characterization of copper nanoparticles was analyzed. The peak of the surface plasmon resonance shifts from 240 to 300 nm. Optical characterizations of copper doped PVA and PVA/PVP composite films were established. The transmittance spectra of 1.851 wt% Cu-doped PVA and 0.590 wt% Cu-doped PVA/PVP showed light blocking in the wavelength ranges of 190–282 nm (PVA) and 289 nm (PVA/PVP). According to the absorption spectra, the surface plasmon resonance (SPR) is induced by Cu NPs at a wavelength of 260 nm. The indirect energy gap, Eg, was determined and found to decrease with an increase in the doping of Cu. Nonlinear optical properties such as nonlinear refractive index, linear optical susceptibility, and third-order nonlinear optical susceptibility were obtained. These findings will aid in producing a plasmonic novel material for optical applications.

Phase tuning of nebulized spray deposited manganese oxide thin films by the effect of annealing temperature and their linear and non-linear optical parameters

In this work, the annealing temperature induced effect on the formation of various forms of manganese oxide (Mn3O4, Mn3O4:Mn2O3 and Mn2O3) thin films were deposited on glass and quartz substrates by nebulized spray pyrolysis technique. The X-ray diffraction patterns confirm that the film exhibited a phase transition from tetragonal-Mn3O4 to cubic-Mn2O3 structure. From the micro-Raman spectra, the A1g, T2g and Eg modes of Mn3O4 and Mn-O stretching vibration of Mn2O3 are identified. The surface morphological study showed the formation of granular particles and nanorods on the surface. The observed peaks corresponding to Mn2+ and Mn3+ ions in the XPS study are confirmed the formation of Mn3O4 in the as-deposited film. The continuous reduction in optical transmittance of the prepared films was observed as a function of annealing temperature. The in-depth optical parameters like optical energy band gap, dielectric constant, skin depth, Urbach energy, steepness parameter and optical conductivity of the films were extracted from the optical data as a function of annealing temperature. The as-deposited Mn3O4 film has an excellent surface quality due to the lower extinction coefficient value. The Mn2O3 film is highly active in the near-infrared region, because of higher optical conductivity compared to the Mn3O4 films. The obtained optical parameters were further analyzed to determine the non-linear refractive index, linear and third order non-linear optical susceptibility of the films.

Structural and optical characterization of Mg2SiO4 and Mg2SiO4-Pr6O11 nanocomposite for optical devices

The knowledge on optical properties of magnesium orthosilicate (Mg2SiO4) and its composite materials are very important as these silicate-based materials play a significant role in the field of optics and electronics. Mg2SiO4 nanomaterial and Mg2SiO4-Pr6O11 nanocomposite materials were therefore chosen in the present study, and they were synthesized in the present work, by simple sol-gel route. Powder x-ray diffraction (PXRD) pattern, Fourier-transform infrared (FT-IR) spectroscopy and ultraviolet–visible (UV–vis) spectroscopy techniques were adopted to understand the structural and optical properties of the prepared samples. The crystalline size of the two samples were estimated using Debye–Scherrer's equation and they are found to be 43 nm (Mg2SiO4) and 52 nm (Mg2SiO4-Pr6O11). The FT-IR results of Mg2SiO4-Pr6O11 revealed the SiO4 stretching and PrO vibrations clearly. The optical absorbances were used to determine the absorption coefficient α and hence the optical band gap energies Eg whose values are 5.60 eV and 5.17 eV for the samples Mg2SiO4 and Mg2SiO4-Pr6O11 respectively. Further with the help of UV–Vis spectra, the refractive index (n), extinction coefficient (k), optical conductivity (σ), real and imaginary part of dielectric constant (ε′ and ε''), volume energy loss function (VELF), surface energy loss function (SELF), linear susceptibility and non-linear susceptibility were investigated with respect to the incident photon energy. The Urbach energy was calculated using ln α vs graph and they are found to be 21 meV and 265 meV for Mg2SiO4 and Mg2SiO4-Pr6O11. The non-linear optical properties of the samples were also discussed by deriving the linear and non-linear optical susceptibilities and by exploring the possibilities of usage of this composite in optical devices.

Effect of cycle numbers on the structural, linear and nonlinear optical properties in Fe2O3 thin films deposited by SILAR method

Fe2O3 thin films were deposited by Successive Ionic Layer Adsorption and Reaction (SILAR) method onto glass substrates at different cycle numbers to investigate structural, linear and nonlinear optical properties. X-Ray Diffraction (XRD) analysis revealed that the Fe2O3 thin films have a non-crystalline nature. The morphological properties of the films were investigated by Field Emission-Scanning Electron Microscopy (FE-SEM) and the results show that the films’ surfaces are porous. The linear and nonlinear optical parameters were evaluated and analyzed by using transmittance and absorbance measurements. For these measurements, UV–Vis spectroscopy at room temperature was used. The refractive index values were calculated in the range of 1.45–3.23 for visible region (400–700 nm). Obtained results reveal that direct optical band gap changed between 2.62 and 2.68 eV and indirect optical band gap changed between 1.67 and 1.77 eV. Additionally, optical electronegativity, optical dielectric constants, surface and volume energy loss functions, nonlinear refractive index, linear optical susceptibility, third-order nonlinear optical susceptibility, optical and electrical conductivity, and loss tangent values were calculated and discussed in detail. It was found that each parameter studied is dependent on the cycle numbers. Also, it can be stated that Fe2O3 thin films are promising candidate for solar cells and optoelectronic device technology.

Coupling the graphene plasmonic with terahertz emission of truncated conic-shaped InAs/GaAs quantum dots: A passive approach to enhance the intersubband optical properties

Graphene plasmonic (GP) concentrates the electromagnetic waves in small zones beyond the optical diffraction limit. This effect provides strong interactions of radiation with atomic and molecular systems in the vicinity. Here, in this work, we use GP effect to enhance the intersubband optical response of truncated conic-shaped InAs/GaAs quantum dots (QDs) attached to wetting layer (WL). Monolayer graphene flakes with triangular geometries arranged in various configurations are located in the QDs to intensify the electric field and consequently to couple GP with terahertz radiation of QDs. The results show 120-fold enhancement in S-to-P transition dipole moment (TDM) and 1.3 × 10 4 and 6.5 × 10 7 times enhancements, respectively, in the linear and third-order optical susceptibility of QDs. The optimal QDs are those with height of 5 nm and base length of 10 nm. The results of this work are promising to improve the performance of QD-based lasers, detectors, light emitting diodes (LEDs), etc. • Graphene flakes in triangular geometry have been placed in trancated conic-shaped InAs/GaAS quantum dots (QDs). • The emission of QDs has been tuned with graphene plasmonic (GP). • With use of GP effect, S-to-P transition dipole moment (TDM) of QD has been enhanced 120 times. • Linear susceptibility of QD has been multiplied by a factor of 1.3 × 10 4 . • Third-order susceptibility of QD has been multiplied by a factor of 6.5 × 10 7 .