Nonlinear Refractive Index N2 Research Articles

Exploring the influence of sudan IV Azo dye on the structural, optical, and dispersion characteristics of PVA/Su-IV composites

Flexible polymeric film composites consisting of polyvinyl alcohol (PVA) and Sudan IV azo dye (Su-IV) were synthesized using a casting method. Despite the known optical properties of PVA and azo dyes individually, the combined effects of Su-IV doping in PVA on the material’s optical and nonlinear optical properties have not been thoroughly investigated. This study addresses this gap by exploring the interactions between PVA and Su-IV at various doping concentrations (0.1–0.8 wt%) and their subsequent impact on the material’s structural and optical characteristics. Fourier transform infrared (FTIR) spectroscopy was employed to identify distinct vibrational groups within the composites, revealing that the incorporation of Su-IV induced random deviations in most absorption intensities compared to pristine PVA. Notably, new peaks at 519 and 444 cm−1 emerged, intensifying with increasing Su-IV concentrations, indicating significant interactions between the composite constituents. The optical properties were analyzed through transmittance and reflectance measurements, which uncovered new absorption peaks at 518 and 357 nm in PVA/Su-IV composites. These peaks correspond to electronic energy transitions of 2.4 and 3.6 eV, respectively, and their intensities increased with higher Su-IV content. Additionally, the indirect and direct bandgaps were decreased as Su-IV concentrations increased. The refractive index (n) analysis showed typical dispersion behavior between 850 and 2500 nm, aligning with the Wemple-DiDomenico (WDD) model. Furthermore, the oscillator parameters were calculated. Also, the nonlinear optical susceptibility (χ(3)) was boosted from 4.19 × 10−6 for pure PVA to 3.60 × 10−4 for the sample with 0.8 wt% Su-IV. The nonlinear refractive index (n2) was also measured at 8.55 × 10−2 for the doped sample. These findings demonstrate the potential of PVA/Su-IV composites for applications in nonlinear optics and photonics.

Boosting third-order optical nonlinearity in ITO/Au multilayer films via interfacial effects

We present the enhancement of third-order optical nonlinearity in indium tin oxide (ITO)/Au multilayer films via interfacial effects. The overall thickness of prepared ITO and Au layer was kept as 200 nm and 14 nm, respectively, and thus multilayers are 214 nm, i.e., for the sandwich structure ITO/Au/ITO, the thickness of ITO and Au is 100 nm and 14 nm, respectively, while the thickness of ITO and Au is 40 nm and 3.5 nm in the nine-layer films composed of five layers of ITO and four layers of Au. The measured nonlinear refractive index (n2) and absorption coefficient (β) of the multilayers rise as the number of layers increases. The maximum n2 and β in the nine-layer film are 2.6×10−14 m2/W and −3.7×10−8 m/W, which are 3.8 and 2.3 times larger than the values in the pure ITO film, respectively. Such enhancement of optical nonlinearity as the number of layers increases originates from the increase of carrier concentrations in multilayers due to contact of metals/semiconductors (interfacial effects), not following the traditional effective media theory and epsilon-near-zero effect. The results pave a way to modulate the optical nonlinearity in special metal-dielectric multilayers of interfacial effects and indicates the promising applications in nonlinear photonics.

An Investigation of the Photonic Application of TeO2-K2TeO3-Nb2O5-BaF2 Glass Co-Doped with Er2O3/Ho2O3 and Er2O3/Yb2O3 at 1.54 μm Based on Its Thermal and Luminescence Properties.

A glass composition using TeO2-K2TeO3-Nb2O5-BaF2 co-doped with Er2O3/Ho2O3 and Er2O3/Yb2O3 was successfully fabricated. Its thermal stability and physical parameters were studied, and luminescence spectroscopy of the fabricated glasses was conducted. The optical band gap, Eopt, decreased from 2.689 to 2.663 eV following the substitution of Ho2O3 with Yb2O3. The values of the refractive index, third-order nonlinear optical susceptibility (χ(3)), and nonlinear refractive index (n2) of the fabricated glasses were estimated. Furthermore, the Judd-Ofelt intensity parameters Ωt (t=2,4,6), radiative properties such as transition probabilities (Aed), magnetic dipole-type transition probabilities (Amd), branching ratios (β), and radiative lifetime (τ) of the fabricated glasses were evaluated. The emission cross-section and FWHM of the 4I13/2→4I15/2 transition around 1.54 μm of the glass were reported, and the emission intensity of the visible signal was studied under 980 nm laser excitation. The material might be a useful candidate for solid lasers and nonlinear amplifier devices, especially in the communications bands.

Investigation on Physicochemical Properties of Nonlinear Optical (NLO) Single Crystal: Rubidium Hydrogen Fumarate

A solvent evaporation method produced an optically high-quality semiorganic single crystal of Rubidium hydrogen fumarate (RbHF) at room temperature. The structural analysis reported that the RbHF crystallized in triclinic crystal system with centrosymmetric space group P1¯. The Powder XRD pattern indicates the grown crystal have good crystalline nature. FTIR spectroscopy examined the functional group and bonding in the grown molecule. A optical transparency of about 88% were observed in RbHF and having energy bandgap of 3.9 eV were calculated using Tauc’s plot. The grown crystals were thermally stable upto 170°C. Mechanical and dielectric analysis has been carried and their properties were discussed in detail. Intermolecular interactions were studied using Hirshfeld surface maps and 2D fingerprint plots. The grown crystal have positive photoconductivity nature. A Z-scan were used to study the third order NLO response in RbHF crystal. The third order nonlinear susceptibility of RbHF crystal was estimated as (χ3) = 1.60244 × 10-08 esu, nonlinear absorption coefficient (β) = 6.39395 × 10-5 cm2/W and nonlinear refractive index (n2) = 9.15822 × 10-12 cm/W. The observed results of the RbHF single crystal show, it has the potential application in optical and optoelectronic devices.

Comprehensive study of linear and nonlinear optical properties of polyaniline-Al2O3 nanocomposites for optoelectronic applications

This study explores the synthesis of polyaniline-aluminum oxide nanoparticle (PANI-Al₂O₃ NPs) hybrid nanocomposites. An optimized electrochemical polymerization technique was employed to incorporate varying concentrations (5, 10, 15, and 20 wt.%) of Al₂O₃ NPs into the PANI matrix. Comprehensive characterization focused on structural, dielectric, and optical properties, both linear and nonlinear. Williamson-Hall (W-H) analysis revealed average crystallite sizes ranging from 57 nm for pure PANI to 119 nm for 20 wt.% Al₂O₃ nanocomposites. The initial incorporation of a small amount of Al₂O₃ NPs reduced crystallite size, indicating interactions with PANI chains. However, further addition of Al₂O₃ NPs reversed this trend, resulting in increased crystallite size due to NPs aggregation. The Urbach energy, which reflects the width of the tail of localized states in the band gap, increased from 446 meV for pure PANI to 528 meV for 20 wt.% Al₂O₃. Optical bandgap energies showed a slight decrease from 2.56 eV to 2.53 eV for Eg1 and from 3.70 eV to 3.85 eV for Eg2 as Al₂O₃ concentration increased. Furthermore, the plasma frequency resonance (ωₚ) of the materials decreased from 6.68×109 Hz for pure PANI to 3.69×109 Hz for 20 wt.% Al₂O₃, highlighting the impact of Al₂O₃ incorporation on electronic properties. Quantitative evaluation of optical properties revealed substantial improvements. The third-order nonlinear susceptibility (χ³) increased from 2.5 × 10−11 to 7.7 × 10−11 e.s.u. at 15 wt.% Al₂O₃, and the nonlinear refractive index (n₂) increased from 5.8 × 10−10 to 1.9 × 10−9 e.s.u. These findings underscore the potential of Al₂O₃ NPs in enhancing the physical and optical properties of PANI, establishing these nanocomposites as promising candidates for advanced optoelectronic applications.

Using Femtosecond Laser Pulses to Explore the Nonlinear Optical Properties of Ag/Au Alloy Nanoparticles Synthesized by Pulsed Laser Ablation in a Liquid.

Metallic nanoparticles have gained attention in technological fields, particularly photonics. The creation of silver/gold (Ag/Au) alloy NPs upon laser exposure of an assembly of these NPs was described. First, using the Nd: YAG pulsed laser ablation's second harmonic at the same average power and exposure time, Ag and Au NPs in distilled water were created individually. Next, the assembly of Ag and Au NP colloids was exposed again to the pulsed laser, and the effects were examined at different average powers and exposure times. Furthermore, Ag/Au alloy nanoparticles were synthesized with by raising the average power and exposure time. The absorption spectrum, average size, and shape of alloy NPs were obtained by using an ultraviolet-visible (UV-Vis) spectrophotometer and transmission electron microscope instrument. Ag/Au alloy NPs have been obtained in the limit of quantum dots (<10 nm). The optical band gap energies of the Ag/Au alloy colloidal solutions were assessed for different Ag/Au alloy NP concentrations and NP sizes as a function of the exposure time and average power. The experimental data showed a trend toward an increasing bandgap with decreasing nanoparticle size. The nonlinear optical characteristics of Ag/Au NPs were evaluated and measured by the Z-scan technique using high repetition rate (80 MHz), femtosecond (100 fs), and near-infrared (NIR) (750-850 nm) laser pulses. In open aperture (OA) Z-scan measurements, Ag, Au, and Ag/AuNPs present reverse saturation absorption (RSA) behavior, indicating a positive nonlinear absorption (NLA) coefficient. In the close-aperture (CA) measurements, the nonlinear refractive (NLR) indices (n2) of the Ag, Au, and Ag/Au NP samples were ascribed to the self-defocusing effect, indicating an effective negative nonlinearity for the nanoparticles. The NLA and NLR characteristics of the Ag/Au NPs colloids were found to be influenced by the incident power and excitation wavelength. The optical limiting (OL) effects of the Ag/Au alloy solution at various excitation wavelengths were studied. The OL effect of alloy NPs is greater than that of monometallic NPs. The Ag/Au bimetallic nanoparticles were found to be more suitable for optical-limiting applications.

Femtosecond nonlinear optical properties of Ti-doped In2Te3 thin films grown by magnetron co-sputtering

Herein, we successfully prepared Ti-doped In2Te3 and pure In2Te3 films by magnetron co-sputtering at room temperature. The film structure was measured using x-ray diffraction (XRD), scanning electron microscopy (SEM) equipped with energy dispersive x-ray spectroscopy (EDS), and x-ray photoelectron spectroscopy (XPS), while the linear optical constant of the films was measured using a spectroscopic ellipsometer (SE). The nonlinear optical properties of the films were examined using the Z-scan technique, wherein the samples were irradiated with 140 fs laser pulses at a wavelength of 800 nm and a repetition rate of 80 MHz, with an input intensity of 1.2GW/cm2. Ti incorporation led to decreased crystallinity and a reduction (redshift) in the optical bandgap (E g ). All films exhibit reverse saturation absorption (RSA) and self-focusing effect. A ninefold increase in the nonlinear refractive index (n2) and a fourfold increase in the nonlinear absorption coefficient (β) were observed for the Ti-doped S40 sample in comparison to the pure S0 sample. Adjusting the phase transition between amorphous and crystalline states in Ti-doped In2Te3 films further modulated their nonlinear optical properties. The optical limiting (OL) behavior of pure In2Te3 and Ti-doped In2Te3 thin films was investigated, and the results demonstrated that Ti-doped In2Te3 films show great promise as optical limiter devices in nonlinear photonics.

Characterizing of PVA/CMC/MWCNTs nanocomposite films doped Zn0.9Ni0.1S nanoparticles for comprehensive γ-ray radiation shielding performance

Nanocomposite films were prepared from Carboxymethylcellulose (CMC), Polyvinyl alcohol (PVA) polymers and multi-walled carbon nanotubes (MWCNTs) using the casting technique. The resulting PVA/CMC/MWCNTs nanocomposite films have been incorporated with various concentrations of the Zn0.9Ni0.1S nanoparticles. The γ-ray radiation shielding capabilities of the films were discussed in details for various gamma sources using the Phy-X/PSD software in the energy range (0.015–15 MeV). The linear (LAC) and mass (MAC) attenuation parameters, the half-value layer (HVL), the tenth value layer (TVL), the effective atomic number (Zeff) were determined. The γ-ray buildup factors, were also determined for different penetration depths in the range (0.5–40 MFP). Results showed that, the shielding parameters are greatly affected by the density of the samples and the PVA/CMC/MWCNTs samples have the highest shielding ability in the energy region ranges (0.015–0.2 MeV) and (5–15 Mev). The structural and chemical characteristics of the films and the nanoparticles were examined using X-ray diffraction technique. The films elemental composition and morphology were discussed using energy-dispersive X-ray spectroscopy (EDX) and scanning electron microscope (SEM) techniques, respectively. The linear and nonlinear optical properties, including the extinction coefficient (K), the energy gap (Eg), the refractive index (n), the dielectric parameters, nonlinear susceptibilities(χ(1), χ(3)) and nonlinear refractive index (n2), were discussed by UV–Vis spectroscopy's absorbance and transmittance spectra. A reduction in Eg values from 4.55 eV to 4.5 eV and 4.41 eV for films doped with 1 wt% and 3 wt% of Zn0.9Ni0.1S. The uniform distribution of the added nanoparticles at 5 wt% has been confirmed. The energy dispersion parameters confirmed a higher probability of electronic transitions at low energy due to the intermolecular modifications.

Impact of doping with organic dopants and mixed doping with alkali metals and organic dopants on the absorption, electronic, optoelectronic, thermodynamic and nonlinear optical properties of dibenzo[b,def]chrysene in gaseous media: DFT and TD-DFT studies.

In this study, we evaluate the geometrical, absorption, optoelectronic, electronic, nonlinear optical (NLO) and thermodynamic properties of dibenzo[b,def]chrysene molecule derivatives by means of DFT and TD-DFT simulations. In view of the aim of producing new high-performance materials for non-linear optics (NLO) by doping test, two types of doping were used. We obtained six derivatives by doping with organic dopants (Nitro, amide and ticyanoethenyl) and mixed alkali metal (potassium) and organic dopants. Doping with organic dopants produced molecules A, B and C, respectively when substituting one hydrogen with nitro (NO2), amide (CONH2) and tricyanoethenyl (C5N3) groups, while mixed doping involved considering A, B and C and then substituting two hydrogens with two potassiums to obtain compounds D, E and F respectively. The negative values of the various interaction energies calculated for all the doped molecules show that they are all stable, but also that molecules C and F are the most stable in the case of both dopings. The gap energies calculated at the B3LYP level of theory are all below 3eV, which means that all the molecules obtained are semiconductors. Better still, compounds C and F, with gap energies of 1.852eV and 1.204eV, respectively, corresponding to decreases of 35.67% and 58.18% in gap energy compared with the pristine molecule, are more reactive than the other doped molecules. Mixed doping is therefore a highly effective way of narrowing the energy gap and boosting the semiconducting character and reactivity of organic materials. Optoelectronic properties have also been improved, with refractive index values higher than those of the reference material, glass. This shows that our compounds could be used under very high electric field conditions of the order of 4.164 109V.m-1 for C and 7.410 109V.m-1 for F the highest values at the B3LYP level of theory. The maximum first-order hyperpolarizability values for both types of doping are obtained at the CAM-B3LYP level of theory by C: 10-30esu and by F: 10-30esu, and second-order values are also given by these same compounds. These values are higher than the reference value, which is urea, making our compounds potential candidates for high-performance NLO applications. In dynamic mode and at a frequency of 1064nm, at the CAM-B3LYP level of theory, the highest dynamic hyperpolarizability coefficients were obtained by C and F. Hyper-Rayleigh scattering , coefficients of the electro-optical Pockel effect (EOPE), EFISHG, third-order NLO-response degree four-wave mixing , quadratic nonlinear refractive index n2 were also calculated. The maximum values of n2 are obtained by C (6.13 10-20 m2/W) and F (6.60 10-20 m2/W), these values are 2.24 times higher than that of fused silica which is the reference for degenerate four-wave mixing so our molecules could also have applications in optoelectronics as wavelength converters, optical pulse modulators and optical switches. Using the DFT method, we were able to determine the optimized and stable electronic structures of doped dibenzo[b,def]chrysene derivatives in the gas phase. We limited ourselves to using the proven B3LYP and CAMB3LYP levels of theory for calculating electronic properties, and non-linear optics with the 6-311G + + (d,p) basis set, which is a large basis set frequently used for these types of compound. Gaussian 09 software was used to run our calculations, and Gauss View 6.0.16 was used to visualize the output files. TD-DFT was also used to determine absorption properties at the B3LYP level of theory, using the same basis set.

Structural, linear/nonlinear optical characteristics and radiation shielding effectiveness of Cu4O3/Cu2O dual-phase thin films: Influence of oxygen flow rate in reactive sputtering process

In the present work, we investigated the impact of oxygen flow rate on the structural, linear, and nonlinear optical characteristics while also evaluating the radiation shielding effectiveness during reactive radio frequency (rf) sputtering in the deposition of Cu4O3/Cu2O dual-phase thin films. Microstructural analysis revealed distinct changes with increased OFRs, switching from a Cu2O cubic structure phase to a Cu4O3 tetragonal structure phase. The XRD patterns revealed good crystallinity, and the crystallite size of the film reduced from 28 nm to 22 nm, and the microstrain exhibited an opposing trend as the oxygen flow rate increased. In contrast, investigating the optical properties of dual-phase Cu4O3 and Cu2O thin films using UV–Vis–NIR spectroscopy revealed intriguing trends in the absorbance spectra, absorption coefficient, and extension index. The apparent bandgap increases from 2.0 eV to 2.62 eV with increasing oxygen flow rates. In addition, nonlinear optical parameters, including the nonlinear refractive index n2 linear, nonlinear sensitivity (χ1 and χ3), and nonlinear absorption coefficient βc were calculated to demonstrate the applicability of these materials. The dual-phase structure of the films enhances their potential for effective radiation shielding. Our findings provide valuable insights into the design of properties of Cu4O3/Cu2O dual-phase thin films for applications ranging from photoelectric and nonlinear optical devices to radiation shielding effectiveness.

Comprehensive investigation of 2-methylquinolinium-5-sulphosalicylate monohydrate: Synthesis, characterization, multifaceted analysis of molecular structure, optical, and nonlinear optical properties

We introduce the synthesis and characterization of a novel molecular salt crystal, 2-methylquinolinium-5-sulphosalicylate monohydrate (MQSSA), obtained through an equimolar reaction between donors (D) and acceptors (A) employing crystal engineering principles. The resulting proton transfer complex, MQSSA, crystallized into a monoclinic crystal system with space group P21/C, as revealed by SCXRD analysis. Significant peaks observed in PXRD analysis confirmed the crystallinity and purity of the material. FT-IR and FT-Raman spectroscopy were employed to analyze various functional groups present in the molecule. UV–Vis-NIR spectroscopy provided insights into absorbance transmittance, lower cutoff wavelength, and optical band gap, suggesting it's suitability for diverse optical applications, while characteristic emission was identified using PL measurements. Thermal stability was assessed via TG-DTA and TG-DSC techniques. Nonlinear absorption coefficient (β), nonlinear refractive index (n2), and third-order nonlinear susceptibility (χ3) were quantified using the Z-scan technique. Hirshfeld surface analysis and fingerprint plots were utilized to gain insight into intermolecular interactions and atomic arrangements within the MQSSA crystal, emphasizing the roles of crystal structure in H...H and O...H/H...O interactions. Additionally, quantum computational methods were employed to evaluate various molecular-level electronic characteristics, including molecular orbitals, molecular electrostatic potential maps, and first and second-order nonlinear optical (NLO) polarizability, providing insights into the molecular-level NLO response properties.

Band-gap tailoring and third-order optical nonlinearity enhancement through B-site V doping in SrSnO3 films

Perovskite oxide vanadium-doped strontium stannate (SrSn1-xVxO3) thin films with different concentrations x = 0.1–0.9 were fabricated by using pulsed-laser deposition, and the effects of V doping on the structure, optical band gap and the third-order optical nonlinearity were systematically investigated. With the increase of x value, the lattice parameters of SrSn1-xVxO3 decrease from 3.997 to 3.862 Å gradually, while the optical band gaps firstly increase from 4.18 to 4.26 eV, and then decrease to 3.66 eV with a boundary at x = 0.3. The third-order nonlinear optical responses were studied via the z-scan technique. The closed-aperture measurements show a negative nonlinear refractive index n2, and the open-aperture measurements demonstrate a saturable absorption β. Both n2 and β responses vary with the increase of V doping level. The maximum values of n2and β are 2.01×10−13 m2/W and 7.66×10−8 m/W, respectively, which are observed in the SrSn0.5V0.5O3sample. The metal-oxygen chemical bond along with the localized V5+Sn2+V5+complex contribute to the enhancement of optical nonlinearity.

Silicon nanocrystal slab optical waveguide by multi-energy ion implantation: Linear and nonlinear optical properties

Silicon nanocrystals (Si-nc) have gained attention in optics and photonics research areas in recent years due to their advanced optical nonlinear properties. However, a nonlinear integrated optical platform that allows the fabrication of photonic devices with different Si-nc composition is yet under investigation. In this work, we experimentally demonstrated a nonlinear optical waveguide based on ion implantation that offers advantages in terms of material composition, low propagation losses, and enhanced nonlinear optical properties, such as a high nonlinear refractive index. In this work we present the fabrication of Si-nc containing waveguiding structures, and a study of their linear and nonlinear optical properties. Our nonlinear integrated optical platform presents a two-photon absorption coefficient β = 3.17 × 10−6 cm W−1 and a nonlinear refractive index n2 = 1.19 × 10−10 cm2 W−1, which shows potential applications in all-optical signal processing devices, such as single-photon sources.

Growth of L asparagine monohydrate doped potassium dihydrogen phosphate semiorganic crystals and its structural, thermal and optical properties

A novel semiorganic crystal is harvested by doping organic amino acid L asparagine monohydrate (LAM) with inorganic compound Potassium dihydrogen phosphate (KDP) by adopting slow evaporation method. Rietveld refinement of the XRD data was performed and the structural study exhibits single phase nature of the LAM doped KDP (LAM-KDP) crystals with a slight decrease in c-axis of the unit cell parameters. Other crystallographic parameters such as crystallite size and strain were also evaluated. The interaction of LAM with KDP was studied from FT-IR analysis by detecting functional groups. The constituting elements of the crystal were identified by energy dispersive X-ray (EDX) analysis. Etching study has been employed to study surface morphology of these crystals. From UV–vis transmittance data, optical band gap and different optical constants like Urbach energy, dielectric constants, electrical and optical conductivities were evaluated. Optical transparency of the LAM-KDP crystals is observed to increase. The third order nonlinear susceptibility χ(3) and nonlinear refractive index n2 of the grown crystals have been predicted using empirical Miller's rule. The value of χ(3) has increased from 1.87 × 10−13 esu to 4.29 × 10−13 esu due to LAM doping. Change in enthalpy (ΔH), change in Gibb's free energy (ΔG) and activation energy Ea during chemical reaction were calculated by thermogravimetric analysis (TGA). Thermal decomposition characteristics of the crystals were analyzed by differential scanning calorimetry (DSC). The high transparency of LAM-KDP crystals in the entire visible spectrum and larger values of nonlinear susceptibility χ(3) and nonlinear refractive index n2 make the synthesized crystal applicable for NLO and optoelectronic devices applications.

Characterizing the properties of Li2O–B2O3–SiO2– P2O5–TiO2 glasses: A multidimensional investigation of their structure, optical properties, and gamma-ray shielding capability

A series of lithium borophosphosilicate glass doped with TiO2 was produced with melt-quenching procedure with empirical formula (20-x) Li2O–40B2O3–20SiO2– 20P2O5–xTiO2, where x can be changed between 0 and 16 mol%. By adding titanate, the bulk density of BSPLT glass increased from 3.61 to 4.812 g/cm3. The amorphous nature of glasses is demonstrated by XRD analysis. Different optical characteristics, including the refractive index and optical band gap (Eopt), were determined by recording optical absorption spectra in the 250–2500 nm range. The observed range (Eopt) values from 3.09 eV to 2.64 eV suggests that the (Eopt) decreases as the content of TiO2 in the BSPLT samples increases. The linear optical susceptibility χ(1), third-order non-linear optical susceptibility (χ(3)), and the non-linear refractive index (n2) were determined. Higher-density glasses provide more effective radiation shielding because they are better at absorbing and slowing down radiation particles. BSPLT-16 glass exhibits the highest FNRCS value among the samples tested, indicating its superior performance in shielding against fast neutrons. It is noted that the BSPLT-16 sample, has the highest density among the glasses tested, shows the greatest effective for radiation shielding applications according to the results.

Novel third order nonlinear optical stilbazolium crystal replaced with 3-methoxy benzaldehyde as donor for optical device applications

A novel organic nonlinear optical stilbazolium group single crystal of 1-methyl-2-[2-(3-methoxystyryl)]-pyridinium iodide (subsequently referred to as MSMI) was grown by the solution growth technique using the method of slow evaporation at ambient temperature. The Single-crystal XRD investigation indicates that the MSMI crystal belongs to a monoclinic crystal system with a centrosymmetric space group. CHN elemental analyser confirms the weight percentage of carbon (C = 51.00 %) hydrogen (H = 4.55 %) and nitrogen (N = 3.94 %) in the MSMI crystal structure. The presence of 16 hydrogen atoms and 15 carbon atoms in the MSMI was affirmed by the Nuclear Magnetic Resonance (NMR) spectroscopic analysis. Fourier Transform Infrared (FTIR) studies confirmed the fundamental vibrations for different functional groups found in the MSMI crystal. The Hirsfeld surface analysis figured out the hydrogen bond interaction and π…π interaction which supports the stability of the crystal structure. The crystal is found to exhibit transmittance of wavelength above 400 nm and has a band gap of 3.05 eV ascertained from UV–Vis-NIR spectroscopic analysis. Photoluminescence (PL) studies reveal that the title crystal has an emission wavelength of 572 nm. The surface characteristics of the title crystal were examined by Atomic Force Microscopy (AFM), and etching studies. The value of Meyer's number is n = 1.8 which is determined by the Vickers microhardness studies. The value of the third-order nonlinear refractive index (n2) is 4.662×10−8 cm2/W, the nonlinear absorption coefficient (β) is 1.305×10−3 cm/W, nonlinear susceptibility (χ(3)) is 9.297×10−5 esu and the optical limiting threshold is 11.43 J/cm2 was ascertained form the Z-scan technique. The results indicate that the MSMI crystal is a potential optical limiter and has promising applications in nonlinear optical devices.

Improvements of multifunctional spintronic and optoelectronic applications of nanostructured Eu-doped ZnS thin films through magnetic and linear, nonlinear optical investigations

This study describes the spintronic and optoelectronic improvements upon Eu substitution in Zn atomic site of the nanostructure ZnS thin films. The electron beam deposition technique has been used to deposit a series of Zn1-xEuxS thin films on a glass substrate with different Eu dopants (x = 0, 0.01, 0.03, 0.05, and 0.08). The nanostructure nature of the Eu-doped ZnS thin film has been confirmed from structural and morphology studies performed by the X-ray diffraction (XRD) and atomic force microscope (AFM) measurements. XRD investigations further show a hexagonal-type structure with no detectable extra phases with the lattice parameter c increasing, while a decrease linearly with increasing Eu-dopant in the ZnS hosted lattice. The microstructures analysis reveals a reduction in the mean crystallite size and increasing in the lattice strain of the films with rising Eu doping. The Fourier transform infrared spectra display the existence of chemical bonds in the thin films whereas photoluminescence reveals near-band edge emission. The linear optical parameters were obtained from the analysis of the transmission data measured by the spectrophotometer technique. The results reveal that the band gap energy (EgOpt) reduces by raising ohe Eu doping ratio, which is ascribed to the structural deformation (strain and/or defects) confirmed from structural analysis, density of localized states and PL measurements. The index of refraction n was calculated using the Swanepoel method. The values were found to increase as the level of Eu doping grows, which is associated with the rise in polarizability. Wemple and DiDomenico's (WDD) model was utilized to compute the dispersive and oscillator energies (Eo, and Ed), the nonlinear absorption coefficient βc, nonlinear refractive index n2, and nonlinear optical susceptibility χ3. The results demonstrate that the adjustability of EgOpt , Eo, and Ed of ZnS: Eu films is conducted to improve the nonlinear optical characteristics, providing it well-suited for optoelectronic device implementations. On the other hand, ZnS doped with Eu film displays inherent ferromagnetic properties at room temperature, as evidenced by the results of the magnetic investigation. This finding could be attributed to the presence of sulphur defects (vacancies), as supported by photoluminescence (PL) measurements, which lead to the creation of the bound magnetic polaron. These discoveries indicate the potential of utilizing Eu-doped ZnS film in the effective development of spintronic devices.

Defects assisted the enhancement of optical and ferromagnetism in Zn1-xCoxS quantum dots: Toward efficient optoelectronic and spintronic applications

Colloidal Co-doped ZnS Quantum dots (QDs) were successfully synthesized through a facile and effective chemical co-precipitation method using polyethylene glycol (PEG) as a capping agent. A comprehensive study on the structure, optoelectronic, and magnetic properties of ZnS: Co2+ QDs was thoroughly carried out using diverse characterization techniques. Transmission electron micrographs reveal spherical QDs with a mean particle size of 5 ± 0.5 nm, whereas the X-ray diffraction (XRD) analysis and Raman spectroscopy confirm the exclusive presence of cubic ZnS phase structure, without any signs of Co-related impurity phases. Energy-dispersive x-ray (EDX) analysis verifies the presence of only three elements: Zinc, Cobalt, and Sulphur, with nearly stoichiometric proportions. X-ray photoemission (XPS) analysis confirmed the presence of Co2+ ions in the divalent oxidation state as well as the fair existence of sulphur vacancies. Optical measurements demonstrate that Co-doping in ZnS leads to a decrease in the optical band gap owing to the presence of defects that create localized states within the band structure. In addition, the refractive index (n) is found to increase with Co-doping level due to the increase in the polarizability. The outcomes of optical properties reveal that the tunability of the optical band gap and dispersive oscillator parameters in Co-doped ZnS QDs results in an enhancement of the non-linear optical parameters, such as third-order non-linear optical susceptibility χ(3), and non-linear refractive index n2, rendering them well-suited for applications in optoelectronic devices. Furthermore, the room-temperature photoluminescence (PL) spectra revealed that the Co-doped ZnS QDs have two broad emission bands, including the blue emission, and the green emission. By varying the level of Co-doping, it becomes possible to effectively control the relative PL intensities of dual-color emissions, highlighting their potential for producing adjustable color outputs. The room temperature ferromagnetic behaviour of the QDs has been observed and analyzed in accordance with the bound magnetic polarons model. These findings suggest that Co-doped ZnS QDs can be utilized effectively in the design of spintronic devices.

Dispersion of two-photon absorption and nonlinear refraction in β -Ga2O3 from 350 to 515 nm

We report the wavelength dependencies of the two-photon absorption coefficients β as well as the nonlinear refractive index n2 of undoped β-Ga2O3 single crystal in the spectral range 350–515 nm (0.51 &amp;lt; Ephoto/Eg &amp;lt; 0.75). Femtosecond Z-scan measurements show that n2 decreases monotonically toward the shortwave side, while the maximum value of n2 is 5.0 × 10−19 m2/W near half of the bandgap, Eg. Interestingly, a second upward trend in β was observed when the incident photon energy is larger than 0.6Eg, indicating the impact of additional inter-band transitions with higher energy. A higher-energy band-to-band transition around 6.0 eV was determined by both femtosecond nondegenerate two-photon absorption spectroscopy and ab initio calculations. Our results could provide guidance for designing nonlinear β-Ga2O3 photonic devices in the UV-visible spectral range.

Ultrafast Dynamics, Optical Nonlinearities, and Chemical Sensing Application of Free-Standing Porous Silicon-Based Optical Microcavities.

The present work demonstrates the ultrafast carrier dynamics and third-order nonlinear optical properties of electrochemically fabricated free-standing porous silicon (FS-PSi)-based optical microcavities via femtosecond transient absorption spectroscopy (TAS) and single-beam Z-scan techniques, respectively. The TAS (pump: 400 nm, probe: 430-780 nm, ∼70 fs, 1 kHz) decay dynamics are dominated by the photoinduced absorption (PIA, lifetime range: 4.7-156 ps) as well as photoinduced bleaching (PIB, 4.3-324 ps) for the cavity mode (λc) and the band edges. A fascinating switching behavior from the PIB (-ve) to the PIA (+ve) has been observed in the cavity mode, which shows the potential in ultrafast switching applications. The third-order optical nonlinearities revealed an enhanced two-photon absorption coefficient (β) in the order of 10-10 mW-1 along with the nonlinear refractive index (n2) in the range of 10-17 m2 W-1. Furthermore, a real-time sensing application of such FS-PSi microcavities has been demonstrated for detecting organic solvents by simultaneously monitoring the kinetics in reflection and transmission mode.