Nonlinear Optical Applications Research Articles

Substituent effects on the emission quantum efficiency in pyrene-based luminogens featured two-photon absorption: A theoretical and experimental study

Pyrene-based luminogens have attracted significant attention for their potential applications in organic electronics, nonlinear optics and bioimaging. The attainment of a large two-photon absorption (TPA) cross section (σtpa) and a high emission quantum efficiency (Φf) are crucial goals in material design. However, the intrinsic modulation guidelines have rarely been revealed. In this study, we investigated the substituent effects on the excited-state properties in pyrene-based donor-π-acceptor (D-π-A) dyes. In the dimethyl sulfoxide (DMSO) solution, we performed first-principles calculations on σtpa, Φf and the TPA brightness (σtpa × Φf). The results demonstrate that both the H-parent compound and F-substituted derivative exhibit high Φf values. Nevertheless, they have low σtpa values due to the weak push-pull effect, resulting in small σtpa × Φf values in solution. Conversely, the CHO-substituted derivative has high σtpa and Φf values, leading to a large σtpa × Φf. However, the NMe2-substituted derivative possesses high σtpa but relatively low Φf owing to the small energy gap. Therefore, it has a modest σtpa × Φf in solution. In the solid state, we conducted experimental measurements to determine Φf. It is found that the solid powders of the H-, F- and CHO-substituted derivatives show considerably lower Φf values compared to the DMSO solution. In contrast, the NMe2-substituted derivative displays a higher Φf. The discrepant Φf values can be attributed to the different patterns in which the dimers pack themselves in the aggregated state. Our study not only provides a deep understanding for the photophysical properties of pyrene-based luminogens, but also lays the groundwork for the rational design of efficient two-photon fluorescent emitters.

Analyzing Soliton Solutions of the [formula omitted]-dimensional generalized Kadomtsev–Petviashvili equation: Comprehensive study of dark, bright, and periodic dynamics

This paper investigates the (n+1) dimensional integrable extension of the Kadomtsev–Petviashvili (KP) equation. The study focuses on extracting Auto-Bäcklund transformations for the given model using the extended homogeneous balance (HB) method in conjunction with Maple. These transformations are then employed to obtain explicit analytic solutions for the equation. Additionally, a Bilinear Bäcklund transformation is constructed based on the Hirota bilinear form, leading to the acquisition of exponential function solutions. Furthermore, complexiton solutions for the KP equation are obtained utilizing the bilinear form and the extended transformed rational function technique. The physical properties of the obtained solutions are explored through visualization techniques, including 3D, 2D, and contour plots. The analysis reveals the presence of dark, bright, and periodic solitons. The obtained solutions of the KP equation have practical applications in nonlinear optics, plasma physics, and wave propagation analysis.

Structural, electronic, optical and elastic properties of AgMO2 (M = K, Rb, Cs): ab initio investigation

Silver alkali oxides (AgMO2; M = K, Rb, Cs) properties are investigated in depth via pseudo-potential plane-wave (PP-PW) scheme within the density functional theory (DFT) framework. The reflectivity, loss function and all the elastic properties of AgKO2, AgRbO2, AgCsO2 compounds are newly studied here. As unveiled by the band structure the AgMO2 materials are indirect bandgap semiconductors. The density of states illustrates the covalent character of silver oxygen bonds (Ag–O). Moreover, the notable contribution of O-2p in the edge of the valence band provokes the delocalization of the holes, consequently improving the p-type conductivity in the studied compounds. Optically analyzed, our systems show birefringent behavior, with high positive Δn0, allowing them to be candidate in non-linear optical devices applications. The obtained elastic constants state that our materials are mechanically stable, with a pronounced anisotropic nature. Finally, from the thermal investigation, the three oxides AgKO2, AgRbO2 and AgCsO2 have lower thermal conductivity, synonymous of lower melting temperature.

AGe2O4Q (A = Ba, Sr; Q = S, Se): A series of heteroanionic oxychalcogenides with large birefringence

Heteroanionic materials are of current research interest owing to their varied structural chemistry and properties. Recently, a number of heteroanionic materials have been synthesized that can be used for water splitting, battery materials, thermoelectrics, and nonlinear optical applications. Birefringent heteroanionic materials are still rarely researched. Herein, we report a series of new oxychalcogenides, AGe2O4Q (A = Ba, Sr; Q = S, Se), that are synthesized by solid-state reactions in fused silica tubes with their structures determined by single-crystal X-ray diffraction. Optical property measurements show that AGe2O4Q (A = Ba, Sr; Q = S, Se) exhibit large birefringences, 0.13–0.19 @ 1064 nm. These are one-order of magnitude larger than their single-anionic homologue, BaGe2O5 - 0.03 @ 1064 nm. This suggests that constructing heteroanions through using chalcogenides to partially substitute O in tetrahedral foundation building units (FBUs) is a viable method for designing new birefringent materials. Furthermore, the crystal structures, UV–vis–NIR diffuse reflectance spectra, infrared and Raman spectra as well as the first-principles calculations for AGe2O4Q (A = Ba, Sr; Q = S, Se) are also reported.

Panchromatic and Perturbed Absorption Spectral Features and Multiredox Properties of Dicyanovinyl- and Dicyanobutadienyl-Appended Cobalt Corroles.

Four new β-functionalized π-extended cobalt corroles with one and two dicyanovinyl (DCV) or dicyanobutadienyl (DCBD) moieties at the 3- and 3,17-positions have been synthesized and characterized by various spectroscopic techniques. Interestingly, the synthesized DCV- and DCBD-appended cobalt corroles displayed panchromatic and near-infrared absorption in the range 300-1100 nm in CH2Cl2 and pyridine solvents. (MN)2-(Cor)Co and A2MN2-(Cor)Co exhibited 8-9 times enhancement in the molar absorptivity of the Q band compared to the parent corrole ((Cor)Co). The unique absorption spectral features of these β-functionalized cobalt corroles are splitting, broadening, and red-shifting in the Soret and Q bands. One DCV unit brings a 30-46 nm red shift, whereas one DCBD unit brings a 40-75 nm red shift in the Q band compared to the corresponding precursors. This is rare that the intensity of the longest Q band is greater than or equal to the Soret-like bands. These corrole derivatives exhibit UV-vis spectral features similar to those of chlorophyll a. A 220 mV positive shift per DCV group and 160 mV positive shift per DCBD group were observed in the first oxidation potentials compared to (Cor)Co in the desired direction for the utility of these cobalt complexes in electrocatalysis. DFT studies revealed that HOMO and LUMO were stabilized after appending DCV and DCBD groups on the corrole macrocycle and exhibited a "push-pull" behavior leading to promising material applications in nonlinear optics (NLO) and catalysis.

Synthesis, photophysical properties and nonlinear response of a bisquinoline A-D-A with aggregation-induced emission for potential application in optoelectronic devices

The present work reports the synthesis and characterization of a bisquinoline (BQT) with very attractive aggregation-induced emission (AIE) and optical nonlinear response. BQT was characterized by FTIR spectroscopy and mass spectrometry to confirm the product obtained. Linear optical characterization was performed using UV-Vis and fluorescence spectrophotometry. Maximum absorption and emission wavelengths of 408 nm and 539 nm, respectively, were determined in solution; the optical band gap on the film is 1.95 eV. BQT exhibits aggregation-induced emission (AIE), a property exhibited by some fluorescent molecules that broaden the range of applications in which they can be used. BQT exhibits two-photon absorption with a negative nonlinear refractive index. This response is associated with the charge transfer processes that favour the A-D-A architecture of the molecule. Their HOMO and LUMO energy levels (-5.39 eV and -3.67 eV, respectively) and electrochemical band gap (-1.72 eV) were determined by cyclic voltammetry; these values indicate that BQT is an attractive organic semiconductor which energy levels could match those required for photovoltaic applications. The results suggest that BQT is an attractive material for its application in optoelectronic devices such as OLEDs and nonlinear optical applications.

Tailored Dispersion and Nonlinear Effects in Flint Glass Honeycomb PCF for Optical Communication

This paper describes a highly nonlinear flint glass-based honeycomb photonic crystal fiber (FGH-PCF) with a wavelength of 1550 nm. The PCF’s distinctive honeycomb lattice structure, combined with the nonlinear capabilities of flint glass, enables a wide range of nonlinear optical applications. To adjust the PCF's dispersion and nonlinear effects, numerical simulations and optimization approaches were used. To achieve maximum performance, fabrication procedures were carefully regulated. Dispersion values of −436.6 ps/(nm.km) for x polarization and −448.1 ps/(nm.km) for y polarization were verified by experimental characterization. The PCF displayed low confinement losses of 2.289 dB/cm (x polarization) and 4.935 dB/cm (y polarization), as well as birefringence of 2.202×10-3. The PCF measured 558.8 and 547.9 W-1 km-1 for x and y polarization, respectively, indicating a high nonlinear coefficient. The highly nonlinear FGH-PCF shows promising potential for nonlinear optical applications such as four-wave mixing, supercontinuum generation, frequency conversion, and parametric amplification. This research paves the way for compact and efficient nonlinear devices in modern optical communication systems and other cutting-edge technologies.

Growth, optical, morphological, thermal, laser induced damage threshold, microhardness properties of an organic novel single crystal: Piperazinium 2-Furoate

The novel organic crystal Piperazinium 2-Furoate (P2F) was created using the slow evaporation method. The solubility test for the P2F was determined by gravimetric analysis. The nucleation kinetics such as metastable zone width, induction period and interfacial energy has been calculated. The novel crystallographic parameters were determined, the crystal has a position in the triclinic system and the cell parameters found to be a = 6.30 Å, b = 6.88 Å, c = 17.46 Å. The UV–Vis spectrum was analyzed and the crystal has a cut-off wavelength of 267 nm. The bandgap energy from Tauc's plot was identified to be 4.64 eV, and other optical parameters like refractive index, extinction co-efficient etc., were calculated. The vibrational spectral studies was analyzed using FTIR and FT-Raman analysis. The thermal analysis confirmed that the P2F crystal has good thermal stability upto 261 °C. The yellow luminescence is produced at 572 nm in the fluorescence analysis. The laser induced damage threshold value of the P2F crystal is 1.889 GW/cm2. The mechanical stability of the grown crystal was tested and it shows that the crystal belongs to soft material category. The EDX analysis confirmed the well combination of the crystal compound. The P2F's SEM micrographs confirmed that it has a micro-sized range irregular oval shaped and an uneven distribution. The nonlinear optical (NLO) property of P2F crystal confirm its suitability for higher order nonlinear optical applications.

Synthesis, crystal growth, structural, optical, and laser damage threshold characterizations on 2-amino-4,6-di­methyl­pyrimidinium hydrogen sulfate single crystal for nonlinear optical applications

2-Amino-4,6-di­methyl­pyrimidinium hydrogen sulfate (2AMPHS) organic single crystal was successfully grown by slow evaporation solution technique (SEST) for the first time. A good transparent 2AMPHS single crystal with dimensions of 5 mm × 5 mm × 2 mm was grown after a 25-day growth period. The 2AMPHS single crystals structural parameters were confirmed and well matched with the reported values. The good crystalline nature of 2AMPHS crystal was characterised using SXRD, PXRD, UV–Visible NIR, laser damage threshold, and third harmonic generation (THG). The optical property of 2AMPHS crystal was investigated by UV–visible-NIR analysis. Laser damage threshold analysis was performed with an Nd: YAG laser, and the laser wavelength is 1064 nm. The third harmonic generation study was analysed by a Z-scan study. The He-Ne laser source with a wavelength of 632.8 nm has used for Z-scan analysis.

Characterization of sol gel derived spin coated copper incorporation of CdS films for nonlinear optical applications

The sol-gel derived spin-coated Copper (Cu) doped cadmium sulphide (CdS) thin films were deposited on glass substrates. The structural, optical, electrical, and non-linear properties of the films have been investigated in detail. The crystal structure of the Cu-doped CdS films was found to be the hexagonal phase, and an improvement in the crystallinity was observed. The optical absorbance was found to change with deposition parameters, and the bandgap of the films was found to be 2.3 eV, which varied with doping and annealing. The photoluminescent properties of the films showed green and near band edge emission. The electrical characteristics of the Cu-doped CdS films were investigated by Hall effect measurements. The copper doped CdS thin films exhibited prominent NLO properties. The NLA coefficients β obtained are of the order of 10−9m/W. The nonlinear refractive index n2 and nonlinear susceptibility χ (3) values were found to be of the order of 10−11 esu.

Enhancing second harmonic generation of monolayer WS2 with edge plasmon

Transition-metal dichalcogenide (TMD) monolayers possess large second-order nonlinear susceptibility and have shown great potentials in on-chip nonlinear optical devices. However, the thickness of TMD monolayers is less than 1[Formula: see text]nm, resulting in a rather low second harmonic generation (SHG) efficiency. In this paper, we propose a physical scheme of enhancing SHG of TMD monolayers with edge plasmon. As a proof of concept demonstration, we constructed a hexagonal gold nanoplates/monolayer WS2 heterostructure with high interface quality. By performing SHG measurements, we show that SHG was enhanced by a factor of about 60. Our results set a foundation for on-chip nonlinear optical applications with TMD monolayers.

Tailoring the optical limiting response of methyl orange via protonation

In order to realize effective optical limiting (OL), it is necessary to utilize materials that exhibit distinct traits, such as a large and rapid nonlinear optical response, high photothermal stability, and cost-effectiveness. In the present study, the nonlinear optical (NLO) response of methyl orange (MO) is modified by inducing conformational and structural changes through appropriate modification of pH conditions. The NLO properties of MO under two different pH conditions were investigated via the z-scan technique under 7 nanoseconds excitation in the visible region (532 nm). From z-scan results, the nonlinear absorption coefficient of pristine MO and protonated-MO (P-MO) was estimated. Compared to MO, the nonlinear absorption coefficient of P-MO increased by 3.6 times, and it can be attributed to the redistribution of energy levels of MO, which favored resonant absorption in the system. Molecular energy shift and the corresponding apparent red shift in the absorption spectrum of MO are confirmed from both experimental and theoretical analysis. The mechanism behind the nonlinear absorption (NLA) and OL activity of MO is found to be effective two-photon absorption. The closed aperture (CA) z-scan data reveal a negative nonlinear refraction response of MO and P-MO. These findings suggest an efficient way to tune the NLO response of MO through protonation, and this method readily applies to numerous nonlinear optical applications, including but not limited to OL.

UiO-66 metal organic framework as stable platform for non-linear optical applications

We report on the experimental study the non-linear optical properties of UiO-66 metal-organic framework with high thermal and chemical stability. We demonstrate the coherent conversion of high-intensity incoming radiation into the third harmonics ranging from 450 to 600 nm. Moreover, eclipse z - scan of single UiO-66 microcrystals made it possible to determine the saturable absorption coefficient (βeff = −1.415·10-2 cm/GW at 515 nm and −3.865·10-1 cm/GW at 1030 nm), thereby, bringing UiO-66 to the list of nonlinear and stable MOFs for real-life photonic applications.

Theoretical study of static and frequency-dependent nonlinear optical properties of 1-phenyl-2,5-di(thiophen-2-yl)-1H-pyrrole based D-π-A chromophores through π-linkers modifications: A gateway towards giant nonlinear optical compounds

Designing materials with proficient nonlinear optical (NLO) amplitudes is the frontier area of research. To address the briskly mounted demand for potentially useful NLO materials in optoelectronic and electrical applications, static and frequency-dependent NLO response properties of 1-phenyl-2,5-di(thiophen-2-yl)-1H-pyrrole (PDTP) based D-π-A chromophores were computed at 1907.21 nm, 532 nm, and 1064 nm laser wavelength for exploring SHG β (−2ω, ω, ω) and EOPE β (−ω, ω, 0). The PDTP-based organic dye (MC28) is selected to serve as a reference, and the quantum chemical models of its ten derivatives (SLN1-SLN10) are constructed by incorporating a variety of previously reported π-linkers into the reference. DFT and TD-DFT calculations reveal that π-linker modification tunes the NLO characteristics in SLN1-SLN10. The photophysical, electronic aspects, molecular electrostatic potential (MEP), frontier molecular orbital (FMO), density of state (DOS), transition density matrix (TDM), natural population analysis (NPA), and frequency-dependent NLO response properties of investigated dyes were evaluated. Giant NLO responses due to a much lower energy gap than the reference dye was found in SLN1-SLN10 confirmed by FMO analysis. UV–Vis analysis determined that the maximum absorption wavelength of the studied dyes was in the visible spectrum (383–413 nm). The proposed dye’s active NLO sensitivity and charge separation state was shown to have resulted from the migration of electrons from D to A via π-linkers using natural population analysis (NPA) analysis. In addition, molecular electrostatic potential (ESP), electron localization function (ELF), and localized orbital locator (LOL) topological assessments are carried out to evaluate the transfer of charge that takes place within SLN1-SLN10 as well as high NLO features. Maximum values of linear polarizability (αo) and first-hyperpolarizability (βo) were calculated to be 5.64 × 102 a.u. and 1.89 × 104 a.u., respectively in SLN3. At 1907.21 nm, SLN3 with terthiophene linker showed a remarkable SHG β(−2ω,ω,ω) and EOPE β (−ω,ω,0) response of 2.60 × 104 a.u. and 2.09 × 104 a.u. respectively. The theoretical structure provided conclusive evidence that the dyes under investigation possess excellent static and NLO potential at different laser wavelengths and should be considered for use in future NLO applications.

Synthesis, Characterization, and Biological Evaluation of Bis(Aroyl Thiourea) Derivatives: Insights into Their Potential Applications through DFT Analysis

This study was aimed to synthesize and characterize a series of novel bis(thiourea) compounds (1–3) featuring ortho phenylenediamine substitutions and assess their potential biological properties. A range of analytical and spectroscopic techniques, including elemental analyses, UV–visible, FT-IR, NMR, and mass, were employed to confirm successful compound synthesis. Single-crystal X-ray diffraction was utilized to validate their crystal structures. Density functional theory calculations were conducted to compare optimized molecular geometries with experimental data. Furthermore, various molecular properties were assessed, indicating the potential suitability of these compounds for nonlinear optical applications. The compounds were also evaluated for their anticancer activity against MCF-7, A549, and Vero cells, demonstrating promising results. Additionally, the antioxidant properties of these new compounds were investigated using 1,1-diphenyl-2-picrylhydrazyl in spectrophotometric analysis. Compound 3 displayed notable antioxidant activity, evaluated in comparison with the standard drug ascorbic acid. In summary, this research introduces a promising series of compounds with potential applications in medicine and material science, without delving into specific numerical results and computational intricacies.

Nucleophilic transformation of 3-substituted-6,8-dimethylchromones with phenylhydrazine under various reaction conditions: Theoretical, spectroscopic characterization and in silico ADME studies

The chemical behavior of 3-substituted-6,8-dimethylchromones 1–3 was examined towards phenylhydrazine under various reaction conditions. Under different molar ratio, reaction of aldehyde 1 with phenylhydrazine produced hydrazone 4 and pyrazole 5. Depending on the solvent used, reacting carbonitrile 2 with phenylhydrazine produced a variety of products; through ring-opening and ring-closure mechanisms. Reaction of carboxamide 3 with phenylhydrazine, afforded chromeno[4,3-c]pyrazole derivative 8. Finally, boiling carboxamide 3 in KOH solution gave 4-hydroxy-6,8-dimethylcoumarin-3-carboxaldehyde (9). Molecular geometries were examined using density functional theory, (DFT/B3LYP) with 6–311 G(d,p) basis sets, to investigate the bond lengths of certain bonds. DFT was also used to compute some global reactivity descriptors including electronegativity (χ), chemical potential (μ), electrophilicity index (ω), softness (S) and hardness (η). Compound 4 is the softest, while compound 9 is more electrophilic and more electronegative. In addition, MEP surface maps were investigated to predict the chemical reactivity of the current molecules. The chemical shifts values of 1H and 13C NMR were assessed utilizing the GIAO method, and the results were compared with those obtained experimentally. The current compounds are appropriate for non-linear optical applications, according to their first order hyperpolarizability values which found 1.5–3 times greater than those of urea. SwissADME was used to explore the features of current compounds' absorption, delivery, metabolism, and excretion (ADME).

Synthesis, SC-XRD structure, spectroscopy, intermolecular interactions, DFT/TD-DFT investigation, and (static, dynamic) NLO properties of (2E,5Z)-3-(4-fluorophenyl)-2-(4-fluorophenylimino)-5-((E)-3-(2-nitrophenyl) allyliden) thiazolidin-4-one

This paper describes the synthesis of a novel fluorine-substituted thiazolidin-4-one compound, (2E,5Z) -3-(4-fluorophenyl) -2-(4-fluorophenylimino) -5-((E)-3-(2-nitrophenyl) allyliden) thiazolidin-4-one, abbreviated as F2NTh. Its structure was subsequently characterized by Fourier transform infrared (FTIR), 1H and 13C nuclear magnetic resonance (NMR), UV–Visible, and single crystal X-ray diffraction (SC-XRD). For a better comprehension of the electronic structure of F2NTh, experimental data collected from the X-ray diffraction pattern were then compared to theoretical results computed by the density functional theory (DFT) using both B3LYP and CAM-B3LYP functionals with a 6–311 G (d, p) basis set. Theoretical results exhibited a good correlation with those established through the experimental analysis. To identify intra- and intermolecular interactions, Hirshfeld surface (HS) and reduced density gradient (RDG) analyses were performed. The results, including 2D fingerprint plots, indicated that H…H interactions played a major role, accounting for 23.6 % of the overall intermolecular contacts. To investigate the charge transfer and ascertain the electronic properties of F2NTh, frontier molecular orbitals and global and local chemical reactivity descriptors were studied. By simulating the molecular electrostatic potential (MEP) and using MPA, NPA, ESP, and MC5 atomic charges, reactive sites within the molecule responsible for electrophilic and nucleophilic attacks were identified. Some thermodynamic parameters and functions (enthalpy, heat capacity, and entropy) obtained from spectroscopic data were also examined in the temperature range of 100−1000 K. Finally, to test the title molecule in the non-linear optical (NLO) domain, the corresponding properties were predicted using B3LYP and CAM-B3LYP functionals. The predicted static NLO parameters (μ = 4.93 D, α = 56.23×10−24 esu, β = 28×10−30 esu, and γ = 244.98 × 10−36 esu) revealed highly promising outcomes, exhibiting the molecule's utility in NLO applications. This activity was confirmed by the dynamic NLO parameters showing a high third-order response.

Influence of Sm doping on the optical, mechanical, electrical, thermal and z-scan analysis of sulphamic acid single crystal for nonlinear optical device applications

Influence of Sm doping on the optical, mechanical, electrical, thermal and z-scan analysis of sulphamic acid single crystal for nonlinear optical device applications

Crystal growth, structural, Hirshfeld surface analysis, optical and laser damage threshold analysis of 2-Methylimidazolium glutarate single crystal: third-order nonlinear optical applications

Crystal growth, structural, Hirshfeld surface analysis, optical and laser damage threshold analysis of 2-Methylimidazolium glutarate single crystal: third-order nonlinear optical applications

Design of High-Performance Organic Nonlinear Optical and Terahertz Crystals by Controlling the van der Waals Volume.

In the development of new organic crystals for nonlinear optical and terahertz (THz) applications, it is very challenging to achieve the essentially required non-centrosymmetric molecular arrangement. Moreover, the resulting crystal structure is mostly unpredictable due to highly dipolar molecular components with complex functional substituents. In this work, new organic salt crystals with top-level macroscopic optical nonlinearity by controlling the van der Waals volume (VvdW ), rather than by trial and error, are logically designed. When the VvdW of molecular ionic components varies, the corresponding crystal symmetry shows an observable trend: change from centrosymmetric to non-centrosymmetric and back to centrosymmetric. All non-centrosymmetric crystals exhibit an isomorphic P1 crystal structure with an excellent macroscopic second-order nonlinear optical response. Apart from the top-level macroscopic optical nonlinearity, new organic crystals introducing highly electronegative fluorinated substituents with strong secondary bonding ability show excellent performance in efficient and broadband THz wave generation, high crystal density, high thermal stability, and good bulk crystal growth ability.