Nonlinear Optical Properties Research Articles

Nonlinear Optical Properties of Bis(dehydrobenzoannuleno)benzenes: An Experimental and Computational Approach.

Given their molecular properties and electronic structure, graphyne and graphdiyne are promising materials with numerous applications in different fields of material science. Dehydrobenzoannules (DBAs) are candidates that can serve as building blocks for synthesizing and designing new 2D carbon allotropes; however, only a few graphynes have been produced on a practical scale. Herein, we present our investigation of three DBAs, which serve as a model to understand the relationship between the structure and property, contributing to 2D carbon allotropes' rational design and synthetic effort. We performed entangled and classical two-photon absorption at 790 nm, revealing that minor structural changes within acetylenic units significantly impact the magnitudes of the entangled and classical two-photon cross sections. Later, we deconvolved the excited-state dynamics through femtosecond transient absorption, and the lifetimes on the nanosecond time scale were measured using time-correlated single-photon counting. Finally, electronic structure calculations were performed to compute the oscillator strength and energy associated with electronic transitions between the ground and excited states and among the excited states. The results reveal that the remarkable difference in nonlinear optical properties among the DBAs, despite their structural similarities, stems from the transition dipole moment associated with transitions among excited states.

Meso-β, β-β' trifused porphyrins: synthesis, spectral, electrochemical and DFT studies and their femtosecond third-order nonlinear optical properties.

Meso-β, β-β' trifused porphyrins incorporating two distinct active methylene groups (MN = malononitrile and IND = 1,3-indanedione) and their corresponding metal complexes with Cu(II) and Zn(II) have been synthesized with good to excellent yields and characterized by various spectroscopic techniques and spectrometric methods. Single crystal X-ray analysis of the Zn(II) complex ZnTFPMB(MN)2 (where TFP = trifused porphyrin and MB = mono benzo) revealed a ruffled nonplanar 'armchair' type conformation with a twist angle of 24.10°. The absorption spectra showed a significant bathochromic shift in both the B- and Q-bands, extending into the near-infrared (NIR) region, particularly for π-extended trifused porphyrins. The cyclic voltammograms of MN-appended trifused porphyrins revealed unusual redox behavior, likely due to chemical reactions occurring at the electrode surface during electroreduction. The HOMO-LUMO energy gap for the π-extended porphyrins (MTFPMB(VCN)2) was effectively reduced to ≤1.5 V, compared to ∼2.23 V for the parent porphyrins. Additionally, the femtosecond third-order nonlinear optical properties of the synthesized trifused porphyrins and reported Ni(II) complexes were investigated using the Z-scan technique. Most of the studied porphyrins exhibited promising three-photon absorption coefficients and cross-section values, suggesting their potential applications in optical limiting, bio-imaging, and advanced optoelectronics.

A Cu(I)-Based MOF with Nonlinear Optical Properties and a Favorable Optical Limit Threshold.

The exploitation of high-performance third-order nonlinear optical (NLO) materials that have a favorable optical limit (OL) threshold is essential due to a rise in the application of ultra-intense lasers. In this study, a Cu-based MOF (denoted as Cu-bpy) was synthesized, and its third-order NLO and OL properties were investigated using the Z-scan technique with the nanosecond laser pulse excitation set at 532 nm. The Cu-bpy exhibits a typical rate of reverse saturable absorption (RSA) with a third-order nonlinear absorption coefficient of 100 cm GW-1 and a favorable OL threshold of 0.75 J cm-2 (at a concentration of 1.6 mg mL-1), which is lower than that of most NLO materials that have been reported on so far. In addition, a DFT calculation was performed and was in agreement with our experimental results. Furthermore, the mechanism of the third-order NLO properties was illustrated as one-photon absorption (1PA). These results investigate the relationship between the structure and the nonlinear optical properties of Cu-bpy, and provide an experimental and theoretical basis for its use in optical limiting applications.

Comparison of linear and nonlinear optical properties of lead borate and bismuth borate glasses

Comparison of linear and nonlinear optical properties of lead borate and bismuth borate glasses

Synthesis, crystal structures and third-order nonlinear optical properties of Ni2+/Mn2+/Zn2+ naphthalene-1,5-disulfonates

Abstract In this study, we present the synthesis and characterization of three transition metal 1,5-naphthalenedisulfonates: [Ni(PTP)₂]·(1,5-NDS)·2H₂O (1), [Mn(PTP)(1,5-NDS)] (2), and [Zn(PTP)(1,5-NDS)(H₂O)]2·2.5H₂O (3). Herein, PTP refers to 4′-phenyl-2,2′:6′,2″-terpyridine while 1,5-NDS denotes the naphthalene-1,5-disulfonate dianion. Compound 1 exhibits a structure in which the sulfonate groups of the 1,5-naphthalenedisulfonate anions are not engaged in coordination. In compound 2, the Mn(II) ions are interconnected through 1,5-NDS anions to form chains along the c axis. Compound 3 features a chain structure via coordination interactions between the metal cations and the 1,5-naphthalenedisulfonate anions; adjacent chains are linked by hydrogen bonds to create a double-chain arrangement. Solid diffuse reflection spectra reveal that these compounds exhibit maximum absorption around 290 nm. The third-order nonlinear optical (NLO) properties of these complexes was investigated using the single-beam Z-scan techniques under laser irradiation at a wavelength of 532 nm. All three compounds demonstrate significant third-order nonlinear optical absorption effects with absorption coefficients of 1.85 × 10−5 m W−1 for compound 1, 1.12 × 10−5 m W−1 for compound 2 and 1.73 × 10−5 m W−1 for compound 3. The corresponding calculated values for third-order NLO susceptibility χ³ are 3.00 × 10⁻7 esu, 1.81 × 10⁻7 esu and 2.80 × 10⁻7 esu, respectively.

Selective Novel Metal‐Coordinated Biomedical Agents Encompassing Tetradentate Salen Ligand: Structural Elucidation, DFT Calculation, Cytotoxic, and Antioxidant Activities Supported by Molecular Docking Approach

ABSTRACTSeveral physicochemical and analytical methods were employed to elucidate the structural analysis of some novel complexes derived from the {3,4‐bis‐[(3‐ethoxy‐2‐hydroxy‐benzylidene)‐amino]‐phenyl}‐phenyl‐methanone (ESAB ligand). Decomposition point determination, elemental analysis (CHN), spectroscopy (IR, NMR, and mass spectrometry), conductivity, magnetic susceptibility, UV–Vis spectrum study, and theoretical investigations were among these methods. With conductance values ranging from 7.5 to 15.12 Ω−1 cm2 mol−1, molar conductance values showed that the Zn (II), Cu (II), and Ru (III) complexes are nonelectrolytes in fresh DMSO solutions, with the exception of the ESABRu complex, which is a monoelectrolyte. According to IR spectra, the ligand uses the (N & O) donor sites from the (C=N & C‐O) groups in the ligand moiety to coordinate through the metal ions in a tetradentate form. A 1:1 (metal:ligand) molar ratio was proposed by Job's approach based on analytical data from solution complexation. According to the stability constant (Kf) values, the complexes' stability order was found to be ESABRu > ESABCu > ESABZn. The pH profile showed that the complexes under study are stable throughout a broad pH range, usually between pH = 4 and pH = 10. The complexes' geometric structures and ligand coordination capabilities were inferred with the use of magnetic and electronic spectrum studies. The DFT method uses quantum chemical simulations to evaluate the electronic structures of the ligand under investigation and its complexes. The unbound ligand's B3LYP level, B3LYP/6/311G* degree, and the complexes' B3LYP/6/311G**/LANL2DZ functional categories were employed in the computations of the density function concept (DFT). The findings revealed the consistency between the experimental and DFT computations. Natural bond orbital (NBO) analysis was used to investigate bond strength between molecules' charge exchange, hyperconjugative connections, and molecular equilibrium. By computing the hyperpolarizability (β) and molecular polarizability (α) parameters, the ensuing nonlinear optical properties were investigated, leading to a number of surprising optical properties for the produced compounds. The antipathogenic activity of the generated materials was experimentally verified against a subset of gram (+) and gram (−) bacteria as well as some fungi using the agar well diffusion method. Additionally, hepatic cellular carcinomas, cells from colon and breast cancer, were utilized to test the cytotoxic activity of the ESAB ligand and its metal chelates. Furthermore, the examined compounds' ability to suppress the DPPH radical was examined. Additionally, simulations of molecular docking were performed to ascertain how the produced compounds attached to the specific protein binding sites.

Can Low Structural Anisotropy Produce High Optical Anisotropy? Anomalous Giant Optical Birefringent Effect in PI4AlI4 in Focus.

Tetrahedral halides with broad transparency and large second harmonic effects have the potential to serve as mid-infrared wide-bandgap materials with balanced nonlinear-optical (NLO) properties. However, their regular tetrahedral motifs tend to exhibit low optical birefringence (Δn < 0.03) due to limited structural anisotropy, which constrains their practical phase-matched capability. A significant challenge in halide structural chemistry and material exploration is to enhance the Δn of tetrahedral halides while maintaining their balanced properties. The question of whether tetrahedra with low structural anisotropy can produce high optical anisotropy remains unanswered. In this study, in addition to the conventional strategy of enhancing Δn by increasing structural anisotropy, we identify a previously unreported strategy of enhancing Δn by increasing electronic anisotropy. This novel strategy model unprecedentedly enhances the Δn of an existing tetrahedral halide, PI4AlI4, to a degree not achievable by conventional techniques, with the value reaching up to 0.31@1 μm. The anomalous increase in Δn is achieved by anisotropic charge redistribution resulting from a unique charge transfer effect between the anionic and cationic tetrahedral motifs. First-principles analysis provides further corroboration of the detailed chemical bonding electronic distributions and charge transfer illustrations. It is predicted that analogous AsI4AlI4 and TeI4ZnI4 will exhibit a greater propensity for giant Δn (> 0.5@1 μm). This finding will greatly enrich the structural chemistry of sp3-hybridized tetrahedra and provide seminal ideas for the design and modulation of highly birefringent structures.

Co-assemblies of Silver Nanoclusters and Fullerenols With Enhanced Third-Order Nonlinear Optical Response.

Exploring potential third-order nonlinear optical (NLO) materials attracts ever-increasing attention. Given that the atomically precise and rich adjustable structural features of silver nanoclusters (Ag NCs), as well as the unique π-electron conjugated system of carbon-based nanomaterials, a supramolecular co-assembly amplification strategy to enhance the luminescent intensity and NLO performance of the hybrids of the two components, are constructed and the relationship between structures and optical properties are investigated. By combining water soluble Ag NCs [(NH4)6[Ag6(mna)6] (H2mna = 2-mercaptonicotinic acid, abbreviated to Ag6─NCs hereafter) containing uncoordinated carboxyl groups with water-soluble fullerene derivatives modified with multiple hydroxyl groups (fullerenols, C60─OH), the π-electron delocalization is expanded owing to non-covalent hydrogen bonding effect between Ag6─NCs and C60─OH, which provides a feasible basis for realizing the NLO response. Then, the co-assemblies are doped into a PMMA matrix to prepare composite film and its NLO properties are evaluated by Z-scan technique. Remarkably, the effective nonlinear absorption coefficients β is of two orders magnitude higher than those of the Ag6─NCs assemblies at the absence of C60─OH. This work showcases a new approach for amplifying NLO responses which greatly facilitates the development of integrated photonic devices.

Enhanced Linear, Nonlinear Optical, and Modulus Dielectric Properties of Fluorescein Sodium Salt Dye Embedded Within Epoxy Resin Composite Materials for Renewable Energy Applications

Enhanced Linear, Nonlinear Optical, and Modulus Dielectric Properties of Fluorescein Sodium Salt Dye Embedded Within Epoxy Resin Composite Materials for Renewable Energy Applications

In silico investigation of physicochemical and nonlinear optical properties of Azobenzene based novel molecules

In silico investigation of physicochemical and nonlinear optical properties of Azobenzene based novel molecules

Hafnium-Based Chiral 2D Organic-Inorganic Hybrid Metal Halides: Engineering Polarity and Nonlinear Optical Properties via Para-Substituent Effects.

Two-dimensional (2D) organic-inorganic hybrid metal halides (OIMHs), characterized by noncentrosymmetric structures arising from the incorporation of chiral organic molecules that break inversion symmetry, have attracted significant attention. Particularly, chiral-polar 2D OIMHs offer a unique platform for multifunctional applications, as the coexistence of chirality and polarity enables the simultaneous manifestation of distinct properties such as nonlinear optical (NLO) effects, circular dichroism (CD), and ferroelectricity. In this study, we report the first synthesis of hafnium (Hf)-based chiral 2D OIMHs, achieved through the strategic incorporation of para-substituents on the benzene ring of chiral organic components. By tuning the substituents, we successfully modulate the polarity of the crystal structures, resulting in both chiral-nonpolar and chiral-polar systems. Our analysis of structural and optical properties, supported by density functional theory calculations, demonstrates that the polarity of these materials can be systematically tuned, enabling adjustable band gaps and CD in the UV range (200-280 nm). Notably, halogen substitution at the para-position of the benzene ring in the organic layer produces tunable optical band gaps ranging from 4.33 to 4.48 eV, the widest reported to date for chiral-polar 2D OIMHs. Furthermore, these materials exhibit enhanced NLO properties, including a remarkable 3.3-fold increase in second-harmonic generation intensity in chiral-polar compounds compared to their chiral-nonpolar counterparts. These findings position Hf-based chiral 2D OIMHs as promising candidates for UV-region applications, such as UV NLO devices and self-driven circularly polarized light detectors, offering new opportunities for designing multifunctional optoelectronic materials by harnessing the interplay between chirality and polarity.

Mechanical Twisting-Induced Enhancement of Second-Order Optical Nonlinearity in a Flexible Molecular Crystal.

Flexible molecular crystals are essential for advancing smart materials, providing unique functionality and adaptability for applications in next-generation electronics, pharmaceuticals, and energy storage. However, the optical applications of flexible molecular crystals have been largely restricted to linear optics, with nonlinear optical (NLO) properties rarely explored. Herein, we report on the application of mechanical twisting of flexible molecular crystals for second-order nonlinear optics. The crystal formed through the self-assembly of the model compound 9-anthraldehyde (AA) features an intrinsic chiral and noncentrosymmetric structure, demonstrating high efficiency second harmonic generation (SHG) and NLO circular dichroism, which could be greatly enhanced by macroscopic mechanical twisting. The anisotropic molecular stacking imparts the AA crystal with mechanical flexibility of combined elastic bending and plastic twisting. The isochiral mechanical twisting could greatly enhance the SHG intensities by an order of magnitude depending on their M- or P-configuration. Meanwhile, the SHG circular dichroism factor gSHG-CD of the isochiral twisted crystal is greatly increased, achieving the highest reported NLO anisotropy factor among organic NLO materials. These boosted NLO performances of SHG intensity and nonlinear chiroptical response are expected to greatly expand the photonic applications of flexible molecular crystals.

Tailored Metal‐Oxygen Bonding in Amorphous Perovskite CoSnO3 for Broadband Ultrafast Laser State Active Manipulation

AbstractAmorphous perovskite CoSnO3 has attracted significant attention due to its unique properties and various modification methods. However, modifying metal‐oxygen bonds on the nonlinear optical (NLO) characteristics remains uncharted. In this study, a dehydration method is employed to convert the metal‐hydroxyl bonds (M─OH) of hydroxide CoSn(OH)6 into metal‐oxygen bonds (M─O), successfully preparing amorphous CoSnO3 with oxygen vacancies. Subsequently, effective regulation of the metal‐oxygen bonds in amorphous CoSnO3 is achieved through an ion exchange strategy, yielding Fe‐doped CoSnO3 (Fe‐CoSnO3). Comprehensive characterization and analysis revealed that the regulation of metal‐oxygen bonds accelerated the electron transition rate, resulting in a fast recovery time of ≈245.1 fs for Fe‐CoSnO3, accompanied by a significant boost in broadband NLO properties. Notably, when Fe‐CoSnO3 is utilized as a saturable absorber (SA), it exhibited superior mode‐locking characteristics compared to CoSnO3 in the range of 1–2 µm. Specifically at the communication band of 1.5 µm, the dynamic switching between single‐wavelength and dual‐wavelength mode‐locking operations is achieved. With the ultrafast laser state manipulation, a digital encoding is also demonstrated. This work confirmed that the tailoring of metal‐oxygen bonds makes Fe‐CoSnO3 an excellent NLO material for ultrafast optical applications, and this tailoring strategy provides new insights for designing advanced NLO materials.

Deciphering nonlinear optical properties in functionalized hexaphyrins via explainable machine learning.

Over the years, several studies have aimed to elucidate why certain molecules show more enhanced nonlinear optical (NLO) properties than others. This knowledge is particularly valuable in the design of new NLO switches, where the ON and OFF states of the switch display markedly different NLO behaviors. In the literature, orbital contributions, aromaticity, planarity, and intramolecular charge transfer have been put forward as key factors in this regard. Based on our previous work on functionalized hexaphyrin-based redox switches, we aim at identifying through explainable machine learning the driving forces of the first hyperpolarizability related to the hyper-Rayleigh scattering (βHRS) of meso-substituted and/or core-modified [26]- and [30]hexaphyrins. The significant correlation between βHRS and the HOMO-LUMO energy gap can be further improved by including other orbitals as well as charge-transfer features in a 6-fold cross-validated kernel-ridge-regression model. Our Shapley additive explanations (SHAP) analysis shows that the charge transfer excitation length is more important for 30R systems, whereas the transition dipole moment between the ground and first excited state is one of the main contributors for 26R systems. We also demonstrate that, besides various hexaphyrin-based redox states, the ML model can describe to a large degree the βHRS response of other hexaphyrins, differing in substitution pattern and topology (26D and 28M).

Generation of Dark Pulses in Mode‐Locked Erbium‐Doped Fiber Ring Laser Operating in L‐Band Region Using Sc2O3 Absorber

ABSTRACTBy incorporating scandium oxide (Sc2O3) powder into a PVA film, a Sc2O3 saturable absorber (SA) was successfully developed, boasting a modulation depth of 25%. When integrated into a ring erbium‐doped fiber laser, the Sc2O3‐SA facilitated the production of mode‐locked dark pulses featuring multi‐wavelength emission, leveraging its saturable absorbing ability along with the nonlinear properties inherent in the Sc2O3 thin film and the long erbium‐doped fiber. Mode‐locking operation was achieved within a pumping range of 209.3–239.8 mW, resulting in a peak pulse energy of 0.71 nJ. Operating at 1597.8 nm, the mode‐locked laser demonstrated a repetition rate of 10.42 MHz and a pulse width of 23 ns. Domain‐wall dark pulse operation was demonstrated in the L‐band region, achieving a relative stability with a signal‐to‐noise ratio of 55.6 dB, utilizing a Sc2O3 thin film absorber and an 8‐meter‐long active fiber. These findings underscore the promising potential of Sc2O3 to be used in pulsed laser systems, particularly due to its exceptional nonlinear optical properties.

Relevance of linear and nonlinear optical properties of Erythrosine B thin films for photonic application

Relevance of linear and nonlinear optical properties of Erythrosine B thin films for photonic application

Enhancement in the Nonlinear Optical Properties of Silver Nanoprisms through Graphene Oxide Anchoring

Enhancement in the Nonlinear Optical Properties of Silver Nanoprisms through Graphene Oxide Anchoring

Bend, don't break: exploring the mechanochromic, AIE and nonlinear optical properties of carbazole–thiobarbituric acid hybrids

Multifunctional organic NLOphores are being developed to expand the market potential of organic NLO materials by combining NLO properties with other desirable functionalities.

Experimental and Theoretical Investigation of Nonlinear Optical Properties in Novel Anthracene-Based Chalcone Compounds

Experimental and Theoretical Investigation of Nonlinear Optical Properties in Novel Anthracene-Based Chalcone Compounds

Corrigendum to “Linear and non-linear optical properties of (Ge1S2)100-x(As2Te3)x (0 ≤ x ≤ 100) films” [Opt. Mater. 149 (2024) 1–9/114972

Corrigendum to “Linear and non-linear optical properties of (Ge1S2)100-x(As2Te3)x (0 ≤ x ≤ 100) films” [Opt. Mater. 149 (2024) 1–9/114972