Third-order Nonlinear Optical Materials Research Articles

Physicochemical properties of 2-amino-5-methylpyridinium 3-carboxy-4-hydroxybenzenesulfonate single crystal: An efficient material for optoelectronic applications

A novel third-order organic nonlinear optical (NLO) material with promising excellent properties in the crucial NLO application. For the first time high NLO active 2-amino-5-methylpyridinium 5-sulfosalicylic acid (2A5MP3C4H) has been rationally designed and single crystals have been grown by the slow evaporation solution growth technique (SEST). X-ray diffraction analysis revealed that 2A5MP3C4H belongs to the category of triclinic system and has a Centro symmetric space group of P1. Remarkably, the grown crystal exhibits competitive and even superior physical properties including high thermal stability and wider transparency than the standard NLO single crystal. The morphology of the as-grown 2A5MP3C4H crystal was equivalent to the theoretically produced morphology. Fourier transform infrared spectroscopy (FTIR) was used to investigate the molecular vibrations of 2A5MP3C4H. The optical characteristics of 2A5MP3C4H recorded optical transmittance spectrum reveals that the 2A5MP3C4H crystal possesses good optical transparency in the range between ultraviolet (UV) and near-infrared (NIR) regions. Intriguingly, the short cut-off edge of the grown crystal is found to be about 345 nm which is more favourable for developing modern photonic and optoelectronic devices application. The Laser Damage Threshold (LDT), were investigated to understand its effectiveness to be utilized in the area of optoelectronics and photonics. The thermal and mechanical stability of 2A5MP3C4H was tested using Thermo gravimetric Differential Thermal Analysis (TG-DTA) and Vickers hardness test. The third-order nonlinear optical properties of 2A5MP3C4H single crystals were analyzed, which involves studying the absorption coefficient and refractive index behaviour using a continuous wave laser. Additionally, the grown crystal exhibits outstanding third-order NLO response and wide LDT, which are crucial characteristics for developing practical NLO devices. There are various 2-amino-5-methylpyridine (2A5MP) derivative single crystals available in the literature. However 2A5MP3C4H crystal has not been reported earlier. So, we have carried out our researcher on this new novel crystal. Our findings consequently open a novel path for the logical design of enormous, thermally stable and NLO-active organic complexes for true NLO applications.

Third Harmonic Generation in Thin NbOI2 and TaOI2.

The niobium oxide dihalides have recently been identified as a new class of van der Waals materials exhibiting exceptionally large second-order nonlinear optical responses and robust in-plane ferroelectricity. In contrast to second-order nonlinear processes, third-order optical nonlinearities can arise irrespective of whether a crystal lattice is centrosymmetric. Here, we report third harmonic generation (THG) in two-dimensional (2D) transition metal oxide iodides, namely NbOI2 and TaOI2. We observe a comparable THG intensity from both materials. By benchmarking against THG from monolayer WS2, we deduce that the third-order susceptibility is approximately on the same order. THG resonances are revealed at different excitation wavelengths, likely due to enhancement by excitonic states and band edge resonances. The THG intensity increases for material thicknesses up to 30 nm, owing to weak interlayer coupling. After this threshold, it shows saturation or a decrease, due to optical interference effects. Our results establish niobium and tantalum oxide iodides as promising 2D materials for third-order nonlinear optics, with intrinsic in-plane ferroelectricity and thickness-tunable nonlinear efficiency.

Cyclotriphosphazene-based organic frameworks as third-order nonlinear optical materials

CTP-NLOphore based imine (CTP-TAPB) and vinylene-linked (CTP-TCPB) organic frameworks have been synthesized and their NLO properties explored using non-resonant fs laser excitations.

Designed metal-organic π-clusters combining the aromaticity of the metal cluster and ligands for a third-order nonlinear optical response.

The pivotal role of clusters and aromaticity in chemistry is undeniable, but there remains a gap in systematically understanding the aromaticity of metal-organic clusters. Herein, this article presents a novel metal-organic π-cluster, melding both metal-organic chemistry and aromaticity, to guide the construction of structurally stable Os-organic π-clusters. An in-depth analysis of these clusters reveals their bonding attributes, π-electronic composition, and origins of aromaticity, thereby confirming their unique metal-organic π-cluster properties. Furthermore, the Os5 cluster exhibits a promising third-order nonlinear optical (NLO) response, attributable to its narrow band gap and uniform electron/hole distribution, suggesting its potential as an optical switching material. This research introduces a fresh perspective on clusters, centered on delocalization, and broadens the domain of aromaticity studies. It also presents a novel method for designing efficient third-order NLO materials through consideration of the structure-activity relationship.

Physical Mechanism of One-Photon Absorption, Two-Photon Absorption, and Electron Circular Dichroism of 1,3,5 Triazine Derivatives Based on Molecular Planarity.

We provide a method to regulate intramolecular charge transfer (ICT) through distorting fragment dipole moments based on molecular planarity and intuitively investigate the physical mechanisms of one-photon absorption (OPA), two-photon absorption (TPA), and electron circular dichroism (ECD) properties of the multichain 1,3,5 triazine derivatives o-Br-TRZ, m-Br-TRZ, and p-Br-TRZ containing three bromobiphenyl units. As the position of the C-Br bond on the branch chain becomes farther away, the molecular planarity is weakened, with the position of charge transfer (CT) on the branch chain of bromobiphenyl changing. The excitation energy of the excited states decreases, which leads to the redshift of the OPA spectrum of 1,3,5-triazine derivatives. The decrease in molecular plane results in a change in the magnitude and direction of the molecular dipole moment on the bromobiphenyl branch chain, which weakens the intramolecular electrostatic interaction of bromobiphenyl branch chain 1,3,5-triazine derivatives and weakens the charge transfer excitation of the second step transition in TPA, leading to an increase in the enhanced absorption cross-section. Furthermore, molecular planarity can also induce and regulate chiral optical activity through changing the direction of the transition magnetic dipole moment. Our visualization method helps to reveal the physical mechanism of TPA cross-sections generated via third-order nonlinear optical materials in photoinduced CT, which is of great significance for the design of large TPA molecules.

Design of tunable notch filter based on plasmonic and InGaAsP waveguide

A highly efficient compact tunable optical notch filter is proposed and analyzed using the 2D Finite Element Method (FEM). The proposed structure consists of a slanted stub plasmonic resonator, Metal–Insulator–Metal (MIM) waveguide, and InGaAsP as a third-order non-linear optical material. By altering the pumping state of the InGaAsP, the filtered wavelengths may be easily controlled continuously over 200 nm a range. The suggested notch filter can remove four narrow bands of wavelengths, each around 50 nm wide, and a transmission of about − 17 dB. The proposed filter’s key advantages are its high transmission coefficient and fabrication simplicity with compact size. For future integrated plasmonic devices such as outdoor visible light communications and optical imaging, the proposed filter can be manufactured using an oblique angle shadow evaporation technique.

Single-Wall-Carbon-Nanotube– VSe2 Nanohybrid for Ultrafast Visible-To-Near-Infrared Third-Order Nonlinear Optical Limiters

An ideal third-order nonlinear optical material, which can efficiently absorb and refract light over a broad spectral range, is of both fundamental and technological significance as it enables many helpful functionalities in photonics. However, the optical nonlinearities are rather weak due to their perturbative nature and are limited to electronic resonances, thus restricting the response to a narrow spectral range. A charge-coupled donor-acceptor material pair can enhance the nonlinear optical response and circumvent the narrow spectral range limitation. However, such studies on potential material pairs remain largely unexplored. Here, we report the experimental observation of ultrafast third-order nonlinear optical response spanning the entire visible-to-near-infrared (400--900 nm) region in single-wall-carbon-nanotube (SWCNT)--${\mathrm{VSe}}_{2}$ nanohybrid in the strong coupling regime, enabled by efficient charge transfer. Compared to control systems, the measured nonlinear absorption and refraction of the nanohybrid show unprecedented or many-fold enhancements. Further, our density-functional theory and Bader-charge analysis show the strong electronic coupling of the nanohybrid in which the electrons are transferred from ${\mathrm{VSe}}_{2}$ to SWCNT, verified by steady-state and time-resolved photoluminescence measurements. The physics of the ultrafast nonlinear optical response is well captured by our five-level rate-equation model both qualitatively and quantitatively. Using the nanohybrid, we design a liquid cell-based optical limiter with an order of magnitude better device performance parameters, such as the optical limiting onset ($2.5--8.0\phantom{\rule{0.2em}{0ex}}\mathrm{mJ}\phantom{\rule{0.2em}{0ex}}{\mathrm{cm}}^{\ensuremath{-}2}$) and the differential transmittance ($0.42--0.62$), compared to several other benchmark optical limiters in the femtosecond regime.

Design, crystal growth and characterizations of novel bis morpholinium zinc bromide single crystals for optoelectronic applications

A novel metal-organic third-order nonlinear optical (NLO) material with promising excellent properties in the crucial solar blind UV region. For the first time, high NLO active metal-organic complex of bis-morpholinium zinc bromide (BMZB) single crystal has been rationally designed and single crystals have been grown by slow evaporation solution technique (SEST). Remarkably, the grown crystal exhibits competitive and even superior physical properties including high thermal stability and wider transparency than the standard NLO single crystal. The title compound crystallizes in the monoclinic crystal system with the space group of P21/cc and four molecules are accumulated in the unit cell (unit cell parameters are a = 6.7860 (6) Å, b = 16.6239 (2) Å, c = 14.8875 (2) Å, β = 94.937 (3)° and Z = 4). Further, the phase purity and the crystallinity of the grown sample were analyzed through powder X-ray diffraction (PXRD) analysis. The Fourier transform infrared (FTIR) spectroscopy analysis has been used to determine the presence of multifarious functional groups in the grown crystal. The recorded optical transmittance spectrum reveals that the BMZB crystal possesses good optical transparency in the range between deep ultraviolet (UV) and near-infrared (NIR) regions. Intriguingly, the short cut-off edge of the grown crystal is found to be about 227 nm which is more favorable for developing modern photonic and optoelectronic devices in the solar blind UV region. The thermal and mechanical stabilities of the grown crystals have been studied using Vickers microhardness and thermogravimetry (TG) and differential thermal analysis (DTA) respectively. Moreover, key requirements for designing practical NLO devices such as large laser damage threshold (LDT) and excellent third-order NLO response have been observed in the grown single crystal. Therefore, our findings open up a new avenue to the rational design of thermally stable and large NLO active metal-organic complexes for practical NLO applications.

Nonlinear optical properties of symmetrical and asymmetrical benzene derivatives with click chemistry modification

PurposeThis paper aims to prepare third-order nonlinear optical (NLO) organic materials with large nonlinear optimization value, high damage threshold and ultrafast response time.Design/methodology/approachA series of novel symmetric and asymmetric compounds possessing third-order NLO properties were synthesized using 1,3,5-tribromobenzene as the basis. The photophysical and electrochemical properties, as well as the click reactions, were characterized by means of UV–VIS–NIR absorption spectroscopy and cyclic voltammetry.FindingsThe donor–acceptor chromophores were inserted into compound, making the molecule to have a broader absorption in the near-infrared regions and a narrower optical and electrochemical band gap. It also formed an electron-delocalized organic system, which has larger effects on achieving a third-order NLO response. The third-order NLO phenomenon of benzene ring complexes was experimentally studied at 532 nm using Z-scan technology, and some compounds showed the expected NLO properties.Originality/valueThe click products exhibit more NLO phenomena by performing different click combinations to the side groups, opening new perspectives on using the system in a variety of photoelectric applications.

Enhancing Third-Order Nonlinear Optical Property by Regulating Interaction between Zr4(embonate)6 Cage and N, N-Chelated Transition-Metal Cation

Herein, the combination of anionic Zr4L6 (L = embonate) cages and N, N-chelated transition-metal cations leads to a series of new cage-based architectures, including ion pair structures (PTC-355 and PTC-356), dimer (PTC-357), and 3D frameworks (PTC-358 and PTC-359). Structural analyses show that PTC-358 exhibits a 2-fold interpenetrating framework with a 3,4-connected topology, and PTC-359 shows a 2-fold interpenetrating framework with a 4-connected dia network. Both PTC-358 and PTC-359 can be stable in air and other common solvents at room temperature. The investigations of third-order nonlinear optical (NLO) properties indicate that these materials show different degrees of optical limiting effects. It is surprising that increasing coordination interactions between anion and cation moieties can effectively enhance their third-order NLO properties, which can be attributed to the formation of coordination bonds that facilitate charge transfer. In addition, the phase purity, UV-vis spectra, and photocurrent properties of these materials were also studied. This work provides new ideas for the construction of third-order NLO materials.

A self-defocusing third-order nonlinear optical material l-Alanine Barium Chloride single crystal used in optoelectronic device applications

Slow evaporation method was used to produce a single crystal of l-Alanine Barium Chloride (LABC), a semi-organic nonlinear optical material. The grown crystal non-centrosymmetric nature can be seen in the results of a single-crystal XRD analysis. Using Fourier transform infrared spectral analysis, the unique functional groups and chemical makeup of LABC compounds were found. The lower cut-off wavelength is observed down to 253 nm and direct optical band gap was calculated as 4.54 eV. A photoluminescence experiment found the LABC crystal emission spectrum. EDAX spectrum analysis revealed the crystal metal ion (Ba) existence. The Z-scan method with an Nd: YAG laser at 532 nm was used to analyse the third-order optical nonlinearity characteristics of LABC in detail. A Vicker's microhardness tester was used to measure the microhardness of the LABC crystal under the same load.

A new class of third-order nonlinear optical materials: laser pulse-duration dependant saturable absorption and nonlinear refraction in platinum(II) diimine-dithiolate complexes.

The third-order nonlinear optical (NLO) properties of a series of platinum diimine-dithiolate complexes [Pt(N^N)(S^S)] were investigated by means of Z-scan measurements, revealing second hyperpolarizability values up to 10-29 esu, saturable absorption properties, and nonlinear refractive behaviour, which were rationalized also by means of DFT calculations.

Application of third-order nonlinear optical materials in complex crystalline chemical reactions of borates

Abstract In order to explore the application of third-order nonlinear optical (NLO) materials in complex borate crystalline chemical reactions, the laser light source with limited wavelength range can be extended to ultraviolet (UV) and deep UV region by using NLO crystal materials and frequency conversion technology, which has become a hot research direction of deep UV light source. The experimental results show that the UV cutoff edge of the grown KLi(HC3N3O3)·2H2O crystal is 237 nm. The refractive index of the crystal was measured by prism coupling technique, and the Sellmeier equation of the refractive index of the crystal was fitted. The chemical bond of the crystal is a fundamental means to understand the relationship between structure and properties. With the emergence of a large number of hybrid functional crystals, the composition and structure of crystals become more complex, and the chemical bond theory has also been greatly developed, and then the chemical bond theory of meta crystals or complex crystals has emerged. Once proposed, the theory has been widely used, such as analyzing the eligibility of luminescent crystals, NLO crystals and high-temperature superconductor crystals. NLO materials are the dominant field of China in the world. Crystals with good nonlinear behavior have more complex crystal structures, due to the theory of amorphous structure, the exploration of this aspect is particularly difficult. For the first time, the influence of the composition of rare earth-doped bismuth borate glass on the crystal precipitation and glass microstructure of NLO materials was systematically studied, which laid a theoretical foundation for further development and understanding of new bismuth borate optical systems.

Design of A-D-A-Type Organic Third-Order Nonlinear Optical Materials Based on Benzodithiophene: A DFT Study.

The acceptor-donor-acceptor (A-D-A) type conjugated organic molecule has been widely applied in the organic optoelectronics field. A total of Nine compounds (1–9) were designed under the A-D-A framework, with the electron donor benzodithiophene as the core and dicyanomethylene as the acceptor moiety, modifying the benzodithiophene with the phenyl, naphthyl, and difluorinated phenyl groups. The conjugation length can be changed by introducing a thiophene π-conjugated bridge. The geometric structures, electronic structure, excited state properties, aromaticity, and the static- and frequency-dependent second hyperpolarizabilities were investigated by employing high-precision density functional theory (DFT) calculations with an aug-cc-pVDZ basis set. As a result, the three compounds with the longest conjugation length exhibit a smaller energy gap (Egap), larger UV-vis absorption coefficient, and response range, which are the three strongest third-order nonlinear optical (NLO) response properties in this work. This work systematically explored the connection between molecular structure and NLO response, which provides a rational design strategy for high-performance organic NLO materials.

Third-order nonlinear optical studies of Bis(4-methylbenzylammonium) tetrachloridocuprate metal-organic crystal with optical limiting behavior: Experimental and theoretical investigations

The metal-organic nonlinear optical (NLO) compound Bis(4-methylbenzylammonium) tetrachloridocuprate (4MBA) was synthesized and grown by the slow evaporation method. X-ray crystal analysis revealed the crystal structure and conformation. Density functional theory (DFT) at B3PW91/LanL2DZ basis set level was applied and computed the optimized geometry, electronic structure, vibrational spectra, frontier molecular orbitals (FMO), molecular electrostatic potential (MEP), and natural bonding orbitals (NBO). UV–Vis-NIR spectroscopic measurements revealed the optical transparency range from 310 to 1100 nm and excited-state properties. The thermal behavior and stability of the compound were analyzed using TGA/DTA, and the suitability of the optical material is weighed. The dielectric parameters and AC conductivity were investigated as a function of frequency and temperature. Second-harmonic generation (SHG) efficiency was measured using the Kurtz and Perry powder approach and found 4MBA to be 0.8 times the KDP. The nonlinear refractive index (n2), nonlinear optical absorption (β) and third-order nonlinear optical susceptibility (χ(3)) measured values are 1.548 × 10−9 cm2 W−1, 0.0538 × 10−4 cm W−1, and 6.049 × 10−8 esu respectively, and shows that the 4MBA molecule is a third-order nonlinear optical material. The optical limiting threshold value is determined as 7.632 × 103 W cm2 for 532 nm continuous-wave laser, representing that the 4MBA is a strong candidate for the optical limiting application. The static and dynamic nonlinear optical parameters were computed with three different functions including B3PW91, M06 and PBE0 using LanL2DZ basis set. The outcomes revealed that the 4MBA molecule under study might be a promising NLO material for frequency generators and optical limiters applications.

Phenothiazine metal-organic framework materials with excellent third-order nonlinear properties

The third-order nonlinear optical material with excellent performance is a molecule with a large π-conjugated structure for absorption structure and a high degree of delocalization. Nitrogen-sulfur derivatives have lone pairs of electrons in their N and S atoms, which makes them have a strong intramolecular charge transfer ability, which is conducive to the formation of donor-acceptor molecules. In this paper, phenothiazine is used as the matrix structure of the third-order nonlinear optical material, modified, and then metal coordination is performed to obtain [Zn(Py)2Cl2]n and [Cd(Py)2Cl2]n. Its structure is characterized by infrared spectroscopy, single crystal X-ray diffraction and powder X-ray diffraction. The morphology of the material was characterized by scanning electron microscopy. The photophysical properties, thermal properties and third-order nonlinear properties were tested, and the theoretical verification was carried out with the DFT calculation method, and the relationship between the structure and the third-order nonlinear properties was summarized. The experimental results show that phenothiazine has good electron donating ability, the two-photon absorption coefficient β is between 1.334–38.400 × 10−10 m/W, and the third-order nonlinear polarizability χ(3) is between 2.752–79.247 × 10−11 esu, The second-order hyperpolarizability γ of the ligand molecule is 5.213 × 10−34 esu. The χ(3) values of [Zn(Py)2Cl2]n and [Cd(Py)2Cl2]n are 4 orders of magnitude higher than ordinary α-quartz (χ(3) = 2.6 × 10−14 esu).

Remarkable Nonlinear Properties of a Novel Quinolidone Derivative: Joint Synthesis and Molecular Modeling.

A novel 4(1H) quinolinone derivative (QBCP) was synthesized and characterized with single crystal X-ray diffraction. Hirshfeld surfaces (HS) analyses were employed as a complementary tool to evaluate the crystal intermolecular interactions. The molecular global reactivity parameters of QBCP were studied using HOMO and LUMO energies. In addition, the molecular electrostatic potential (MEP) and the UV-Vis absorption and emission spectra were obtained and analyzed. The supermolecule (SM) approach was employed to build a bulk with 474,552 atoms to simulate the crystalline environment polarization effect on the asymmetric unit of the compound. The nonlinear optical properties were investigated using the density functional method (DFT/CAM-B3LYP) with the Pople’s 6-311++G(d,p) basis set. The quantum DFT results of the linear polarizability, the average second-order hyperpolarizability and the third-order nonlinear susceptibility values were computed and analyzed. The results showed that the organic compound (QBCP) has great potential for application as a third-order nonlinear optical material.

Crystal growth and characterization of 2-amino-6-methylpyridinium p-chlorobenzoate dihydrate single crystal: a novel third-order nonlinear optical material for optoelectronic applications

Crystal growth and characterization of 2-amino-6-methylpyridinium p-chlorobenzoate dihydrate single crystal: a novel third-order nonlinear optical material for optoelectronic applications

Novel Third-Order Nonlinear Optical Materials with Craig-Möbius Aromaticity.

Electron delocalization in aromatic materials significantly impacts their third-order nonlinear optics (NLO). Despite organometallic complexes with Craig-Möbius aromaticity attracting great attention for their unusual physicochemical properties, their third-order NLO have been little studied to date. Herein, 12 Craig-Möbius aromatic organometallics with a stable structure similar to osmapentalyne, namely, carbolong complexes, are screened by DFT. They exhibit high third-order NLO responses because of the d and p electron delocalization in the organometallic ring. Furthermore, electron-hole distribution analyses draw a conclusion that extending the conjugated plane will increase the π-conjugation system to enhance the local excitation in the plane, and the introduction of typical aromatic ligands can result in the organometallic ring-to-ligand charge transfer (RLCT), which are effective methods to improve the third-order NLO response. This study opens a new window in the application of Craig-Möbius aromatic complexes and provides a new approach for third-order NLO materials design.

Physical and theoretical investigations on piperazinium 3,5-dinitrobenzoate (PDNB) single crystal: A potential candidate for third-order nonlinear optical (NLO) applications

A potential third-order nonlinear optical (NLO) material of piperazinium 3,5-dinitrobenzoate (PDNB) has been synthesized from the pure aqueous solution through protonation reaction and its single crystals have been successfully grown by slow evaporation solution technique (SEST) within a span of 75 days. The structural properties of the grown single crystals have been evaluated by single-crystal X-ray diffraction (SXRD) analysis. It reveals that the grown crystal crystallizes in a triclinic crystal system with centrosymmetric space group Pī. The existence of various crystalline planes and phase purity of the title material were confirmed by powder X-ray diffraction (PXRD) analysis with the 2θ scanning range of 10° to 50° The proton (1H1) nuclear magnetic resonance (NMR) spectrum has been recorded to elucidate the molecular structure of the synthesized PDNB material. The presence of multiple functional groups and optical properties of the title material have been evaluated by Fourier transform infrared (FT–IR) and UV–Vis NIR spectroscopy analyses, respectively. The photoluminescence property of the PDNB crystal has been examined by the excitation and emission spectra. The grown crystal possesses good thermal stability (stable upto 197 °C), which is determined by thermogravimetric (TG) and differential thermal analysis (DTA). The grown crystal possesses excellent third-order NLO property when irradiation of He-Ne laser of wavelength 632.8 nm. Theoretical investigations such as optimized geometry, HOMO-LUMO, first-order hyperpolarizability and Hirshfeld surface analyses have been carried out and their interesting results have been discussed. The overall experimental and theoretical results lead to conclude that the title PDNB single crystal is a potential candidate for the NLO and optoelectronic applications.