Third-order Nonlinear Optical Susceptibility Research Articles

Study of the Crystalline Perfection, Homogeneity, Chemical Etching on the Surface, and Third‐Order Nonlinear Optical Properties of (1 1 0) Oriented Hydroxyethylammonium D‐Tartrate Monohydrate Single Crystal and Hirshfeld Surface Analysis

AbstractThe single crystal of hydroxyethylammonium D‐tartrate monohydrate (HEDT) is grown along the (1 1 0) plane using the Sankaranarayanan–Ramasamy method. The powder X‐ray diffraction and the high‐resolution X‐ray diffraction analyses are used to corroborate the growth plane and perfection of the crystallinity, respectively. The birefringence experiment has proven crystalline homogeneity and estimated birefringence value (Δn) is 0.109. The surface morphology of the grown crystal is examined by chemical etching analysis and irregular hillock patterns are found. The transmittance for the (1 1 0) plane of the HEDT is inspected by a UV‐Vis analysis. The second harmonic generation efficiency of the HEDT crystal is 1.7 times that of potassium dihydrogen phosphate (KDP). The third‐order nonlinear optical (TONLO) properties of the grown HEDT crystal are scrutinized by the Z‐scan experiment. The estimated TONLO susceptibility of HEDT crystal is 6.827 × 10−8 esu. The laser damage threshold value of HEDT is discovered to be 5.24 GW cm−2. The 3D Hirshfeld surface visualizes the interaction between HEDT molecules and analyzes the distance from the surface of the molecule to the farthest and the nearest atom. The important contributions of crystal packing are explored by 2D‐fingerprint plots.

Synthesis, Linear and Nonlinear Optical Properties of Ag/Al2O3 Nanocomposites.

This work reports a detailed study of the synthesis, characterization and third-order nonlinear optical properties of Ag and Al2O3 nanoparticles and their polymer nanocomposites. Ag and Al2O3 nanoparticles were prepared by the chemical precipitation method. The X-ray diffraction studies confirmed the purity and the crystalline nature of the sample and revealed the crystallite size. The linear optical properties and the structural morphology of the nanoparticles were confirmed using UV–visible spectroscopy and SEM analysis. The prepared nanoparticles were introduced into the polymer matrix by the spin-coating technique. Open-aperture and closed-aperture Z-scan technique was used to study the nonlinear absorption and nonlinear refraction of the samples under a Q-switched Nd:YAG laser at 532 nm. The observed third-order nonlinear optical susceptibility (χ(3)) was on the order of 10−6 esu, which indicates that these materials are potential candidates for photonic applications.

Optical and electrical properties of BaSnO3 and In2O3 mixed transparent conductive films deposited by filtered cathodic vacuum arc technique at room temperature

For the crystalline temperature of BaSnO3 (BTO) was above 650 °C, the transparent conductive BTO-based films were always deposited above this temperature on epitaxy substrates by pulsed laser deposition or molecular beam epitaxy till now which limited there application in low temperature device process. In the article, the microstructure, optical and electrical of BTO and In2O3 mixed transparent conductive BaInSnO x (BITO) film deposited by filtered cathodic vacuum arc technique (FCVA) on glass substrate at room temperature were firstly reported. The BITO film with thickness of 300 nm had mainly In2O3 polycrystalline phase, and minor polycrystalline BTO phase with (001), (011), (111), (002), (222) crystal faces which were first deposited at room temperature on amorphous glass. The transmittance was 70%–80% in the visible light region with linear refractive index of 1.94 and extinction coefficient of 0.004 at 550-nm wavelength. The basic optical properties included the real and imaginary parts, high frequency dielectric constants, the absorption coefficient, the Urbach energy, the indirect and direct band gaps, the oscillator and dispersion energies, the static refractive index and dielectric constant, the average oscillator wavelength, oscillator length strength, the linear and the third-order nonlinear optical susceptibilities, and the nonlinear refractive index were all calculated. The film was the n-type conductor with sheet resistance of 704.7 Ω/□, resistivity of 0.02 Ω ⋅cm, mobility of 18.9 cm2/V⋅s, and carrier electron concentration of 1.6 × 1019 cm−3 at room temperature. The results suggested that the BITO film deposited by FCVA had potential application in transparent conductive films-based low temperature device process.

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.

Tuning of third-order nonlinear optical susceptibility of Eu3+ doped alkali borate glasses in visible region by embedding gold nanoparticles

Tuning of third-order nonlinear optical susceptibility of Eu3+ doped alkali borate glasses in visible region by embedding gold nanoparticles

Nonlinear optical response, theoretical efficiencies, and high photosensitivity of CH3NH3PbI3−xClx thin films for photonic applications

In this paper, we have investigated the nonlinear optical response and theoretical efficiency of CH3NH3PbI3−xClx thin films from the optical transmission and reflection measurements. The dispersion of the complex refractive index is evaluated using the Wemple–DiDomenico single oscillator model. The oscillator energy (E0) of CH3NH3PbI3−xClx follows by an empirical relationship with optical bandgap (Eg) as E0 ≈ 2.41 Eg for chemical dip coating, spray, and E0 ≈ 1.63 Eg for dipping deposited samples, respectively. The long wavelength refractive index, average oscillator wavelength, and oscillator strength are also determined using the Sellmeier oscillator equation. The estimated third-order nonlinear optical susceptibility is found to be the order of 10−12 esu. The incident photon and charge carrier interaction in CH3NH3PbI3−xClx is studied from the dielectric response of the samples. The charge carrier excitation is found higher at lower wavelength and experienced bulk excitation in volume while surface excitation on the surface region. The optical conductivity of CH3NH3PbI3−xClx is notably high, which leads to an increase in carrier transfer through the extrinsic halide perovskite material expedient for higher conversion efficiency. The highest theoretical efficiency of CH3NH3PbI3−xClx is estimated to be 17.4%, which is in excellent agreement with the experimental report. From photosensitivity study, it is confirmed that CH3NH3PbI3−xClx films are highly photosensitive. All these results comprehend that CH3NH3PbI3−xClx is a potential candidate for photonic applications.

Single crystal, a lead-free hybrid organic-inorganic perovskite material: {[(C6H5)NH3]+}4.I.[BiI6]3-.H2O with optical and third-order nonlinear properties

A lead-free organic–inorganic halide perovskite (LFHP) single crystal, tetrakis(phenylammonium) iodide hexaiodidebismuthate monohydrate (TIHM): {[(C6H5)NH3]+}4.I.[BiI6]3-.H2O, was successfully synthesized by a simple condensation reaction method in ambient environment. The bismuth iodide-based crystal compound was grown by using methanol solvent. The crystal lattice comprised of a discrete (BiI6)3− anion surrounded by tetrakis(phenylammonium) cations, iodide anion, and a water molecule. The structure related to monoclinic crystal system with P21/c space group: a ​= ​21.921 (4) Å, b ​= ​8.5521 (15) Å, c ​= ​21.105 (4) Å, β ​= ​102.398 (3) °, and Z ​= ​4. The full geometry optimization was performed by density functional theory (DFT) calculation at B3LYP functional with 6–311++G(d,p) and LanL2DZ mixed basis sets by using GAUSSIAN software. The gaussian predicted peak emission at 479 ​nm with bandgap of 2.97 ​eV. The HRTEM analysis reveals that the titled LFHP nanocrystal has a size below 5 ​nm. The centrosymmetric crystal exhibit third-order nonlinear optical susceptibility of 1.0228 ​× ​10-5 ​esu with Im χ3 response higher than Reχ3, and, hence, it can be concluded that the hybrid perovskite has promising optical limiting properties.

Nonlinear Optical Behavior Due to Charge Transfer within Selected Heterocyclic Anthracenyl Chalcones under Continuous Wave Laser Excitation

Three new heterocyclic-chalcone (HC) derivatives consisting of the π-conjugated system attached to anthracene moiety were proposed for nonlinear optical properties and optical limiting application. The NLO behavior is confirmed through obtained χ3 by Z-scan method. The closed aperture z-scan showed the HC possesses a self-defocusing effect with a negative nonlinear refractive index, n 2 ∼ 10−8 cm/W, with a magnitude of real part of the third-order nonlinear optical susceptibilities, Re χ( 3 ) of the order of 10−7 esu. Open Z-scan results showed that the HC samples demonstrate a reverse saturable absorption (RSA), β ∼ 10−4 cm/W, corresponding to large imaginary parts, Im χ( 3 ) in the order of 10−6 esu. Overall, the Z-scan analysis unveils an excellent value of χ3 in order of 10−6 which indicates good nonlinear material under 532 nm continuous wave laser. The optical limiting study reveals that AC exhibit a strong limiting behavior with action beginning from 0.8 KW/cm2, and seems to be promising optical limiting candidates for future optoelectronic applications. Through B3LYP/6-311G++d,p level of theory Density Functional Theory (DFT), Global Reactivity, Natural Bond Orbital (NBO), and Natural Population were calculated and investigated. Delocalization and hyperconjugation interactions, intramolecular charge transfers, and stabilization energies were discovered using NBO and NPA. The comprehensive studies of Hirshfeld surface (HS) and fingerprint plots (FP) calculations were done in order to evaluate the nature of intermolecular interactions in the compounds. The inclusion of a strong donor and the π-conjugated system improved charge transfer, chemical stability, and optoelectronic properties of the anthracene-heterocyclic chalcone derivatives. As a result, the present work realizes the potential of designed derivatives that can be used in NLO applications.

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

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

Experimental analysis of excited state dynamics in Anderson-type POM@porphyrin hybrids in relevance to third-order nonlinear optical properties

This work accounts for the active contribution of life time decay in the field of nonlinear optics, especially for an energetic donor acceptor couple (porphyrin and polyoxometalate (POM)). Currently, two POM free porphyrins (Di-Tris-N@Por and Di-Tris@Por) and their two hybrids with POM (Di-Tris-NPor@Di-AndPOM-1 and Di-TrisPor@Di-AndPOM-2) have been studied keenly in nanosecond time span and resulted lifetimes ([Formula: see text]1 and [Formula: see text]2) have been compared with nonlinear optical parameters. The results demonstrated that Di-Tris-NPor@Di-AndPOM-1 exhibited better third-order nonlinear optical susceptibility [Formula: see text]3, second hyperpolarizability [Formula: see text] and nonlinear absorption [Formula: see text] and Di-TrisPor@Di-AndPOM-2 than Di-TrisPor@Di-AndPOM-2. This superiority of nonlinear optical parameters was supported by lifetime decay studies and electrochemical studies. It is revealed that more relaxation time in excited states lower will be the NLO response. The lifetime decay ([Formula: see text]1) value of Di-Tris-NPor@Di-AndPOM-1 is 3.86ns which is higher than Di-TrisPor@Di-AndPOM-2 possessing lifetime decay ([Formula: see text]1) value of 2.45ns. Moreover, lower energy of charge separated state (-0.88 eV) of Di-Tris-NPor@Di-AndPOM-1 indicates the facile electron transfer in Di-Tris-NPor@Di-AndPOM-1 than Di-TrisPor@Di-AndPOM-2 which experienced more energy of charge separated state. Rapid intersystem crossing is also responsible for the electron transfer from porphyrin moiety to POM moiety.

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

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

Crystal growth and physico-chemical characterization of methyl ammonium chloride doping on the characteristics of potassium dihydrogen phosphate crystal for nonlinear optical applications

• The KDP and MACKDP single crystals were grown by the slow evaporation method. • The UV–Vis-NIR spectrums reveal that the title compounds can be used as nonlinear optical materials. • KDP and MACKDP crystal belong to the soft material category. • Third-order nonlinear optical susceptibility (χ 3 ) was found to be 5.391 × 10 −8 esu and 5.412 × 10 −8 esu for KDP and MACKDP, respectively. Potassium dihydrogen phosphate (KDP) and Methyl ammonium chloride doped KDP (MACKDP) were made into nonlinear optical single crystals using the ambient temperature slow evaporation method. An examination of powder X-ray diffraction reveals that the reflection lines of the doped KDP crystal are almost identical to those of the pure parent chemical KDP, with just a little difference in peak intensity. The space group and lattice parameters of the crystal structure were determined using XRD measurements on a single crystal. FTIR spectrum studies indicated the existence of numerous functional groups due to the shifting of peak positions. According to the results of UV–Vis-NIR testing, the UV cutoff wavelength for pure KDP is 381 nm and for methyl ammonium chloride doped potassium dihydrogen phosphate crystal is 383 nm. Growing crystals have reduced permittivity and dielectric loss tangent at increasing frequencies and temperatures. There were 1.12 times more correlated second harmonic (SHG) powers in the doped crystal than there were in pure KDP, according to the Kurtz and Perry approach. Thermogravimetric and differential thermal analysis were used to evaluate the thermal properties of an KDP doped MACKDP crystals. Vickers microhardness experiments have examined the impact of methyl ammonium chloride mixing on the hardness parameters of KDP crystal. The encouraging third-order nonlinear properties were examined employing a Z-scan technique using an Nd: YAG laser at 532 nm. To be considered a viable choice for nonlinear optical devices, the title material must exhibit a wide range of noteworthy physicochemical and optical nonlinear features.

The Effect of ZnO, MgO, TiO2, and Na2O Modifiers on the Physical, Optical, and Radiation Shielding Properties of a TeTaNb Glass System.

Novel glass samples with the composition 75TeO2–5Ta2O5–15Nb2O5–5x (where x = ZnO, MgO, TiO2, or Na2O) in mole percent were prepared. The physical, optical, and gamma radiation shielding properties of the glass samples were studied over a wide energy spectrum ranging between 0.015 and 20 MeV. The glasses’ UV–vis spectra were utilized to evaluate the optical energy gap and refractive index. Glass samples had a refractive index ranging from 2.2005 to 2.0967. The results showed that the sample doped with zinc oxide (ZnO) recorded the highest density (ρglass), molar polarizability (αm), molar refraction (Rm), refractive index (n), and third-order nonlinear optical susceptibility (χ3) and the lowest optical energy gap (Eopt) among the samples under investigation. When comparing the current glass system with various standard glass shielding materials, the prepared glass system showed superior shielding performance at energies ranging between 40 and 85 keV. These findings indicate that the prepared glass systems can be used in diagnostic X-rays, especially in dental applications.

Large third-order optical nonlinear susceptibility in natural dye derived from Clitoria ternatea petal

The third-order nonlinear optical response of Clitoria ternatea (CT) petal’s dye in various solvents were characterized via Z-scan technique with a diode pumped solid state (DPSS) laser at 532 nm. The observations from the closed aperture z-scan showed the dye possess a self-defocusing effect with a negative nonlinear refractive index, n2 with a moderate magnitude of real part of the third-order nonlinear optical susceptibilities, Re χ(3) of the order of 10−10 esu. Open z-scan results showed that the CT dyes samples demonstrate a reverse saturable absorption (RSA) with strong two-photon absorption (TPA) coefficients, β ~ 10−3 cm/W, corresponds to large imaginary parts, Im χ(3) in the order of 10−5 esu. The highest values of n2 and β was observed in CT dye in ethanol and dimethyl sulphoxide, respectively. Not only the linear absorption spectra depends on the type of solvent used, but also the nonlinear characteristics are drastically influenced by it. On the whole, large χ(3) of the dye samples were found to be in order of 10−5 esu. Based on the measured value of nonlinear susceptibility, χ(3), the natural dye derived from CT petals can be a candidate for applications such as optical limiting and switching.

Computation and experimental results on spectroscopic and physicochemical properties of efficient piperidine driven passive optical limiting material

The computation and experimental results on structural, mechanical, thermal, linear, and third order nonlinear optical properties of an organic material 4-methyl-N-((1-(4-methylbenzoyl)piperidin-4-yl)methyl)-benzamide (1) for an efficient optical limiting application with easy preparation and decent performance are presented. Its response to single-crystal x-ray diffraction allowed to investigate the molecular structure of 1, which is optimized using computational density functional theory at the B3LYP/6-311G** level. Calculated frontier molecular orbitals and Mulliken charge are served to realize the intramolecular charge transfer in 1 and its electronegative nature responsible for optical nonlinearity. Hirshfeld analysis investigated the structural property and the magnitude of interatomic and molecular interactions to help understand structure-property relation. The FTIR and NMR spectroscopic study further confirmed the formation of 1 and the vibrational states of its functional group. The title crystal showed acceptable thermal (stable up to 130 °C) and mechanical (stable up to 50 grams of applied load) stability, which is optimal for laser device applications. With an optical bandgap of 4.32 eV, the title material possesses much less linear optical absorption across the visible region of the electromagnetic spectrum. The nonlinear optical absorption (β), nonlinear refractive index (n 2) and third-order nonlinear optical susceptibility (χ (3)) values are measured as (0.0139 ± 0.001) × 10−4 cmW−1, (1.49 ± 0.05) × 10−10 cm2W−1 and (4.2 ± 0.3) × 10−8 esu respectively shows that the title molecule is third-order nonlinear optical active. The onset optical limiting threshold value is determined as (7.092 ± 0.01)×103 Wcm−2 for 532 nm, continuous-wave laser irradiation indicating that the title material is a good candidate for the optical limiting application.

Investigation of the third-order optical nonlinearity of Au/GO-CeO2 nanocomposites under different high-energy ball milling parameters

A high-energy ball milling process along with the hydrothermal method was applied to synthesize Au/GO-CeO2 nanocomposites. X-ray diffraction analysis and FT-IR spectroscopy confirmed the successful synthesis of nanocomposites. The ball milling parameters dependence of the nonlinear optical response of Au/GO-CeO2 nanocomposites was investigated by using the Z-scan measurements under pulsed Nd: YAG laser irradiation at 532 nm. The measurements showed that Au/GO-CeO2 nanocomposites have negative nonlinearity which can be controlled by ball milling parameters to achieve higher values for third-order nonlinear optical susceptibility of the order of 10−8 esu. The investigations showed that ball milling parameters such as ball milled time and the number of hardened zirconia oxide balls are important factors in the resultant nonlinear optical parameters. The results suggest that Au/GO-CeO2 nanocomposites with a strong nonlinear optical response can be a promising nonlinear medium that can open a new avenue to graphene-based nonlinear optics.

Study on the third-order nonlinear optical properties of Cd2+ ion doped ZnS/PVP nanocomposite films

Cd2+ ion doped ZnS/PVP nanocomposite films have been prepared using in-situ chemical method. XRD studies confirm the cubic structure of ZnS for all the films. The SEM micrograph shows the mono dispersion of ZnS nanoparticles in PVP matrix. FTIR spectra confirm the formation of nanocomposites containing ZnS nanoparticles and PVP polymer. Optical absorption spectra reveal the blue shift on the absorbance onset with the comparison of bulk ZnS. Photoluminescence spectra show a blue emission peak for all the films. The Z-scan results of all the films show a reverse saturation absorption process in open Z-scan experiment and self-focusing behavior in closed Z-scan experiment. Both ZnS/PVP and Cd2+ ion doped ZnS/PVP films exhibited the large optical nonlinearity and the value of nonlinear refractive index (n2), nonlinear absorption coefficient (β), third-order nonlinear optical susceptibility (χ(3)) and figure of merit (FOM) increase with Cd doping. The estimated n2, β, χ(3) and FOM values are found to be 1.771 × 10−10 m2 W−1, 4.148 × 10−3 mW−1, 1.603 × 10−4 esu and 9.576 × 10−6 esu m 6 mol% Cd doped ZnS/PVP nanocomposite film. The experimental results clearly showed that the Cd2+ ion doped ZnS/PVP nanocomposite film is a worthy candidate for the future nonlinear optical device fabrication.

Ni-doped metal-organic frameworks as nonlinear optical material used in saturable absorption for Q-switched Tm: YAP laser

Metal-organic frameworks (MOFs) have received significant attention owing to their nanometer-sized void spaces, large surface areas, and tunable bandgaps. The properties of MOFs can be adjusted by doping other metal motifs or organic ligands. MOFs are widely employed in nanodevices and optical thin film materials; however, their third-order nonlinear optical (NLO) properties are rarely investigated, and their application in solid-state laser (SSL) has not been reported. In this paper, the NLO properties of Ni-doped MOFs are investigated comprehensively, wherein the value of the nonlinear refractive index and that of the real part of the third-order nonlinear optical susceptibility are obtained, i.e., <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$6.10\times10^{-9}$</tex-math></inline-formula> cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> /W and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$6.20\times10^{-7}$</tex-math></inline-formula> esu, respectively. Consequently, an SSL that coupls Ni-doped MOFs with a saturable absorber (SA) is constructed. An average output power of 0.68/1.10 W is acquired with a 1.5 % or 2.5% transmission of the output coupler (OC) under a passive Q-switch mode operation, corresponding to a per pulse energy of 6.29/10.90 μJ. When coupled with Tm: YAP, the as- constructed SSL exhibits a stable and short pulse (1.97 μs) at 1987.5 nm, indicating that Ni-doped MOFs can be applied to broadband SAs to achieve a fast photonic in the near-infrared spectra.

Novel C[sbnd]H•••O hydrogen-bonded supramolecular complexes of 18-crown-6 with 1-alkylpyridinium iodide and its amino derivatives: Third-order nonlinear optical properties and Hirshfeld surface analysis

Five supramolecular complexes of 18-crown-6 (18C6) with 1-alkylpyridinium iodide and its amino derivatives were synthesized successfully from methanolic solution by slow evaporation solution growth technique. Crystal structure elucidated by single-crystal X-ray diffraction reveals that all the cocrystals belong to the monoclinic system. Cocrystals bis(1-methylpyridinium iodide)-18C6 (I), bis(4-amino-1-methylpyridin-1-ium iodide)-18C6 (IV), and bis(4-amino-1-ethylpyridin-1-ium iodide)-18C6 (V) crystallize centrosymmetrically with space group C2/m and other two crystals bis(2-amino-1-methylpyridin-1-ium iodide)-18C6 (II) and bis(3-amino-1-methylpyridin-1-ium iodide)-18C6 (III) crystallize in P21/n centric space group. Intra- and inter-molecular hydrogen bonding interactions and weak Van der Walls forces construct the supramolecular architecture in the crystal packing. Interestingly, all the 1-alkylpyridin-1-ium cations interact with 18C6 moiety through C-H•••O hydrogen bonding interactions and N-H•••O interactions are observed only in the case of (II). Fingerprint plots of Hirshfeld surfaces were used to locate and analyze the percentage of hydrogen bonding interactions. Direct band gap energies are estimated using diffuse reflectance data by the application of the Kubelka – Munk algorithm. The third-order nonlinear optical susceptibilities (χ(3)) for the compounds are, 5.57 × 10−6 esu for (I), 3.62 × 10−6 esu for (II), 4.37 × 10−6 esu for (III), 5.30 × 10−6 esu for (IV), and 4.24 × 10−6 esu for (V), respectively.

Surface functionalization of Ta4C3 MXene for broadband ultrafast photonics in the near-infrared region

Recently, MXene has set off a great research boom in the optoelectronic field benefiting from its strong conductivity, eminent broadband absorption, and tailorable electronic/optical properties. In this paper, two-dimensional tantalum carbide (Ta4C3) MXene nanosheets were successfully synthesized based on a two-step liquid exfoliation strategy. Firstly, the role of surface termination with different adsorption structures on the electronic and diverse optical properties of Ta4C3Tx MXene were firstly investigated theoretically via first-principles with density functional theory. Interestingly, the simulation revealed that the oxidized and hydroxylated Ta4C3 MXene featured significantly enhanced optical absorption properties in the near-infrared (NIR) band compared with the pristine bare Ta4C3 nanosheets. Besides, the third-order nonlinear optical (NLO) characteristics of the surfaced terminated Ta4C3 nanosheets were measured by the typical Z-scan techniques at 1 μm. The maximum effective nonlinear absorption coefficient was determined to be -0.78 cm/GW, indicating the great potential as a nonlinear material in NIR band. The nonlinear refractive index, real and imaginary parts of the third-order NLO susceptibility were also obtained. Furthermore, the endowment as an excellent broadband optical modulator was strongly acknowledged utilizing Ta4C3 MXene as saturable absorbers for NIR mode-locking operation at 1044 nm and 1557 nm, respectively. Both highly stable dissipative soliton and traditional soliton pulses were generated. Our results demonstrated the excellent broadband nonlinear absorption in NIR regime of terminal functionalized Ta4C3 MXene and might open a new avenue to the Ta4C3-based advanced ultrafast photonic devices.