Third-order Optical Nonlinearity Research Articles

Third order nonlinear investigations of CuLaSe2 and ZnCuLaSe2 quantum dots

Environmentally friendly quantum dots (QDs) with high two-photon absorption coefficients in the near-infrared region are important for nonlinear optics (NLO) applications. In this work, CuLaSe2 and ZnCuLaSe2 QD are successfully synthesized and characterized using UV–Vis, Photoluminescence and HRTEM analysis. Next, the third-order NLO properties of these materials are studied using the femtosecond Z-scan method. The samples showed efficient nonlinear responses. The nonlinear absorption coefficient (β), the nonlinear refractive index (n2) and the third-order nonlinear susceptibility (χ(3)) values for all samples are deduced and discussed in detail. The results reported here pave the way towards building CuLaSe2 and ZnCuLaSe2 QDs-based nonlinear photoelectric devices operating in the near-infrared field.

Photoluminescence and third-order nonlinear optical limiting properties of Sn1-xNdxO2 thin films deposited via spray pyrolysis

In the present work, spray pyrolysis method was adopted to synthesis nano thin films of Sn1-xNdxO2 (x = 0.01 to 0.1) possessing tetragonal structure with (1 1 0) plane orientation. Nd doping reduced the overall crystallinity of the films, however Sn0.92Nd0.08O2 film showed crystallite size of 18.7 nm, similar to that of the pure film. The morphology changed to distinct grains at lower doping concentration, beyond which a fibrous nature evolved but again changed to smaller grains with further increase in the doping. The oxidation states of the constituent elements were confirmed using XPS. The transmittance of the films reduced due to incorporation of Nd ions. A decrease in the energy band gap was also noticed in the films following dopant addition. The PL emissions corresponding to the Nd ion transitions was found in the NIR region resulting from internal 4f-shell transitions of Nd3+ ions. Other defect related emissions like the one from oxygen vacancies also showed up in the UV and visible wavelength regions, which were responsible for a near white light emission. The third-order optical nonlinearity of the films was confirmed using the Z-scan technique. All the Sn1-xNdxO2 films till 8 at. % of doping showed reverse saturable absorption. The highest and lowest nonlinear absorption coefficient was exhibited by Sn0.92Nd0.08O2 and Sn0.98Nd0.02O2 films, respectively. Depending on the Nd concentration, the films either showed self-focusing or self-defocusing behavior and influenced the nonlinear refractive indices of the films. The least optical limiting values among the doped films was obtained in the range of 1.73 kJ/cm2 for Sn0.92Nd0.08O2 films.

Investigation on growth, crystal structure, third-order optical nonlinearity properties and DFT computational studies of novel proton transfer 3-aminopyridine P-nitrobenzoate P-nitrobenzoic acid (3APPNB) single crystal for third-order NLO applications

A new organic single crystal of 3-aminopyridine p-nitrobenzoate p-nitrobenzoic acid (3APPNB) with a size of 8 × 4 × 2 mm3 was grown by slow evaporation solution growth technique at room temperature using methanol solvent. The lattice parameter values were evaluated with the help of single crystal XRD and it confirms that the 3APPNB crystal belongs to triclinic crystal structure and the space group P-1. Crystal unit cell parameters are a = 9.3384(5) Å, b = 10.0403(5) Å, c = 11.094(6) Å, α = 109.4940(10)°, β = 93.964(2)°, γ = 99.890(2)° and V = 957.03 (9) (Å3) were determined. The 3APPNB crystal crystallizes in a centrosymmetric nature, triclinic system and space group P-1. SCXRD study shows that both the anion and the cation are interlinked to each other by two types of symmetrical intermolecular C–H…O and N–H···O hydrogen bonds. The crystalline nature and hkl phases have been determined using Powder XRD studies. The presence of different vibrational groups in the 3APPNB compound is examined by employing Fourier transform infrared (FT-IR) spectral analysis. UV–Vis-DRS spectral analysis signifies that the 3APPNB has a wide transmittance (98 %) and a cut-off wavelength of around 317 nm. The etch pit density (EDP) of 3APPNB crystal was examined by a chemical etching analysis. The thermal studies expose that 3APPNB is thermally stable up to 172 °C. The surface morphology of the 3APPNB is analyzed by SEM. The nonlinear properties like β, n2 and χ(3) were measured through the Z-scan analysis and the values were calculated to be 5.78 × 10−5 m/W, 8.05 × 10−12 m2/W) and χ(3) = 8.936 × 10−9. The third-order nonlinear optical (TONLO) χ(3) values are higher. The achieved TONLO χ(3) value when compared to other similar constituents is owing to the tarnish movement of π-electron configuration from the donor to an acceptor that makes the molecules highly polarized. The results reveal that the 3APPNB crystal finds applications in devices like optical switching and optical limiting. The quantum-chemical theoretical analyses are performed to measure the intrinsic properties of the 3APPNB molecules using DFT calculation. The band gap, orbital energy and second hyperpolarizability are also studied using changing the applied field. Furthermore, Quantum chemical calculations are used to obtain the MESP, HOMO-LUMO and first-order hyperpolarizability for the 3APPNB compound.

Third-order nonlinear optical properties of choline chloride based deep eutectic solvents: Theoretical and experimental studies

In this work, the preparation of three deep eutectic solvents (DES) based on choline chloride as hydrogen bond acceptor and urea, malonic acid, and phenylpropionic acid as hydrogen bond donor is reported. These series of DES were used as models to measure, for the first time, the third-order optical nonlinearities in eutectic solvents. The nonlinear refractive index (n2) originated from the fast electronic response was determined by the close aperture Z-scan technique under excitation of laser ultrafast pulses at 800 nm, resulting in values of the order of ∼3 × 10-16 cm2 W−1, which are similar to those reported recently for ionic liquids. These values are also similar to those exhibited by some traditional polar protic organic solvents such as water and ethanol. At relatively low energy pulses, the DES presented only pure refractive response, but at high energies two of them exhibited nonlinear absorption. On the other hand, ab initio theoretical calculations using density functional theory (DFT) allowed to determine the static and dynamic second hyperpolarizabilities for the DES with M11/6-311G(d,p) level of theory. The tendency of the theoretical results agrees satisfactorily with the values of n2 obtained experimentally. Our results suggest that the presence of aromatic cloud makes that choline chloride:phenylpropionic acid contributes to produce relatively high n2 values. This study provides relevant information to be considered when DES are intended as an alternative to standard organic solvents in the development of photonic materials.

Highly stable femtosecond pulse generation enabled by the indium tin oxide nanocrystals

The ultrafast third-order optical nonlinearity of indium tin oxide nanocrystals (ITO NCs) and their application in femtosecond laser generation have been investigated experimentally. The ITO NCs exhibit a large modulation depth of ∼25%, nonlinear refractive behavior with self-focusing, ultrafast carrier recovery time of ∼300 fs, and high damage threshold of ∼1.16 TW cm−2, and the stable femtosecond Er-doped fiber laser can be delivered with a signal-to-noise ratio over 80 dB modulated by the ITO NCs successfully. The experimental results indicate that the ITO NCs can be excellent ultrafast nonlinear optical materials for developing highly stable photonic and optoelectronic devices.

Green Synthesis of Blue Light-Emitting Carbon Dots Using Tridax procumbens Leaves: Optical and Electrochemical Studies

We report the preparation of biocompatible blue emitting carbon dots (CDs) using Tridax procumbens (T. procumbens) leaf extract as a bio-source. A one-step hydrothermal method was employed to prepare highly effective photoluminescent CDs. As-synthesized CDs were characterized using Ultraviolet-visible spectroscopy (UV-visible), Photoluminescence (PL), Fourier transform infrared (FT-IR), transmission electron microscopy (TEM) and Confocal Raman spectroscopy techniques. In addition, the third-order optical nonlinearity of the prepared CDs was carried out using Z-scan technique with the help of continuous wave diode pumped Nd:YAG laser (532 nm). The nonlinear optical (NLO) susceptibility, nonlinear absorption coefficient and nonlinear refractive index were calculated. The synthesized CDs exhibited good excitation dependent properties. The CDs/Nafion modified glassy carbon electrode (CDs/Nf/GCE) was prepared and its electrochemical and catalytic properties were evaluated by using cyclic voltammetry (CV). The CDs/Nf/GCE exhibited high electrocatalytic activity for dopamine oxidation in physiological condition. This new CDs/Nf/GCE showed a linear range of Dopamine (DA) detection from 40 to 220 μM with the limit of detection (LOD) of 2.7 μM. The stability and reproducibility of the electrode were also investigated which indicated that this green synthesized CDs could be used for the development of electrochemical sensor to determine DA concentration in biological samples.

Nanocomposites Based on Spin-Crossover Nanoparticles and Silica-Coated Gold Nanorods: A Nonlinear Optical Study.

A nanocomposite based on silica-coated AuNRs with the aminated silica-covered spin-crossover nanoparticles (SCO NPs) of the 1D iron(II) coordination polymer with the formula [Fe(Htrz)2(trz)](BF4) is presented. For the synthesis of the SCO NPs, the reverse micelle method was used, while the gold nanorods (AuNRs) were prepared with the aspect ratio AR = 6.0 using the seeded-growth method and a binary surfactant mixture composed of cetyltrimethylammonium bromide (CTAB) and sodium oleate (NaOL). The final nanocomposite was prepared using the heteroaggregation method of combining different amounts of SCO NPs with the AuNRs. The nonlinear optical (NLO) properties of the hybrid AuNRs coated with different amounts of SCO NPs were studied in detail by means of the Z-scan technique, revealing that the third-order NLO properties of the AuNRs@SCO are dependent on the amount of SCO NPs grafted onto them. However, due to the resonant nature of the excitation, SCO-induced NLO switching was not observed.

Modulation of photoluminescence and optical limiting properties of spray-coated tin oxide thin film through Eu doping

This work reports the effect of Eu doping on the structural, morphological, linear, and nonlinear optical properties of Sn1−xEuxO2 (x = 0 to 0.10) thin films prepared using spray pyrolysis. The films crystallized in tetragonal structure and the crystallite size reduced due to Eu incorporation. The film morphology consisted of evenly distributed dense grains with trapezohedron or bipyramidal shape. The Eu doping reduced the transmittance and energy band gap of the deposited films. The photoluminescence (PL) emission spectra comprised the contributions from both the transitions related to the Eu3+ ions and the defects, such as oxygen vacancies and tin interstitials in the host lattice. The films also showed a near white light emission due to the different defect-related PL emissions. The Z-scan technique revealed the third-order optical nonlinearity shown by the films. Amongst the doped films, Sn0.92Eu0.08O2 films exhibited least optical limiting threshold.Graphical abstract

Microstructured All-Optical Switching Based on Two-Dimensional Material

Microstructured all-optical switching, possessing the unique function of light controlling light, is an important part of the on-chip ultra-fast optical connectivity network and integrated logic computing chip. Microstructured all-optical switching has attracted extensive research interest, the latest great developments of which have also yielded progress in nanophotonics, nonlinear optics, optical communications, and integrated optics, etc. The emergence of two-dimensional materials with good third-order optical nonlinearity provides an important driving force for the improvement of all-optical switches. This paper reviews the implementation principles, novel configurations, improved performance indexes, and research progress based on different two-dimensional materials for micro/nano all-optical switching. Not only is a systematic discussion of the current state provided, but also, a brief outlook is afforded on the remaining challenges in the pursuit of the application of practical on-chip microstructured all-optical switching that is based on two-dimensional materials.

Effect of cycloalkanone ring size on second and third order nonlinear optical properties of bischalcones

With the objective of establishing the effect of cycloalkanone ring size on the NLO properties of bischalcones para-substituted diarylideneacetone and substituted diarylidenecycloalkanone derivatives were synthesized by the Claisen–Schmidt condensation reaction and characterized by using UV–Vis, FT-IR, 1H NMR, 13C NMR and mass spectrometry. The second harmonic generation (SHG) efficiencies and third-order nonlinear optical (NLO) properties of the synthesized compounds were studied using the Kurtz-Perry method and the Degenerate Four Wave Mixing (DFWM) technique respectively. Among all the synthesized compounds that we have reported here, 2,6-bis-(4-methoxydibenzylidene) acetone showed the highest SHG efficiency (12.96 times that of urea) and 2, 6-bis-(4-methylthiobenzylidene) cyclopentanone showed the highest third order NLO property with χ (3) value of 2.650 ± 0.023 × 10−13 esu. Though diarylideneacetones exhibited the highest SHG efficiency, among the diarylidenecycloalkanones SHG efficiency decreased with an increase in the cycloalkanone ring size. Diarylidenecyclopentanone series showed better third order NLO activity followed by diarylideneacetone, diarylidenecycloheptanone and diarylidenecyclohexanone series. The results indicate that the cycloalkanone ring size as well as the presence of substituents on the aryl rings affect the NLO properties. The experimental findings correlated well with the results of in silico studies with a correlation factor, R2 = 0.9285.

Crystal growth and vibrational spectroscopic studies on the novel nlo active piperazine-1,4-diium 3-phenyl-2-propenoate single crystal by experimental and computational technique

An organic nonlinear optical (NLO) single crystal of piperazine-1,4-diium 3-phenyl-2-propenoate (PAPP) is synthesized and delineated by spectroscopic techniques in association with quantum chemical computation. The quantum chemical calculation is performed utilizing density functional theory (DFT) with B3LYP/6-311 G(d,p) basis set. The FT-IR and FT-Raman techniques are adopted to point out the presence of various functional groups in PAPP molecule. The natural bond orbital (NBO), natural charge, molecular electrostatic potential (MEP) and HOMO-LUMO analyses are performed to spot hydrogen bonds and charge transfer interaction present in the molecule. Hole-electron analysis is performed to identify the types of interaction present in the molecule. Interaction region indicator analysis is performed to identify the steric effect, van der Waals force and hydrogen bonds. The optical quality of PAPP single crystal and the band gap energy is found out using UV–visible analysis. The nonlinear optical behaviour of the PAPP molecule is established by evaluating dipole moment, polarizability and hyperpolarizability. The third-order NLO parameters of PAPP crystal are estimated by employing the Z-scan technique.

Electrically controlled liquid crystal nonlinear optical devices prepared by multi-layer composite structures

In this study, a multi-layer composite structure is used to prepare nonlinear optical devices from multi-walled carbon nanotubes (MWCNTs)/liquid crystal (LC) composite systems. Their third-order optical nonlinearity is investigated. The MWCNTs were coated and modified to improve their dispersion in the solvent. The coated and modified MWCNTs were characterized by IR absorption spectroscopy and transmission electron microscopy (TEM). The nonlinear optical (NLO) properties of the devices prepared by the multi-layer composite structures with varying design parameters were studied. The conventional devices were also prepared by mixed doping method for comparison with the proposed devices. Both devices underwent Z-scan testing. The third-order nonlinear polarizability of the conventional hybrid-doped devices was calculated with a value of 5.39 × 10-10 esu. The third-order nonlinear polarizability of the proposed devices prepared by the multi-layer composite structures has a value of 2.97 × 10-9 esu, which is about five times the corresponding value for the hybrid-doped devices. So, the devices prepared by the multi-layer composite structures have better NLO properties. Moreover, the third-order nonlinear polarizability of the proposed devices was further increased up to 3.88 × 10-9 esu, which is an increase of almost 31% after applying voltage to these devices prepared by the multi-layer composite structures. The limiting threshold of S-CTAB/MWCNTs@BHR33400 is 0.245 J/cm2 after voltage application. Applying voltage plays a role in promoting the NLO properties of the devices. Using the multi-layer composite structure to prepare the liquid crystal nonlinear optical devices can significantly improve the NLO properties of the devices. Such prepared devices can be electrically tuned, providing new avenues for preparing nonlinear optical devices.

π-Extended Octupolar Cyclized Indole Tetramer and Trimer Derivatives with Second- and Third-Order Nonlinear Optical Properties.

Several aromatic-fused octupolar tetraindole (TTI) and triindole (TI) derivatives have been synthesized via POCl3-promoted cyclopolymerization of the aromatic-fused oxindoles. As a result, the terminal phenyls of TTI and TI are fused with the phenyl group, indenyl group, and benzothienyl group separately in the π-extended target compounds TTIp and TIp, TTIid and TIid, and TTIbt and TIbt (including pairs of syn- and anti-isomers). Single-crystal X-ray diffraction disclosed that the tetramer syn-TTIbt keeps an S4-symmetric architecture and crystallizes in the P42/n space group. With the extension of the π-conjugation, the absorption and emission bands of the above tetramers and trimers are remarkably red-shifted. The second-order nonlinear optical (NLO) coefficients (β value) of syn-TTIbt and anti-TTIbt have been calculated to be 1.5 and 2.1 times that of their parent compound TTI, respectively. In the domain of the third-order NLO, the two-photon absorption sections (δ value) of syn-TIbt and anti-TIbt have been measured to be 37 and 102 times that of TI, respectively. These results indicate that the π-extension strategy here is successful, and the anti-isomers have better NLO properties and better π-conjugation than their corresponding syn-isomers.

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.

Coordination-Induced Symmetry Breaking on Metal-Porphyrinic Framework Thin Films for Enhanced Nonlinear Optical Limiting

Structural asymmetry affecting the nonlinear optics (NLO) of metal-organic frameworks (MOFs) is very important in fundamentals and applications but is still a challenge. Herein we develop a series of indium-porphyrinic framework (InTCPP) thin films and provide the first study on the coordination-induced symmetry breaking on their third-order NLO. The continuous and oriented InTCPP(H2) thin films were grown on quartz substrates and then postcoordinated with different cations (Fe2+ or Fe3+Cl-) in InTCPP(H2) (named InTCPP(Fe2+) and InTCPP(Fe3+Cl-)). The third-order NLO results reveal the Fe2+ and Fe3+Cl- coordinated InTCPP thin films have substantially enhanced NLO performance. Moreover, InTCPP(Fe3+Cl-) thin films cause symmetry breaking of microstructures, resulting in a 3-fold increase in the nonlinear absorption coefficient (up to 6.35 × 10-6 m/W) compared to InTCPP(Fe2+). This work not only develops a series of nonlinear optical MOF thin films but also provides new insight into symmetry breaking on MOFs for nonlinear optoelectronic applications.

Synthesis, physico-chemical characterization and quantum chemical studies of 2, 3-dimethyl quinoxalinium-5-sulphosalicylate crystal

2,3-dimethylquinoxalinum-5-sulphosalicylate (MQSA) was synthesized and grown into single crystals by slowly evaporating the solvent in methanol at room temperature. According to the lattice parameters found by the SCXRD analysis method (a = 8.8031 (17) Å, b = 17.768(3) Å, c = 10.7979(16) and α = γ = 90°, β = 90.611 (7) °), the crystal belongs to monoclinic crystal system with the P21/n space group. Moreover, powder X-ray diffraction investigation supported the crystalline nature. The compound's UV–Vis spectra exhibited a CT-band with a wavelength maximum of 372 nm, as well as its NIR spectra revealed good optical transmittance in the visible region with a low cut-off wavelength of 376 nm and an optical band gap of 5.12 eV. Dual emission bands at 418 and 484 nm are observed in the PL emission spectra. The synthesized crystal was examined using FT-IR, FT-Raman, and NMR spectral methods. The crystal is thermally stable up to 274 °C, furthermore, TG-DTA and DSC methods were employed to study the degradation process. The second and third-order NLO efficiencies of the crystal was analyzed by Kurtz-Perry powder and Z-scan methods, respectively. The single crystal of MQSA is further studied through Hirshfeld surface analysis, fingerprint plots, and crystal voids analysis to understand the intermoleculiar interactions and individual atomic arrangements inside the crystal. The H…H and O…H/H…O interactions are greatly aided by crystal structure. Additionally, the quantum computational methods were used to assess several molecular level electronic properties, including molecular orbitals, molecular electrostatic potentials maps, linear polarizability and static third-order nonlinear optical (NLO) polarizability, which is a molecular-level NLO response property. The isotropic linear polarizability and NLO polarizability of MQSA are 29.99 × 10−24 esu and 28.45 × 10−36 esu, respectively, in the M06–2X/6–311G* method, which demonstrates the decent potential of the synthesized crystal for its use as NLO materials. Furthermore, the frontier molecular orbitals, molecular electrostatic potentials, and UV–Visible spectrum were calculated and discussed.

Imaging Low-Temperature Phases of Ice with Polarization-Resolved Hyperspectral Stimulated Raman Scattering Microscopy.

Water freezes into various phases of ice under different cryogenic temperatures and pressure conditions, such as ice Ih and ice XI at normal pressure. Vibrational imaging with high spectral, spatial, and polarization resolutions could provide detailed information on ice, including the phases and crystal orientations at the microscopic level. Here, we report in situ stimulated Raman scattering (SRS) imaging of ice to analyze the vibrational spectral changes of the OH stretching modes associated with the phase transition between ice Ih and ice XI. In addition, polarization-resolved measurements were performed to reveal the microcrystal orientations of the two phases of ice, with the spatial-dependent anisotropy pattern indicating the inhomogeneous distribution of their orientations. Furthermore, the angular patterns were theoretically explained by third-order nonlinear optics with the known crystal symmetries of the ice phases. Our work may provide new opportunities to investigate many intriguing physical chemistry properties of ice under low-temperature conditions.

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.

Ultrafast Third-Order Optical Nonlinearity of Indigo Carmine Excited by Pico-second Pulsed Laser at 405 nm

Ultrafast Third-Order Optical Nonlinearity of Indigo Carmine Excited by Pico-second Pulsed Laser at 405 nm