Third-order Nonlinear Optical Properties Research Articles

Fabrication, Characterization of Basic Blue 7 Dye-Doped PVA Films and Their Third-Order Nonlinear Optical Properties.

In this work, we report on the fabrication, characterization and the third-order nonlinear optical (NLO) properties of basic blue 7 (BB 7) dye‒doped polyvinyl alcohol (PVA) polymer thin films. The absorption spectra of BB 7 dye‒PVA films were measured by UV‒visible absorption studies. The functional groups of BB 7‒PVA films have been identified by FT‒IR spectroscopic analysis. The surface morphology was examined by AFM and SEM analysis which shows that the BB 7 dye‒doped PVA films have a homogenous and smooth surface. The nonlinear absorption and refraction of BB 7‒PVA films were respectively explored by open aperture and closed aperture Z‒scan technique using a 5 mW semiconductor diode laser of 635nm wavelengths. The BB 7‒PVA films exhibit the reverse saturable absorption (RSA) and self-defocusing effect and the measured third‒order nonlinear susceptibility χ(3) values of these films were found to be of the order of 10- 5 esu. The present experimental results show that BB 7‒PVA films may have potential applications in future photonic and NLO 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.

Growth and characterization of D-Alanine DL-Mandelic acid single crystals for antibacterial activity and optical limiting applications

A promising optically prospective D-Alanine DL-Mandelic acid (DADLMA) an organic single crystal was successfully grown at room temperature by a slow solvent evaporation approach. The monoclinic crystal structure of the title crystal with space group C2 has been verified. The existence of multiple operational groups and linkages in the DADLMA crystal was ensured with the FTIR spectrum. The grown crystal was investigated to determine optical absorption cut-off wavelength (274 nm), energy band gap and linear refractive index by the UV–Visible absorption spectrum. The luminescence response has been observed to probe the compatibility of the material for the production of optical devices and the grown crystal shows a peak at 570 nm. The major focus of our work was to determine NLO properties of the sample and the DADLMA crystal was investigated for the first attempt by Z-scan measurement to bring out third-order nonlinear optical properties. The determined values are β (0.0149 × 10-4 cm/W), n2 (3.351 × 10-10 cm2/W) and χ(3) (1.674 × 10-7esu). The antibacterial activity of the title compound was investigated against a few foodborne pathogens (Streptococcus aureus, Klebsiella pneumoniae, Streptococcus pneumoniae and Escherichia coli) by measuring the zone of inhibition. Existing data indicate that the synthesized crystals are potential candidates for opto-electronic devices, optical limiting devices and biological applications.

Third-order nonlinear optical properties of mono and biphasic β-tricalcium phosphate in continuous wave regime

Third-order nonlinear optical properties of mono and biphasic β-tricalcium phosphate in continuous wave regime

Influence of embedded NiO-nanoparticles on the nonlinear absorption of tungsten disulfide nanolayers

2D transition metal dichalcogenides possess fascinating properties due to their direct bandgap, strong spin-orbit coupling, and promising electronic/mechanical properties. In this work, we synthesized pure tungsten disulfide (WS2) nanolayers and NiO nanoparticles (NPs) decorated in few-layered WS2 and measured the third-order nonlinear optical properties using femtosecond Z-scan measurements. The open aperture Z-scan data illustrated that the inclusion of NiO nanoparticles into the WS2 layers increases the nonlinear absorption at 800 and 400 nm wavelengths. Furthermore, we observed the switchability of the nonlinear absorption from saturable absorption to two-photon absorption or reverse saturable absorption by changing the pump intensity. Thus, the embedded NiO NPs played a crucial role in the variation of intensity-dependent nonlinear absorption mechanism of WS2 nanolayers and thus can be helpful for various optical applications such as laser pulse compression and optical limiting to prevent over-exposure of protective photosensitive sensors by intense ultrashort laser pulses.

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.

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.

Crystal growth, structural and DFT study of novel single crystal (E)-N’-(2-chlorobenzylidene)-4-fluorobenzohydrazide for nonlinear optical applications

Nonlinear optical (NLO) material, (E)-N'-(2-chlorobenzylidene)-4-fluorobenzohydrazide (CBBH) novel single crystal was grown via a Schiff base chemical reaction. A single crystal X-ray diffraction technique was utilized for the recognition of the crystal structure of the CBBH. The imperfection of novel CBBH crystal was checked by high resolution X-ray diffraction (HRXRD) study. Hirshfeld surface study through colour coding was applied to know the intra and intermolecular force interactions. Fourier transforms infrared (FTIR), proton 1H and carbon 13C nuclear magnetic resonance (NMR) spectra were employed to elucidate the various functional groups and structure of the crystal. The absorption maxima from UV–Vis plot for the CBBH molecule was found at 314 nm, which reveals the π-π* transition. Photololuminescence (PL) study reveals that emission observed in the blue-violet region. The HOMO and LUMO energies were investigated using the density functional theory (DFT) method. Natural bond orbital (NBO) analysis explored the donor-acceptor exchanges and it's endurance into intra-molecularly. The first-order hyperpolarizability value, β0 = 23.73 × 1030 esu was observed for CBBH crystal, which is ∼64 times larger than that of urea molecule (0.3728 × 1030 esu). Z-scan experiment on CBBH crystal supports its third-order nonlinear optical (NLO) properties. Optical limiting analysis indicates reverse saturation absorption behavior of CBBH crystal.

The intra/valence-band linear and third-order nonlinear optical properties of a laser-dressed double GaAsSb/GaAs parabolic quantum well: the effect of the geometry of the well and antimony content

The intra/valence-band linear and third-order nonlinear optical properties of a laser-dressed double GaAsSb/GaAs parabolic quantum well: the effect of the geometry of the well and antimony content

Investigation of linear and third-order nonlinear optical properties of laser-dressed GaAs/GaAsSb/GaAs parabolic valence-band quantum wells

Investigation of linear and third-order nonlinear optical properties of laser-dressed GaAs/GaAsSb/GaAs parabolic valence-band quantum wells

Donor–Acceptor Covalent Organic Frameworks Films with Ultralow Band Gaps to Enhanced Third-Order Nonlinear Optical Properties

Covalent organic frameworks (COFs) have attracted much attention in porous materials because of their structural tunability and stability. However, the problems of low transmittance and large light scattering due to the difficulty of powder phase processing have severely limited their practical applications in third-order nonlinear optics (NLO). Herein, we report the first successful synthesis of a series of donor–acceptor (D–A) COFs films (thickness of ∼100 nm) with uniform transparency and narrow optical band gap by the solvothermal and solid–liquid interface methods for third-order NLO applications. Most importantly, the designed PT–PA film exhibits excellent NLO performance, including a normalized transmission value of ∼2.55 at the beam focus, a modulation depth (As) of 139%, and a high nonlinear absorption coefficient (β) of 1.83 × 106 cm GW–1 at the pulse energy of 1 μJ, which is superior to most recently reported third-order NLO materials. The excellent third-order NLO properties are mainly attributed to the homogeneous transparency of the COFs films and the extended-ordered conjugated structure and narrow optical band gap of the COFs films, which enhance the charge transfer in their structures and thus yield excellent third-order NLO behavior. This work provides an option for the development of high-performance NLO optical devices and opens a new path for the future development of COFs films in the optical fields.

Role of Sm in tuning the third-order nonlinear optical properties of spray coated Sn1-xSmxO2 films

In this work, the different physical and optical properties of spray coated nanostructured Sn1-xSmxO2 (x = 0.0 to 0.1) films were analyzed using various characterization techniques. All the films exhibited tetragonal structure with (1 1 0) as the prominent plane. The doping in general reduced the crystalline nature of the films along with narrowing of the bandgap values. Among the doped films, the most transmitting film was the 2 at.% Sm doped film, whereas the most crystalline was the 7 at.% Sm doped film. The fibrous morphology changed to distinct grains with the increase in Sm concentration. The oxidation states of the constituent elements were confirmed using X-ray photoelectron spectroscopy (XPS). The photoluminescence (PL) intensity was influenced by doping and emissions corresponding to the host SnO2 lattice were observed in the UV and visible regions. The PL emissions corresponding to the Sm ion transitions could not be found in the spectra. All the films exhibited third-order nonlinear optical nature with reverse saturable absorption. The suitability of these films as optical limiting material was identified. The magnitude of third-order nonlinear susceptibility χ(3) was also estimated to be in the range of 10−3-10−2 esu and the least optical limiting threshold was shown by Sn0.93Sm0.07O2 films.

Synthesis and characterization of linear/nonlinear optical properties of graphene oxide and reduced graphene oxide-based zinc oxide nanocomposite

In this paper, we aimed to investigate the linear and nonlinear optical properties of GO-ZnO and RGO-ZnO nanocomposites in comparison with pure GO and reduced graphene oxide (RGO). For this purpose, GO, RGO, GO-ZnO, and RGO-ZnO were synthesized and characterized by Fourier transform infrared (FT-IR), Ultraviolet–Visible (UV–Vis) absorption, X-ray diffraction (XRD) and energy dispersive X-ray spectroscopy (EDX). XRD and EDX analysis indicated the reduction of GO as well as the successful synthesis of GO-ZnO and RGO-ZnO nanocomposites. The FT-IR spectroscopy showed that absorption bands were at 3340 cm−1, 1630 cm−1, 1730 cm−1 and 480 cm−1 related to OH, C=C, C=O, and Zn–O stretching vibrations, respectively. The direct band gaps of GO, RGO, GO-ZnO and RGO-ZnO from UV–Vis spectra were at 3.36, 3.18, 3.63 and 3.25 eV, sequentially. Moreover, the third-order nonlinear optical properties were investigated using a z-scan technique with Nd: YAG laser (532 nm, 70 mW). It can be seen that the nonlinear absorption coefficient value (upbeta ) increased from 5.3 × 10–4 (GO) to 8.4 × 10–3 cm/W (RGO-ZnO). In addition, nonlinear refractive index (n2) of the GO, RGO, GO-ZnO, and RGO-ZnO was obtained as 10.9 × 10–10, 14.3 × 10–10, 22.9 × 10–10, and 31.9 × 10–10 cm2/W respectively.

Investigation of third-order nonlinear optical properties in two novel ethyne-linked chromophores: Effect of donor-acceptor alternation

Two novel compounds of the alternating donor (D)/acceptor (A) system were designed and synthesized. In BSB (A-π-D-π-A) and SBS (D-π-A-π-D), thiophene, 2,1,3-benzothiadiazole (BTD) and ethylene act as donor, acceptor groups and π-bridge moiety, respectively. Z-scan experiments at 532 nm with various pulse durations show a transition from saturable absorption to reverse saturable absorption and self-defocusing effects in both compounds. The different alternating modes of D-A units lead to an order of magnitude increment in the second-order hyperpolarizability γ of SBS (4.4 × 10−28 esu) compared to BSB. Ultrafast transient absorption spectroscopy was carried out to analyze the enhancement of second-order hyperpolarizability. Results indicate that this enhancement originates from excited state absorption of the long-lived intramolecular charge transfer state. Using quantum chemical calculations, the stronger symmetrical intramolecular charge transfer in SBS can be demonstrated by the difference between the ground- and excited-state dipole moments Δμge. It is shown intuitively in the S0–S1 hole-electron analysis. All of the experimental and theoretical results suggest that changing the D-A alternation in organic molecules can effectively modulate the third-order nonlinear optical behavior, which may serve as a guide for future molecular design.

Ta2C MXene: Nonlinear optical properties and application in femtosecond fiber laser

Broadband optical response and strong optical nonlinearity have enabled MXenes to be applied in numerous ultrafast photonic devices. Here, we explored the nonlinear optical properties of a novel MXene, Ta2C, and demonstrated a femtosecond fiber laser with a Ta2C-based saturable absorber (SA). First-principles calculations were employed to fully reveal the structural and electronic properties of the Ta2C MXene. The third-order nonlinear optical properties of the as-prepared Ta2C nanosheets were measured from the visible to near-infrared regime by the commonly used open-aperture Z-scan technique. Its maximum nonlinear absorption coefficient was fitted to be −0.42 cm/GW, implying its broad application prospects in nonlinear photonic devices. Moreover, Ta2C MXene-coated microfibers as SAs were integrated into erbium-doped fiber laser cavities. Long-term stable mode-locked pulses centered at 1560.1 nm were generated by the constructed laser device. The ultrashort pulse duration of about 774 fs and high signal-to-noise ratio of over 50 dB indicate that Ta2C MXene is a promising material for generating ultrafast pulses.

Investigation of linear and third-order nonlinear optical properties in a laser-dressed parabolic quantum dot with a hydrogenic donor impurity in the presence of a static electric field

Investigation of linear and third-order nonlinear optical properties in a laser-dressed parabolic quantum dot with a hydrogenic donor impurity in the presence of a static electric field

Synthesis, growth, crystal structure analysis, optical characterization, thermal and dielectric studies on 2-amino-5-chloropyridinium phenoxyacetate (2A5CPA): An efficient new organic single crystal for nonlinear optical applications

The new organic 2-amino-5-chloropyridinium phenoxyacetate (2A5CPA) nonlinear optical (NLO) crystal was synthesized and grown from methanol solvent by slow evaporation method successfully. The complete 2A5CPA crystal structure was solved by single crystal XRD analysis and it indicates that the 2A5CPA crystal belongs to the tetragonal crystal system with the space group P41212. From the structure, the possible hydrogen bonding interactions have been analyzed. The presence of distinctive functional peaks in the 2A5CPA crystal was affirmed by FTIR analysis. The optical investigation reveals that the crystal was completely transparent in the UV–Vis–NIR region. The TG-DTA investigation assured that the 2A5CPA compound is thermally stable up to 134°C without any decomposition. The sharp endo thermic peak at 205°C in the DTA trace indicates the melting point of the crystal. The broad emissive band at 382[Formula: see text]nm implies the violet emission characteristics of the 2A5CPA crystal. The dielectric study of the 2A5CPA crystal portrays the normal behavior to that of optical materials. The high work-hardening coefficient of 2.94 indicates the soft material nature of the crystal. The LDT value of the 2A5CPA crystal is estimated as 0.6135[Formula: see text]GW/cm2. The third-order NLO properties of the 2A5CPA crystal were analyzed through Z-Scan experiment.

Porphyrin metal-organic frameworks with bilayer and pillar-layered frameworks and third-order nonlinear optical properties.

It is recognized that dimensions have a decisive influence on the properties of materials. Metal-organic frameworks as third-order nonlinear optical (NLO) materials have attracted much attention recently. However, research on the influence of dimensions on third-order NLO properties of MOFs has not been reported. In this work, we synthesized two porphyrin MOFs (PMOFs) constructed with π-conjugated tetracarboxyphenylporphyrin (TCPP) and in situ formed 1,2-bis(1H-benzo[d]imidazol-2-yl)ethene (BIE) conjugated ligands. In both PMOFs, Zn2(CO2)4 paddlewheel units are connected by TCPP-Zn ligands to form a 2D layer. Interestingly, these layers are linked by BIE ligands to form a bilayer in PMOF-1 and a 3D pillar-layered framework in PMOF-2, which serve as structural models to evaluate the influence of dimensions on third-order NLO properties. It is speculated that the 3D pillar-layered framework in PMOF-2 with BIE conjugated pillars is more conducive to interlayer charge transfer than the two-dimensional bilayer in PMOF-1, thus achieving a better third-order NLO performance. The third-order NLO test results of PMOFs in a polydimethylsiloxane (PDMS) matrix showed that PMOF-2 displayed a higher nonlinear absorption coefficient, large third-order susceptibility and lower limiting threshold than PMOF-1/PDMS, which may be mainly attributed to the fact that the 3D pillar-layered framework is more conducive to interlayer charge transfer than the two-dimensional bilayer. This work reveals the influence of dimensions on third-order nonlinear properties which will help to explore new MOF materials with excellent third-order NLO properties.

Effect of Ba/Sr ratio on the nonlinear optical properties of Ba1-xSrxTiO3 (x = 0.1–0.9) thin films

Perovskite-structured barium strontium titanate (Ba1-xSrxTiO3, x = 0.1–0.9) films have been epitaxially fabricated by using a pulsed-laser deposition technique. The third-order nonlinear optical properties were studied through a z-scan method, allowing the resolution of the nonlinear refractive and absorptive contributions to the responses. Although all the samples show almost the same value of nonlinear absorption coefficient, the extracted nonlinear refractive index of the sample of x = 0.3 is apparently larger than that of other samples. Dependency of the nonlinear optical properties on the Ba/Sr ratio is discussed in terms of the crystal phase transformation and metal-oxygen bond length of the selected materials.

Nonlinear optical properties of porphyrin-based covalent organic frameworks determined by steric-orientation of conjugation

The influences of conjugation on the third-order nonlinear optical (NLO) properties of covalent organic frameworks (COFs) provide guidelines to design the structures for desired applications.