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Enhanced piezoresponse and nonlinear optical properties of fluorinated self-assembled peptide nanotubes
摘要： Self-assembled L,L-diphenylalanine (FF) nanostructures offer an attractive platform for photonics and nonlinear optics. The nonlinear optical (NLO) coefficients of FF nanotubes depend on the diameter of the tube [S. Khanra et al. Phys. Chem. Chem. Phys. 19(4), 3084–3093 (2017)]. To further enhance the NLO properties of FF, we search for structural modifications. Here, we report on the synthesis of fluorinated FF dipeptides by replacing one ortho-hydrogen atom in each of the phenyl groups of FF by a fluorine atom. Density-functional theoretical calculations yield insights into minimum energy conformers of fluorinated FF (Fl-FF). Fl-FF self-assembles akin to FF into micron-length tubes. The effects of fluorination are evaluated on the piezoelectric response and nonlinear optical properties. The piezoelectric d15 coefficient of Fl-FF is found to be more than 10 times higher than that of FF nanotubes, and the intensity of second harmonic generation (SHG) polarimetry from individual Fl-FF nanotubes is more than 20 times that of individual FF nanotubes. Furthermore, we obtain SHG images to compare the intensities of FF and Fl-FF tubes. This work demonstrates the potential of fluorine substitution in other self-assembled biomimetic peptides for enhancing nonlinear optical response and piezoelectricity.
关键词： piezoresponse,density-functional theory,nonlinear optical properties,fluorinated self-assembled peptide nanotubes,second harmonic generation
更新于2025-09-11 14:15:04
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Nonlinear optical properties of tungsten disulfide as saturable absorber based on Q-switched fiber laser
摘要： In this paper, nonlinear optical properties of tungsten disulfide are studied. Tungsten disulfide (WS2) is prepared as saturable absorber (SA) with the microstructured optical fiber. When the SA based on WS2 is assembled into a fiber laser, Q-switched operation is demonstrated. The 2 nm spectral width is obtained at the central wavelength of 1531 nm. The signal-to-noise ratio is about 80 dB, which indicates that the fiber laser is very stable. The shortest pulse duration is 800 nm at the maximum input power of 650 mW. The conclusion shows that WS2 is a good nonlinear optical material.
关键词： Saturable absorber,Fiber laser,Tungsten disulfide,Nonlinear optical properties
更新于2025-09-11 14:15:04
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Stable all-fiber passively Q-switched erbium-doped fiber laser based on plasmonic Zn doped CuGaO <sub/>2</sub> nanoplates
摘要： In this letter, we synthesized p-type Zn doped hexagonal CuGaO2 (CGZO) nanoplates (NPs) by hydrothermal reaction and utilized the nonlinear optical properties of these plasmonic NPs to realized stable passively Q-switched erbium-doped fiber laser output. We achieved tunable saturable absorbers (SAs) by changing the doping ratio of CGZO NPs. With the increase of the doping ratio, pulse duration decreases from 2.532 μs to 2.276 μs and the optical-optical conversion efficiency of the Q-switched laser increases from 1.36% to 1.70%. Our result suggests that CGZO is promising to allow tunable SAs to generate passively Q-switched fiber lasers.
关键词： Q-switched fiber laser,plasmonic Zn doped CuGaO2 nanoplates,saturable absorbers,nonlinear optical properties
更新于2025-09-11 14:15:04
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An Harmonic Mode‐Locked Er‐Doped Fiber Laser by the Evanescent Field‐Based MXene Ti <sub/>3</sub> C <sub/>2</sub> T <i> <sub/>x</sub></i> (T?=?F, O, or OH) Saturable Absorber
摘要： MXenes, as a legendary family of 2D van der Waals nanosheets materials, are extensively studied due to their unique characteristics of broadband nonlinear optical response. In particular, MXenes have excellent nonlinear optical properties of very large nonlinear absorption coefficients and very large nonlinear refractive indexes, which have attracted people’s great attentions to study the application of MXenes in photonics, electronics, and optoelectronics in recent years. However, the high-repetition-rate (HRR) ultrafast pulses are not explored based on these kinds of materials. MXene Ti3C2Tx saturable absorber (SA) based on micro-fiber is fabricated by optical deposition method. Here, MXene Ti3C2Tx SA is used to achieve 36th harmonic mode-locking with a repetition rate of 218.4 MHz, a central wavelength of 1566.9 nm, the pulse width of 850 fs, and the spectral width of 3.51 nm. The maximum average output power and pulse energy are 6.95 mW and 0.032 nJ, respectively. This research based on MXene Ti3C2Tx light modulator opens a bright avenue for advanced nonlinear photonics.
关键词： harmonic mode-locking,MXene Ti3C2Tx,nonlinear optical properties
更新于2025-09-11 14:15:04
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Anisotropic nonlinear optical response of phosphorene
摘要： The pseudorelativistic behavior of carriers is found in the energy bands of certain class of two dimensional (2D) semi-conducting materials such as phosphorene. In this article, the nonlinear optical response of pseudorelativistic electrons in phosphorene under intense applied electromagnetic field is investigated. Using Floquet theory, we demonstrate the anisotropic behavior of anomalous Rabi oscillations in phosphorene, which occurs far from the conventional resonance. The role of anisotropy on anomalous Rabi oscillations in phosphorene is also justified numerically. The Bloch-Siegert shift is observed under strong driving field that strongly depends on the anisotropy of the energy bands of phosphorene. A theoretical description of the pump-probe experiment is given to detect the anomalous Rabi oscillations in phosphorene. The differential transmission coefficient shows a sinusoidal behaviour as a function of pump pulse duration whose amplitude exhibits a power law decay, which is quite different from graphene (relativistic fermionic system). So the Floquet theory can be used to characterize the different fermionic systems.
关键词： Anisotropic Optical Materials,Nonlinear Optical Properties,Nonlinear Optical Materials,Phosphorene
更新于2025-09-10 09:29:36
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Structural, vibrational and optical properties of an organic-inorganic hybrid crystal of benzyl 4-aminopyridinium tetrabromocadmate(II) based on DFT calculations
摘要： An organic-inorganic hybrid crystal, [Bz-4-NH2Py]2[CdBr4](1) (Bz-4-NH2Py = 1-benzyl-4'-aminopyridinium), was grown successfully by slow evaporation solution growth method at room temperature and characterized. In tetrachlorocadmate(II) dianion, the CdII ion is coordinated by four Br atoms in a close to tetrahedral geometry. The crystal packing is stabilized by C-H···Br hydrogen bonds between [Bz-4-NH2Py]+ cations and [CdBr4]2- anion forming a three-dimensional network. Powder XRD diffraction study confirms the crystalline nature of the title compound. Thermal stability and the gaseous products of decomposition at 362 oC were examined by TG-DTA-MS technique. The Fourier transform infrared (FT-IR) and Raman spectra were recorded and analyzed with the aid of DFT calculations in order to make a suitable assignment of the observed bands. UV-vis spectral analysis was used to determine the band gap energy, and the nonlinear optical (NLO) effect of the compound was predicted using DFT. Further, the title compound exhibits strong fluorescence emission at 394, 329 and 467 nm in the solid at room temperature.
关键词： Nonlinear optical properties,Tetrabromocadmate(II) dianion,Benzyl 4-aminopyridinium,Density functional theory calculation,Crystal structure
更新于2025-09-10 09:29:36
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A systematic study of the effects of thionation in naphthalene dimide derivatives to tune their nonlinear optical properties
摘要： In the present study, the number and position of sulfur atoms on naphthalene diimide (NDI) is systematically investigated to tune its nonlinear optical (NLO) response properties. Our DFT calculations for third-order polarizability (γ) show that the thionation significantly influences the nonlinear optical property of NDI as it is seen among its several designed derivatives (NDI-1 to NDI-10). The smallest and the largest γzzzz amplitudes are 503.49×10?36 and 1299.5×10?36 esu for NDI-1 (having tetraone group) and NDI-10 (having tetrathione group), respectively. The increase in γzzzz amplitude for NDI-10 is 796×10?36 esu, which is ~150% from the γzzzz amplitude of NDI-1. A comparison of the γzzzz amplitudes of our designed derivatives are made with para-nitroaniline i.e. a prototype NLO molecule. The γzzzz amplitude of pNA is found to be 42.64×10?36 esu at the same B3LYP/DZVP2 level of theory. Using two-level model, the origin of larger γzzzz amplitudes is traced in lower transition energy of NDI-10. Furthermore, the calculation of vertical ionization potentials (VIPs) shows that the thionation does not affect the stability of designed derivatives, where a slight difference of 0.06 eV is seen between the VIPs of NDI-1 (6.63 eV) and NDI-10 (6.57 eV). Thus, a systematic comparison of the third-order polarizability and other electro-optical properties of our designed derivatives shows that our derivative systems possess good potential for their practical realization in the field of optical and NLO materials.
关键词： Naphthalene Diimide,Nonlinear Optical Properties,Third order-NLO polarizability,Polarizability,Frontier Molecular Orbitals
更新于2025-09-09 09:28:46
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Effect of Aluminium doping on photoluminescence and third-order nonlinear optical properties of nanostructured CdS thin films for photonic device applications
摘要： The work presented here reports the influence of Aluminium (Al) doping on CdS thin films for the structural, morphological, optical and third-order nonlinear optical (NLO) properties. Thin films of Pure CdS and Al-doped CdS (Cd1-xAlxS) with x= 0, 0.01, 0.05 and 0.1 are prepared on the glass substrate at 350oC using the spray pyrolysis technique. The observed X-Ray Diffraction (XRD) patterns of CdS films are found to a polycrystalline hexagonal structure and are not much affected by Al doping. Also the films have been examined by Field Emission Scanning Electron Microscopy (FESEM) images. The transmittance of the CdS films is observed to be 50 to 60% in the visible region and that decreased at higher doping concentrations and with higher Al doping the direct optical band gap is decreased from 2.52 to 2.38 eV. To understand the defect states characteristics, the corresponding room-temperaturephotoluminescence (RTPL) spectra have also been taken and found the nonlinear behavior in a band to band-edge emission in the prepared samples upon Al incorporation. The sign and the magnitude of the third-order NLO properties were determined using the Z-scan technique with a continuous wave laser as the excitation source. It is observed that the material exhibit strong two-photon absorption (2PA) with the nonlinear absorption (NLA) coefficient (β) in the range of 10-4 cmW-1 and nonlinear refractive index (NRI) n2 ~10-9 cm2W-1. The third-order NLO susceptibility has found to be enhanced from 3.12 x10-5 esu to 6.36 x10-5 esu upon Al incorporation. Optical limiting characteristics of the prepared films are studied at the experimental wavelength. The results suggest that the Cd1-xAlxS is a promising material for nonlinear optical devices at 532 nm and optical power limiting applications.
关键词： photoluminescence,spray pyrolysis,Al-doped CdS thin films,Z-scan,structural,nonlinear optical properties
更新于2025-09-09 09:28:46
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Tailoring the Linear and Second-Order Nonlinear Optical Responses of the Titanium-MIL-125 Metal-Organic Framework through Ligand Functionalization: A First Principles Study
摘要： Density functional theory calculations have been performed to investigate the linear and second order nonlinear optical (NLO) properties of titanium-based MIL-125 metal-organic frameworks in crystalline form, in which the 1,4-benzene-dicarboxylate (BDC) linkers are modified by introducing different functional groups or by extending BDC ligand to contain two (MIL-126) and three (MIL-127) benzene rings. Our results reveal that the functionalization of BDC linker tends to increase the dielectric constants and the magnitude of birefringence of MIL-125, especially for the aminated derivatives. Correspondingly, the incorporation of substituent group will improve the phase matching performance of MIL-125. As for the second harmonic generation (SHG) susceptibility, the SHG activity of the pristine MIL-125 is comparable to KDP, which can be attributed mostly to the contributions of TiO5(OH) octahedra. It is noted that after introducing substituent group into BDC linker, the organic part will have a remarkable influence on the SHG intensity. However, the specific effect on the NLO response is dependent on the type of functional group incorporated into BDC ligand, and only the inclusion of amine group that is strongly electron-donating can obviously enhance the SHG activity of MIL-125. In addition, MIL-126 and MIL-127 with longer aromatic linking unit are not suitable to act as NLO materials due to their poor phase matching abilities, but they are the promising candidates for the low dielectric constant materials. The present study can provide theoretical insights to design new second-order NLO materials based on MIL-125.
关键词： Nonlinear Optical Properties,Density Functional Theory,Hybrid Materials,Ligand Functionalization,Metal-Organic Framework,Plasmonics,Optical,Magnetic
更新于2025-09-04 15:30:14
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Nonlinear optical organic–inorganic crystals: synthesis, structural analysis and verification of harmonic generation in tri-( <i>o</i> -chloroanilinium nitrate)
摘要： The structural and nonlinear optical properties of a new anilinium hybrid crystal of chemical formula (C6H7NCl+NO3?)3 have been investigated. The crystal structure was determined from single-crystal X-ray diffraction measurements performed at a temperature of 100 K which show that the compound crystallizes in a noncentrosymmetric space group (Pna21). The structural analysis was coupled with Hirshfeld surface analysis to evaluate the contribution of the different intermolecular interactions to the formation of supramolecular assemblies in the solid state that exhibit nonlinear optical features. This analysis reveals that the studied compound is characterized by a three-dimensional network of hydrogen bonds and the main contributions are provided by the O···H, C···H, H···H and Cl···H interactions, which alone represent ～85% of the total contributions to the Hirshfeld surfaces. It is noteworthy that the halogen···H contributions are quite comparable with those of the H···H contacts. The nonlinear optical properties were investigated by nonlinear diffuse femtosecond-pulse reflectometry and the obtained results were compared with those of the reference material LiNbO3. The hybrid crystals exhibit notable second (SHG) and third (THG) harmonic generation which confirms its polarity is generated by the different intermolecular interactions. These measurements also highlight that the THG signal of the new anilinium compound normalized to its SHG counterpart is more pronounced than for LiNbO3.
关键词： structural analysis,Hirshfeld surface analysis,intermolecular interactions,nonlinear optical properties
更新于2025-09-04 15:30:14