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- 2019
- Distributed optical fiber sensing
- Optical frequency domain reflection
- Polynomial regression algorithm
- Nonlinear tuning compensation
- Optoelectronic Information Science and Engineering
- Hebei University of Technology
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Polarized THz Emission from In-Plane Dipoles in Monolayer Tungsten Disulfide by Linear and Circular Optical Rectification
摘要： Recent advances in the development of polarized terahertz (THz) emission from nanomaterials have not only opened up a new “TeraNano” interdiscipline but also provided a new tool for nonlinear optical process research. Herein, THz radiation mechanism of monolayer tungsten disulfide (WS2) is first investigated by both linear and circular polarization laser excitations at room temperature. The results reveal that polarized THz emission is dominated by the optical rectification based on in-plane nonlinear dipoles, which is totally different from that of bulk WS2. The mechanism is verified by the azimuthal angle and pump polarization angle dependence of THz emission in both experiment and theory. Furthermore, controllably elliptically polarized THz emission is observed with the maximum ellipticity of ≈0.52 based on nonresonant nonlinear process under the circularly polarized excitation. A clear understanding of THz radiation mechanism of 2D materials will facilitate further design, optimization, and polarization control of integrable 2D THz optoelectronics.
关键词： THz radiation,monolayer WS2,in-plane nonlinear dipoles,optical rectification,elliptically polarized THz emission
更新于2025-09-23 15:23:52
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Crystal growth and characterization of γ-glycine grown from AgSO4 for nonlinear optical applications
摘要： In the present work 0.1 M to 0.5 M proportions of silver sulphate (AgSO4) added glycine single crystals were grown by slow solvent evaporation method. The Powder XRD study confirms that the grown crystals have γ-glycine crystal structure and it crystallizes into a hexagonal structure with a non-centrosymmetric space group of P31. The dielectric constant and dielectric loss of grown crystal was carried out as a function of frequency and the results were discussed. The positive photoconducting nature of the grown crystals was studied by the photoconductivity study. Second harmonic generation (SHG) efficiency of the grown γ-glycine crystal was assessed by using Nd: YAG laser. The results confirms that the grown crystals have higher efficiency compared to the reference (KDP) crystal.
关键词： B2. Dielectric Materials,A1. X-ray diffraction,A1. Crystal structure,B2. Nonlinear optic materials
更新于2025-09-23 15:23:52
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Graphdiyne: A promising nonlinear optical material modulated by tetrahedral alkali-metal nitrides
摘要： A new series of the functionalized graphdiyne (GDY) material was designed by adsorbing the tetrahedral Li3NM molecules on the largely delocalized π-conjugated GDY surface, namely Li3NM@GDY (M = Li, Na, K), and its structure, chemical stability, electronic property, and the first hyperpolarizability were investigated by using the density functional theory computations. Our results reveal that the Li3NM molecules can interact with three triangular holes on the GDY surface, in which the van der Waals interactions play a crucial role in enhancing the structural stability. Meanwhile, the total NPA charges on the Li3NM molecules are gradually increased from Li to K, and the Li3NM molecules can transfer an electron to GDY, forming intramolecular electron donor and acceptor pairs. All of studied complexes exhibit the giant static first hyperpolarizabilities (βtot), up to ~2.88 × 105 a.u. for Li3NK@GDY, which can be explained by two-level expression from the TDDFT calculations. This study will inevitably stimulate further synthesis of the novel graphdiyne-based nonlinear optical materials.
关键词： Graphdiyne,Electronic structure,TDDFT,Charge transfer,Nonlinear optical property
更新于2025-09-23 15:23:52
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PAPR reduction in all-optical OFDM based on time interleaving odd and even subcarriers
摘要： In this paper, a new all-optical approach for reducing peak-to-average power ratio (PAPR) in all-optical orthogonal frequency division multiplexing (AO-OFDM) system based on time interleaving odd and even subcarriers (TIOES) is proposed and analytically modeled. In this approach, all subcarriers are initially modulated with higher modulation format such as m-array quadrature amplitude modulation (mQAM) and encoded by return-to-zero (RZ) coder. Then, odd and even subcarriers are temporally interleaved. An analytical model for estimating the impact of the interleaved time on PAPR reduction and induced nonlinear phase noise (NPN) is developed. The effect of reducing PAPR on performance of AO-OFDM system is also numerically investigated using VPItransmissionMaker? commercial software. This system utilizes an optical coupler-based inverse fast Fourier transform/fast Fourier transform. The results reveal that minimum PAPR is occurred when interleaved time between odd and even subcarriers equal to half symbol duration where the PAPR has been reduced by 3 dB. In addition, by employing proposed technique, the signal to noise ratio (SNR) is improved by about 2.5 dB at transmission distance of 800 km as compared with 4QAM AO-OFDM without PAPR technique.
关键词： PAPR reduction,mQAM modulation,Nonlinear phase noise,Fiber nonlinearity,AO-OFDM systems
更新于2025-09-23 15:23:52
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Construction of a Noncentrosymmetric Luminescent Coordination Polymer from [BaL <sub/>3</sub> ] Unit (L = Pyridine-2,6-dicarboxylate Acid) and Li(I) Ion
摘要： This work presents the synthesis, crystal structure and properties of a novel noncentrosymmetric (NCS) coordination polymer (CP), namely, (Me2NH2)3[BaLi(2,6-PyDC)3(H2O)] (1) (2,6-PyDC = pyridine-2,6-dicarboxylate acid), which represents the first example of BaLi-CPs with 2,6-PyDC ligand. Single-crystal X-ray structural analysis reveals that the compound features a two-dimensional (2D) layered structure. The simplified structure of each layer belongs to the hcb topology. The second harmonic generation (SHG) response of 1 is about 0.5 times that of KH2PO4 (KDP) marker. What is more, 1 emits bright blue light upon the excitation of 365 nm UV light with the quantum yield (QY, Φ) of 1.63%. The successful construction of this compound convinces the feasibility of constructing NCS CPs via the combination of [BaL3] unit and Li(I) ion.
关键词： noncentrosymmetric,heterometallic complex,luminescence,nonlinear optics
更新于2025-09-23 15:23:52
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Structure, growth and characterization of a new naphthalene family crystal for fluorescence and third order nonlinear optical applications
摘要： In the present work we have investigated the fluorescence and nonlinear optical property of a new naphthalene family crystal, Decyl 6-(decyloxy)naphthalene-2-carboxylate (D6DN2C). This crystal was grown for the first time by slow evaporation solution technique (SEST). Single crystal X-ray diffraction analysis reveals that D6DN2C belongs to triclinic crystal system with centrosymmetric space group of Pī. The determined lattice parameters are a = 8.669(3) ?, b = 9.495(3) ?, c = 19.757(6) ?, α =82.697(1)°, β =77.726(1)°, γ = 65.465(1)°and volume = 1444.17(8)?3. Functional groups present in D6DN2C were identified by FT-IR studies. Transparency of the title crystal in UV–Visible region was analyzed and the optical band gap energy was found to be 3.51eV. Fluorescence spectra were recorded for the excitation wavelength of 300 nm. The negative third order nonlinear optical parameters like refractive index (n2), absorption coefficient (β) and susceptibility (χ(3)) were estimated by Z-scan studies.
关键词： Crystal structure,Characterization,Growth from solutions,Nonlinear optic materials,Organic compounds
更新于2025-09-23 15:23:52
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Modulation stability analysis and solitary wave solutions of nonlinear higher-order Schr?dinger dynamical equation with second-order spatiotemporal dispersion
摘要： In optical fibers, the higher-order nonlinear Schr?dinger (NLS) dynamical equation which describes the beyond the classic slowly varying envelopes and spatiotemporal dispersion of pulses is investigated. By applying the proposed modified extended mapping method, the optical soliton solutions of higher-order NLS dynamical equation with the coefficients of group velocity dispersion, second-order spatiotemporal dispersion and cubic nonlinearity are deduced. The obtained solutions have important applications in applied sciences and engineering. The formation conditions are specified on parameters in which optical solitons can exist for this media. The moments of some constructed solutions are presented graphically which facilitate the researchers to comprehend the physical phenomena of this equation. The modulation instability analysis is utilized to discuss the model stability, which verifies that all obtained solutions are stable and exact. Other such forms of the system arising in sciences and engineering can also be solved by this steadfast, influential and effective method.
关键词： Solitary wave solutions,Higher-order nonlinear Schr?dinger equation,Solitons,Modified extended mapping method
更新于2025-09-23 15:23:52
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New Coumarin-benzoxazole derivatives: Synthesis, photophysical and NLO properties
摘要： In this work, a series of novel D-π-A structure coumarin-benzoxazole derivatives have been synthesized. The third-order NLO properties of the coumarin derivatives in DMSO are investigated by Z-scan measurement, and the photophysical properties of the compounds are studied through experimental and theoretical calculation methods. The results showed that the introducing specific functional groups at multiple active sites of coumarin reduced the π-π intermolecular stacking, while the formation of push-pull structure decreased E-gap of entire molecule. The excellent third-order NLO responses based on chromophore 4c with maximum nonlinear absorptive coefficients is 50.64 × 10-13 esu and the largest second-order NLO hyperpolarizability is 7.12 × 10-30 esu. Experimental results have also been confirmed through DFT, TDDFT and ZINDO calculations. Our results indicate that the coumarin fluorescent dyes are promising candidate materials for NLO applications.
关键词： ZINDO calculation,DFT,Fluorescent,Third-order nonlinear,Coumarin derivatives
更新于2025-09-23 15:23:52
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Enhanced nonlinear optical properties of LiNbO3 crystal embedded with CuZn alloy nanoparticles by ion implantation
摘要： LiNbO3 crystal, as a typical nonlinear optical material, has attracted considerable interest in photonic device applications. However, LiNbO3 shows weak nonlinear optical responses due to its low laser damage threshold. Herein, the optical nonlinearities of LiNbO3 are enhanced by inducing CuZn alloy nanoparticles (NPs). The structural and optical properties of LiNbO3 with embedded NPs were investigated in detail. The third-order nonlinear susceptibilities of CuZn: LiNbO3 nanocomposites exhibit nearly 4 orders of magnitude greater than the untreated LiNbO3 due to the localized surface plasmon resonance effect. Furthermore, the nanocomposites suffer conversion from reverse-saturable absorption to saturable absorption compared with the pure LiNbO3. This feature makes the nanocomposites a potential saturable absorber leading to the realization of efficient pulse lasers.
关键词： Ion implantation,Optical nonlinearities,CuZn alloy nanoparticles,Nonlinear materials
更新于2025-09-23 15:23:52
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Calcination-free synthesis of high strength self-cleaning anti-reflective MgF2-TiO2 coating
摘要： In order to understand the nonlinear dynamic behavior of a planar mechanism with clearance, the nonlinear dynamic model of the 2-DOF nine-bar mechanism with a revolute clearance is proposed; the dynamic response, phase diagrams, Poincar′e portraits, and largest Lyapunov exponents (LLEs) of mechanism are investigated. The nonlinear dynamic model of 2-DOF nine-bar mechanism containing a revolute clearance is established by using the Lagrange equation. Dynamic response of the slider’s kinematics characteristic, contact force, driving torque, shaft center trajectory, and the penetration depth for 2-DOF nine-bar mechanism are all analyzed. Chaos phenomenon existed in the mechanism has been identi?ed by using the phase diagrams, the Poincar′e portraits, and LLEs. The e?ects of the di?erent clearance sizes, di?erent friction coe?cients, and di?erent driving speeds on dynamic behavior are studied. Bifurcation diagrams with changing clearance value, friction coe?cient, and driving speed are drawn. The research could provide important technical support and theoretical basis for the further study of the nonlinear dynamics of planar mechanism.
关键词： Lyapunov exponent,nonlinear dynamics,chaos,clearance joint,bifurcation
更新于2025-09-23 15:23:52