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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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Mode-Locked Er-Doped Fiber Laser by Using MoS2/SiO2 Saturable Absorber
摘要： The two-dimensional (2D) layered material MoS2 has attracted numerous attentions for electronics and optoelectronics applications. In this work, a novel type of MoS2-doped sol-gel glass composite material is prepared. The nonlinear optical properties of prepared MoS2/SiO2 composite material are measured with modulation depth (ΔT) of 3.5% and saturable intensity (Isat) of 20.15 MW/cm2. The optical damage threshold is 3.46 J/cm2. Using the MoS2/SiO2 composite material as saturable absorber (SA), a passive mode-locked Er-doped fiber (EDF) laser is realized. Stable conventional soliton mode-locking pulses are successfully generated with a pulse width of 780 fs at the pump power of 90 mW. In the pump power range of 100–600 mW, another stable mode-locking operation is obtained. The pulse width is 1.21 ps and the maximum output power is 5.11 mW. The results indicate that MoS2/SiO2 composite materials could offer a new way for optical applications.
关键词： Nonlinear optical materials,Saturable absorbers,Transition metal dichalcogenides
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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Nonlinear manipulation of surface plasmons on graphene-TMDC Bragg reflectors
摘要： In this study, we benefit from the nonlinear optical tunability of the graphene-transition metal dichalcogenide (G-TMDC) heterostructure and the strong confinement of the electromagnetic fields of surface plasmon polaritons (SPPs) on graphene in order to propose a highly tunable nonlinear optical Bragg reflector. Recently, two-dimensional (2D) TMDCs are the subject of intense researches because of their nonlinear optical properties at near infrared wavelengths which are very intriguing for various optical applications. We choose two kinds of 2D-TMDCs, MoSe2 and WSe2, with the strongest second order optical nonlinearity at near infrared range to properly design the periodic variation of the propagating SPP waves on the graphene layer. We utilize theoretical method of quantum electrostatic heterostructure to compute the dielectric function of graphene-TMDCs. Different nonlinearities of two TMDCs lead to noticeable tuning of the full width at half maximum (FWHM) and the central Bragg wavelength of the reflector which let design various optical devices. We design an add/drop filter, a nonlinear switch, and an AND/OR optical logic gate based on our proposed Bragg reflector. Our finite difference time domain numerical and transfer matrix analytical results reveal that by increment of the optical intensity up to 6 MW/cm2 which is below the pulse damage threshold of graphene, due to the second order nonlinearity, a 10-nm red-shift in central Bragg wavelength is observed and the 20-nm FWHM at linear regime decreases to 1.5 nm. The SPP intensities of 0.8 MW/cm2 and 1.53 MW/cm2 fulfill the requirements for AND and OR logical operations with 57 and 66.51 dB extinction ratios, respectively.
关键词： Nonlinear optical materials and devices,Surface plasmons,Nonlinear optics,Optical switches,Bragg grating
更新于2025-09-10 09:29:36
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[IEEE 2018 20th International Conference on Transparent Optical Networks (ICTON) - Bucharest (2018.7.1-2018.7.5)] 2018 20th International Conference on Transparent Optical Networks (ICTON) - Third Harmonic Generation of Azo-Based Thin Films
摘要： This paper presents investigation results of the linear and nonlinear optical properties for thin films containing azo-based compounds. Thin films were deposited on a glass substrate using spin coating technique. The linear optical properties were examined by using Absorption method. The nonlinear optical properties as well as Third Harmonic Generation were examined by means of Maker fringe technique by exploiting Nd:YAG laser at a wavelength 1064 nm. Third-order nonlinear optical susceptibility were calculated using theoretical model.
关键词： third harmonic generation,azo-based compounds,nonlinear optical response,thin film,nonlinear susceptibility
更新于2025-09-10 09:29:36
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Structural, optical and nonlinear optical properties and TD-DFT analysis of heteroleptic bis-cyclometalated iridium(III) complex containing 2-phenylpyridine and picolinate ligands
摘要： In this work, we studied the structural, optical and nonlinear optical properties and UV–visible absorption spectrum of the heteroleptic bis-cyclometalated iridium(III) complex (tfmppy)2Ir(pic) recently synthesized with tfmppy = 5-trifluoromethyl-2-phenylpyridine and pic = picolinate. The calculations were performed by means of density functional theory (DFT) and time-dependent density functional (TD-DFT) methods using four functionals B3LYP, PBE0, CAM-B3LYP and M06-2X. Calculated geometric parameters agree with the experimental data. CAM-B3LYP and M06-2X lower the HOMO energy level and give a large energy gaps compared with B3LYP and PBE0. The four functionals show that LUMO is delocalized over ??? ppy and dIr orbitals. The studied complex gets a remarkably large first-order NLO response. B3LYP would provide good estimates of the energy gap and shows the strongest values of the first hyperpolarizabilities βHRS; M06-2X and CAM-B3LYP functionals overestimate the gaps and lower βHRS values. PBE0 and B3LYP spectra agree better with the experimental spectrum in the visible region, while CAM-B3LYP and M06-2X are more accurate in UV-C region. Natural transition orbital analysis shows that the weak band observed at 468 nm corresponds to MLCT/LLCT charge transfer transitions and the intense band observed at 270 nm is mainly assigned to intra-ligand state.
关键词： Excited states,Wiberg indices,Absorption spectrum,Hyperpolarizability,Complexes,Iridium,NTO,TD-DFT,Optical, nonlinear optical,Picolinate
更新于2025-09-10 09:29:36
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Correlated Materials Characterization via Multimodal Chemical and Functional Imaging
摘要： Multimodal chemical imaging simultaneously offers high resolution chemical and physical information with nanoscale, and in select cases atomic resolution. By coupling modalities that collect physical and chemical information, we can address scientific problems in biological systems, battery and fuel cell research, catalysis, pharmaceuticals, photovoltaics, medicine and many others. The combined systems enable local correlation of material properties with chemical makeup, making fundamental questions in how chemistry and structure drive functionality approachable. In this review we present recent progress and offer a perspective for chemical imaging used to characterize a variety of samples by a number of platforms. Specifically, we present cases in infrared and Raman spectroscopies combined with scanning probe microscopy; optical microscopy and mass spectrometry; nonlinear optical microscopy; and finally, ion, electron and probe microscopies with mass spectrometry. We also discuss the challenges associated with the use of data originated by the combinatorial hardware, analysis, and machine learning as well as processing tools necessary for interpretation of multidimensional data acquired from multimodal studies.
关键词： raman spectroscopy,ion microscopy,nonlinear optical microscopy,mass spectrometry,electron microscopy,infrared spectroscopy,chemical imaging,scanning probe microscopy,data analytics,optical microscopy
更新于2025-09-10 09:29:36