- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Improved femtosecond third-order nonlinear optical properties of thin layered Cu3Nb2O8
摘要： Thin motif-layered triclinic Cu3Nb2O8 was prepared through solid-state reaction at 700 °C, 12 h and their nonlinear optical (NLO) properties with ultrafast [800 nm, 150 fs (fs) pulses, 80 MHz repetition rate] pulse laser excitation were studied. A peculiar shift from reverse saturable absorption (RSA) to saturable absorption (SA) at a peak intensity of 40 MW/cm2 was observed. The involvement of excited state absorption (ESA) is confirmed from the decrease in the nonlinear absorption coefficient with increase in peak intensity and the observed nonlinearity is ascribed to a sequential 2 PA process (1 PA+ESA). Formation of layered structure in Cu3Nb2O8 acted as a transport layers which yielded high nonlinear absorption coefficient (7.8 × 10^{-10} m/W), nonlinear refractive index (5.17 × 10^{-16} m^2/W) and nonlinear optical susceptibility (25.6 × 10^{-11} esu) when compared to other known copper niobates. The observation of low onset-limiting threshold (78.79–26.26 μJ/cm^2) renders Cu3Nb2O8 a prospective material for ultrashort pulse laser protecting device and biomedical microsurgery tools. A transition of mixed phase CuNb2O6-Cu3Nb2O8 into pure triclinic Cu3Nb2O8 along with change in morphology from pore to layered structure with increase in sintering time was confirmed from powder XRD, Raman, FESEM measurements and UV–Visible absorption studies.
关键词： Femtosecond,Copper niobate,Optical limiting,Z-scan
更新于2025-09-23 15:23:52
-
Optical limiting property of gold nanorods/ormosil gel glass composites
摘要： Sol–gel derived ormosil gel glass can act as matrix for different functional molecules or nanomaterials due to its many advantages. Gold and silver colloidal nanoparticles have great application potential in nonlinear optical field due to their ultrafast optical response. In this letter, the nanocomposites of gold nanorods and ormosil gel glass were prepared by a solvent-assisted dispersing process and characterized by UV–vis spectra, TEM, XRD and optical limiting measurement. The results showed that these gold/ormosil nanocomposites could preserve optical limiting property of gold nanorods and had enhanced thermostability due to thermostable silica matrix. Such nanocomposite material of metal-doped gel glass matrix could be considered as a promising candidate for optical limiter against tunable laser.
关键词： Nanocomposites,Optical limiting,Ormosil gel glass,Thermostability,Gold nanorods
更新于2025-09-23 15:23:52
-
Growth, optical, mechanical and nonlinear optical properties of Furfurylaminium 2-chloro-5-nitrobenzoate single crystal
摘要： The furfurylaminium 2-chloro-5-nitrobenzoate (FC) is a modernized organic material possessing enhanced order three nonlinearity. The crystals of FC of dimensions 17 × 4 × 2 mm3 were yielded on slow evaporation with the usage of ethanol-water mixed solvent (1:1). The precise peaks in powder XRD analysis reveal the crystalline property of the compound. The lattice parameters was estimated (a = 11.77 ± 0.012 ?, b = 6.84 ± 0.012 ? and c = 16.33 ± 0.028 ? and volume = 1342 ?3) from powder XRD using XRDA software. The FC crystal corresponds to the system of monoclinic with the space group P21/c. The UV-visible spectrum of FC crystal sample furnishes the lower cut off wavelength (325 nm) and the band gap (3.57 eV) for FC crystal. The dispersion factors Eo and Ed was calculated to be 4.24 eV and 15.20 eV respectively from Wemple and Di Domenico single oscillator model. Using these values, the oscillator strength value was calculated to be 64.5134 (eV) 2 and the moments of optical spectra was estimated to be M -1 = 3.580 (eV) 2 and M -3= 0.198 (eV) 2. The optical conductivity (σ) value of FC crystal at 532 nm was found out to be 0.21 ×1010 s-1. A red emission peak at 691 nm was obtained in photoluminescence spectra when the FC sample was excited at 325 nm. Single shot LDT value for FC crystal was calculated to be 14.40 GW/ cm2. The third order optical susceptibility (χ(3)) of the molecule was enumerated as 4.02 ×10-6 esu from Z-scan technique and the second order hyperpolarizability (γ) value is calculated to be 2.64 × 10-35 esu. The coupling factor (ρ*) is estimated to be 0.047, on utilizing the calculated values of (Re χ(3) = 0.19 × 10-6 esu) and (Im χ(3) =0.19 × 10-6 esu) from Z scan technique. The specific heat capacity (Cp) at 50°C was calculated as 1.5810 (Jg-1 K-1) and thermal diffusivity (α) as 1.750 ×10-6 m2/s. Thus using α the thermo-optic coefficient was deliberated to be 5.34 × 10-6 K-1. The maximum output power of FC indicates its optical limiting behaviour.
关键词： third order susceptibility,optical limiting,Solution growth,Optical materials,Z-scan
更新于2025-09-23 15:22:29
-
Quantum dots of two-dimensional Ruddlesdena??Popper organica??inorganic hybrid perovskite with high optical limiting properties
摘要： Hybrid perovskites have been investigated for various potential applications because of their tunable optical properties. In this paper, we report the synthesis of quantum dots (QDs) of two-dimensional (2D) Ruddlesden–Popper (RP) hybrid perovskite using a top-down approach. The QDs of the developed 2D RP perovskite exhibit high and sharp photoluminescence in the ultraviolet region. The sharp peak in the absorption spectrum and the intense photoluminescence in the ultraviolet region indicate strong quantum confinement in these particles, which is further confirmed by x-ray photoelectron spectroscopy. These QDs show superior nonlinear optical scattering and absorption properties with the optical z-scan technique and strong nonlinear absorption property with the photoacoustic z-scan technique. Evaluating the nonlinear optical properties using two complementary techniques provides a deeper understanding of the nonlinear mechanism involved in the optical limiting process. The two-photon absorption coefficient obtained by optical z-scan is 7.2 × 102 cm/GW, which is larger than that of most perovskite nanocrystals and nanosheets. Our studies, therefore, reveal a new class of material, 2D RP perovskite QDs, which show important nonlinear properties that are important for optical limiting applications.
关键词： Ruddlesden–Popper perovskite,optical limiting,nonlinear optical properties,Quantum dots,two-photon absorption
更新于2025-09-23 15:21:01
-
Optical limiting properties of hybrid nickel naphthalocyanine-titania nanoparticals thin films
摘要： In this work, an ultrathin nanocomposite films containing tetracarboxylic Nickel (Ⅱ) naphthalocyanine (NiNc) and titania nanoparticles are fabricated through electrostatic self-assembled layer-by-layer (LBL) technique. UV–Vis spectroscopy, X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) are utilized to characterize the film. The optical limiting properties of the composite films are investigated through intensity-dependent transmittance measurements at 600 nm with 18 ps laser pulses. The results show that the composite films have notable optical limiting response (β ～ 5.4 × 10?7 m/W), which is strongly enhanced compared to both TiO2 and NiNc-only samples. Our results suggest that the nanocomposite films possess the potential for optical limiting applications in the phototherapeutic window.
关键词： Optical limiting,Naphthalocyanine,Nanostructure,Self-assembly
更新于2025-09-23 15:21:01
-
Enhanced nonlinear optical properties of ZnS nanoparticles in 1D polymer photonic crystal cavity
摘要： The enhanced nonlinear optical absorption and optical limiting properties of polymeric one dimensional photonic crystal (1DPhC) with ZnS nanoparticles as defect are reported. The 1DPhC was fabricated by spin coating technique, using polystyrene (PS) and cellulose acetate (CA) as high and low refractive index materials. ZnS nanoparticles were synthesized in CA solution by laser ablation technique and the structural, morphological and non linear optical characterizations were done. A microcavity structure with cavity resonance around 532 nm was designed by inserting ZnS NPs/CA defect layer between two Bragg reflectors comprising 10 bilayers of CA/PS. A significant enhancement (4.6 times) in both nonlinear absorption and optical limiting properties of 1DPhC with ZnS defect layer was observed under 532 nm pulse excitation compared to the ZnS reference sample. The enhancement in the observed nonlinear optical properties of the system could be accredited to the confinement of optical field due to the localization of photons in the cavity mode. The current system can play crucial roles in designing practical nonlinear optical devices, such as optical limiters, optical switchers etc.
关键词： 1D Photonic crystal,Nonlinear absorption,Optical limiting,Z-scan
更新于2025-09-19 17:15:36
-
PbS and PbS/CdS quantum dots: Synthesized by photochemical approach, structural, linear and nonlinear response properties, and optical limiting
摘要： In this work, PbS and PbS/CdS core–shell quantum dots (QDs) were synthesized by a new photochemical approach. Prepared QDs were characterized by means of x-ray diffraction (XRD), ?eld emission scanning electron microscopy (FESEM), energy dispersive x-ray analysis (EDAX), UV–Vis, and Z-scan analyses. Synthesized QDs were in a cubic phase with a spherical morphology, and the crystallite sizes are estimated using the strain–size method. A uniform shift of Bragg diffraction peaks and quenching (200) Bragg plane are interpreted as the growth of the CdS shell. Linear optical properties were investigated using Urbach analysis and Tauc formula. It was found that the density of states of QD conduction and valence bands are three dimensional. The estimated sizes of PbS QDs and PbS/CdS using exciton absorption peaks at room temperature are 1.8 and 2.7 nm, respectively, which are in good agreement with the strain–size plot analysis. The growth of the CdS shell resulted in a considerable decrease in the nonlinearity refractive index and a signi?cant increase in the nonlinear absorption.
关键词： PbS/CdS,photochemical synthesis,PbS,optical limiting,quantum dots,nonlinear optical properties
更新于2025-09-19 17:13:59
-
Standards, Methods and Solutions of Metrology || Third-Order Nonlinear Optical Properties of Quantum Dots
摘要： Quantum dots (QDs) are semiconducting nanocrystalline particles. QDs are attractive photonic media. In this chapter, we introduce third-order nonlinear optical properties and a brief idea about the physics of QDs. Z-scan technique and theoretical analysis adopted to obtain nonlinear parameters will be discussed. Analysis of third-order nonlinear optical parameters for PbS QDs suspended in toluene with radii 2.4 and 5.0 nm under different excitation beam power level and three different wavelengths (488, 514, and 633 nm) will be detailed. Third-order optical susceptibility χ(3) and optical-limiting behavior of PbS QD suspended in toluene are presented. Irrespective of their size, QDs are a good example of optical limiters with low threshold.
关键词： Z-scan technique,semiconductor,nonlinear absorption coefficient,third-order optical susceptibility,quantum dot,optical limiting,nonlinear optics,optical switching,nonlinear index of refraction
更新于2025-09-16 10:30:52
-
Photoacoustic Identification of Laser-induced Microbubbles as Light Scattering Centers for Optical Limiting in Liquid Suspension of Graphene Nanosheets
摘要： Liquid suspensions of carbon nanotubes, graphene and transition metal dichalcogenides have exhibited excellent performance in optical limiting. However, the underlying mechanism has remained elusive and is generally ascribed to their superior nonlinear optical properties such as nonlinear absorption or nonlinear scattering. Using graphene as an example, we show that photo-thermal microbubbles are responsible for the optical limiting as strong light scattering centers: graphene sheets absorb incident light and become heated up above the boiling point of water, resulting in vapor and microbubble generation. This conclusion is based on direct observation of bubbles above the laser beam as well as a strong correlation between laser-induced ultrasound and optical limiting. In-situ Raman scattering of graphene further confirms that the temperature of graphene under laser pulses rises above the boiling point of water but still remains too low to vaporize graphene and create graphene plasma bubbles. Photo-thermal bubble scattering is not a nonlinear optical process and requires very low laser intensity. This understanding helps us to design more efficient optical limiting materials and understand the intrinsic nonlinear optical properties of nanomaterials.
关键词： Raman,photoacoustics,bubble scattering,graphene,optical limiting
更新于2025-09-16 10:30:52
-
Investigating the nonlinear optical properties of poly eosin-Y phthalate solution under irradiation with low power visible CW laser light
摘要： In this work, the study of the nonlinear optical properties of poly eosin-Y phthalate solution using the diffraction ring patterns and the Z-scan methods are presented. The diffraction ring patterns were observed when a low power laser beam of wavelength of 473 nm passed through the poly eosin-Y phthalate solution. It was found that the number of rings and diameter of the outer-most ring in each pattern depends on the incident intensity of the laser beam and type of the beam wave front. The Fresnel-Kirchhoff diffraction integral theory was used to simulate the diffraction ring patterns and found good agreement with experimental results. Both diffraction ring patterns and closed aperture Z-scan techniques were used to calculate the nonlinear refractive index, while open aperture Z-scan was used to calculate the nonlinear absorption coefficient of the poly eosin-Y phthalate solution. The possibility of using the sample as an optical limiter is tested.
关键词： Nonlinear refractive index,Self-phase modulation,Optical limiting,Diffraction ring pattern,Z-scan technique,Thermal nonlinearity
更新于2025-09-12 10:27:22