Preparation and Nonlinear Optical Properties of Au Colloid

Journal of Physical Chemistry C, 2017

The linear and nonlinear optical properties of metal nanoparticles are highly tunable by variation of parameters such as particle size, shape, composition and environment. To fully exploit this tunability, however, quantitative information of nonlinear absorption cross sections is required, as well as a sufficient understanding of the physical mechanism underlying these nonlinearities. In this work, we present a detailed and systematic investigation of the wavelength-dependent nonlinear optical properties of Ag nanoparticles embedded in a glass host, in which the most important parameters determining the nonlinear behavior of the system are characterized. This allows a proper quantification of absorption cross sections and elucidation of the excitation mechanism. Based on small-angle X-ray scattering measurements average particle diameters of 3 nm and 17 nm are estimated for the studied samples. The nonlinear optical properties of the nanoparticle-glass composite are studied in an extended wavelength range with the open aperture z-scan technique. The experiments reveal a strong dependence of the nonlinear optical response on the excitation wavelength. Based on the wavelength-dependent response, excited state absorption is determined as the excitation mechanism of the nanoparticles. Electromagnetic simulations demonstrate that the contributions from electric field enhancement and plasmonic coupling between the particles in the diluted glasses is limited, which implies that the very high two-photon absorption cross section at 460 nm ((6.9 ± 1.6)•10 6 GM for the 3 nm particles and (19.5 ± 2.2)•10 9 GM for the 17 nm particles) is an intrinsic property. In addition, irradiance dependent measurements elucidate the role of saturation of the excited-state absorption process on the observed nonlinearities.

Applied Physics Letters, 2008

Z-scan revealed thermal and electronic contributions for the nonlinear refractive index of highly stable colloid containing different concentrations of gold nanoparticles. Large enhancement factors were observed for values of n 2 and dn / dT of the colloid, due to the presence of the nanoparticles. Our results suggest that thermal effects will play an important role in the development of photonic applications involving nanostructured materials and in the investigation of nonlocal nonlinear phenomena.

Optical Materials, 2024

Gold nanoparticles (AuNPs) colloids were synthesized using Gum Arabic (GA) in distilled water to improve their properties for optical applications. The nonlinear optical properties (NLO) of Gum-Arabic coated gold nanoparticles (GA-AuNPs) colloids were explored through the Z-scan technique. The nonlinear refractive index (n2) and the nonlinear absorption coefficient (Beff ) were measured at a constant wavelength of 637 nm and different laser intensities (1.1–1.5 kW/cm2). GA-AuNPs were synthesized by the reduction technique in distilled water and stabilized by Gum Arabic with the help of NaOH at various reaction times and temperatures. The absorption spectra, shape, and size of GA-AuNPs colloids were evaluated using Ultra-high-resolution scanning electron microscopy (SEM) and ultraviolet–visible (UV–vis) spectrophotometer. The synthesized nanoparticles have a spherical shape with a mean size ranging from 7 to 16 nm. No considerable effect on the size of nanoparticles (NPs) when the reaction time varies for the same temperature, however, this effect is noticed when the temperature is raised to 80 ◦C. As the intensity of the laser increases, the n2 and Beff indices were also increased. The results suggest that GA-AuNPs have strong nonlinear absorption and scattering coefficients, which make them promising candidates for various applications, including optical limiting.

In this study, the nonlinear optical properties and optical limiting performance of the silver nanoparticles (AgNPs) in distilled water are investigated. The nonlinear absorption coefficient of the colloid is measured by the Z-scan technique. The optical limiting behavior of the AgNP suspension is investigated under exposure to nanosecond laser pulses at 532 nm. The results show that nonlinear scattering can increase the performance of the optical limiting. A theoretical analysis is suggested investigating the observed nonlinear behavior of the AgNPs. It will be shown that nonlinear light scattering occurs at high beam intensity due to induced refractive mismatch between the silver nanoparticles and water. The experimental Z-scan data is fitted with the proposed theoretical model and this has allowed extracting the values of nonlinear absorption coefficient, linear and nonlinear scattering coefficients for the AgNP suspension.

Microelectronics Journal, 2009

In this work we have synthesized silver nanoparticles in Poly (methyl methacrylate) (PMMA). This was achieved by polymerizing the mixture of monomer and corresponding metal compound, followed by post-heating treatment. The linear absorption coefficient of the samples was measured using a spectrophotometer, where an absorption peak at 420 nm was observed. This peak grows up and shifts as a function of the concentration of the radical initiator. The linear refractive index was measured using the Fresnel equations and agrees with previous reported results. The nonlinear properties were obtained using the single lens Z-scan method, where the nonlinear absorption coefficient (Da) was found between 5.5975514 and 17.9483493 cm À1 . The nonlinear refractive index coefficient (DZ) was found to be negative and its value oscillates between 12.9099 E-06 and 22.4276 E-06. Finally, the third-order coefficient (w (3) ) was calculated in the range of 233-787 E-9 esu.

2013 15th International Conference on Transparent Optical Networks (ICTON), 2013

In the present work the nonlinear optical response of some Αu x Ag (1-x) alloy nanoparticles (NPs) prepared by a femtosecond laser ablation process is studied using Z-scan technique employing 4 ns, 532 nm laser pulses. The prepared NPs with diameters of 15 -20 nm, had different compositions, i.e. gold molar fractions (GMF) x, ranging from x = 0 (pure Ag) to x = 1 (pure Au) and they were exhibiting surface plasmon resonance (SPR) peak whose spectral position and strength were varying depending on GMF. The Αu x Ag (1-x) NPs were found to exhibit negative nonlinear refraction, corresponding to self-defocusing behavior and negligible nonlinear absorption. The nonlinear optical response of the Αu x Ag (1-x) alloy nanoparticles was found to be strongly dependent on the GMF of the nanoalloy, since the surface plasmon resonance peak enhances the nonlinear optical response of the metallic nanoalloys when it is close to the excitation wavelength.

Europhysics Letters (epl), 1998

We determined the third-order susceptibility |χ(3)| of a thin composite film formed by silver nanoclusters embedded in soda-lime glass. Ag aggregation was promoted by irradiating an Ag-Na ion-exchanged glass with an N+ beam. |χ(3)| dispersion was measured by phase-mismatched degenerate four-wave mixing in the 380 470 nm spectral range, with 0.5 ps laser pulse duration. Close to the surface plasmon resonance of Ag metallic clusters, the χ(3) amplitude exceeds by a factor of 104 the value of substrate glass. We also measured a phase of 83° and a dynamics characterized by ~ 30, 3 and 0.9 ps decay times, ascribed to hot-electrons-lattice thermalization in the clusters, followed by thermal diffusion toward the matrix and relaxation of the whole system to the starting temperature.

Applied Physics B

Optical glasses possessing large third-order optical nonlinear susceptibility and fast response times are promising materials for the development of advanced nonlinear photonic devices. In this context, gold nanoparticle (NP)-doped borate glasses were synthesized via the melt-quench method. The nonlinear optical (NLO) properties of thus prepared glasses were investigated at different wavelengths (i.e., at 532 nm using nanosecond pulses, at 750 nm, 800 nm, and 850 nm wavelengths using femtosecond, MHz pulses). At 532 nm, open aperture (OA) Z-scan signatures of gold NP-doped borate glasses demonstrated reverse saturable absorption (RSA), attributed to mixed intra-band and interband transitions, while in the 750-850 nm region, the OA Z-scan data revealed the presence of saturable absorption (SA), possibly due to intra-band transitions. The NLO coefficients were evaluated at all the spectral regions and further compared with some of the recently reported glasses. The magnitudes of obtained NLO coefficients clearly demonstrate that the investigated glasses are potential materials for photonic device applications.

INTERNATIONAL CONFERENCE OF NUMERICAL ANALYSIS AND APPLIED MATHEMATICS ICNAAM 2019, 2020

In this paper, we investigate the linear and nonlinear (NL) optical properties of gold nanoparticles (Au-NPs) with different sizes. A colloidal gold nanoparticles solution has prepared to utilize the chemical reduction method by interacting gold chloride solution HAuCl4 with trisodium citrate solution. By using a hotplate and vigorous stirring the flask, which has the mixture solution, was heated to produce a 0.05 mg/ml of colloidal gold nanoparticles. The characterization of gold nanoparticles is executed by the utilization of different techniques. The information about nanoparticles size was achieved from the spectra measured by transmission electron microscopy (TEM). As well as the compositional characteristics are obtained using FTIR and XRD techniques. Finally, the Surface Plasmon Resonance (SPR) peaks were measured using a UV-Vis spectrophotometer. A Z-scan technique was utilized to study the nonlinear optical properties of Au nanoparticles. From the preparation of the nanoparticles, the shape of gold nanoparticles was almost spherical and has two different sizes. The nonlinear refractive index of Au nanoparticles was obtained in the order of 10-10 cm 2 /w extracted from a closed aperture z-scan. The nonlinear absorption of these nanoparticles was measured at 10-5 cm/w range obtained from an open aperture z-scan technique.

Journal of Nanomaterials, 2016

Nanoparticles of gold and silver were prepared by a reduction method and by employing green chemistry principles such as using curcumin as a reducing and a stabilizing agent. The formation of nanoparticles was confirmed by UV-Vis absorption spectra and TEM. Mie theory was used to determine the particle sizes. The nonlinear refraction and absorption properties of the particles were measured using the z-scan technique. A large value of third-order nonlinearities was obtained using the nanoparticles produced.