The two-photon absorption coefficient and Kerr of bulk crystalline silicon are determined near the telecommunication wavelengths 1.3 1.55 μm using femtosecond pulses a balanced Z-scan technique. A phase shift sensitivity order 1 mrad is achieved, enabling accurate measurement third-order nonlinear coefficients at fluences smaller than 100 μJ/cm2. From (β∼0.8 cm/GW) (n2∼4×10−14 cm2/W) wavelength λ=1.54 μm, value F∼0.35 for figure merit all-optical switching determined.

When an ultrathin metal film of thickness $h$ $(<20\text{ }\text{ }\mathrm{nm})$ is melted by a nanosecond pulsed laser, the temperature nonmonotonic function and achieves its maximum at certain ${h}^{*}$. This consequence time dependence energy absorption heat flow. Linear stability analysis nonlinear dynamical simulations that incorporate such intrinsic interfacial thermal gradients predict characteristic pattern length scale $\ensuremath{\Lambda}$ decreases for $h>{h}^{*}$, in contrast to...

We demonstrate a promising synthesis route based on pulsed laser dewetting of bilayer films (Ag and Co) to make bimetallic nanoparticle arrays. By combining experiment theory we establish parameter space for the independent control composition diameter nanoparticles. As result, physical properties, such as localized surface plasmon resonance (LSPR), that depend particle size can be readily tuned over wavelength range one order magnitude greater than pure Ag The LSPR detection sensitivity...

Reduced degradation (oxidation) of silver nanoparticles (NPs) is achieved by contacting Ag with immiscible Co NPs. The relative decay the plasmon peak (plot) shows that pure NPs (blue dashed curve) 25% in ca 20 days, whereas AgCo last about 10 times longer, requiring nearly five months for a similar (red solid curve). TEM images both and were taken after 50 days storage under ambient conditions.

Interaction of photons with matter at length scales far below their wavelengths has given rise to many novel phenomena, including localized surface plasmon resonance (LSPR). However, LSPR narrow bandwidth (BW) is observed only in a select few noble metals, and ferromagnets are not among them. Here, we report the discovery ferromagnetic Co CoFe alloy (8% Fe) contact Ag form bimetallic nanoparticles prepared by pulsed laser dewetting. These plasmons metal-ferromagnetic nanostructures, or...

The two-photon absorption coefficient of an indirect gap semiconductor (phonon-assisted absorption) in the presence a strong dc-electric field applied perpendicular to direction propagation optical is calculated using formalism developed elsewhere (Aspnes 1996 Phys. Rev. B. 147 554). We show that depending on type transition (i.e., allowed–allowed, allowed–forbidden or forbidden–forbidden), followed different dispersion relations. In limit weak electric field, we recovered results previously...

<title>Abstract</title> we report for the first time to our knowledge on polarization rotation as function of magnetic field entangled photons in Iron dope Cd0.85Mn0.15Te:Fe crystal. These results open door study magneto-optics effects, and absorption reflection spectroscopy condense matter systems with single photons. We show that predictions quantum mechanics are excellent agreement experimental results, but underlying physics universality accepted quantities like Verdet constant system...

The Mie theory gives the exact solution to scattering from spherical particles while Fresnel provides optical behavior of multilayer thin film structures. Often, bridge between two theories explain materials such as nanoparticles in a host dielectric matrix, is done by effective medium approximation (EMA) models which exclusively rely on dipolar response objects. Here, we present way capture multipole effects using EMA. complex function composite derived Clausius–Mossotti relation and...

We have developed a self-consistent technique to predict the behavior of plasmon resonances in multicomponent systems as function wavelength. This approach, based on tight lower bounds Bergman-Milton formulation, is able optical data, including positions, shifts, and shapes plasmonic peaks ternary nanocomposites without using any fitting parameters. obtained excellent predictions experimental data for mixtures $\mathrm{Ag}:\mathrm{Cu}:{\mathrm{SiO}}_{2}$ alloys...

Using an electrically focus tunable lens (EFTL) in F-scan setup and a femtosecond-pulse laser (Mai Tai HP), we were able to measure the degenerated two-photon absorption coefficient (in transmission) of CdS ZnSe extended range wavelengths (690-1040 nm), with 5 nm resolution. The process measuring takes less than 30 minutes. We compared our results theoretical approaches for dispersion relations nonlinear properties semiconductors found excellent agreement experimental results. also compare...

The nonlinear refractive index n2 of silica fiber (24 m) and erbium-doped (10 is measured to within an accuracy 5% by use time-delayed photorefractive beam coupling intense 53-ps, 1.064-microm pulses that experience self-phase modulation in the fibers. resultant induced grating autocorrelation response yields a value n2/A(eff) calibration standard for fiber. A phase shift order 0.19pi can be detected limited only laser amplitude fluctuations. unique advantage this technique its ability...

We have investigated the nanostructure and microstructure resulting from simultaneous ns laser irradiation with deposition of Co films on Si(001) substrates. The spatial order length scales nanopatterns their crystalline were as a function film thickness h energy density E using combination atomic force, scanning electron transmission microscopies. results could be classified into two distinct categories based used. It was observed that thickness-dependent required to melt (ECo) lower than...

The lower and upper bounds for the nonlinear susceptibility of a multi-component nanocomposite composed glass host nanoparticles multiple metals are calculated within context Hashin–Shtrikman formulation. We have applied this effective medium theory to following ternary composites: AgCu:SiO2 AgAu:SiO2 in form mixtures. These were used estimate limits third-order composite as function wavelength, volume fraction particle size. It is shown that modulation metal by local-field enhancement due...

The two-photon absorption (TPA) coefficient β and the nonlinear index of refraction n2 for bulk cuprous oxide (Cu2O) direct gap semiconductor single crystal have been measured by using a balance-detection Z-scan beam technique, with an excellent signal to noise ratio. Both coefficients were at 790 nm 65 fs laser pulse repetition rate 90.9 MHz, generated Ti:Sapphire oscillator. experimental values explained model that includes allowed-allowed, forbidden-allowed, forbidden-forbidden...

We report for the first time, to our knowledge, a technique that has capability measure both Raman gain coefficient and nonlinear refractive index of an optical fiber, using same experimental setup. This measurement utilizes induced-grating autocorrelation (IGA) technique, which is based upon time-delayed four-beam coupling in photorefractive crystal. The standard IGA trace, two-beam coupling, fits simple model on pure self-phase modulation (SPM). demonstrate that, negligible-dispersion...

The $N$-photon absorption coefficient of a direct gap semiconductor under the influence uniform electric field perpendicular to layer and neglecting excitonic effects is calculated. For $N=2$ we recover familiar results for low-field regime. system also shows same universal behavior as $N=1$ case. Below ${E}_{g}∕2$ edge develops exponential tail characteristic $N=1$, but with different photon energy dependency while above Franz-Keldysh oscillations strong damping features are present. An...

A 980-nm pump-induced nonlinear refractive-index (n2) change in erbium-doped (20-m) and ytterbium-doped fibers has been measured at 1064 nm by time-delayed photorefractive beam coupling a co-propagating counterpropagating geometry. It was found that n2 decreases the wavelength of probe when pump is present. We present semiclassical theory based on four-state system accounts for n2. Both theoretical experimental results show significant index change, order 10%, can be obtained cw powers as...

We have calculated the two photon absorption coefficient for Ge within effective mass approximation direct as well indirect gap region. By including all possible contributions to nonlinear based on band structure, we found excellent agreement with recent experimental report in Ge. It is that even though transition stronger than process, a tail at low end of energy spectrum appears, and ultimate limit half energy.

The localized surface plasmon resonance (LSPR) of nanoparticles can be a powerful and sensitive probe chemical changes in nanoscale volumes. Here we have used the LSPR silver (Ag) to study oxidation kinetics nanoscopic volumes cobalt (Co) metal. Bimetal immiscible Co–Ag system prepared by pulsed laser dewetting were aged ambient air resulting signal bandwidth kinetics. Co was found preferentially oxidize first. This resulted significant enhancement factor 8 or more lifetime stable Ag...

Discovery of new plasmonic behaviors from nanostructured materials can be greatly accelerated by the ability to prepare and characterize their near‐field with high resolution in a rapid manner. Here, an efficient cost‐effective way is reported make 2D periodic nanostructures on electron‐transparent substrates for characterization transmission electron microscopy. By combining nanosphere lithography substrate float‐off technique, large areas achieved. For this study, synthesis Ag, magnetic...