Subpicosecond time response of third-order optical nonlinearity of small copper particles in glass

Abstract

Femtosecond pump-probe experiments with a time resolution of 100 fs have been performed for copper particles with a radius of 4 nm. Differential absorption spectra for a pump centered at 2.05 eV indicates the broadening of the absorption band due to the surface plasmon. The nonlinear response time derived from the recovery time of the nonlinear absorption is dependent on the pumping laser fluences, and is as short as 0.7 ps for 210 μJ/cm2. The relaxation dynamics of nonequilibrium electrons can be described by the usual electron-phonon coupling model.

Negative photoconductivity in silver nanocubes prepared by simple photochemical method

“…In most cases, silver nanoparticles can be obtained by reduction of silver nitrate. Also, to retain their nanosize, one often prepares nanocomposites by embedding the nanoparticles in glass [12], silica [13] or polymers [14][15][16][17][18] such as polyvinyl alcohol (PVA), polyacrilic acid or polymethyl methacrylate, etc. Out of these, PVA is used extensively as host matrix as it is water soluble, optically transparent and gives homogeneity to the silver nano dispersion.…”

Copper Nanoparticle Composites in Insulators by Negative Ion Implantation for Optical Application

“…Insulating substrates used were amorphous (a-)SiO 2 , magnesium aluminate spinel MgO2.4(Al 2 O 3 ) single crystal of (100) plane and xcut LiNbO 3 single crystal. The refractive index of the substrates, determined by spectroscopic ellipsometry, is n = 1.47 at 600 nm for a-SiO 2 , 1.7 for MgO2.4(Al 2 O 3 ), and 2.2 for LiNbO 3 . The diameter of the substrates was 15 mm and the thickness was 0.5 mm.…”

“…[1][2][3][4] The unique properties with picosecond response is attributed to surface plasmon oscillation modes, [5][6][7] but the large optical nonlinearity is limited around surface plasmon resonance in the visible light region. For optical device applications, it is imperative to tune the resonance band for a photonic signal.…”

Many-body correlation effects in the ultrafast non-linear optical response of confined Fermi seas

“…During this incoherent stage, the hot electrons can be characterized by a thermalized Fermi-Dirac distribution with time-dependent temperature T (t), while the phonons can be characterized by a Bose-Einstein distribution with time-dependent temperature T l (t). During the cooling of the hot electron gas, the SP width decreases [132,133,134,135,136,126,127,137,138]. As soon as the electrons have equilibrated among themselves, one can study the subsequent time evolution by using a set of coupled differential equations for the temperatures T (t) and T l (t), referred to as the two-temperature model [141,142,144,145,146,147]:…”