Nonlinear optical properties of Ag nanoparticles

trextemperMechanics

Feb 22, 2014 (3 years and 5 months ago)

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Nonlinear optical properties of Ag nanoparticles

prepared by laser ablation in liquids


V.A. Karavanskii
1*
, A.V. Simakin
2
, V.I. Krasovskii
1
, P.V. Ivanchenko
1

1
Natural Sciences Center of A.M.Prokhorov General Physics Institute,

Russian Academy of Sciences
, 38/L2 Vavilov str., Moscow, 119991 Russia

2
Wave Research Center of A.M.Prokhorov General Physics Institute,

Russian Academy of Sciences, 38, Vavilov str., Moscow, 119991 Russia

* e
-
mail:
karavan@kapella.
gpi.ru




Optical properties and third order optical nonlinearity (ONL) of liquid metal
colloids prepared by laser ablation in water and ethanol are investigated. It was shown
that fresh colloids undergo full or partial sedimentation with changing of ONL
characteristics. It was found out that water colloids took stable state after partial
sedimentation with changing of ONL sign during sedimentation process. The induced
nonlinear optical absorption inherent for fresh colloids transformed to induced nonlinea
r
transparency after sedimentation. The optical absorption spectra are interpreted within the
framework of Drude model for metallic particles with taking into account the effect of
nanoparticles sizes on optical properties. The evolution of ONL sign is exp
lained by the
coexistence of two type Ag particles in colloid solution after ablation in water. The large
particles undergo the sedimentation and the small Ag particles with presumable oxide
shell form stable colloid. The sizes of small Ag particles were c
alculated and nonlinear
optical absorption parameters were measured by z
-
scan technique. The nature of induced
transparency is discussed.