Nonlinear optical response of a CdS-coated Ag particle

In this paper, we present an experimental observation of the optical nonlinear characteristics of a CdS-coated Ag particle at room temperature. By using sub-picosecond pulses generated by a tunable optical parametric amplification system, we confirm that the light intensity scattered by the particle considerably decreases with an increase in the incident light intensity at a photon energy higher than the energy corresponding to the interband absorption edge of CdS. The nonlinear phenomena presented in this paper are observed in an event in which localized surface plasmons enhance the two-photon absorption in CdS and cause the valence electrons to be excited into the conduction band of CdS and to further move to a higher energy band of Ag without additional energy supply. (C) 2008 The Japan Society of Applied Physics.