| Abstract: | Optical nonlinearities in aggregates of nanoparticles formed in silver hydrosols (SHs) are studied under pico- and nanosecond
pulsed laser excitation. The dependence of the nonlinear refractive index n
2 on the degree of hydrosol aggregation is studied experimentally at the wavelength λ=1.064 μm. It is found that n
2 changes sign when the degree of hydrosol aggregation is increased. Various physical effects occurring in resonant domains
of the aggregates are analyzed using a simple physical model of two bound silver nanoparticles. The theory takes into account
thermal, elastic, electrostatic, and light-induced effects. Experimental results are discussed in the context of this theory. |
