Nonlinear susceptibility of colloids consisting of silver nanoparticles in carbon disulfide

Measurements of the effective third-order susceptibility χ(3)eff(ω,ω,−ω,ω) of a colloid consisting of silver nanoparticles (NPs) in liquid carbon disulfide (CS2) are reported for excitation at 532 nm. Changes in χ(3)eff(ω,ω,−ω,ω) were controlled varying the NP filling factor f. Cancellation and sign reversal of the nonlinear (NL) index of refraction and the NL absorption coefficient of the colloid were observed owing to competing contributions from the NP and the CS2 molecules. The Re χ(3)eff(ω,ω,−ω,ω) and Im χ(3)eff(ω,ω,−ω,ω) change linearly when f assumes values from 0.4×10−5 to 4.0×10−5. An analysis of the results is provided using a generalized Maxwell Garnett model that allowed evaluation of the NL susceptibility of the NP.