Measurement of second hyperpolarizability components of a conjugated polymer

A method has been proposed to determine the components of the second hyperpolarizability γ(-ω4;ω3,ω2,ω1) of a conjugated polymer in the off-resonant region based on the attenuated- total-reflection technique. By doing a least-square fit to the experimental data of γ(-ω;0,0,ω) for the quadratic electro-optic effect, the frequency-independent term of the components of γ(-ω4;ω3,ω2,ω1) is obtained, from which the components of γ(-ω4;ω3,ω2,ω1) are determined .