Frequency conversion of picosecond radiation in fullerene-doped polyimide films and colloidal metals
Аннотация
Investigations of third-harmonic generation (THG) of picosecond Nd:YAG laser radiation in C70-doped polyimide films and colloidal metals (Pt and Cu) are presented. The nonlinear susceptibility χ(3)(-3ω;ω,ω,ω) of the fullerene-doped film was measured to be (9±4.5)×10-13 esu (for 0.5% C70 in polyimide 6B film). The influence of nonlinear refraction of fullerene-doped films on the phase-matching conditions of THG was responsible for deviation from the cubic power dependence of the third-harmonic signal on the fundamental radiation intensity I3ω(Iω) and restriction of THG efficiency in 0.5% C70-doped polyimide film. THG efficiencies were found to be 6×10-6 and 7×10-7 for 0.5% C70-doped polyimide film and colloidal platinum respectively. The maximal predicted efficiency of THG in 0.5% C70-doped polyimide film at weak focusing has been achieved. Nonlinear susceptibilities χ(3)(-3ω;ω,ω,ω) of colloidal platinum and copper were measured to be (1.5±0.75)×10-14 and (1±0.5)×10-14 esu respectively.