Pump-wavelength-dependent second-harmonic generation in SiC-nanopowder-doped polymer films

Second-harmonic generation in polymer films doped with silicon carbide nanocrystals with typical sizes of 10-80 nm is experimentally studied. A substantial enhancement of second-harmonic generation was achieved by decreasing the wavelength of femtosecond pump pulses, produced by an optical parametric amplifier. This strong pump-wavelength dependence of diffuse second-harmonic generation indicates a significant role of scattering effects in nonlinear-optical interactions in nanopowder materials, suggesting strategies for a radical enhancement of second-harmonic generation in nanopowders by tuning the relation between the film thickness and the elastic-scattering length of photons.