Optical limiting of semiconductor nanoparticles for nanosecond laser pulses

Optical limiting of nanosecond laser pulses at 532 nm has been observed in CdxAg1-xS semiconductor nanoparticles within organic solution of polymeric ionic aggregates. Both free-carrier absorption (FCA) and nonlinear scattering contribute to the optical limiting performance. The optical limiting response of CdS nanoparticles, in the diameter range of 2-9 nm, increases with the increase of particle size. It can be further increased by surface coating of the CdS particle with a thin layer of Ag2S or forming ternary CdxAg1-xS particle. The FCA cross sections of CdxAg1-xS solutions were estimated to be between 10(-19) and 10(-18) cm(2), which are comparable with those of bulk semiconductors. (C) 2004 American Institute of Physics.