Optical Limiting in ZnO Nanocomposites

In this article, we present the optical limiting response of ZnO nanocomposites prepared by colloidal chemical synthesis. Due to the broad spectral extent of weak absorbance, ZnO nanocomposites can be used as broadband optical limiters throughout the visible and IR regions. Nonlinear optical response of these samples is studied using nanosecond laser pulses at 532 nm. These nanoconnposites show good nonlinear absorption behaviour which can be attributed to enhancement of exciton oscillator strength. The observed nonlinear absorption is explained by two photon absorption followed by weak free carrier absoption, interband absorption and nonlinear scattering. ZnO nanocomposites are found to be good optical limiters and the optical limiting threshold of ZnO nanocomposites is observed to be low. ZnO nanocomposites are potential optoelectronic materials for the development of nonlinear optical devices with a relatively small limiting threshold.