Studies on NiO-PVA Composite Films for Opto-Electronics and Optical Limiters

We report optical, excited-state lifetime, and nonlinear optical (NLO) properties of nickel oxide (NiO)/poly vinylalcohol (PVA) polymer free-standing films for opto-electronics and optical limiting applications. Optical absorption studies of NiO-loaded PVA films show that the exciton peaks are centered at 330 nm. Fluorescence studies reveal that the emission is due to exciton recombination and defects in NiO. Time-resolved fluorescence studies show that the recombination in PVA happens through NiO, where NiO has a faster decay time than the pure PVA. NLO measurements carried out using a 532 nm, 10-ns Nd: YAG laser, show that for a given energy, NiO/PVA shows good optical limiting, and the obtained NLO behavior is due to effective two-photon absorption.