Tungsten oxide filled nanofibers for optical limiting in near infrared region

In this study, tungsten trioxide (WO3) nanoparticles synthesized by a slightly modified reduction method were used as nanofillers in polyvinylpyrrolidone (PVP) nanofibers produced via electrospinning. SEM images revealed well incorporated WO3 nanoparticles into PVP nanofibers. Linear optical analysis showed that the increased nanofiller content in PVP nanofibers increased light-matter interaction, decreased band gap and increased localized defect states. All of the composite nanofibers had nonlinear absorption (NA) behavior, which weakened with an increase in the input intensity. The main NA mechanism was TPA for 10 wt% WO3 filled PVP composite nanofibers, while the OPA, excited state absorption (ESA) and TPA were the main NA mechanisms for 12 wt% WO3 filled PVP composite nanofibers. The stronger effect of the defect states on NA was revealed with comparison analysis of TPA and NA coefficient values. The lower optical limiting threshold was determined as 0.94 x 10-5 J/cm2 for 12 wt% WO3 filled PVP composite nanofibers. The promising optical limiting characteristics of the WO3 nanofilled PVP composite nanofibers make them good candidates as strong contenders for effective optical limiting applications in near infrared region.