Impact of photoinduced energy transfer and LSPR of Au nanoparticles prepared by pulsed laser ablation technique on nonlinear optical response of zinc tetraphenyl porphyrin

Nonlinear optical (NLO) response and optical limiting activity in zinctetraphenyporphyrine (ZnTPP)/Au nanocomposites are examined using z-scan experiment aiding pulsed laser that delivers 7 ns pulses at 532 nm wavelength. ZnTPP/Au nanocomposite is prepared by ablating Au target in ZnTPP solution using nanosecond laser pulses. Nanocomposite formation in ZnTPP with Au NPs is confirmed from the modification of absorption spectrum and quenching of fluorescent emission spectrum. When compared to the well-known pristine constituents, the nonlinear optical properties and optical limiting (OL) activity in ZnTPP/Au nanocomposites have been enhanced significantly, that accounts the photo-induced energy transference between ZnTPP and Au NPs along with the local field effect of Au NPs. The nanocomposite formation induces additional energy transfer pathways that are responsible for enhanced excited-state absorption. In addition, the augmentation will be supported by local field effects of the Au NPs, which significantly increase the interaction field strength on the surface of the NPs and in the surrounding medium. The excited state absorption is the major mechanism of NLA and optical limiting activity. The threshold value of the optical limiting of the compound is found to be superior to the values reported for many compounds under similar experimental conditions. We anticipate that the suggested method will be of great interest for the eventual implementation of optical limiting-based photonic devices suitable for integrated optics.