Optical limiting with phthalocyanines and one-dimensional nanomaterials

Abstract

In this thesis, we experimentally examine the optical limiting (OL) properties of series of phthalocyanines (Pcs). Some of these compounds show much better OL properties than C60 at 532 nm with nanosecond laser pulses. A five-level model of excited states absorption is employed to explain the observed nonlinear absorption in the Pcs compounds.We also extend our investigation into the OL response of one-dimensional (1-D) nanomaterials, such as a series of metal (Ni, Pt, Pd, Ag, Cu and Co) nanowires and semiconductor (Si and MoS2) nanowires or nanotubes, at both 532 nm and 1064 nm with nanosecond laser pulses. Compared with multiwalled carbon nanotubes, stronger broadband OL effects are observed, which made these nanomaterials promising candidates in the application of OL. Nonlinear scattering properties are measured in order to gain insight of the observed systematically nonlinear optical effects in the nanowires and nanotubes. Possible mechanisms are discussed.