Determination of large third-order optical nonlinearities in tetra-tert-butylphthalocyaninatogallium iodide film

Abstract

Using the Z-scan technique with 532 nm 4 ns laser pulses at various energy levels and repetition rates, we investigated the optical nonlinearities of tetra-tert-butylphthalocyaninatogallium iodide (t-Bu)4PcGaI. As a result, we found that the soluble peripherally tert-butyl-substituted phthalocyanine bound with the core of gallium iodide exhibited a giant two-photon absorption coefficient and Kerr refractive index. This suggests the potential applications of this material in numerous fields of nonlinear optics. However, when tackling the large nonlinearly induced loss and phase distortion analytically, we failed to fit the corresponding experimental results with the existent series sum formulas, which retain only the first few terms in the expansion. We performed the fitting by retrieving the high-order terms and justified this approach by dealing with the light-matter interaction and wave propagation.