The compound of tetra tert-butylnaphthalocyanine lead was synthesized. The structure of the compound was characterized by means of elemental analysis, infrared spectrum and hydrogen nuclear magnetic resonance spectrum. A frequency-doubled Q switched Nd:YAG pulse laser system with ns/ps laser pulse was used for studying the nonlinear and optical limiting properties of the synthesized compound at the wavelength of 532 nm. The nonlinear refracting index, n₂, and third-order nonlinear polarizability, χ⁽³⁾ were determined to be 2.54×10^－11 and 9.51×10^－12 esu, respectively. The molecular polarizability of the compound γ' was calculated to be 3.3×10^－29 esu. When visible light transmittance was 69%, the limiting threshold value was 1522 mJ/cm², the clamp value was 553 mJ/cm², and the ratio of absorption sectional area of effective excited state to that of ground state was 3.16.

Key words: nonlinear optics, Z-scan, naphthalocyanine