Preparation and optical limiting of a novel soluble phenylacetylene copolymer bearing nonlinear chromophoric pendants

A novel soluble conjugated phenylacetylene copolymer containing nonlinear chromophore, poly {[4-ethynyl-4'-(N,N-diethylamino) azobenzene]-co-phenylacetylen} was prepared and its optical limiting (OL) properties were investigated in three different concentration solution with 8 ns pluses at 532 nm wavelength. The excited state absorption cross-section σ_ex of this polymer was measured with the Z-scan technique. The optical limiting mechanism was discussed based on nonlinear absorption theory. The results show that this polymer possesses the larger excited state absorption cross-section than the ground state, indicating that the OL performance of this polymer mainly arises from the reverse saturable absorption (RSA).