Third-order nonlinear optical properties of a new type of D–π–D unsymmetrical phenoxazinium chloride with resonance structures

Abstract: A new series of unsymmetrical phenoxazinium chlorides, featuring a heterocyclic aromatic π-bridge with dialkylamino donors, were evaluated in acetonitrile solution for third-order nonlinear optical properties at 532nm using a Z-scan technique. The title compounds exhibit strong reverse saturable absorption and nonlinear refraction. The third-order nonlinear optical properties were obtained under nanosecond and picosecond laser beams. The nonlinear mechanism is revealed by the excited-state nonlinearity, as observed from a picosecond pump-probe response experiment for one of the compounds. They are potential nonlinear optical materials because they also have good solubility in polar solvents and good thermal stability. [Copyright &y& Elsevier]