Third-order nonlinear optical properties of the phenothiazinium chlorides at 532 nm

A series of phenothiazinium chlorides, which have good solubility in polar solvents and good thermal stability, were evaluated in dimethyl sulfoxide solution for third-order nonlinear optical properties at 532 nm using a nanosecond and picosecond Z-scan technique. The title compounds exhibit strong reverse saturable absorption and nonlinear refraction. The third-order nonlinear optical properties were obtained under irradiation with either a nanosecond or picosecond laser. The nonlinear mechanism is revealed as excited-state nonlinearity by a picosecond pump-probe response experiment for one of the compounds. The absorption and emission maxima, Stokes shift and quantum yield are also reported.