Study On Optical Nonlinearity Of Benzothiadiazole Derivatives

With the rapid development of nonlinear optics, there has been considerable interest in searching and designing materials with good optical nonlinearity. Among them, the organic materials with donor-acceptor(D-A) molecular have recently attracted widespread attention due to their better optical nonlinearity and plasticity. A series of organic materials has been supposed to be optical nonlinear materials by more decorating.In this paper, The nonlinear properties of benzothiadiazole derivateives(BTDs) is studied at 532 nm, including 4-((7-Bromobenzo[c][1, 2, 5] thiadiazol-4-yl)ethynyl)-N, Ndimethylaniline(BTD-B) and N, N-Dimethyl-4-((7-(piperidin-1-yl)benzo[c] [1,2,5]-thiadiazol-4-yl) ethynyl) aniline(BTD-P). Both of them are the donor-acceptor(D-A) molecular organic materials based on benzothiadiazole, where the donor parts consist of N,N-dimethylaniline units, while benzothiadiazole works as the acceptor. The results indicated that both of them exhibit nonlinear optical properties including nonlinear reverse absorption and negative refractive effects. However, because of the different substitution groups, the degree of the nonlinear response is different.The dynamics of the samples’ optical nonlinearity is discussed via the picosecond time-resolved pump probe technique at 532 nm.And combining with the result of their nanosecond Z-scan experiment and simplified three-level model, a series of their nonlinear optical parameters are calculated out. The result verifies that the samples have good optical nonlinearity which implies their potential applications in nonlinear optical field.