Investigation of ultrafast broadband optical nonlinearity and intensity-dependent nonlinear absorption in novel hydrazone derivatives

•Investigate the modulation of optical nonlinearities by ICT and planar π conjugation in hydrazone derivatives.•The broadband (600–900 nm) RSA resulting from TPA-induced ESA.•The intensity-dependent nonlinear absorption under multiple pulse widths (fs, ps, ns) was explored.•Transient absorption spectroscopy revealed the ultrafast dynamics processes and discussed in detail.