We prepared the new heterocyclic nonlinear optical (NLO) chromophores that show fairly high microscopic nonlinearity through intramolecular charge transfer. Phenothiazine unit played an important role to contribute high electron donability and connect the resonance pathway via conjugative effect in the cyclized ring beside the aromatic ring. Three NLO chromophores were tethered to the aromatic core to synthesize the 1st-generation trifunctional dendrimer. We compared the electro-optic (EO) properties of two samples with single chromophore or trifunctional dendritic chromophore. Real time pole and probe method was employed to investigate the change of the EO signal during poling. EO properties and their relaxation behaviors of the guest-host systems containing synthesized chromophores were thoroughly investigated. (c) 2006 Elsevier B.V. All rights reserved.