“…Second-order nonlinear optical (NLO) materials based on organic polymer and small functional molecules have attracted widely attention. These NLO materials have been identified to have potential applications in high-speed electro-optical (EO) conversion devices, such as frequency converters, optical switches and EO modulators. − These organic polymeric NLO materials have also shown prominent merits in EO effect, response time, bandwidth, and driving voltage, over their inorganic counterparts of lithium niobate. − For decades, researchers have been encouraged to synthesize many NLO polymers with large EO coefficients, high optical and thermal stability, as well as good optical transparency to satisfy the requirements of practical applications. − However, the use of NLO polymers remains problematic for two primary reasons: (1) it is difficult to translate efficiently the large first order hyperpolarizability of organic chromophores into large macroscopic EO coefficients of the polymers; (2) organic EO polymers suffer from poor long-term stability. The cause of these deficiencies is that the organic chromophores with large dipole moment improve the intermolecular interactions among the chromophore molecules, and these can cut down the poling efficiency. − Originally, researchers from the group of Jen and Dalton introduced site isolation chemical groups around the chromphores, which can efficiently reduce the interactions. , Though many EO polymers with larger macroscopic EO coefficients have been reported in host–guest systems based on this theory, the problem of long-term stability has not yet been resolved.…”