New copolymers for nonlinear optics applications that incorporate delocalized pi-electron subunits with well-defined conjugation lengths

During the past three years it has become more evident that long conjugation sequences in electroactive materials may not be a stringent requirement for high third order nonlinear optical (NLO) activity. Since long conjugation lengths in these materials often make them difficult to process, the resulting insolubility often precludes the formation of optical quality films for device applications. The incorporation of shorter electroactive segments alternating with flexible non-active spacers may allow high NLO activity coupled with good optical film forming capability. In this paper we would like to present several approaches to copolymer design which incorporate various electroactive oligomer segments with well-defined conjugation lengths. The control one obtains in this appmach allows the design of sharp optical windows, and the ability to tailor absorption characteristics to particular frequencies.