A novel type of multifunctional polymers that contain a conjugated backbone for third and pendant chromophores for second-order nonlinear optics (NLO) have been investigated. We synthesized the 1,6-heptadiyne derivatives appendaging NLO chromophores. The resulting monomers were easily homopolymerized and also copolymerized with triethyl dipropargyl phosphonoacetate (TDPA) using a metathesis catalyst to give corresponding polymers with large optical nonlinearities. Molecular structural characterizations for the resulting polymers were achieved by $^1H$ and $^{13}C$ NMR, FTIR, and UV-visible spectroscopies. The polymers obtained were found to be amorphous, and showed thermal stability up to 250℃. The homogeneous polymer solutions could be spin coated to the optical quality thin films on the ITO glass substrates. These films have been oriented by an electric contact poling process. The electro-optic coefficient, $r_{33}$, of the poled polymer films were in the range of 1.7~0.1 pm/V, and the nonresonant values of the third-order NLO coefficient, $χ^{(3)}$ were found to be 2.1 to $3.3Ⅹ10^{-11}$ esu.
For photonic switching devices, we sysnthesize the second-order NLO chromophore monomer with hexyl sulfone group. The resulting monomer was easily copolymerized with methyl methacrylate using AIBN initiator. The polymer solution could be spin coated to the optical quality thin films on the ITO glass substrates. The electro-optic coefficient at the wavelength of 1.3 ㎛ was 3 pm/V for the 40 mol % poly(SC-1) poled at the 100 V/㎛.
New NLO moiety-doped polyimides as host-guest systems were developed. NLO moieties based on dialkylamino alkylsulfonyl stilbene (DASS) and dialkylamino nitro stilbene DANS) were synthesized as guest chromophores. Owing to the newly introduced flexible alkyl chains to the NLO chromophore terminal groups, the compatibility between guest chromophores and host polyamic acid in NMP solvent was improved and the solubility of the alkylated-NLO moieties to the host polyimide was increased up to the 40 wt %. These polyimide-based guest-host systems exhibited a significant improvement in the thermal stability at high temperatures exceeding 250℃ by the TGA. The electrooptic coefficient at 0.63㎛ is 13 pm/V for the 40 wt % DASS-doped polyimide system poled at the 135 V/㎛.
