NOVEL CROSS-LINKED GUEST-HOST SYSTEM WITH STABLE 2ND-ORDER NONLINEARITY

An epoxy-based nonlinear optical (NLO) polymeric material incorporating 4-(4'-nitrophenylazo) phenylamine has been synthesized and subsequently functionalized with acryloyl groups. A glass transition temperature (T(g)) of 108-degrees-C and a degradation temperature (air) of 251-degrees-C were recorded. After crosslinking at 160-degrees-C for 2 hours, the T(g) of the polymer increased to 146-degrees-C. In order to increase the nonlinear optical chromophore concentration and the crosslinking density, the crosslinkable NLO dye, 2,4-acryloyloxy (4'-phenylazo nitrobenzene), was processed and poled in this epoxy-based NLO material matrix in a manner similar to a typical guest-host system, and thermally crosslinked under the above condition in the poled phase. The crosslinked guest-host material was found to be amorphous with a T(g) of approximately 132-degrees-C. It also exhibits a second-order nonlinear optical coefficient d33 of 14.14 pm/V at a maximum doping level of 33% by weight of the NLO dye, and retains 93% of its original d33 value after being subjected to thermal treatment at 100-degrees-C for 168 hours. The behavior of the crosslinked polymer and the crosslinked guest-host polymer is discussed.