Nonlinear optical polymers. Second harmonic generation in corona-poled thin films

The synthesis and second harmonic coefficients, d(3,1) and d(3,3) as well as the related susceptibilities x(zzz)((2)) of five series of (NLO-dye methacrylate)-(methyl methacrylate) copolymers were investigated. The NLO-chromophores bound covalently to the polymer backbone were 5-(2,2-dicyanovinyl)-or 4-(2-cyano-2-methoxycarbonyl)vinyl-1-piperidino-2-thiophene (P-1 and P-2), 4-nitro-4'-alkoxy-stilbene (P-3), 4-nitro-3'-methoxy-4'-alkoxy-stilbene (P-4) and 4-nitro-4'-alboxy-alpha-cyano stilbene (P-5). The second order nonlinear optical properties of corona-poled aligned thin polymer films, using a needle electrode in order to induce noncentrosymmetry, were evaluated. Nonlinear susceptibilities, chi(zzz)((2)), of the films were derived from the analysis of full-angle Maker fringe patterns at 1064 nm, chi(zzz)((2)) values as high as 1.98x10(-7) esu for P-2 copolymers and of 1.19x10(-7) esu for P-3 copolymers could be achieved.