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 χ (2) zzz 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′‐alkoxystilbene (P 4 ) and 4‐nitro‐4′‐alkoxy‐α‐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, χ (2) zzz , of the films were derived from the analysis of full‐angle Maker fringe patterns at 1064 nm, χ (2) zzz values as high as 1.98×10 −7 esu for P 2 copolymers and of 1.19×10 −7 esu for P 3 copolymers could be achieved.