Persistent, Efficient Frequency Doubling by Poled Annealed Films of a Chromophore-Functionalized Poly(p-hydroxystyrene)

摘要

All synthetic strategies for polymeric second-harmonic generation (SHG) materials must address the crucial issues of maximizing chromophore densities while achieving maximum, persistent noncentrosymmetry. An attractive alternative to poling glassy polymers simply doped with nonlinear optical (NLO) chromophores are materials in which NLO chromophores are covalently linked to the polymer backbone, thus offering potential impediment both to phase separation at high chromophore densities and to deleterious relaxation of poling-induced chromophore alignment. We report here an embodiment of this strategy which employs structure-enforcing hydrogen-bond networks, achieves high chromophore densities, and affords polymer films with persistent (on a timescale of months) second-harmonic coefficients equal to or in excess of the corresponding value for LiNbO3. General observations relevant to NLO film processing and the applicability of current theoretical models are also reported. Lithium niobates, Polystyrenes, Reprints. (mjm)