Abstract

Previously, corona-onset poling at elevated temperatures (COPET) was demonstrated to produce large orientational order by aligning nonlinear chromophores in a polymeric host.^1,2 The film system consisted of nonlinear azo dye chromophores dissolved in polymethyl methacrylate (PMMA). The films exhibited large and stable second harmonic intensities, but the films were strongly absorbing in the visible. For this investigation, new materials were developed that consisted of a coumarin-based chromophore attached to a PMMA backbone through an alkyl spacer with various dye concentrations. Spincast films on BK7 substrates were poled with the COPET technique. The poled nonlinear copolymer films were characterized by spectroscopic absorption and second harmonic generation. The second harmonic properties are presented as a function of concentration, thickness, poling temperature, and poling current. Large, stable second harmonic coefficients of the order of 19 pm/V are observed. Additionally, the films exhibit low absorption at wavelengths exceeding 450 nm.

© 1989 Optical Society of America