Second-harmonic generation in poled organic monomeric glasses

Abstract

Novel second-order nonlinear optical films are prepared from glasses of two organic compounds, (S)-2-N-α-(methylbenzylamino)-5-nitropyridine and 2-N-(cyclooctylamino)-5-nitropyridine, cooled rapidly from the isotropic liquid above the melting point. Extremely slow crystallization in the vicinity of the glass transition temperature Tg permits a polar orientation of these organic molecules under high electric fields at temperatures above Tg. Subsequent cooling to temperatures below Tg freezes in the polarization. A maximum value of the d33 nonlinear susceptibility of 7.5 pm/V and reasonable waveguiding properties are obtained. The poling dynamics of these organic glasses near Tg as monitored by second-harmonic generation exhibit a typical William–Landel–Ferry temperature dependence that is identical to their dielectric relaxation characteristics.