Photorefractive gratings in the organic crystal 2-cyclooctylamino-5-nitropyridine doped with 7,7,8,8-tetracyanoquinodimethane

Abstract

The photorefractive properties of single crystals of the organic material 2-cyclooctylamino-5-nitropyridine doped with 7,7,8,8-tetracyanoquinodimethane are investigated with two-wave mixing experiments. Refractive-index gratings with an amplitude of up to 1.8 × 10−6 could be recorded for grating vectors along the twofold axis. The phase gratings showed a phase shift of between 20° and 70° with respect to the intensity grating. An experimental procedure for determining phases and amplitudes of absorption and phase gratings is discussed in detail.