Carbazole-based Photorefractive Organic Glass Showing High Diffraction Efficiency at Low External Electric Field

Abstract

Photorefractive organic glass, 9-(2-ethyl-hexyl)-3-[2-(4-nitro-phenyl)-vinyl]-9 H -carbazole (EHCN), showing large coupling gain and high diffraction efficiency at low external electric field was synthesized and characterized. EHCN showed the glass transition at 25°C and the good thermal stability up to 400°C. Photorefractivity of EHCN was investigated by using 100 µm thick films (S1, S2, S3) doped with 0%, 0.5%, and 1% 2,4,7-trinitrofluorenone (TNF), respectively. Two-beam coupling net gain of 50.8 cm -1 was obtained for the 0.5% TNF-doped EHCN sample (S2) at 40 V/µm field. The highest internal diffraction efficiency, obtained from the degenerate four-wave mixing at 30 V/µm field, reached 90% for the 1% TNF-doped EHCN sample (S3).