Permanently poled fully functionalized photorefractive polyesters

Abstract

Crystallization and phase separation are severe degradation mechanisms of photorefractive (PR) guest-host systems. Additionally, the response time of PR guest-host systems is in some cases limited by a large contribution of slow chromophore reorientation to the PR effect. The synthesis of fully functionalized systems with glass transition temperatures well above room temperature is a way to restrict these degradation mechanisms and to reduce the PR effect to a pure charge generation and transport phenomenon. We present novel, fully functionalized PR polymers based on polyester. Permanent poling of the systems is demonstrated and quantitatively investigated. The PR properties are measured by degenerate four-wave mixing and two-beam coupling experiments as a function of the external electric field and the degree of permanent poling. One of the systems shows response times of approximately 200 ms with ⌬n Ϸ 1 ϫ 10 Ϫ3. To our knowledge, this work presents the first characterization of PR efficiencies for fully functionalized polymers as a function of the permanent Pockels coefficient (2) (Ϫ;, 0).

The photorefractive effect in polymeric systems

“…Most of them are based on plasticised poly(vinylcarbazole) (PVCz), 12, 19, 31 ± 33, 50 ± 54 carbazolyl-substituted polysiloxanes (PSX-Cz) 55 ± 57 and polyethers. 58,59 In such polymeric media the major contribution to the creation of a phase grating comes from the linear orientation polarisation. Under these conditions, the diffraction efficiency buildup rate is determined by rotational diffusion of the chromophore and is described as follows: 60,61…”

Materials Design and Physics of Organic Photorefractive Systems

“…Secondly, FFPs demonstrate slow grating dynamics, on the order of 200 ms or longer, and are limited by the slow build-up of the space-charge field. [61] Furthermore, the refractive index modulations and the two-beam coupling gains were low. The slow response arises from the poor photoconductivity.…”

Correlation between Dispersivity of Charge Transport and Holographic Response Time in an Organic Photorefractive Glass

“…We used two different setups for degenerate four-wave mixing (DFWM) experiments. One of those has been described previously . To achieve higher writing intensities, we used a second setup with a dye ring laser (Coherent 899-21) operating at a wavelength of λ write = 645 nm.…”