A novel hybrid composite employing rhodamine 6G and fullerene C60 under the same liquid crystal structure for dynamic holography

الملخص EN

Liquid crystals (LC) are highly nonlinear optical materials, which, due to their susceptible property, become active under even relatively low optical fields.

Several nonlinear mechanisms investigated so far have revealed the promising characteristics of these materials.

The difference in refractive indices, for fields polarized along, and perpendicular to, the director axis brings about a large birefringence property from the visible to the infrared spectral regime.

This property presents an opportunity for various applications [1].

Director axis reorientation-based effects causing a change of refractive index and observations of several interesting dynamic and storage wave-mixing effects have been extensively studied so far [1–5].

Compared with others, LC based systems require lower characteristic voltages to be applied for the realization of molecular gratings and relatively lower light power for efficient modulation of the refractive index.

It is experimentally proved that doping with a small amount of dye decreases the required threshold of molecular reorientation even further in LC materials.

This phenomenon has potential applications such as holographic data storage.

Fullerene doped LC systems have also been studied for similar purposes [6, 7].

This work concentrates on the co-usage of a dye and fullerene at the same time, so that an efficient reorientation process could be experienced.

In dye-doped samples, light–molecule interaction could take place by different mechanisms, depending on the type of the dye.

Although details of these mechanisms are not in the scope of this work, photo–excited dopants bring about the formation of space-charge complexes and their induced fields force the molecules to reorient by enhancing the photoconductivity.

Indeed, the effect of fullerene on the reorientation process is explained by this approach [6, 7, 11].

Our work exploits this mechanism with the fullerene component, while absorbance-based reorientation is also at work with the dye component in the structure of the same system