Size dependence of rotation frequency of individual laser trapped liquid crystal droplets

We report the development of an all-optical liquid-crystal (LC) switch real ized by laser manipulation of a three-dimensionally trapped micrometer-size nematic liquid-crystal droplet. Transmission of a polarizer/LC droplet/ana lyzer system can be modulated at a frequency as high as 10(3) Hz for microm eter sized LC droplets. An optical switching corresponds to the rotation of the LC droplet by an angle of pi/4. The dependence of rotation frequency o n LC droplet size is explained in terms of the circularly polarized light s cattering by the molecules of the LC droplet. This scattering is responsibl e for the transfer of angular momentum from the light to the LC droplet.