Optical Angular Momentum Flux in Liquid Crystals

ABSTRACT

In this paper the role played by the angular momentum of light in the optical reorientation of a nematic liquid crystal was studied in the case of a normal incident elliptically shaped laser beam with circular polarization. Above the threshold power for the OFT, the molecular director suffered a stationary reorientation due to the balance between the orbital and spin angular momentum of light transferred to the sample. The director started to rotate only above a second threshold power. The experimental results qualitatively matched theoretical predictions.

Keywords:

• angular momentum
• liquid crystals
• nonlinear optics

Acknowledgments

I thank MIUR (Ministero dell'Istruzione, Università e Ricerca) and INFM (Istituto Nazionale per la Fisica della Materia). Special thanks are to Prof. Enrico Santamato for enlightening discussions and valuable advices.