Special Beam Shapes Induced by Metal-Q-Plate
Wei Ji2, Chun-Hong Lee1, Peng Chen2, Wei Hu2, Yang Ming2, Lijian Zhang2, Chien-Tsung Hou1*, Tsung-Hsien Lin1, Vladimir Chigrinov3, Yan-Qing Lu2
1Department of Photonics, National Sun Yat Sen University, Kaosuing, Taiwan
2National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures and College of Engineering and Applied Sciences, Nanjing University, Nanjing, China
33Centerfor Display Research,Department of Electronic and Computer Engineering, Hong Kong University of Science and Technology, Clear WaterBay, Kowloon, Hong Kong, China
* presenting author:Chien-Tsung Hou, email:a7810192000@gmail.com
Beam shaping induced by manipulation of multiple degrees of freedom of light has attracted much attention recently, and it is favorable for various applications such as optical trapping. In this research, the production of extraordinary beam shape by virtue of meta-q-plate featured by arbitrarily space-variant optical axes is proposed. To fabricate meta-q-plates, a novel photo-alignment setup schematically illustrated in. In addition, the photo-rewritable, sulphonic azo-dye SD1 is used as the photo-alignment agent, and the direction of the alignment layer is dependent on the last illuminated-polarization. Further, the designed optical axis orientation α is recorded into the cell step by step. Due to the reciprocity of LC director, the α modulo π is considered. Firstly, every from 0 to π is equally divided into eighteen sub-regions, and endowed a uniform director value, from 0 to 17π /18 in intervals of π/18 respectively. Secondly, the adjacent five sub-regions are assembled as a sum-region and exposed simultaneously. The subsequent sum-region shifts one sub-region while the polarizer rotates π/18 synchronously. Finally, after the multi-step partly-overlapping exposure, each sub-region is exposed for five times with five different polarizations. After LC E7 is infiltrated, a more continuously space-variant LC orientation is obtained owing to the pronounced continuity and fluidity of LCs. Therefore, the designed meta-q-plate is obtained. Correspondingly, special beam shapes implemented by meta-q-plates are demonstrated in including elliptical, asymmetrical, multi-ringed and hurricane profiles. Further, our technique drastically enhances the capability of optical beam shaping and settles a fundamental requirement in the fields of optical manipulations.

Keywords: Meta-Q-Plate, Beam Shaping