Inverse Design of Freeform Metagratings for Higher Efficiency and Arbitrary Polarization Deflection

Yun-Chien Wu^1*, Huan-Teng Su¹, Yao-Wei Huang¹

¹Department of Photonic, National Yang Ming Chiao Tung University, Hsinchu city, Taiwan

* Presenter:Yun-Chien Wu, email:yunchien.ee11@nycu.edu.tw

Conventional forward design methods in metasurface engineering primarily harness the principles of geometry phase and propagation phase. These methods effectively manipulate light by altering the size or orientation of nanopillars, a strategy that has historically yielded notable results. However, these forward design processes, while potent, encounter limitations when tasked with the exploration of intricate and unconventional shapes necessary for achieving optimal performance. Fortunately, inverse design allows us to break free from those limitations and design unconventional and simple patterns. In our work, we have leverage the power of inverse design to reshape the geometric configurations of metagratings, resulting in notable efficiency improvements when compared to their conventionally forward-designed counterparts. Moreover, we extend the reach of optimization techniques to non-orthogonal polarization pairs, demonstrating that inverse design can yield results that rival those of forward design methods applied to orthogonal polarization states. This expansion of functionality has promising implications for applications such as polarization cameras, where the ability to optimize metasurfaces for a wider range of polarization scenarios can significantly enhance performance and versatility.

Keywords: Metagrating, inverse design, freeform inverse design