Complex-Birefringent and Chiral Waveplates with Metasurfaces

Abstract

Metasurfaces composed of arrays of nano-resonators are a powerful tool for manipulation of polarization of light [1], All-dielectric metasurfaces do not suffer absorption losses and are highly transparent in contrast to metallic structures, and combined with recent advances in their design and fabrication, have enabled efficient polarization manipulation and arbitrary phase shaping [2,3]. A new regime of complex-valued birefringence has been recently suggested [4], extending the notion of real-valued birefringence through the specially introduced polarization-sensitive loss or gain. This can enable fundamentally new possibilities for polarization control, such as amplifying the angle between polarization vectors to improve detection sensitivity. However, a practical realization of complex-valued birefringence concept was missing. In particular, the theoretical approach in Ref. [4] was based on a complicated metamaterial with loss and gain, which is challenging to fabricate and not suitable for quantum applications.