Dual-polarization topological rainbow concentrators based on glide-reflection symmetry

Topological rainbow concentrators (TRCs) have attracted intense attention due to their capability of capturing photons with varying frequencies to distinct positions. However, the design of TRCs is not straightforward, especially for wideband and dual-polarization ones. In this paper, we propose a general and efficient methodology to realize TRCs by employing the glide-reflection symmetry operation. Starting from an ordinary photonic crystal with complete band gaps, and employing the two degrees of freedom of glide-reflection symmetry, i.e., the position of mirror reflection and the gliding length, wideband and dual-polarization TRCs are constructed successfully. Very interestingly, by monitoring the distance between the trapping positions of the two polarizations, the incident light frequency can be derived precisely. This paper introduces an efficient and flexible approach to configure TRCs, and may contribute to the wide applications in spectral analysis and polarization demultiplexing.