Broadband and wide-view cholesteric liquid crystal polarization selective reflectors

The Bragg reflection of a cholesteric liquid crystal (CLC) gradually turns into phase retardation effect as the incident angle increases, which causes the polarization degradation in the CLC medium and explains why it is challenging to achieve a broadband response over a wide viewing angle. In this paper, we propose three novel solutions to address this issue, including a newly designed helicoidal structure, using a biaxial LC material, and laminating a compensation film to the CLC layer. All the results presented in this work are based on theoretical analysis and numerical simulations. By studying the polarization behavior and the eigenstates of the structures, we reveal the underlying principles behind the broadband, wide-view performance. Through optimization, our proposed methods can achieve nearly 100% reflectance across the visible spectrum up to ±45° incident angle, while keeping a decent contrast ratio. These findings offer new insights for realizing broadband and wide-view CLCs for display applications.