Broadband Achromatic Quarter-Waveplate Using 2D Hybrid Copper Halide Single Crystals
Yixuan Dou, Marie Solange Tumusange, Jianbo Jin, Xiaoming Wang, Erin R. Crater, Sunhao Liu, Liyan Zhu, Samir Zuberi, G. G. Harman, Conner Weaver, Balaji Ramanujam, Ambalanath Shan, Robert B. Moore, Nikolas J. Podraza, Yanfa Yan, Li Na Quan
Abstract
Achromatic quarter waveplates (A-QWPs), traditionally constructed from multiple birefringent crystals, can modulate light polarization and retardation across a broad range of wavelengths. This mechanism is inherently related to phase retardation controlled by the fast and slow axis of stacked multi-birefringent crystals. However, the conventional design of A-QWPs requires the incorporation of multiple birefringent crystals, which complicates the manufacturing process and raises costs. Here, we report the discovery of a broadband (540–1060 nm) A-QWP based on a two-dimensional (2D) layered hybrid copper halide (HCH) perovskite single crystal. The 2D copper chloride (CuCl 6 ) layers of the HCH crystal undergo Jahn–Teller distortion and subsequently trigger the in-plane optical birefringence. Its broad range of the wavelength response as an A-QWP is a consequence of the out-of-plane mosaicity formed among the stacked inorganic layers during the single-crystal self-assembly process in the solution phase. Given the versatility of 2D hybridhalide perovskites, the 2D HCH crystal offers a promising approach for designing cost-effective A-QWPs and the ability to integrate other optical devices.