Birefringent crystals (BFC) have been extensively used in imaging spectrometer, laser devices, and optical components. Seeking new BFC is of important for both fundamental research and industrial application. Employed first-principles density functional theory (DFT), we found that LaOBiS2 (space group P4/nmm), the parent phase of recently discovered BiS2-superconductor, exhibits superior birefringence with a maximum value of 2.94, which is 13.4 times larger than the extensively used YVO4 (0.22). Furthermore, LaOBiS2 is an indirect semiconductor with a band-gap of 0.9 eV, which is suitable for optical applications. The origin of giant inherent birefringence is discussed.
Cite
@article{arxiv.1304.5032,
title = {Giant birefringence in layered compound LaOBiS2},
author = {Hai Wang},
journal= {arXiv preprint arXiv:1304.5032},
year = {2014}
}