Phys.org   September 27, 2023 Materials with large birefringence are sought after for polarization control, nonlinear optics, micromanipulation, and as a platform for unconventional light–matter coupling, such as hyperbolic phonon polaritons. Layered 2D materials can feature some of the largest optical anisotropy; however, their use in most optical systems is limited because their optical axis is out of the plane of the layers and the layers are weakly attached. A team of researchers in the US (University of Wisconsin, Washington University, University of Southern California, Oak Ridge National Laboratory, Lawrence Berkeley National Laboratory) demonstrated that a bulk crystal with subtle periodic […]