Material anisotropy as a degree of freedom in optical design

We present an approach for the design of refractive optical elements using materials degrees of freedom that are accessible via engineered materials. Starting from first principles and an unconstrained general material, we specify homogeneous refractive lenses that focus light with diffraction-limited resolution resulting from a tailored anisotropic refractive index. We analyze the performance, physical feasibility, and advantages over isotropic lenses. Materials degrees of freedom enable new flexibility for imaging system designs with lower complexity expanding the existing aspheric and graded index paradigms.