Focusing light into deep subwavelength using metamaterial immersion lenses.

We propose and demonstrate metamaterial immersion lenses by shaping plasmonic metamaterials. The convex and concave shapes for the elliptically and hyperbolically dispersive metamaterials are designed using phase compensation method. Numerical simulations verify that the metamaterial immersion lenses possess exceptionally large effective numerical apertures thus can achieve deep subwavelength resolution focusing. We also discuss the importance of the losses in modulating the optical transfer function and thus in enhancing the performance of the metamaterial immersion lenses.