Two-dimensional diffraction gratings for use with far-field superlenses

Far-field superlenses (FSLs) allow a new type of optical microscopy that can resolve features below the diffraction limit. Such remarkable resolution is achieved by encoding sub-wavelength features in Moiré patterns, which are produced by diffraction gratings embedded in the FSLs. Typically these diffraction gratings are quasi-one-dimensional structures; this means that the shape and orientation of objects that can be successfully resolved is limited. We investigate two-dimensional grating designs and show that engineering an appropriate grating can lift restrictions on the orientation of the object relative to the diffraction grating. We also describe the impact that grating structure has on the range of spatial frequencies that can be resolved.