High-resolution Fourier lens utilizing transformation materials

A large-bandwidth, high-resolution Fourier transform lens is proposed based on transformation optics, where the conformal space mapping is approximately obtained by adjusting the in-plane principal stretches to be equivalent step by step. The output surface of a Luneburg lens is deformed into a planar configuration through this transformation, while maintaining its relaxed dependence on paraxial approximations for optical Fourier transform. The numerical simulation results show that the smallest angular separation of two incident plane waves can be improved up to 60% compared to conventional lenses in the given conditions, confirming that the proposed lens has enhanced focus separation as well as Fourier transform resolution.