Near-Field Plates: Metamaterial Surfaces/Arrays for Subwavelength Focusing and Probing

In this paper, we present a brief overview of near-field plates, which are nonperiodic grating-like surfaces/arrays that can focus electromagnetic field to subwavelength resolutions. The general properties of near-field plates are described, and the procedure used to design these devices is outlined. The design of two separate near-field plates is discussed in detail. One of the near-field plates produces a subwavelength line (1-D) focus while the other a spot (2-D) focus. Potential applications of near-field plates are also reviewed.