Area-coded effective medium structures, a new type of grating design

Abstract

We propose a new way to design gratings with desired diffraction properties by using subwavelength feature sizes perpendicular to the ordinary superwavelength grating period. This is different from well-known one-dimensional binary-blazed gratings that use a structuring along the grating period and thus opens new flexibility in generating arbitrary effective-index distributions in the direction of the grating period. Since the subwavelength features form contiguous areas, they are called area-coded effective medium structures (ACES). Compared with well-known binary subwavelength structures in two-dimensional arrangements consisting of pillars, ACES are more stable and have comparable efficiency properties. As an example we show how to design in principle a four-level area-coded effective medium grating, compare the efficiency of ACES with binary-blazed and échelette gratings, and optimize the subwavelength period of ACES.

Asymmetrical excitation of surface plasmon polaritons on blazed gratings at normal incidence

“…Therefore, the diffraction spectrum of this 2D grating is similar to that of a 1D grating, with the blazing effect induced by the local effective refractive index modulation within each period along the x direction. 8,10 The classical slanted grating in Fig. 1͑b͒, however, achieves the blazing effect with the aid of its asymmetrical surface-relief profile.…”

“…In electron-beam lithography ͑EBL͒, controlling the in-plane dimensions of a binary structure is much easier than modulating its depth. Based on this consideration, Kleemann et al 8 proposed a novel type of binary-blazed gratings, called the blazed area-coded effective-medium structures ͑BLACES͒, to achieve the blazing effect through an effective index variation in a single layer by modulating the local filling factor of a binary two-dimensional ͑2D͒ grating pattern. Unlike the 1D slanted gratings or conventional binary-blazed gratings with high-aspect-ratio ridges or pillars, 9 the BLACES have more reasonable dimensions and are easier to fabricate with, e.g., standard EBL.…”

Micro‐ and nanooptics – an overview

“…water waves [14] and IR applications [15]. Later, significant improvements were suggested concerning the design, the understanding of the possible gain in diffraction efficiency with respect to conventional blazed diffraction gratings [16] as well as feasible approaches to the realization [17].…”

Surface plasmons on zig-zag gratings

“…Periodic arrays of holes in metal films, which are in essence simple bi-gratings, have also stimulated much interest over the last decade because of their enormously enhanced optical transmission [13,14] mediated by diffractively coupled SPPs. With the recent advances in large-area nano-fabrication, optical scientists are now able to explore more complex diffraction grating geometries [15][16][17]. Here, we study the optical excitation of diffractively coupled SPPs on a grating geometry with significantly reduced symmetry, a "zig-zag" grating ( Fig.…”