Negative refraction in semiconductor metamaterials

Abstract

An optical metamaterial is a composite in which subwavelength features, rather than the constituent materials, control the macroscopic electromagnetic properties of the material. Recently, properly designed metamaterials have garnered much interest because of their unusual interaction with electromagnetic waves. Whereas nature seems to have limits on the type of materials that exist, newly invented metamaterials are not bound by such constraints. These newly accessible electromagnetic properties make these materials an excellent platform for demonstrating unusual optical phenomena and unique applications such as subwavelength imaging and planar lens design. 'Negative-index materials', as first proposed, required the permittivity, epsilon, and permeability, mu, to be simultaneously less than zero, but such materials face limitations. Here, we demonstrate a comparatively low-loss, three-dimensional, all-semiconductor metamaterial that exhibits negative refraction for all incidence angles in the long-wave infrared region and requires only an anisotropic dielectric function with a single resonance. Using reflection and transmission measurements and a comprehensive model of the material, we demonstrate that our material exhibits negative refraction. This is furthermore confirmed through a straightforward beam optics experiment. This work will influence future metamaterial designs and their incorporation into optical semiconductor devices.

Detection of microwave phase variation in nanometre-scale magnetic heterostructures

“…Lasing [1][2][3] , superconducting microwave properties 4,5 , negative refraction 6,7 and stimulated phonon emission ('sasing') 8,9 all require some degree of coherence in the EM phases across layers. Phasesensitive electric fields have been measured for short light pulses in ionized gases 10 ; interferometric (wave mixing) techniques have been used to resolve the complex polarizationP of near bandedge absorption in single semiconductor quantum wells or thick films 11 .…”

Zero phase delay in negative-refractive-index photonic crystal superlattices

“…Metal-based NIMs 3-11 have been actively studied because of their unusual physical properties and their potential for use in many technological applications [12][13][14][15][16][17][18][19][20][21][22] ; however, they usually have the disadvantage of demonstrating large optical losses in their metallic components. As an alternative to metal-based NIMs, dielectricbased photonic crystals (PhCs) have been investigated and shown to emulate the basic physical properties of NIMs [23][24][25][26][27] , while also having relatively small absorption losses at optical frequencies.…”

Reducing the losses of optical metamaterials

“…Such materials were carefully studied by different groups [51][52][53][54][55][56][57][58][59][60][61][62][63]. It is shown that indefinite media can have negative group refraction, backward-wave effect, and partial focusing.…”

“…But the double resonance scheme also causes large resonance losses and technical difficulties in design and fabrication. In addition to negative index materials, both theoretical and experimental studies show the properties of negative refraction and subwavelength imaging can also occur in some uniaxially anisotropic media, which can have lower losses and be easier to fabricate [51][52][53][54][55][56][57][58][59][60][61].…”

“…A lot of work has been done in anisotropic metamaterials, both experimentally [53,56] and theoretically [51,52,54,55,[57][58][59][60][61]. Liu and Zhang [61] derived the hyperbolic dispersion only theoretically in the Maxwell-Garnett approximation.…”