Loss compensation in metal-dielectric layered metamaterials

Abstract

We analyze a possibility of gain-induced compensation of losses in a one-dimensional layered structure, consisting of alternating layers of metal and dielectric with gain. Using an exact approach without effective medium approximations, we demonstrate that losses can be completely compensated for a certain value of the longitudinal component of the wave vector and partially reduced for other wave numbers. In the systems with larger values of the gain coefficient, convective instabilities can appear. At certain frequencies, losses can be greatly reduced for a broad range of the incidence angles. We find that in the canalization regime when the isofrequency contours are close to straight lines, the loss compensation becomes possible for a wide spatial spectrum being useful for improvement of the subwavelength imaging capability.

Nonlocal quantum gain facilitates loss compensation and plasmon amplification in graphene hyperbolic metamaterials

“…Concurrently, moving deeper into the sub-wavelength region, the models, currently used to predict properties of such systems, lose their applicability: the medium homogenization approximations fail when the wavelengths are comparable to the unit cell thickness 22,23 ; non-local effects have a significant influence on the graphene properties for the excitations with wavevectors approaching the Dirac cone 24 . At the same time, Ohmic losses, which are an inherent problem to all hyperbolic metamaterials (HMMs) with conductive sheets 25 , are an important issue for graphene-based HMMs (GHMMs) too. However, calculation of losses had been limited due to the approximations of the local graphene conductivity model.…”

Transmission enhancement in loss-gain multilayers by resonant suppression of reflection

“…Using active slabs, losses can be compensated in surface plasmonic waveguides [16][17][18] and negative-refractive-index metamaterials [19,20] under optical and electrical pumping. Loss compensation in metal-dielectric multilayers is mainly directed towards the hyperbolic metamaterials improvement [21][22][23] and can be used for enhancement of spontaneous emission [24] ameliorating of surface plasmon resonances [25], as well as for tuning gain/absorption spectra in graphene HMMs [26].…”

Bringing the ‘perfect lens’ into focus by near-perfect compensation of losses without gain media

“…Unfortunately, current negative index metamaterial designs are not suitable for optical imaging due to the extreme sensitivity to absorptive losses in the constitutive components [28,29]. A number of metamaterial loss compensation schemes using gain media have been proposed [30][31][32][33][34][35]. However, the use of gain media for loss compensation can result in instability and spasing [36].…”