American Chemical Society
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Anisotropic Optical Response of Nanostructures with Balanced Gain and Loss

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journal contribution
posted on 2016-06-17, 00:00 authored by Alejandro Manjavacas
Photonic systems containing active and passive elements with balanced gain and loss are attracting increased attention due to their extraordinary properties. These structures, usually known as PT-symmetric systems, display strongly asymmetric behaviors. Here we study the optical response of finite nanostructures composed of pairs of active and passive nanospheres operating close to the PT-symmetry condition. We find that, despite their highly regular geometry, these systems scatter light predominantly toward the gain side of the structure when illuminated perpendicularly to their axis. Furthermore, the backscattering intensity for illumination parallel to the axis depends strongly on the side of incidence, being several times larger for light coming along the gain side. Interestingly, under the same conditions, the forward scattering and, consequently, the extinction cross-section remain independent of the side of incidence. This leads to an asymmetric absorption cross-section that can be made arbitrarily small for light impinging on the gain side of the structure. These results contribute to the basic understanding of the optical properties of active–passive finite nanostructures with potential applications for the design of novel nanostructures displaying asymmetric and tunable responses.