Metamaterials and plasmonics potentially offer an ultimate control of light to enable a rich number of non-conventional devices and a testbed for many novel physical phenomena. However, optical loss in metamaterials and plasmonics is a fundamental challenge rendering many conceived applications not viable in practical settings. Many approaches have been proposed so far to mitigate losses, including geometric tailoring, active gain media, nonlinear effects, metasurfaces, dielectrics, and 2D materials. Here, we review recent efforts on the less explored and unique territory of “virtual gain” as an alternative approach to combat optical losses. We define the virtual gain as the result of any extrinsic amplification mechanism in a medium. Our aim is to accentuate virtual gain not only as a promising candidate to address the material challenge, but also as a design concept with broader impacts.

中文翻译：

---

具有虚拟增益的超材料和等离子体的损耗补偿 [邀请]

超材料和等离子体可能提供对光的最终控制，以实现大量非常规设备和许多新物理现象的试验台。然而，超材料和等离子体中的光学损耗是一个基本挑战，使得许多设想的应用在实际环境中不可行。迄今为止，已经提出了许多减轻损耗的方法，包括几何剪裁、有源增益介质、非线性效应、超表面、电介质和 2D 材料。在这里，我们回顾了最近在探索较少和独特的“虚拟增益”领域作为对抗光学损耗的替代方法的努力。我们将虚拟增益定义为介质中任何外在放大机制的结果。我们的目标是强调虚拟收益不仅是解决物质挑战的有希望的候选人，