Abstract
Metamaterials intrigue many exciting applications in the broad electromagnetic spectrum ranging from microwave to optics. However, many of the envisaged applications still remain in theory, largely because of the intrinsic loss and dispersion associated with passive metamaterials. Incorporating active devices or media into conventional passive metamaterial structures for loss compensation, as well as dispersion control, is very attractive and may finally enable many desired applications. In addition, because of the added design degree of freedom in active metamaterials, new and rich physical phenomena and insights can be discovered. In this paper, we review the recent progress in the realm of active, gain-assisted metamaterials. Physical limitations on loss and bandwidth of metamaterials are firstly discussed. Recent experimental efforts in transmission-line and volumetric metamaterials with net gain in the microwave and optical regime are then examined. The idea of utilizing non-Foster active devices to reduce the dispersion and achieve broad bandwidth is also presented. Finally, one of the important issues of active metamaterial design, stability, is briefly discussed.
Original language | English (US) |
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Pages (from-to) | 944-959 |
Number of pages | 16 |
Journal | Applied Computational Electromagnetics Society Journal |
Volume | 29 |
Issue number | 12 |
State | Published - Dec 1 2014 |
Keywords
- Active metamaterials
- Gain
- Negative index
ASJC Scopus subject areas
- Astronomy and Astrophysics
- Electrical and Electronic Engineering