title: Microwave gain medium with negative refractive index.
abstract: Artificial effective media are attractive because of the fantastic applications they may enable, such as super lensing and electromagnetic invisibility. However, the inevitable loss due to their strongly dispersive nature is one of the fundamental challenges preventing such applications from becoming a reality. In this study, we demonstrate an effective gain medium based on negative resistance, to overcompensate the loss of a conventional passive metamaterial, meanwhile keeping its original negative-index property. Energy conservation-based theory, full-wave simulation and experimental measurement show that a fabricated sample consisting of conventional sub-wavelength building blocks with embedded microwave tunnel diodes exhibits a band-limited Lorentzian dispersion simultaneously with a negative refractive index and a net gain. Our work provides experimental evidence to the assertion that a stable net gain in negative-index gain medium is achievable, proposing a potential solution for the critical challenge current metamateiral technology faces in practical applications.
authors.affiliation: 1] Laboratory of Applied Research on Electromagnetics (ARE), Zhejiang University, Hangzhou 310027, China [2] Department of Electrical and Computer Engineering, University of Arizona, Tucson, Arizona 85721, USA.
authors.forename: Dexin
authors.initials: D
authors.lastname: Ye
authors.affiliation: Department of Electrical and Computer Engineering, University of Arizona, Tucson, Arizona 85721, USA.
authors.forename: Kihun
authors.initials: K
authors.lastname: Chang
authors.affiliation: Laboratory of Applied Research on Electromagnetics (ARE), Zhejiang University, Hangzhou 310027, China.
authors.forename: Lixin
authors.initials: L
authors.lastname: Ran
authors.affiliation: 1] Department of Electrical and Computer Engineering, University of Arizona, Tucson, Arizona 85721, USA [2] Department of Physics, University of Arizona, Tucson, Arizona 85721, USA.
authors.forename: Hao
authors.initials: H
authors.lastname: Xin