We were awarded ONR grant for diffraction-unlimited flat lens! [Aug 21, 2015]
We were awarded by Office of Naval Research about $375K research grant for three years to develop a loss-free prototype metamaterial flat lens with diffraction-unlimited resolution. The project team includes Prof. Guney (PI) and collaborators Dr. Phil Evans (Oak Ridge National Laboratory), Prof. Martin Wegener (Karlsruhe Institute of Technology, Germany), Prof. Joshua Pearce (ECE/MSE), and Prof. Elena Semouchkina (ECE). The field of electromagnetic metamaterials has provided us with a new look at the materials by mimicking nature through engineering in subwavelength scales. This has led to the possibility of previously unthought-of applications such as flat lens [1], perfect lens [2], hyperlens [3-5], ultimate illusion optics [6-8], perfect absorber [9, 10], quantum levitation [11], and many others. We envision that control over constitutive parameters of electromagnetic materials will transform the way we design electromagnetic devices in the entire spectrum, ranging from radio to ultraviolet frequencies. Not only conventional devices will be impacted but also many other exotic and novel devices will appear. Electromagnetic phenomena in metamaterials will continue to inspire new discoveries extrapolated into the territories of acoustics [12], electronics [13], and quantum electrodynamics [14, 15].
However, despite tremendous progress in theory and experimental realizations, the major current challenges, which are often overlooked in most proposals, will seem to delay the metamaterial era to come. For instance, how to achieve full isotropy, bulk fabrication, broad bandwidth, and compensation of dissipative losses especially are among the open basic scientific questions [16, 17]. Perhaps, the most critical of all is how to avoid losses – especially in large-volume structures – where the losses will cause the structures to cease to function. The proposed devices dramatically degrade and become useless especially at optical frequencies due to significant ohmic losses arising from the metallic constituents of the metamaterials. In some sense, the loss problem is analogous to the “decoherence” problem in quantum computing field. There are raising self-criticisms among quantum computing community whether quantum computing scalable enough to meet the practical needs will be ever possible due to the decoherence problem.
Incorporation of gain medium [68-74] pumped by either electrical or optical means to compensate the losses actively in metamaterials has been so far proposed as the most exciting but not the most effective solution to the loss challenge. There has been no single experimental demonstration of any metamaterial structure clearly proven to benefit from gain medium approach.
In this three-year project we will attack exactly the “loss challenge.” We have very recently discovered a viable interesting passive loss compensation scheme which is originally inspired by gain medium concept but does not use gain medium to compensate the losses (see Figure below). To explore this novel loss compensation scheme, the proposed project will involve basic research in three different parts of the electromagnetic spectrum: visible, mid-infrared, and microwave frequencies. Our goal will be to demonstrate the superiority of our novel loss compensation scheme over gain medium in improving the performance of metamaterial devices. To achieve this, in the visible spectrum, we will demonstrate in a proof of principle experiment on how the proposed loss compensation scheme actually works. We will build on our previous research on surface plasmon driven negative index metamaterial structures, which are ideal platforms for the proposed loss compensation scheme. To demonstrate the effectiveness of our proposed loss compensation scheme on metamaterial applications, we will target imaging applications, particularly hyperlens and superlens, since they have been so far proposed as the most interesting and exotic applications of metamaterials. In this proof of principle demonstration, we will work in the microwave frequencies for the superlens and in the mid-IR frequencies for the hyperlens. If we become successful, the outcome of the project will be a major leap in realizing the early magical dreams of the metamaterials.
Conceptual loss-free metamaterial. Surface plasmon polaritons (SPPs) propagate from the side superlattices to central superlattice forming the metamaterial and excite the metamaterial eigenmode (lower panel), which in turn amplifies the domestic SPPs in the metamaterial. Finally, the amplified SPPs couple to free-space modes.
References
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