Abstract
The phase interplay between overlapping electric and magnetic dipoles of equal amplitude generated by exclusively alldielectric structures presents an intriguing paradigm in the manipulation of electromagnetic energy. Here, we offer a holistic implementation by proposing an additive manufacturing route and associated design principles that enable the programming and fabrication of synthetic multi-material microstructures. In turn, we compose, manufacture and experimentally validate the first demonstrable 3d printed all-dielectric electromagnetic broadband absorbers that point the way to circumventing the technical limitations of conventional metal-dielectric absorber configurations. One of the key innovations is to judicially distribute a dispersive soft matter with a high-dielectric constant, such as water, in a low-dielectric matrix to enhance wave absorption at a reduced length scale. In part, these results extend the promise of additive manufacturing and illustrate the power of topology optimisation to create carefully crafted magnetic and electric responses that are sure to find new applications across the electromagnetic spectrum.
Highlights
The phase interplay between overlapping electric and magnetic dipoles of equal amplitude generated by exclusively alldielectric structures presents an intriguing paradigm in the manipulation of electromagnetic energy
Additive manufacturing (AM) research is broadly divided along two delineations; the development of composite 3d printable dielectrics[3] and; the imposition of converting transformation optics (TO) inspired metamaterial designs into 3d amenable structures which are often inconsistent with additive manufacturing (AM) ideology[4,5,6]
We propose an additive manufacturing route and associated design principles that enable programming and fabrication of synthetic multi-material microstructures
Summary
Our analysis starts with the theoretical conditions required for total absorption of normally incident plane waves by an infinite 1d periodic array of fictitious electric and magnetic dipoles as established by the antenna theory[22,23]. When the magnetic and electric dipole scattered response are both equal to negative one-half of the incident wave amplitude and resonates at the same frequency with equal width, the result will be a zero transmission and reflection composition (Supplementary Fig. 4(a,b)). Let us examine the effective refractive index n and wave impedance Z extracted from the simulated reflection and transmission coefficients These offer additional insights into the working of our structure that are not evident from the dipole moments alone. The enhanced magnetic and electric dipole moments effect is such that the power flow is directed into the central water reservoir (position 4) where dissipation of the impending energy ensures zero fields evident at the cylinder centre (Supplementary Fig. 9(b)) and no leakage in the forward direction. Our use of unorthodox materials coupled with a re-imagining of Huygens’ principle will serve to drive further technology breakthroughs across the electromagnetic spectrum by using inspired design methodologies
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