Bjarklev, Anders Overgaard

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Downloaded from orbit.dtu.dk on: Dec 20, 2017Microwave and Photonic MetamaterialsBjarklev, Anders OvergaardPublication date:2014Document VersionPeer reviewed versionLink back to DTU OrbitCitation (APA):Bjarklev, A. O. (2014). Microwave and Photonic Metamaterials [Sound/Visual production (digital)]. XX ItalianMeeting on Electromagnetics, Padova, Italy, 15/09/2014Microwave and Photonic Metamaterials Anders O. Bjarklev, MSc(Eng), PhD, Dr.Techn.  President Technical University of Denmark Plenary Speech Riunione Nazionale di Elettromagnetismo (RiNEm 2014) 15 September 2014             Technical Intuition?             Photonic Crystals? 1887 Lord Rayleigh studies 1D periodic structures 1987 Yablonovitch and John propose Photonic Crystals 1998 Knight et al. demonstrate real optical device     (Uni. of Bath and DTU collaboration)             Photonic Crystals: State-of-the-Art 500-1000λ 10- 100λ Advanced structures for slowing light to increase material gain  Suggested theoretically by J. P. Dowling et al., JAP (1994),  but never demonstrated experimentally             Photoluminescence  Measurements J. Liu et al., Nature Nanotechnol. (2014)   Spontaneous lasing due to  Anderson localization:   Localisation length ~ 4-6 µm.  Q-factor  ~ 5000 Limits amplifier gain             Metamaterials 1967  Vaselago predicts materials with negative ε and μ  1999    Pendry proposes split ring structures with negative µ   and founds the modern field of metamaterials  2000  Smith et al. demonstrate functional metamaterials  -2014 Explosion of research in metamaterials,  however, most experimental demonstrations at microwaves               Challenges • Broadband operation without distortions • 3D omnidirectional operation • Functional devices at visible wavelengths               Avoiding Metals For The Optical Range?   Metals are the bottleneck of performance in many classes of optical metamaterials: • High losses, large magnitude of permittivity, lack of tunability of  optical properties • Challenges associated with nanofabrication and integration  Metal-free plasmonic metamaterial: • Hyperbolic metamaterials • Semiconductor-based (dilute metals) • Boltaseva et al., Purdue and DTU, 2012 • Al:ZnO/ZnO metamaterial • Negative refraction @ 1.8-2.4 μm (for incident angles of 40 degrees) • Enhanced light-matter interactions due to large photonic density-of-states Massive photonics industry at visible and near-infrared wavelengths              ”Meta-Atoms” Nanoparticles as “meta-atoms”: Bridging the gap  between outer and inner photoelectric effects Photoelectric metamaterials with intricate nanoantennas:  New perspectives in sensing, photo-electro-chemistry, etc. www.cnrs.fr Electrochemistry Microscopic: Interface effect Macroscopic: Bulk-material effect J. L. Alonso-Gómez Chirality sensing B. Willis Optical rectennas             Plasmonic Metamaterial Effect uniform ilumination photocurrent uniform ilumination photocurrent non-centrosymmetric crystals non-centrosymmetric nanoparticles • Conventional plasmonics is an electromagnetic problem;  free electron motion is restricted by the nanoparticle • Conventional metamaterials are also considered as  an electromagnetic problem • Photoelectric effect is a quantum problem • If we relax the restriction of electrons to stay inside a nanoparticle and include photoelectric effects: New photoconductive metamaterial structures, where metamaterials are now introduced merging classic and quantum effects bulk medium effect plasmonic metamaterial effect             Directional Photocurrent 13 Resulting values of effective photogalvanic tensor  exceeds bulk-media values by orders of magnitude!             Optical Fibers • Hollow core fibers with large core dimensions, millimeter level • Proposed @ DTU; Yan & Mortensen, Optics Express, 2009 • Not yet realized, but disruptive possibilities in: Materials processing, Telecommunications and Defense applications       • New advanced production technologies @ Uni. Sydney,  Nature Communications, 2013              Optical Fibers • Miniaturized optoelectronics • Highly sensitive sensors                Smith et al., Nano. Lett. 10, 1 (2010)              Colorful Plastic Using Plasmonics Metasurfaces Clausen et al., Nano Lett. 14, 4499 (2014)             Metasurfaces In Reflectarray Antennas   Unlike natural materials, this surface maintains the sense of circular polarization upon reflection!  Element pattern may be modulated to synthesise a specified radiation pattern for a satellite communication antenna with European coverage. [1] M. Zhou, S.B. Sørensen, O.S. Kim, E. Jørgensen, P. Meincke, and O. Breinbjerg, IEEE Transactions on Antennas and Propagation, vol. 61, no. 4.  pp. 1995-2004, 2013. [2] T.G. Smith, U. Gothelf, O.S. Kim, and O. Breinbjerg, IEEE Transactions on Antennas and Propagation, vol. 62, no. 2.  pp. 661-668, 2014. In close cooperation with Cobham Satcom and Ticra. Metasurface based on sub-wavelength dual split-ring loop resonators.             Measurement results: D = 9.2dB G = 7dB O.S. Kim, S. Pivnenko and O. Breinbjerg, IEEE Transactions on  Antennas and Propagation, vol. 60, no. 10, pp. 4670-4676, 2012 184 mm Sub-wavelength Resonant Scatterers And Antennas Superdirective magnetic dipole array  – designed for DTU-ESA Spherical Near-Field Antenna Test Facility             Spherical split-ring antenna  on ground plane [1] O.S. Kim, IEEE Transactions on Antennas and Propagation, vol. 58, no. 7, pp. 2210-2217, 2010. Electrical size ka=0.18 Other  DTU sub-wavelength antennas Multiarm  spherical helix antenna3 Spherical SRR antenna3 Spherical split-ring antenna3  0.184  [2] O. S. Kim, IEEE Trans. Antennas Propagat., July 2010 Spherical meander antenna5 Sub-wavelength Resonant Scatterers And Antennas             Spherical helix antenna Spherical zigzag antenna ka=0.4 3D printing technology is employed to realize complicated wire antenna structures Sub-Wavelength Resonant Scatterers And Antennas O.S. Kim, IEEE Transactions on Antennas and Propagation, IEEE Explorer, 2014             Looking Towards The Future – Applications  • Lenses for high-gain antennas • Shielding of sensitive medical devices  from disruption by MRI scanners • Cloaks to route cellphone signals  around obstacles • Light concentrators for solar cells    Inspiration for disruptive applications  outside electromagnetics: • Shielding structures from earthquakes • Improving ultrasonic sensors • Shielding from noise               Sonic Applications:  Cloaking              2014, Steven Cummer et al. Acoustic invisibility cloak Duke Unversity              Christensen et al., Scientific Reports 4, 4674 (2014) 2014, DTU & Universitat Politècnica de València Exp. Theory absorption Sonic Applications:  Broadband Noise Absorption Danmarks Tekniske Universitet            Your task is not to foresee the future, but to enable it.  Antoine de Saint-Exupéry        

Microwave and Photonic Metamaterials

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Microwave and Photonic Metamaterials

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