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Tassin P, Koschny T, Kafesaki M, Soukoulis CM. A comparison of graphene, superconductors and metals as conductors for metamaterials and plasmonics. Nat Photon. 2012;6(4):259–64.
Abstract: Recent advancements in metamaterials and plasmonics have promised a number of exciting applications, in particular at terahertz and optical frequencies. Unfortunately, the noble metals used in these photonic structures are not particularly good conductors at high frequencies, resulting in significant dissipative loss. Here, we address the question of what is a good conductor for metamaterials and plasmonics. For resonant metamaterials, we develop a figure-of-merit for conductors that allows for a straightforward classification of conducting materials according to the resulting dissipative loss in the metamaterial. Application of our method predicts that graphene and high-Tc superconductors are not viable alternatives for metals in metamaterials. We also provide an overview of a number of transition metals, alkali metals and transparent conducting oxides. For plasmonic systems, we predict that graphene and high-Tc superconductors cannot outperform gold as a platform for surface plasmon polaritons, because graphene has a smaller propagation length-to-wavelength ratio.
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Clerk A. Quantum phononics: To see a SAW. Nat Phys. 2012;8(4):256–7.
Abstract: Mechanical oscillations of microscopic resonators have recently been observed in the quantum regime. This idea could soon be extended from localized vibrations to travelling waves thanks to a sensitive probe of so-called surface acoustic waves.
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Paiella R. Terahertz quantum cascade lasers: Going ultrafast. Nat Photon. 2011;5:253–255.
Abstract: A new asynchronous coherent optical sampling method allows for the direct visualization of actively mode-locked quantum cascade laser pulses at terahertz wavelengths.
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Mineev VP. Superfluid helium: Order in disorder. Nat Phys. 2012;8:253–254.
Abstract: Confining liquid 3He in porous silica aerogel prepared with strong anisotropy stabilizes a state of axial superfluidity.
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Nozaki K, Shinya A, Matsuo S, Suzaki Y, Segawa T, Sato T, et al. Ultralow-power all-optical RAM based on nanocavities. Nat Photon. 2012;6(4):248–52.
Abstract: Optical random-access memory (o-RAM) has been regarded as one of the most difficult challenges in terms of replacing its various functionalities in electronic circuitry with their photonic counterparts. Nevertheless, it constitutes a key device in optical routing and processing. Here, we demonstrate that photonic crystal nanocavities with an ultrasmall buried heterostructure design can solve most of the problems encountered in previous o-RAMs. By taking advantage of the strong confinement of photons and carriers and allowing heat to escape efficiently, we have realized all-optical RAMs with a power consumption of only 30 nW, which is more than 300 times lower than the previous record, and have achieved continuous operation. We have also demonstrated their feasibility in multibit integration. This paves the way for constructing a low-power large-scale o-RAM system that can handle high-bit-rate optical signals.
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