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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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Novotny L, van Hulst N. Antennas for light. Nat Photon. 2011;5(2):83–90.
Abstract: Optical antennas are devices that convert freely propagating optical radiation into localized energy, and vice versa. They enable the control and manipulation of optical fields at the nanometre scale, and hold promise for enhancing the performance and efficiency of photodetection, light emission and sensing. Although many of the properties and parameters of optical antennas are similar to their radiowave and microwave counterparts, they have important differences resulting from their small size and the resonant properties of metal nanostructures. This Review summarizes the physical properties of optical antennas, provides a summary of some of the most important recent developments in the field, discusses the potential applications and identifies the future challenges and opportunities.
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Lydersen L, Wiechers C, Wittmann C, Elser D, Skaar J, Makarov V. Hacking commercial quantum cryptography systems by tailored bright illumination. Nat Photon. 2010;4(10):686–9.
Abstract: The peculiar properties of quantum mechanics allow two remote parties to communicate a private, secret key, which is protected from eavesdropping by the laws of physics. So-called quantum key distribution (QKD) implementations always rely on detectors to measure the relevant quantum property of single photons. Here we demonstrate experimentally that the detectors in two commercially available QKD systems can be fully remote-controlled using specially tailored bright illumination. This makes it possible to tracelessly acquire the full secret key; we propose an eavesdropping apparatus built of off-the-shelf components. The loophole is likely to be present in most QKD systems using avalanche photodiodes to detect single photons. We believe that our findings are crucial for strengthening the security of practical QKD, by identifying and patching technological deficiencies.
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Kosako T, Kadoya Y, Hofmann HF. Directional control of light by a nano-optical Yagi–Uda antenna. Nat Photon. 2010;4:312–5.
Abstract: The plasmon resonance of metal nanoparticles can direct light from optical emitters in much the same way that radiofrequency antennas direct the emission from electrical circuits. Recently, rapid progress has been made in the realization of single-element antennas for optical waves. Because most of these devices are designed to optimize the local near-field coupling between the antenna and an emitter, the possibility of modifying the spatial radiation pattern has not yet received as much attention. In the radiofrequency regime, a typical antenna design for high directivity is the Yagi–Uda antenna, which essentially consists of a one-dimensional array of antenna elements driven by a single feed element. By fabricating a corresponding array of nanoparticles, similar radiation patterns can be obtained in the optical regime. Here, we present the experimental demonstration of directional control of radiation from a nano-optical Yagi–Uda antenna composed of appropriately tuned gold nanorods.
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Kono J. Coherent terahertz control. Nat Photon. 2011;5:5–6.
Abstract: Spin and charge terahertz excitations in solids are promising for implementing future technologies such as spintronics and quantum computation, but coherently controlling them has been a significant challenge. Researchers have now manipulated coherent spin waves in an antiferromagnet using the intense magnetic field of ultrashort terahertz pulses.
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