The technologies of heating, photovoltaics, water photocatalysis and artificial photosynthesis depend on the absorption of light and novel approaches such as coherent absorption from a standing wave promise total dissipation of energy. Extending the control of absorption down to very low light levels and eventually to the single-photon regime is of great interest and yet remains largely unexplored. Here we demonstrate the coherent absorption of single photons in a deeply subwavelength 50% absorber. We show that while the absorption of photons from a travelling wave is probabilistic, standing wave absorption can be observed deterministically, with nearly unitary probability of coupling a photon into a mode of the material, for example, a localized plasmon when this is a metamaterial excited at the plasmon resonance. These results bring a better understanding of the coherent absorption process, which is of central importance for light harvesting, detection, sensing and photonic data processing applications.

The ability to control the wavefront of light is fundamental to focusing and redistribution of light, enabling many applications from imaging to spectroscopy. Wave interaction on highly nonlinear photorefractive materials is essentially the only established technology allowing the dynamic control of the wavefront of a light beam with another beam of light, but it is slow and requires large optical power. Here we report a proof-of-principle demonstration of a new technology for two-dimensional (2D) control of light with light based on the coherent interaction of optical beams on highly absorbing plasmonic metasurfaces. We illustrate this by performing 2D all-optical logical operations (AND, XOR and OR) and image processing. Our approach offers diffraction-limited resolution, potentially at arbitrarily-low intensity levels and with 100 THz bandwidth, thus promising new applications in space-division multiplexing, adaptive optics, image correction, processing and recognition, 2D binary optical data processing and reconfigurable optical devices.

Electro- and magneto-optical phenomena play key roles in photonic technology enabling light modulators, optical data storage, sensors and numerous spectroscopic techniques. Optical effects, linear and quadratic in external electric and magnetic field are widely known and comprehensively studied. However, optical phenomena that depend on the simultaneous application of external electric and magnetic fields in conventional media are barely detectable and technologically insignificant. Here we report that a large reciprocal magneto-electro-optical effect can be observed in metamaterials. In an artificial chevron nanowire structure fabricated on an elastic nano-membrane, the Lorentz force drives reversible transmission changes on application of a fraction of a volt when the structure is placed in a fraction-of-tesla magnetic field. We show that magneto-electro-optical modulation can be driven to hundreds of thousands of cycles per second promising applications in magneto-electro-optical modulators and field sensors at nano-tesla levels.

The exponential growth of telecommunications bandwidth will require next generation optical networks, where multiple spatial information channels will be transmitted in parallel. To realise the full potential of parallel optical data channels, fast and scalable multichannel solutions for processing of optical data are of paramount importance. Established solutions based on the nonlinear wave interaction in photorefractive materials are slow. Here we experimentally demonstrate all-optical logical operations between pairs of simulated spatially multiplexed information channels using the coherent interaction of light with light on a plasmonic metamaterial. The approach is suitable for fiber implementation and—in principle—operates with diffraction-limited spatial resolution, 100 THz bandwidth, and arbitrarily low intensities, thus promising ultrafast, low-power solutions for all-optical parallel data processing.

We demonstrate that spatial arrangement and optical properties of metamaterial nanostructures can be controlled dynamically using currents and magnetic fields. Mechanical deformation of metamaterial arrays is driven by both resistive heating of bimorph nanostructures and the Lorentz force that acts on charges moving in a magnetic field. With electrically controlled transmission changes of up to 50% at sub-mW power levels, our approaches offer high contrast solutions for dynamic control of metamaterial functionalities in optoelectronic devices.Dynamic control over metamaterial functionalities has become a major research challenge, as the numerous novel and dramatically enhanced functionalities that metamaterials can provide are usually narrow-band and fixed. The use of superconductors [1,2], phase change media [3][4][5], liquid crystals [6][7][8][9], nonlinear materials [10][11][12][13], graphene [14,15], and coherent optical interactions [16,17] has been investigated to achieve metamaterial properties tunable via temperature, external fields, light intensity or phase, or carrier injection [18,19] [27,28]. However, the latter require large ambient temperature changes or engage irreversible structural transitions to achieve significant optical contrast. Therefore, a practical solution for reversible large-range tuning of photonic metamaterial properties is still needed. Here we demonstrate that reconfigurable photonic metamaterials controlled by electrical currents and magnetic fields provide such a practical solution for reversible large-range tuning and modulation of optical metamaterial functionalities. Our approach takes advantage of the changing balance of forces at the nanoscale, where bilayers of nanoscale thickness bend strongly in response to temperature changes and weak elastic forces allow the magnetic Lorentz force to cause substantial deformation of the picogram-scale moving parts.Optical properties of metallic nanostructures, such as the metamaterial investigated here, are determined by the localized plasmonic response of coupled oscillations of conduction electrons and the electromagnetic nearfield induced by the incident light. In this work, dynamic control over metamaterial optical properties is achieved by exploiting the strong electromagnetic inter- * Electronic address: jpv1f11@orc.soton.ac. actions between the metamaterial building blocks, the metamolecules. By changing the physical arrangement of the nanoscale metamolecules we change their coupling and therefore the optical properties of the metamaterial array. Synchronous rearrangement of about 1000 plasmonic resonators at the nanoscale is achieved exploiting two simple physical principles, (i) bilayers consisting of materials with different thermal expansion coefficients will bend in response to temperature changes and (ii) electric charges moving in a magnetic field will be subject to the magnetic Lorentz force, see Fig 1. Selective resistive heating of alternating bridges and thus their deformation by differential thermal expansion, as w...