Coherent control of Snell's law at metasurfaces

It was recently demonstrated that the well-known Snell's law must be corrected for phase gradient metasurfaces to account for their spatially varying phase, leading to normal and anomalous transmission and reflection of light on such metasurfaces. Here we show that the efficiency of normal and anomalous transmission and reflection of light can be controlled by the intensity or phase of a second coherent wave. The phenomenon is illustrated using gradient metasurfaces based on V-shaped and rectangular apertures in a metal film. This coherent control effect can be exploited for wave front shaping and signal routing

Metamaterials: optical activity without chirality

We report that the classical phenomenon of optical activity, which is traditionally associated with chirality (helicity) of organic molecules, proteins, and inorganic structures, can be observed in artificial planar media which exhibit neither 3D nor 2D chirality. We observe the effect in the microwave and optical parts of the spectrum at oblique incidence to regular arrays of nonchiral subwavelength metamolecules in the form of strong circular dichroism and birefringence indistinguishable from those of chiral three-dimensional media

Coherent control of light-matter interactions in polarization standing waves

We experimentally demonstrate that standing waves formed by two coherent counter-propagating light waves can take a variety of forms, offering new approaches to the interrogation and control of polarization-sensitive light-matter interactions in ultrathin (subwavelength thickness) media. In contrast to familiar energy standing waves, polarization standing waves have constant electric and magnetic energy densities and a periodically varying polarization state along the wave axis. counterintuitively, anisotropic ultrathin (meta)materials can be made sensitive or insensitive to such polarization variations by adjusting their azimuthal angle

Fibre-optic metadevice for all-optical signal modulation based on coherent absorption

Recently, coherent control of the optical response of thin films of matter in standing waves has attracted considerable attention, ranging from applications in excitation-selective spectroscopy and nonlinear optics to demonstrations of all-optical image processing. Here we show that integration of metamaterial and optical fibre technologies allows the use of coherently controlled absorption in a fully fiberized and packaged switching metadevice. With this metadevice, that controls light with light in a nanoscale plasmonic metamaterial film on an optical fibre tip, we provide proof-of-principle demonstrations of logical functions XOR, NOT and AND that are performed within a coherent fully fiberized network at wavelengths between 1530 nm and 1565 nm. The metadevice performance has been tested with optical signals equivalent to a bitrate of up to 40 Gbit/s and sub-milliwatt power levels. Since coherent absorption can operate at the single photon level and also with 100 THz bandwidth, we argue that the demonstrated all-optical switch concept has potential applications in coherent and quantum information networks.Comment: 9 pages, 6 figure

All-optical multichannel logic based on coherent perfect absorption in a plasmonic metamaterial

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

Random access actuation of nanowire grid metamaterial

While metamaterials offer engineered static optical properties, future artificial media with dynamic random-access control over shape and position of meta-molecules will provide arbitrary control of light propagation. The simplest example of such a reconfigurable metamaterial is a nanowire grid metasurface with subwavelength wire spacing. Recently we demonstrated computationally that such a metadevice with individually controlled wire positions could be used as dynamic diffraction grating, beam steering module and tunable focusing element. Here we report on the nanomembrane realization of such a nanowire grid metasurface constructed from individually addressable plasmonic chevron nanowires with a 230 nm × 100 nm cross-section, which consist of gold and silicon nitride. The active structure of the metadevice consists of 15 nanowires each 18 μm long and is fabricated by a combination of electron beam lithography and ion beam milling. It is packaged as a microchip device where the nanowires can be individually actuated by control currents via differential thermal expansion