The precise manipulation of a propagating wave using phase control is a fundamental building block of optical systems. The wavefront of a light beam propagating across an interface can be modified arbitrarily by introducing abrupt phase changes. We experimentally demonstrated unparalleled wavefront control in a broadband optical wavelength range from 1.0 to 1.9 micrometers. This is accomplished by using an extremely thin plasmonic layer (~λ/50) consisting of an optical nanoantenna array that provides subwavelength phase manipulation on light propagating across the interface. Anomalous light-bending phenomena, including negative angles of refraction and reflection, are observed in the operational wavelength range.
"conductors) and dielectric materials, have opened up a new window of opportunities for applications in nanophotonic integrated circuits [7–13], surface-enhanced optical spectroscopy [14–16], energy harvesting [17–19], and super-resolution optical imaging [20, 21]. Advancements in transformation optics and nanofabrication techniques (both " top-down " lithography and " bottom-up " chemical synthesis/self-assembly) have also boosted many other applications associated with the intriguing properties of plasmonic metamaterials       . While some of the applications can be fully accomplished with passive plasmonic nanostructures that exhibit constant optical response, it requires reconfigurable or tunable SPs, which is known as active plasmonics , to develop other applications such as plasmonic switches    , plasmonic modulators  , and tunable color filters  . "
[Show abstract][Hide abstract] ABSTRACT: Molecular plasmonics explores and exploits the molecule–plasmon interactions on metal nanostructures to harness light at the nanoscale for nanophotonic spec-troscopy and devices. With the functional molecules and polymers that change their structural, electrical, and/or optical properties in response to external stimuli such as electric fields and light, one can dynamically tune the plas-monic properties for enhanced or new applications, leading to a new research area known as active molecular plasmonics (AMP). Recent progress in molecular design, tailored synthesis, and self-assembly has enabled a variety of scenarios of plasmonic tuning for a broad range of AMP applications. Dimension (i.e., zero-, two-, and three-dimensional) of the molecules on metal nanostructures has proved to be an effective indicator for defining the specific scenarios. In this review article, we focus on structuring the field of AMP based on the dimension of molecules and discussing the state of the art of AMP. Our perspective on the upcoming challenges and opportunities in the emerging field of AMP is also included.
"They can exhibit resonant dispersion mimicking electromagnetically-induced transparency and slow light phenomenon   , be invisible , efficiently convert polarization    or perfectly absorb radiation  . Metasurfaces with gradient structuring anomalously reflect and refract light    and can act as lenses, wave-plates and diffraction gratings    . Planar metamaterials are also able to enhance the light-matter interaction facilitating sensing , energy harvesting  and coherent radiation  . "
[Show abstract][Hide abstract] ABSTRACT: Metasurfaces offer unprecedented flexibility in the design and control of
light propagation, replacing bulk optical components and exhibiting exotic
optical effects. One of the basic properties of the metasurfaces, which renders
them as frequency selective surfaces, is the ability to transmit or reflect
radiation within a narrow spectral band that can be engineered on demand. Here
we introduce and demonstrate experimentally in the THz domain the concept of
wavevector selective surfaces -- metasurfaces transparent only within a narrow
range of light propagation directions operating effectively as tunnel vision
filters. Practical implementations of the new concept include applications in
wavefront manipulation, observational instruments, vision and free-space
communication in light-scattering environments, as well as passive camouflage.
"Electromagnetic surfaces able to dynamically control the reflection angle of an incident beam have been studied for decades in the microwave community  , with applications in satellite communications, terrestrial and deep-space communication links. Non-conventional reflecting surfaces for optical frequencies have also been proposed recently, using metal elements having certain fixed configurations and operating in the plasmonic regime  . However, the high carrier concentration in metals prohibits dynamic control of the reflected beams via these surface elements. "
[Show abstract][Hide abstract] ABSTRACT: Graphene plasmonic nanostructures enable subwavelength confinement of
electromagnetic energy from the mid-infrared down to the terahertz frequencies.
By exploiting the spectrally varying light scattering phase at vicinity of the
resonant frequency of the plasmonic nanostructure, it is possible to control
the angle of reflection of an incoming light beam. We demonstrate, through
full-wave electromagnetic simulations based on Maxwell equations, the
electrical control of the angle of reflection of a mid-infrared light beam by
using an aperiodic array of graphene nanoribbons, whose widths are engineered
to produce a spatially varying reflection phase profile that allows for the
construction of a far-field collimated beam towards a predefined direction.
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