Nonlocal flat optics

Multiresonant Nonlocal Metasurfaces

“…In planar optics, high- Q resonances can be realized through long-range interactions, such as in photonic crystal slabs, − and more recently within the platform of nonlocal metasurfaces. − In contrast to local metasurfaces, the optical modes of nonlocal metasurfaces are induced by the coherent interaction among many identical neighboring units, resulting in guided mode resonances that are highly sensitive to the wavelength and angle of incidence. Recent works have investigated such engineered nonlocality for image differentiation , and to tailor thermal emission .…”

Transmission Efficiency Limit for Nonlocal Metalenses

“…Nonlocal metasurfaces open up a wide range of applications and tailored angle‐dependent responses that are impossible for traditional local metasurfaces. [ 26 ] The efficiency bound in this work provides valuable guidance for this rapidly evolving field. For example, this work suggests that inverse‐designed multi‐layer wide‐FOV metalenses such as in Reference [34] may benefit from expanding the size of each successive layer.…”

“…[9] Nonlocal metalenses with tailored interactions between adjacent building blocks (i.e., the spatial impulse response is extended beyond a delta function) can overcome the limited angular diversity of local metalenses to enable diffraction-limited focusing over a large FOV. [9,25,26] Their strong nonlocality can be realized by the interaction among adjacent meta-atoms [27] or the excitation of guided resonances that travel across the device over large distances. [28,29] Nonlocal metalenses based on doublets [30,31] or aperture stops [32,33] can support focusing efficiencies higher than 50% over a wide FOV, but with NA lower than 0.5.…”

Giant photoinduced reflectivity modulation of nonlocal resonances in silicon metasurfaces

“…Metasurfaces are twodimensional arrangements of nanostructures (or subwavelength elements), called meta-atoms, which allow one to tailor the electromagnetic field at the nanoscale, thus surpassing the capabilities of bulk materials. 1,2 The possibility of introducing abrupt changes in phase and amplitude is of paramount importance to focusing, 3,4 polarization control, 5 nonlinear frequency conversion, 6 and wavefront manipulation. 7 Providing methods to dynamically control a nanoscale device is mandatory to produce flexible and effective tools to manipulate light.…”

“…In the last few decades, the advent of nanofabrication technologies has boosted the interest in optical devices working in the visible and near-infrared (NIR) region. Metasurfaces are two-dimensional arrangements of nanostructures (or subwavelength elements), called meta-atoms, which allow one to tailor the electromagnetic field at the nanoscale, thus surpassing the capabilities of bulk materials 1 , 2 . The possibility of introducing abrupt changes in phase and amplitude is of paramount importance to focusing, 3 , 4 polarization control, 5 nonlinear frequency conversion, 6 and wavefront manipulation 7 …”