Reciprocal space engineering with hyperuniform gold disordered surfaces

Abstract

Hyperuniform geometries feature correlated disordered topologies which follow from a tailored k-space design. Here we study gold plasmonic hyperuniform metasurfaces and we report evidence of the effectiveness of k-space engineering on both light scattering and light emission experiments. The metasurfaces possess interesting directional emission properties which are revealed by momentum spectroscopy as diffraction and fluorescence emission rings at size-specific k-vectors. The opening of these rotational-symmetric patterns scales with the hyperuniform correlation length parameter as predicted via the spectral function method.Coherent control of optical waves by scattering from 2D nanostructured surfaces is revolutionising the way we shape the wavefront of an incoming light beam, opening new avenues for miniaturised optical components for integrated optical circuits [1], flat display technology [2], and energy harvesting [3,4]. Metallic surfaces are in particular attractive due to the strong light-matter interaction associated with surface plasmons, enabling diffraction control through plasmonic crystals [5, 6] and metal nano-particle arrays [7,8], broadband operation and increase of the plasmon mode density [9], enhanced omnidirectional light extraction and coupling [10], broadband absorption [11], fluorescence enhancement [12] and lasing [13,14], and more recently the realisation of ultra thin lenses [15] and metasurface holograms [16].Whereas periodic geometries suffer from limited rotational symmetries, aperiodic and disordered topologies, with their richer symmetries and patterns, can lead to superior optical functionalities [8], as in omnidirectional absorption for solar applications [17,18], scattering-induced light localisation [19] and light extraction from LED/OLED [20]. Moreover, disordered metasurfaces are expected to be more resilient against fabrication imperfection and therefore more apt for technological implementation. Given the vast possible designs of non-periodic topologies, ranging from random to correlated-disordered, their full potential is still to be fully explored.There exists a general class of disordered systems, called hyperuniform disordered (HuD) photonic structures, which are of particular interest because they exhibit wide and isotropic photonic band gaps [21], rotational symmetry and broadband k-space control, and can be systematically generated through a specific design rule via universal tessellation protocol [22,23]. Pioneering experiments on photonic HuD systems have explored IR light diffraction in 3D dielectric structures [24], microwave band-gaps formation [25], polarization filtering [26] and random quantum cascade lasers [27]. Theoretical proposals have been put forward for surface enhanced Raman scattering [28], transparency design [29], high-Q optical cavities and low-loss waveguides [30-32], and microwave photonic circuits [25]. HuD structures fabrication is improving quickly, reaching already the IR range [24] but not yet the visible.Here, we report visible light scatt...

Light-emitting metasurfaces

“…Finally, this approach also extends to designing the radiation pattern of sources based on quasiperiodic and aperiodic systems [65], simply by designing the structure factor. For example, hyperuniform arrangements [66] and Vogel spirals [67] are not periodic but spatially correlated, such that their structure factor presents distinct circular bands in the k-space. These can be used for broadband directional outcoupling of light from emissive metasurfaces, as shown for plasmonic realizations [68][69][70].…”

Fabrication of Nearly‐Hyperuniform Substrates by Tailored Disorder for Photonic Applications

“…Being able to fabricate structures of correlated disorder with tailored statistics bears the potential of a whole new class of materials through novel ways to manipulate k‐space . In terms of optics, to mention one example, one could bring together the advantages of periodic and disordered structures, i.e., enable a strong, grating‐like but spectrally broadband diffraction.…”

Over 65% sunlight absorption in a 1 μm Si slab with hyperuniform texture

“…Hyperuniform disorded (HUD) media are statistically isotropic and possess a constrained randomness such that density fluctuations on large scales behave more like those of ordered solids, rather than those of conventional amorphous materials. [27][28][29][30] HUD patterns naturally arise in many physical systems, from the mass distribution in the early universe, 31 structure of prime numbers, 32 hydrodynamics, 33 structure of amorphous ices, 34 sheared sedimenting suspensions, 35 to wave localisation 36 or colloidal packing. 37 When translated into photonic materials, HUDs exhibit large and robust photonic band gaps as in photonic crystals, but are both complete and isotropic.…”

“…37 When translated into photonic materials, HUDs exhibit large and robust photonic band gaps as in photonic crystals, but are both complete and isotropic. 30 As a result, HUDs display allowed modes that can propagate through the structure in an isotropic fashion as in random media. HUDs are a highly flexible platform to control light transport, emission and absorption in unique ways, beyond the constraints imposed by conventional photonic architectures, [38][39][40][41][42] for the design of freeform waveguides, 43 high-quality factor resonant defects and arbitrarily high-order power splitters, 44,45 hollowcore fibers 46 and photonic bandgap polarizers 47 among others.…”