Unfolding the band structure of non-crystalline photonic band gap materials

Tsitrin, Samuel; Williamson, Eric Paul; Amoah, Timothy; Nahal, Geev; Chan, Ho Leung; Florescu, Marian; Man, Weining

doi:10.1038/srep13301

Cited by 15 publications

(12 citation statements)

References 23 publications

(41 reference statements)

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“…Moreover, C F abruptly drops at about 0.48c th /a, while remaining almost constant in the region 0.42-0.49c th /a, connected to the fact that there is a decrease in the density of states, as is indicated by the decreased density in the number of bands we find over this region. Such a behavior mirrors a similar behavior in photonics 45 . Fig.…”

Section: Frequency Bands Of 2d Structuressupporting

confidence: 78%

Hyperuniform disordered phononic structures

2017

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We demonstrate the existence of large phononic band gaps in designed hyperuniform (isotropic) disordered two-dimensional (2D) phononic structures of Pb cylinders in epoxy matrix. The phononic band gaps in hyperuniform disordered phononic structures are comparable to band gaps of similar periodic structures, for both out-of-plane and in-plane polarizations. A large number of localized modes is identi ed near the band edges, as well as, di usive transmission throughout the rest of the frequency spectrum. Very high-Q cavity modes for both out-of-plane and in-plane polarizations are formed by selectively removing a single cylinder out of the structure. E cient waveguiding with almost 100% transmission trough waveguide structures with arbitrary bends is also presented. We expand our results to thin three-dimensional layers of such structures and demonstrate e ective band gaps related to the respective 2D band gaps. Moreover, the drop in the Q factor for the three-dimensional structures is not more than three orders of magnitude compared to the 2D ones

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Section: Frequency Bands Of 2d Structuressupporting

confidence: 78%

Hyperuniform disordered phononic structures

2017

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“…The experiments are in good agreement with FDTD calculations ( Fig. 5, right panel) obtained with the spectral function method [32]. Specifically, decomposition of a slab's eigenmodes into a plane wave basis can directly predict the farfield angular profile of its directional emission.…”

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confidence: 80%

Reciprocal space engineering with hyperuniform gold disordered surfaces

et al. 2017

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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...

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“…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.…”

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confidence: 99%

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

Tavakoli¹,

Spalding²,

Koppejan³

et al. 2020

Preprint

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Thin, flexible and invisible solar cells will be an ubiquitous technology in the near future. Ultrathin crystalline silicon (c-Si) cells capitalise on the success of bulk silicon cells while being light-weight and mechanically flexible, but suffer from poor absorption and efficiency. Here we present a new family of surface texturing, based on correlated disordered hyperuniform patterns, capable of efficiently coupling the incident spectrum into the silicon slab optical modes. We experimentally demonstrate 66.5% solar light absorption in free-standing 1 µm c-Si layers by hyperuniform nanostructuring. The absorption equivalent photocurrent derived from our measurements is 26.3 mA/cm2, which is far above the highest found in literature for Si of similar thickness. Considering state-of-the-art Si PV technologies, the enhanced light trapping translates to a record efficiency above 15%. The light absorption can potentially be increased up to 33.8 mA/cm2 by incorporating a back-reflector and improved anti-reflection, for which we estimate a photovoltaic efficiency above 21% for 1 µm thick Si cells.

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Unfolding the band structure of non-crystalline photonic band gap materials

Cited by 15 publications

References 23 publications

Hyperuniform disordered phononic structures

Hyperuniform disordered phononic structures

Reciprocal space engineering with hyperuniform gold disordered surfaces

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

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