| 1. |
- Ao, Xianyu, et al.
(författare)
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Black silicon with controllable macropore array for enhanced photoelectrochemical performance
- 2012
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 101:11, s. 111901-
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Tidskriftsartikel (refereegranskat)abstract
- Macroporous silicon with multiscale texture for reflection suppression and light trapping was achieved through a controllable electrochemical etching process. It was coated with TiO2 by atomic layer deposition, and used as the photoanode in photocatalytic water splitting. A conformal pn-junction was also built-in in order to split water without external bias. A 45% enhancement in photocurrent density was observed after black silicon etching. In comparison with nano-structured silicon, the etching process here has neither metal contamination nor requirement of vacuum facilities.
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| 2. |
- Ao, Xianyu, et al.
(författare)
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Broadband Metallic Absorber on a Non-Planar Substrate
- 2015
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Ingår i: Small. - : Wiley. - 1613-6810 .- 1613-6829. ; 11:13, s. 1526-1530
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Tidskriftsartikel (refereegranskat)abstract
- Absorbers for visible and near-infrared light are realized by depositing a thin iron layer on arrays of cones which are replicated from a porous template. The replicated conic structure itself is of several micrometers and ineffective at antireflection, but the subsequent deposition of iron on top generates nanometer-size columnar structures, and thus broadband absorption enhancement is achieved.
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| 3. |
- Ao, Xianyu, et al.
(författare)
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Polarization beam splitter based on a two-dimensional photonic crystal of pillar type
- 2006
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 89:17, s. 171115-
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Tidskriftsartikel (refereegranskat)abstract
- Negatively and positively refractive behaviors are achieved in a two-dimensional photonic crystal of pillar type for TE and TM polarizations, respectively, at the same frequency. The photonic crystal is formed by a triangular lattice of silicon pillars of finite height on a silicon substrate. A polarization beam splitter based on such a photonic-crystal slab is demonstrated. Measurements at near infrared wavelengths indicate that two beams of different polarizations can be split with an extinction ratio of over 10 dB in a wide wavelength range.
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| 4. |
- Ao, Xianyu, et al.
(författare)
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Two-stage design method for realization of photonic bandgap structures with desired symmetries by interference lithography
- 2004
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Ingår i: Optics Express. - 1094-4087. ; 12:6, s. 978-983
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Tidskriftsartikel (refereegranskat)abstract
- Interference lithography for the fabrication of photonic crystals is considered. A two-stage design method for realization of photonic bandgap structures with desired symmetries is developed. An optimal photonic crystal with a large bandgap is searched by adjusting some parameters while keeping some basic symmetry of the unit cell unchanged. A nonlinear programming method is then used to find the optimal electric field vectors of the laser beams and realize the desired interference pattern. The present method is useful for a rational and systematical design of new photonic bandgap structures.
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| 5. |
- Ao, Xianyu, et al.
(författare)
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Unidirectional Enhanced Emission from 2D Monolayer Suspended by Dielectric Pillar Array
- 2018
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Ingår i: ACS Applied Materials and Interfaces. - : AMER CHEMICAL SOC. - 1944-8244 .- 1944-8252. ; 10:41, s. 34817-34821
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Tidskriftsartikel (refereegranskat)abstract
- Monolayers of transition metal dichalcogenides show great promise for optoelectronic devices as atomically thin semiconductors. Although dielectric or metal nanostructures have been extensively studied for tailoring and enhancing emission from monolayers, their applications are limited because of the mode concentrating inside the dielectric or the high optical losses in metals, together with the low quantum yield in monolayers. Here, we demonstrate that a metal-backed dielectric pillar array can suspend monolayers to increase the radiative recombination, and simultaneously, create strongly confined band-edge modes on surface directly accessible to monolayers. We observe unidirectional enhanced emission from WSe2 monolayers on polymer pillar array.
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| 6. |
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| 7. |
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| 8. |
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| 9. |
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| 10. |
- Bao, Fanglin, et al.
(författare)
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First-order correction to the Casimir force within an inhomogeneous medium
- 2015
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Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics. - 1050-2947 .- 1094-1622. ; 91:6
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Tidskriftsartikel (refereegranskat)abstract
- For the Casimir piston filled with an inhomogeneous medium, we regularized and expressed the Casimir energy with cylinder kernel coefficients by using the first-order perturbation theory. When the refractive index of the medium is smoothly inhomogeneous (i.e., derivatives of all orders exist), a logarithmically cutoff-dependent term and a quadratically cutoff-dependent term in the Casimir energy are found. We show that in the piston model these terms vanish in the force and thus the Casimir force is always cutoff independent, but these terms will remain in the force in the half-space model and must be removed by additional regularizations. We give explicit benchmark solutions to the first-order corrections of both Casimir energy and Casimir force for an exponentially decaying profile. The present method can be extended to other inhomogeneous profiles. Our results should be useful for future relevant calculations and experimental studies.
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