| 1. |
- 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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| 2. |
- 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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| 3. |
- 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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| 4. |
- Berrier, Audrey, et al.
(författare)
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Impact of dry-etching induced damage in InP-based photonic crystals
- 2008
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Ingår i: PHOTONIC CRYSTAL MATERIALS AND DEVICES VIII. - : SPIE. ; , s. U9890-U9890
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Konferensbidrag (refereegranskat)abstract
- In this work variations of the carrier lifetime in a GaInAsP/InP quantum well in two-dimensional PhC structures etched by Ar/Cl-2 chemically assisted ion beam etching as a function of the processing parameters is investigated. It is shown that the deposition conditions of the SiO2 mask material and its coverage as well as other process steps such as annealing affect the carrier lifetimes. However the impact of patterning the semiconductor on the carrier lifetime is dominant, showing over an order of magnitude reduction. For given PhC lattice parameters, the sidewall damage is shown to be directly related to the measured carrier lifetimes. A simple qualitative model based on sputtering theory and assuming a conical hole-shape development during etching is used to explain the experimental results.
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| 5. |
- Cai, Fuhong, et al.
(författare)
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Multifunctional optical imaging using dye-coated gold nanorods in a turbid medium
- 2011
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Ingår i: Journal of Biomedical Optics. - : SPIE-Intl Soc Optical Eng. - 1083-3668 .- 1560-2281. ; 16:1, s. 016002-
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Tidskriftsartikel (refereegranskat)abstract
- We report multifunctional optical imaging using dye-coated gold nanorods. Three types of useful information, namely, Raman, fluorescence signals, and absorption contrast, can be obtained from a phantom experiment. These three kinds of information are detected in a nanoparticle-doped-phantom using diffuse optical imaging. Our novel nanoparticle could be used as a multimodality marker for future bioimaging applications.
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| 6. |
- Cai, F., et al.
(författare)
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Vectorial electric field Monte Caro simulations for focused laser beams (800 nm-2220 nm) in a biological sample
- 2013
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Ingår i: Progress In Electromagnetics Research. - 1070-4698 .- 1559-8985. ; 142, s. 667-681
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Tidskriftsartikel (refereegranskat)abstract
- Here we develop a method that combines vectorial electric field Monte Carlo simulation with Huygens-Fresnel principle theory to determine the intensity distribution of a focused laser beam in a biological sample. The proper wavelengths for deep tissue imaging can be determined by utilizing our method. Furthermore, effects of anisotropic factor, scattering and absorption coeffcients on the focal spots are analyzed. Finally, the focal beams formed by objective lenses with different values of numerical aperture are also simulated to study the focal intensity in the biological sample.
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| 7. |
- Cai, Tao, et al.
(författare)
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An efficiently tunable microring resonator using a liquid crystal-cladded polymer waveguide
- 2010
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 97:12, s. 121109-
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Tidskriftsartikel (refereegranskat)abstract
- An electrically tunable polymer microring resonator of large tunability and low applied voltage is demonstrated using active liquid crystal (LC) cladding. A large tuning range of 0.73 nm is achieved due to more homogenous LC molecular alignment and enhanced interaction of the light with the LC cladding in the simplified polymer waveguide structure. The operating voltage decreases to 10 V with a threshold of only 3 V by the utilization of interdigital electrodes.
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| 8. |
- Cai, Yangjian, et al.
(författare)
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Average intensity and spreading of an elliptical Gaussian beam propagating in a turbulent atmosphere
- 2006
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Ingår i: Optics Letters. - 0146-9592 .- 1539-4794. ; 31:5, s. 568-570
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Tidskriftsartikel (refereegranskat)abstract
- An analytical formula for the average intensity of an elliptical Gaussian beam (EGB) propagating in a turbulent atmosphere is derived. The spreading properties of an EGB in a turbulent atmosphere are studied. It is found that an EGB will eventually become a circular Gaussian beam in a turbulent atmosphere. This interesting phenomenon is quite different from the propagation of an EGB in free space. The evolution properties are closely related to the parameters of the beam and the turbulent atmosphere
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| 9. |
- Cai, Yangjian, et al.
(författare)
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Propagation of a partially coherent twisted anisotropic Gaussian Schell-model beam in a turbulent atmosphere
- 2006
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 89:4
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Tidskriftsartikel (refereegranskat)abstract
- Analytical formulas are derived for the propagation of a partially coherent twisted anisotropic Gaussian Schell-model (TAGSM) beam in a turbulent atmosphere. Propagation properties of a TAGSM beam in a turbulent atmosphere are investigated in detail. It is found that a TAGSM beam will become a circular beam in a turbulent atmosphere, and low coherence and larger twist have an effect of anticircularization of the beam spot. The beam spot spreads more rapidly for lower coherence, larger twist, or stronger turbulence.
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| 10. |
- Cai, Yangjian, et al.
(författare)
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Propagation of hollow Gaussian beams through apertured paraxial optical systems
- 2006
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Ingår i: Journal of the Optical Society of America a-Optics Image Science and Vision. - 1084-7529. ; 23:6, s. 1410-1418
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Tidskriftsartikel (refereegranskat)abstract
- On the basis of the generalized Collins formula and the expansion of the hard-aperture function into a finite sum of complex Gaussian functions, an approximate analytical formula for a hollow Gaussian beam propagating through an apertured paraxial stigmatic (ST) ABCD optical system is derived. Some numerical examples are given. Furthermore, by using a tensor method, we derive approximate analytical formulas for a hollow elliptical Gaussian beam propagating through an apertured paraxial general astigmatic ABCD optical system and an apertured paraxial misaligned ST ABCD optical system. Our results provide a convenient way for studying the propagation and transformation of a hollow Gaussian beam and a hollow elliptical Gaussian beam through an apertured general optical system.
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