| 1. |
- Cao, Shun, et al.
(författare)
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Enhancing single photon emission through quasi-bound states in the continuum of monolithic hexagonal boron nitride metasurface
- 2021
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Ingår i: Journal of Physics. - : IOP Publishing. - 2515-7639. ; 4:3
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Tidskriftsartikel (refereegranskat)abstract
- A patterned structure of monolithic hexagonal boron nitride (hBN) on a glass substrate, which can enhance the emission of the embedded single photon emitters (SPEs), is useful for onchip single-photon sources of high-quality. Here, we design and demonstrate a monolithic hBN metasurface with quasi-bound states in the continuum mode at emission wavelength with ultrahigh Q values to enhance fluorescence emission of SPEs in hBN. Because of ultrahigh electric field enhancement inside the proposed hBN metasurface, an ultrahigh Purcell factor (3.3 x 10(4)) is achieved. In addition, the Purcell factor can also be strongly enhanced in most part of the hBN structure, which makes the hBN metasurface suitable for e.g. monolithic quantum photonics.
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| 2. |
- Cao, Shun, et al.
(författare)
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High-temperature ultra-broad UV–MIR high-efficiency absorber based on double ring-shaped titanium nitride resonators
- 2021
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Ingår i: Optics Communications. - : Elsevier B.V.. - 0030-4018 .- 1873-0310. ; 485
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Tidskriftsartikel (refereegranskat)abstract
- An ultrabroad absorber based on double-ring-shaped titanium nitride (TiN) nanoresonators, which can work in high temperatures, is proposed and numerically studied. The absorber with some optimal parameters exhibits an averaged absorption of 94.6% in the range of 200–4000 nm (from ultraviolet to mid-infrared) and a band from 200–3518 nm having an absorption > 90%. We have demonstrated in detail the physical mechanisms of the ultra-broad absorption, including the dielectric lossy property of TiN material itself in shorter wavelengths and plasmonic resonances caused by the metallic property of TiN nano-resonators in longer wavelengths. In addition, the absorber shows polarization independent and wide-angle acceptance. Another absorber with double TiN nano-rings of different heights has flatter and higher absorption efficiency (more than 95% absorption) at 200–2860 nm waveband. These properties make the proposed absorbers based on TiN has great potentials in many applications, such as light trapping, photovoltaics, thermal emitters.
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| 3. |
- Cui, Y., et al.
(författare)
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Transmission enhancement of a metallic slit by a nearby metallic nano-particle
- 2008
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Ingår i: Proceedings of SPIE - The International Society for Optical Engineering. - : SPIE.
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Konferensbidrag (refereegranskat)abstract
- We propose to use a nearby metallic nano-particle to greatly enhance the transmission efficiency of a nano-slit aperture in a metallic film. The metallic nano-particle helps to form a T shape cavity which could effectively transform the propagating incident light into localized near-filed light. Harvest efficiency is enhanced by 20 times for a non-resonant 25 nm-width nano-slit.
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| 4. |
- Dai, Daoxin, et al.
(författare)
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Compact silicon-on-insulator-based multimode interference coupler with bilevel taper structures
- 2005
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Ingår i: Applied Optics. - 1559-128X .- 2155-3165. ; 44:24, s. 5036-5041
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Tidskriftsartikel (refereegranskat)abstract
- A novel compact silicon-on-insulator- (SOI-)based multimode interference (MMI) coupler with bilevel taper structures was designed. The MMI section and the S-bend sections of the input-output waveguides are deeply etched. The input-output waveguides connecting to single-mode fibers or other photonic light circuits are etched shallowly to yield single-mode operation. A bilevel taper is introduced in the transition region between the shallowly and deeply etched regions. It is predicted theoretically that this design will not only improve the quality of the self-imaging in the MMI section but will also make the structure compact. Both the excess loss and the nonuniformity of the MMI coupler are reduced. By use of a three-dimensional beam propagation method, the performance of a 1 × 4 MMI coupler based on a SOI is simulated as a numerical example of the novel design. The simulated nonuniformity and the excess loss are approximately 0.0285 and 0.2 dB, respectively.
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| 5. |
- Dai, Daoxin, et al.
(författare)
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Elimination of multimode effects in a silicon-on-insulator etched diffraction grating demultiplexer with bi-level taper structure
- 2005
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Ingår i: IEEE Journal of Selected Topics in Quantum Electronics. - 1077-260X .- 1558-4542. ; 11:2, s. 439-443
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Tidskriftsartikel (refereegranskat)abstract
- Multimode effects in the free propagation region (FPR) of an etched diffraction grating (EDG) demultiplexer based on silicon-on-insulator are analyzed. The insertion loss and the crosstalk increase due to these undesired multimode effects. A bi-level taper structure between the FPR and the input/output waveguides is proposed. It is shown that such a taper structure can reduce the multimode effects to an almost negligible level. At the same time, the 3-dB passband width is enlarged by increasing the rib width. No additional fabrication process is needed for an EDG with such a design.
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| 6. |
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| 7. |
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| 8. |
- Fu, J., et al.
(författare)
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Enabling Ultrathin Metamaterial Absorbers with Narrow Slits
- 2020
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Ingår i: Advanced Optical Materials. - : Wiley-VCH Verlag. - 2162-7568 .- 2195-1071. ; 8:16
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Tidskriftsartikel (refereegranskat)abstract
- Metamaterial absorbers (MAs) consisting of subwavelength units offer flexible design freedom and prominent advantages over traditional absorbers. Here, it is found that narrow slits provide the MAs a significant passageway to control the absorption behavior and obtain an ultrasmall thickness. As narrowing the slits in an MA gradually, two effects appear in turn, of which the former is that the slits help the localized energy leak away from the resonant units to balance the material absorption and radiation leakage rates and sustain perfect absorption, and the latter is that acting as a capacitor, the slits red-shift the absorption peak. A record ultrathin microwave MA with a thickness of only 1/474 of the working wavelength is demonstrated. Colossal electric field is excited inside ultranarrow slits by the assistance of localized resonance in collecting the incident wave. The finding can be extended to other frequencies, and is fascinating for some areas requiring ultrathin absorption structures or strong interaction between waves and matters.
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| 9. |
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| 10. |
- Gong, Chensheng, et al.
(författare)
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Upconversion enhancement by a dual-resonance all-dielectric metasurface
- 2019
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Ingår i: Nanoscale. - : ROYAL SOC CHEMISTRY. - 2040-3364 .- 2040-3372. ; 11:4, s. 1856-1862
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Tidskriftsartikel (refereegranskat)abstract
- Upconversion nanoparticles (UCNPs) have drawn much attention in the past decade due to their superior physicochemical features and great potential in biomedical and biophotonic studies. However, their low luminescence efficiency often limits their applications. Here, we demonstrated a dual-resonance all-dielectric metasurface to enhance the signals emitted by upconversion nanoparticles (NaYF4:Yb/Tm). An averaged upconversion signal enhancement of around 400 times is detected experimentally. The electric and magnetic dipole resonances of the metasurface are designed to enhance the local excitation field and the quantum efficiency of the upconversion nanoparticles, respectively. Furthermore, the collection efficiency is enhanced due to the directional emission of the UCNPs on the metasurface. Our approach provides a powerful tool to extend the sensing application potential of upconversion nanoparticles.
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