Metal-based negative refractive-index materials have been extensively studied in the microwave region. However, negative-index metamaterials have not been realized at near-IR or visible frequencies due to difficulties...
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Metal-based negative refractive-index materials have been extensively studied in the microwave region. However, negative-index metamaterials have not been realized at near-IR or visible frequencies due to difficulties of fabrication and to the generally poor optical properties of metals at these wavelengths. In this Letter, we report the first fabrication and experimental verification of a transversely structured metal-dielectric-metal multilayer exhibiting a negative refractive index around 2 μm. Both the amplitude and the phase of the transmission and reflection were measured experimentally, and are in good agreement with a rigorous coupled wave analysis.
The results of a study on bi-periodic photonic crystal structures are presented. We show that not only straight waveguides, but also other optical functionalities can show significantly better performances, when bi-pe...
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ISBN:
(纸本)1557527962
The results of a study on bi-periodic photonic crystal structures are presented. We show that not only straight waveguides, but also other optical functionalities can show significantly better performances, when bi-periodicity is introduced.
in this paper, we consider the problem of dynamically regulating the timing of traffic light controllers in busy cities. We use a Stochastic Fluid Model (SFM) to model the dynamics of the queues formed at an intersect...
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A triple-layer omni-directional reflector (ODR) is reported that uses nanoporous SiO2 with refractive index of only 1.23. The mirror loss of triple-layer ODRs is a factor of 7 lower than the mirror loss of conventiona...
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ISBN:
(纸本)1557527954
A triple-layer omni-directional reflector (ODR) is reported that uses nanoporous SiO2 with refractive index of only 1.23. The mirror loss of triple-layer ODRs is a factor of 7 lower than the mirror loss of conventional metal reflectors.
We present a method to create an RF MEMS oscillator with continuous control of the output phase and frequency. When the weakly nonlinear oscillating system becomes synchronized with an imposed sinusoidal force of clos...
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We present a method to create an RF MEMS oscillator with continuous control of the output phase and frequency. When the weakly nonlinear oscillating system becomes synchronized with an imposed sinusoidal force of close frequency, the resonator frequency can be detuned with a DC bias on a resistive actuator to produce an easily controlled phase differential between the injected signal and the resonator feedback. We demonstrate a 26 MHz MEMS oscillator with frequency tunability of 0.3% and phase tunability of 200/spl deg/. By modulating the Joule heat dissipated in the structure, a 26 MHz carrier frequency was either frequency modulated by a 30 kHz baseband signal with a modulation depth of 15 kHz, or phase modulated by a 20 kHz baseband signal with a modulation depth of 160/spl deg/.
Enhancement of light extraction in GaN light-emitting diodes (LEDs) employing omnidirectional reflectors (ODRs) is presented. The ODR consists of GaN, ITO nanorod low-refractive-index layer, and an Ag layer. An array ...
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Enhancement of light extraction in GaN light-emitting diodes (LEDs) employing omnidirectional reflectors (ODRs) is presented. The ODR consists of GaN, ITO nanorod low-refractive-index layer, and an Ag layer. An array of ITO nanorods is deposited by oblique-angle deposition using e-beam evaporation. The refractive index of the ITO nanorods is 1.34 at 461 nm, significantly lower that that of dense ITO, which is n = 2.06 at 461 nm. It is experimentally shown that the GaN LED with GaN/ITO nanorods/Ag ODR show much better electrical properties and higher light-extraction efficiency than LEDs with Ag contact. This is attributed to enhanced reflectivity of the ODR by using an ITO low-refractive-index layer with high transparency, high conductivity, and low refractive index.
We consider the enstrophy cascade in forced two-dimensional turbulence with a linear drag force. In the presence of linear drag, the energy wave-number spectrum drops with a power law faster than in the case without d...
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We consider the enstrophy cascade in forced two-dimensional turbulence with a linear drag force. In the presence of linear drag, the energy wave-number spectrum drops with a power law faster than in the case without drag, and the vorticity field becomes intermittent, as shown by the anomalous scaling of the vorticity structure functions. Using previous theory, we compare numerical simulation results with predictions for the power law exponent of the energy wave-number spectrum and the scaling exponents of the vorticity structure functions ζ2q. We also study, both by numerical experiment and theoretical analysis, the multifractal structure of the viscous enstrophy dissipation in terms of its Rényi dimension spectrum Dq. We derive a relation between Dq and ζ2q, and discuss its relevance to a version of the refined similarity hypothesis. In addition, we obtain and compare theoretically and numerically derived results for the dependence on separation r of the probability distribution of δr⃗ω, the difference between the vorticity at two points separated by a distance r. Our numerical simulations are done on a 4096×4096 grid.
Plasmon-induced magnetism of periodic nanohole arrays has been studied using transmission spectroscopy and magnetic-force microscopy. This second-order nonlinear optical effect can find numerous applications in magnet...
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ISBN:
(纸本)1557527962
Plasmon-induced magnetism of periodic nanohole arrays has been studied using transmission spectroscopy and magnetic-force microscopy. This second-order nonlinear optical effect can find numerous applications in magneto-optical data storage and optical communication and computing.
A triple-layer omni-directional reflector (ODR), which consists of a semiconductor, a transparent quarter-wavelength dielectric layer, and a metal layer, has high reflectivity at all angles of incidence when used as a...
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ISBN:
(纸本)1557527709
A triple-layer omni-directional reflector (ODR), which consists of a semiconductor, a transparent quarter-wavelength dielectric layer, and a metal layer, has high reflectivity at all angles of incidence when used as an internal ODR. In this paper, triple-layer ODRs are demonstrated that incorporate nanoporous SiO/sub 2/, a new low-refractive-index (low-n) material with refractive index /spl Lt/1.46. Internal reflectivity measurements, including the angular dependence of R, are presented. The angle-integrated TE/TM-averaged reflectivity of the triple-layer reflector using nanoporous SiO/sub 2/ is 99.4 %. This is the highest ever reported averaged reflectivity for an internal ODR. The mirror loss of the triple-layer ODR is a factor of 7 lower than the mirror loss of conventional metal reflectors. The results indicate the great potential of the ODR for light-emitting diodes with high light-extraction efficiency.
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