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Optical metasurfaces can be used to realize various peculiar optical effects, and their mechanisms of the controlling optical phase can be roughly categorized into three types: resonant phase, geometric phase, and propagation phase, also known as the dynamic phase. Multiple mechanisms can be employed to manipulate the phase and amplitude of one metasurface. Therefore, discovering more profound and diverse methods can provide additional degrees of application freedom. This paper proposes a control principle based on electric multipole expansion. We found that for a unit structure formed by dual-metal bars on a metasurface, the radiation of its dipole is equivalent to the interference results of the dual-metal bars. Moreover, the radiation of the quadrupole enables independent control for amplitude and phase. Therefore, we used quadrupole radiation to manipulate the phase and amplitude of the light and even investigated some simple applications, including the realization of focusing light and anomalous refraction. Such a new mechanism of controlling light, combined with other methods, can provide significant insights into achieving challenging goals, like steganography and multifunctional metasurfaces. [ABSTRACT FROM AUTHOR]

Fatigue-free 14 mol% La-modified PbTiO[sub 3] (PLT) thin films were grown on Pt/Ti/SiO[sub 2]/Si substrates using pulsed-laser deposition and crystallized by furnace annealing at 600°C. The 220-nm-thick PLT film capacitors with a Pt top electrode showed excellent ferroelectric properties. The remanent polarization (2P[sub r]) and the coercive field (2E[sub c]) were about 20 µC/cm² and 70 kV/cm, respectively, and the PLT capacitors did not show any noticeable fatigue up to 3 × 10[sup 9] read/write switching cycles at a frequency of 1 MHz and switching voltage of 5 V. By comparing the microstructures, electric, and dielectric properties with those of pure PbTiO[sub 3] thin films, the suppression of oxygen vacancies and/or charged defects, and the coral-like microstructures developed in PLT films were attributed to its fatigue-free feature. [ABSTRACT FROM AUTHOR]

The leakage characteristics and dielectric properties of Pt/(Ba,Sr)TiO[sub 3]/Pt thin-film capacitors were found to be remarkably sensitive to the postannealing temperature in oxygen and nitrogen atmosphere. High leakage currents and low-frequency dielectric relaxation were found in as-deposited capacitors after they had been postannealed in nitrogen at 550 °C and subsequently annealed in oxygen at 350 °C. Such results are related to the mobile oxygen ions and oxygen vacancies accumulated in the (Ba,Sr)TiO[sub 3] films. The chemical process of the formation of charged oxygen ions during postannealing is proposed. © 2002 American Institute of Physics. [ABSTRACT FROM AUTHOR]

We report giant fluorescence enhancement in SiC nanocrystals (NCs) embedded in a sodium dodecyl sulfonate dielectric medium by proximately contacted Ag nanoparticles. The enhancement in integrated fluorescence intensity reaches an astonishing 176-fold under 360 nm excitation (53.3-fold enhancement in emission maximum intensity). Finite-element simulation indicates that the strong resonant coupling between the excited SiC NCs and localized surface plasmons of the Ag nanoparticles plays a dominant role in determining fluorescence enhancement. In contrast, the absorption enhancement caused by light concentration around the Ag nanoparticles makes only a slight contribution to the overall enhancement. Our result opens the possibility of applications of these highly enhanced fluorescent SiC NCs in diverse areas such as sensing, optoelectronics and life sciences.