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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]

Hot electron can break through the native limitation of silicon energy gap and expand its photo-response range. Plasmon modes improve detectors responsivity by the high hot electrons production. In this letter, we designed a C-shaped groove array carved on gold/silicon substrate, and numerically studied its optical properties and hot electron responsivity. An especial electromagnetic resonance (the dipole toroidal mode) can be excited in this nanostructure, which brings a nearly perfect absorption (∼98%) at 1395 nm and a higher responsivity. Our simple design demonstrated an effective hot electron photodetector without extra collect electrodes. [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]