A Contrastive Study of Lexical Motivation of Chinese and English

The study of motivation has attracted growing attention from linguists; on the other hand, there still exist such questions as incorrect understanding of the relationship between motivation and arbitrariness and the absence of a unified criterion for classifying motivation. This paper will propose a sound classification and conduct a contrastive study of the lexical motivation of Chinese and English

A novel method for designing crosstalk-free achromatic full Stokes imaging polarimeter

Metasurface-based polarimetry techniques have attracted lots of interests and been extensively studied in the past years, but are still hampered by narrow operating bandwidth and large crosstalk. Recently, Xian-Gang Luo's group proposed a new method of polarization-dependent phase optimization for the design of crosstalk-free, broadband achromatic, and full Stokes imaging polarimeter, which offers a promising platform for a wide range of applications including bio-photonics and integrated optics

Manipulating dc currents with bilayer bulk natural materials

The principle of transformation optics has been applied to various wave phenomena (e.g., optics, electromagnetics, acoustics and thermodynamics). Recently, metamaterial devices manipulating dc currents have received increasing attention which usually adopted the analogue of transformation optics using complicated resistor networks to mimic the inhomogeneous and anisotropic conductivities. We propose a distinct and general principle of manipulating dc currents by directly solving electric conduction equations, which only needs to utilize two layers of bulk natural materials. We experimentally demonstrate dc bilayer cloak and fan-shaped concentrator, derived from the generalized account for cloaking sensor. The proposed schemes have been validated as exact devices and this opens a facile way towards complete spatial control of dc currents. The proposed schemes may have vast potentials in various applications not only in dc, but also in other fields of manipulating magnetic field, thermal heat, elastic mechanics, and matter waves

A Genetic Algorithm for Universal Optimization of Ultrasensitive Surface Plasmon Resonance Sensors with 2D Materials

We present a general optimization technique for surface plasmon resonance, (SPR) yielding a range of ultrasensitive SPR sensors from a materials database with an enhancement of ∼100%. Applying the algorithm, we propose and demonstrate a novel dual-mode SPR structure coupling SPP and a waveguide mode within GeO₂ featuring an anticrossing behavior and an unprecedented sensitivity of 1364 deg/RIU. An SPR sensor operating at wavelengths of 633 nm having a bimetal Al/Ag structure sandwiched between hBN can achieve a sensitivity of 578 deg/RIU. For a wavelength of 785 nm, we optimized a sensor as a Ag layer sandwiched between hBN/MoS₂/hBN heterostructures achieving a sensitivity of 676 deg/RIU. Our work provides a guideline and general technique for the design and optimization of high sensitivity SPR sensors for various sensing applications in the future

Strong coupling of surface plasmon polaritons in monolayer graphene sheet arrays

Here we investigate theoretically and numerically the coupling between surface plasmon polaritons (SPPs) in monolayer graphene sheet arrays that have a period much smaller than the wavelength. We show that when the collective SPP is excited with an out-of-phase illumination, the beam tends to propagate toward the opposite direction of the Bloch momentum, reflecting a negative coupling between the constituent SPPs. In contrast, for in-phase illumination, the incident beam is split into two collective SPPs that are highly collimated and display low propagation loss. Moreover, the coupling between the individual SPPs results in a reduction of the modal wavelength of the SPP in comparison with that of a single graphene sheetThe work is partially supported by the Agency for Science, Technology, and Research (A*STAR) under Grant Nos. 0921450030, 0921540099, 0921540098 and the Ministry of Science and Technology of China under Grant No. 2009DFA52300 for China-Singapore collaborations. F. J. G.-V. acknowledges financial support from the European Research Council under Grant No. 290981 (PLASMONANOQUANTA

Ultrahigh-capacity non-periodic photon sieves operating in visible light

Miniaturization of optical structures makes it possible to control light at the nanoscale, but on the other hand it imposes a challenge of accurately handling numerous unit elements in a miniaturized device with aperiodic and random arrangements. Here, we report both the new analytical model and experimental demonstration of the photon sieves with ultrahigh-capacity of subwavelength holes (over 34 thousands) arranged in two different structural orders of randomness and aperiodicity. The random photon sieve produces a uniform optical hologram with high diffraction efficiency and free from twin images that are usually seen in conventional holography, while the aperiodic photon sieve manifests sub-diffraction-limit focusing in air. A hybrid approach is developed to make the design of random and aperiodic photon sieve viable for high-accuracy control of the amplitude, phase and polarization of visible light. The polarization independence of the photon sieve will also greatly benefit its applications in optical imaging and spectroscopyThis research is supported by the National Research Foundation, Prime Minister’s Office, Singapore under its Competitive Research Program (CRP Award No. NRF-CRP10-2012-04). The work is partially supported by the Institute of Materials Research and Engineering and the Agency for Science, Technology and Research (A*STAR) under Grant 1021740172. We also thank S. Goswami for editing our manuscript. F.J.G.-V. acknowledges the financial support from the Spanish Government under grant MAT2011-28581-C02-0