Band-rejection filter with high extinction ratio using prism-waveguide cascaded coupling system.

A band-rejection filter is proposed based on a prism-waveguide cascaded coupling system, which is composed of an equilateral trapezium prism and a deposited multilayer structure. By properly adjusting the thickness of the coupling layer and the light extinction coefficient of the guiding layer, the radiative and intrinsic dampings matching condition could be well satisfied, and then a series of reflectivity dips will appear in the reflectivity wavelength spectrum. Since the module of reflectivity is smaller than one, the extinction ratio of the rejected frequency via the cascaded coupling system is twice as high as that of the single-coupling technology. By narrowing the guiding layer to a micrometer scale, the free spectral range is broad enough to cover the Raman spectrum scattered from the frequently used sample. In addition, the numerically calculated results show that the light in the free spectral range is mostly reflected, with an insertion loss down to 0.45 dB. Compared to previously reported band-rejection filters, it is relatively simple to manufacture our device, which possesses potential applications to help distinguish the Raman signal from the elastic scattering background.

Two-dimensional transition-metal halide CoBr3 with spin-polarized Dirac cone.

Recently, the discovery of two-dimensional transition-metal materials with non-trivial magnetic and electronic properties has spurred huge interest in investigating their applications in nanotechnology. Here, we report that the monolayer of CoBr3 possesses a quantum anomalous Hall insulating phase generated on the basis of first-principles calculations. We find that the CoBr3 monolayer is an intrinsic two-dimensional ferromagnetic material with a Curie temperature Tc = 264 K predicted from Monte Carlo simulations. The phonon spectra analysis indicates that the CoBr3 monolayer is dynamically stable. Taking into account spin-orbit coupling, this makes the electronic structure of the CoBr3 monolayer topologically non-trivial with a global band gap of 8.7 meV. The anomalous Hall conductivity calculation shows a Chern number C = 2, meaning the presence of a two edge state in nanoribbons of finite width. These findings not only add an experimentally feasible member to the quantum anomalous Hall insulator family, but also pave the way for highly promising application potentials in nanoelectronics and spintronics.

Enhancing the ballistic thermal transport of silicene through smooth interface coupling.

We have performed nonequilibrium molecular dynamics calculations on the length (L) dependence of thermal conductivity (Κ) of silicene both supported on and sandwiched between the smooth surfaces, i.e. h-BN, at room temperature. We find that Κ of silicene follows a power law Κ [proportional] L(ß), with ß increasing from about 0.3-0.4 under the effect of interface coupling, showing an enhancement of the ballistic thermal transport of silicene. We also find that ß can be further increased to about 0.6 by increasing the interface coupling strength for the silicene sandwiched between h-BN. The increase of ß for the supported case is found to come from the variation of the flexural acoustic (ZA) phonon mode and the first optical phonon mode induced by the substrate, whereas the unusual increase of ß for the sandwiched case is attributed to the increment of velocities of all three acoustic phonon modes. These findings provide an interesting route for manipulating the ballistic energy flow in nanomaterials.

Scientific Collaboration in Chinese Nursing Research: A Social Network Analysis Study.

Collaboration has become very important in research and in technological progress. Coauthorship networks in different fields have been intensively studied as an important type of collaboration in recent years. Yet there are few published reports about collaboration in the field of nursing. This article aimed to reveal the status and identify the key features of collaboration in the field of nursing in China. Using data from the top 10 nursing journals in China from 2003 to 2013, we constructed a nursing scientific coauthorship network using social network analysis. We found that coauthorship was a common phenomenon in the Chinese nursing field. A coauthorship network with 228 subnetworks formed by 1428 nodes was constructed. The network was relatively loose, and most subnetworks were of small scales. Scholars from Shanghai and from military medical system were at the center of the Chinese nursing scientific coauthorship network. We identified the authors' positions and influences according to the research output and centralities of each author. We also analyzed the microstructure and the evolution over time of the maximum subnetwork.

Controllable double tunneling induced transparency and solitons formation in a quantum dot molecule.

We consider the coupling effect between interdot tunneling coupling and external optical control field to study the linear optical property and the formation of temporal optical solitons in a quantum dot molecules system, analytically. The results show that the double tunneling induced transparency (TIT) windows are appeared in the absorption curve of probe field because of the formation of dynamic Stark splitting and quantum destructive interference effect from the two upper levels. Interestingly, the width of the TIT window becomes wider with the increasing intensity of the optical control field. We also find that the Kerr nonlinear effect of the probe field can be modulated effectively through coherent control both the control field and the interdot tunneling coupling in this system. Meanwhile, we demonstrate that the formation of dark or bright solitons can be practical regulated by varying the intensity of the optical control field.