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A novel see-through virtual retina display(VRD) system is proposed in this Letter. An optical fiber projector is used as the thin-light-beam source, which is modified from a laser scan projector by separating the laser sources and the scan mechanical structure. A synthetic aperture method is proposed for simple, low-cost fabrication of a volume holographic lens with large numerical aperture. These two key performance-enhanced elements are integrated into a lightweight and ordinary-glasses-like optical see-through VRD system. The proposed VRD system achieves a weight of 30g and a diagonal field of view of 60°. 相似文献
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Alternating-current small-signal admittances of armchair graphene nanoribbons are investigated using the method of non-equilibrium Green's function. The calculated ac admittances show an oscillatory response between inductive and capacitive behaviors, which is a result of the finite length of the graphene nanoribbon. The effects of hydrogen-passivated edges on ac response are demonstrated. At low frequency, the edge effects transform the inductive behavior in a metallic graphene nanoribbon into a capacitive one. Finally, the effects of variations in the width and bandgap of a graphene nanoribbon on its dynamic response are investigated. 相似文献
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Derivative of Electron Density in Non-Equilibrium Green's Function Technique and Its Application to Boost Performance of Convergence 下载免费PDF全文
The non-equilibrium Green's function (NEGF) technique provides a solid foundation for the development of quantum mechanical simulators. However, the convergence is always of great concern. We present a general analytical formalism to acquire the accurate derivative of electron density with respect to electrical potential in the framework of NEGF. This formalism not only provides physical insight on non-local quantum phenomena in device simulation, but also can be used to set up a new scheme in solving the Poisson equation to boost the performance of convergence when the NEGF and Poisson equations are solved self-consistently. This method is illustrated by a simple one-dimensional example of an N++ N+ N++ resistor. The total simulation time and iteration number are largely reduced. 相似文献
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A method for simulating ballistic time-dependent device transport, which solves the time-dependent Sehrǒdinger equation using the finite difference time domain (FDTD) method together with Poisson's equation, is described in detail. The effective mass Schrǒdinger equation is solved. The continuous energy spectrum of the system is discretized using adaptive mesh, resulting in energy levels that sample the density-of-states. By calculating time evolution of wavefunctions at sampled energies, time-dependent transport characteristics such as current and charge density distributions are obtained. Simulation results in a nanowire and a coaxially gated carbon nanotube field-effect transistor (CNTFET) are presented. Transient effects, e.g., finite rising time, are investigated in these devices. 相似文献
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Long-time evolution of charged grains in plasma under harmonic external force and after being withdrawn 下载免费PDF全文
Evolution of the charged grains in a two-dimensional dusty plasma under a spatially harmonic external force,in particular,their long-time behaviors after the force has been withdrawn,is studied by using molecular dynamics simulation.Under an external force and a grain–grain interaction force,initially homogeneously distributed grains can reach a quasistationary state in the form of a disk crystal.After the external force is withdrawn,the disk moves initially with its size and shape nearly unchanged until it rapidly stops moving,and eventually the disk grain rotates like a vortex.The time needed to reach the final state increases with the strength of the initial external force increasing. 相似文献
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