Journal of Optoelectronical Nanostructures
Volume:6 Issue: 1, Winter 2021

In this study, density functional theory (DFT) calculations were performed to investigate the adsorption of CO molecule (via O and C atoms) on the surface of Mg16M— O2 (M=Be, Mg, and, Ca) nanostructures, M is the central atom, at the CAM-B3LYP/6- 311+g(d) level of theory. The electronic properties of Mg16M—O2 nanostructures were significantly affected by the adsorption of the CO molecule. The NBO analysis revealed a charge transfer from the adsorbed CO molecule to the Mg16M—O2 nanostructure. Based on the adsorption energies and enthalpies, a thermodynamically favorable chemisorption process was predicted. The adsorption and binding energy values of the CO molecule (via both O and C atoms) over the Mg16M—O2 nanostructures have increased with increasing the atomic radius of the central atom in the nanostructures through a chemical and exothermic reaction. The Mg16CaO2―CO complex with the smallest bond distance and the largest adsorption energy shows the most tendency to adsorb carbon monoxide molecule.

The transfer matrix method has been widely used to calculate the scattering of electromagnetic waves. In this paper, the second harmonic generation in finite size onedimensional periodically poled LiTaO3 has been investigated. To calculate the conversion efficiency, fundamental and second harmonic wave propagation among proposed structures, we use the transfer matrix method. In the designed nonlinear photonic crystal structure, the linear and nonlinear optical parameters are both periodically modulated, and thus the second harmonic generation efficiency can be several orders of magnitude larger than in a conventional quasi-phase matched nonlinear structure with the same sample length. The reason is that, due to the presence of photonic band gap edges, the density of states of the electromagnetic fields is large, the group velocity is small (as a result, the interaction time is increased), and the local field is enhanced. All three factors contribute to significant enhancement of the nonlinear optical interactions.

In this article, a resonant tunneling diode with AlAs/GaAs double barrier structure using the non-equilibrium green’s function is simulated. A lattice matched InGaAs absorption layer is added to the device for light detecting at the wavelength λ=600 nm. The electric field through the device and energy band diagramprofile were presented. The photo current of the device and source photocurrent curves versus light intensity are compared. At room temperature, the quantum efficiency of 0.95 was obtained for the device. Transient time response of the device was obtained and its dependencies on structural parameters (absorption layer thickness, collector and emitter thickness and doping of the contacts), light intensity, angle of emitted light and voltage bias were simulated and their influences on operation of the device were analyzed. Bandwidth of the device was obtained. The simulation results show that when voltage bias increases, fall time decreases and the response of the device is faster. With changing of absorption layer and contacts thicknesses, time response of RTD-PD changes. The variations of doping in contact layers effect on bandwidth. The result show that variations of light intensity and angle of emitted light change transient time response.

The interaction of the cavity electromagnetic field with the two-level emitter is described by cavity quantum electrodynamics (CQED). A pulsed micro-laser is an array of semiconductor quantum dots (QDs) embedded in an optical micro-cavity. This is one of the basic tools of quantum information technology. In this study, the energy eigenvalues variations and the quantum efficiency of a micro-laser system includes a QD with a decay rate of 0.8μeV embedded in the different micro-cavities, were investigated. The results show that with the increasing coherent interaction rate of micro-laser system, the energy eigenvalues variations of this optical system also increase. The quantum efficiency for this nano-optical system was studied. The results show the smaller micro-cavity decay rate, the higher quantum efficiency at smaller coherent interaction rate. Then, the optimal value of the micro-cavity decay rate was obtained in order to achieve the maximum quantum efficiency. The calculation results showed that the highest quantum efficiency occurs for optical parameters γa=0.8μeV, g=95μeV, γc=177.7μeV, and ηmax=0.991.

In this paper, a structure of thin film SiGe solar cell based on carbon nanotube (CNT) is proposed. We present the design and simulation of the device using Silvaco TCAD. The modeling of the CNT-based SiGe thin film solar cell structure is performed and then compared with conventional SiGe thin film solar cell structure. Results from numerical simulation show that the CNT- based SiGe thin film solar cell has better parameters such as short circuit current, open circuit voltage, fill factor, maximum power and efficiency in comparison with pervious structures. The simulation results also prove that the efficiency increases by 40.36%.

Plasmon-Solitons are quasi-particles resulting from coupling the plasmon modes and solitary solutions. This coupling can be intrinsically resonant in order to form plasmon-solitons with a high localization and large propagation length. This paper deals with the temporal nonlinear dynamics of plasmon-solitons in a plasmonic waveguide. Duffing equation is recognized as the temporal part of the nonlinear amplitude equation governing the plasmonic waveguide. Duffing equation is analytically solved for the low nonlinearity regime. It is shown that the Duffing oscillator waveforms stand for the temporal nonlinear dynamics of plasmon-solitons. The energy exchange of Lorentz-type bright and dark modes gives rise to a Fano resonance. It is thus shown that the interaction of solitons and the formation of plasmonsolitons is inherently nonlinear. It is accordingly indicated that the nonlinear modulation of the plasmon-solitons is achievable via tuning the nonlinearity of the plasmonic waveguide. The results can be appealing for the researchers intending to design the plasmonic waveguides with the high localization as well as the large propagation length. In particular, an all-plasmonic modulation method can be contemplated.

There can be no doubt that nanotechnology will play a major role in our future technology. Computer science offers more opportunities for quantum and nanotechnology systems. Soft Computing techniques such as swarm intelligence, can enable systems with desirable emergent properties. Optimization is an important and decisive activity in structural designing. The inexpensive requirement in memory and computation suits well with nanosized autonomous agents whose capabilities may be limited by their size. To apply in nanorobot control, a modification of PSO algorithm is required. Using birds’ classical conditioning learning behavior in this paper, particles will learn to perform a natural conditional behavior towards an unconditioned stimulus. Particles in the problem space are divided into multiple categories and if any particle finds the diversity of its category in a low level, it will try to move towards its best personal experience. We also used the idea of birds’ sensitivity to the space in which they fly and tried to move the particles more quickly in improper spaces so that they would depart the spaces. On the contrary, we reduced the particles’ speed in valuable spaces in order to do more search. The proposed method was implemented in MATLAB software and compared to similar results. It was shown that the proposed method finds a good solution to the problem regardless of nondeterministic functions or stochastic conditions.