International Journal of Optics and Photonics (IJOP)International Journal of Optics and Photonics (IJOP)
http://iranjournals.nlai.ir/1266/
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http://iranjournals.nlai.ir/1266/
Feed provided by International Journal of Optics and Photonics (IJOP). Click to visit.Laser Micro-Raman Spectroscopy of CVD Nanocrystalline Diamond Thin Film
http://iranjournals.nlai.ir/1266/article_333027_46418.html
Laser micro-Raman spectroscopy is an ideal tool for assessment and characterization of various types of carbon-based materials. Due to its special optical properties (CrN) coated stainless steel substrates. NCD films have been investigated by laser micro-Raman spectroscopy. The fingerprint of diamond based materials is in the spectral region of 1000-1600 cm-1 in the first order of Raman scattering spectrum. By using of Gaussian peak fitting, characteristic peaks in the micro-Raman spectrum of NCD films including diamond peak (D), NCD features, a vibrational density of states (VDOS) in the ultra-nanocrystalline diamond (UNCD) clusters, graphitic (G) band and disordered (D) band can be assigned. These peaks and bands can be broadened, shifted in the spectral region or may be eliminated from the spectra due to NCD films grain sizes, synthesis conditions and other surface effects on the crystals. The increasing grain sizes to about 100 nm and faceted grains as the most important parameters can promote the diamond Raman signal, eliminate the VDOS, UNCD and even NCD features in the Raman spectrum.Considerably Enhanced Second-Harmonic Generation in Resonant U-Shaped Nano-Structures
http://iranjournals.nlai.ir/1266/article_333028_46418.html
In this paper, we perform a detailed study of the spectral response of the gold U-shaped nano-structures for different geometrical parameters and polarizations in order to obtain significant localization factor in the wavelength 1.55 μm. The obtained near-field distribution of electric fields reveals that resonances in these nano-structures correspond to the even and odd plasmonic modes depending on the geometrical parameters and polarization directions. Considerably large localization factor is obtained for the first odd mode in specific geometrical parameters. Then, this structure is considered to be surrounded by a typical second-order nonlinear dielectric. The effective susceptibility is calculated for the considered structure, using the nonlinear retrieval method, to demonstrate the enhanced second-harmonic generation quantitatively. In order to represent the applicability of the investigated structure in nano-scale light sources and frequency doublers, its second harmonic generation efficiency is compared with the efficiency of the nonlinear dielectric alone with the same dimensions.Self-Consistent Analysis of Barrier Characterization Effects on Quantum Well Laser Internal ...
http://iranjournals.nlai.ir/1266/article_333029_46418.html
In this paper, a numerical study of barrier characterization effects on the high-temperature internal performance of an InGaAsP multi-quantum well laser is presented. The softwareused for this purpose self-consistently combines the three-dimensional simulation of carrier transports, self-heating, and optical waveguiding. The laser model calculates all relevant physical mechanisms, including their dependence on temperature and local carrier density. The results have shown that the proposed laser, which operates at 1325 nm, suffers from electron leakage. The electron leakage current decreases by reducing the barrier thickness. Although tensile strain barriers lead to improved laser optical behavior, it increases leakage current because of electron non-uniformity.Transmission Properties of the Periodic Structures Based on Graphene Nonlinear Optical ...
http://iranjournals.nlai.ir/1266/article_333030_46418.html
By developing the terahertz (THz) technology, in addition to generators and detectors of THz waves, the existence of some tools such as modulators and filters are needed. THz filters are important tools for various applications in the field of chemical and biological sensors. Linear and nonlinear optical properties of the graphene have attracted lots of attention. In fact graphene exhibits various nonlinear phenomena. Hence in this paper, by entering the graphene to the field of THz and using the graphene nonlinear properties with utilizing the transfer matrix method and transmission properties of a periodic structure containing graphene are investigated. A fairly straightforward computational method allows us to examine the effect of different structural parameters on the transmittance spectrum. Simulation results show that if the graphene nonlinear response in a periodic structure in the presence of a high-intensity THz field is considered, the proposed structure displays two bands of passes and stopping which can improve the design of the filters and controllers of THz waves.Characteristics of the Temporal Behavior of Entanglement between Photonic Binomial ...
http://iranjournals.nlai.ir/1266/article_333031_46418.html
In the present study, temporal behavior of entanglement between photonic binomial distributions and a two-level atom in a leaky cavity, in equilibrium with the environment at a temperature T, is studied. In this regard, the master equation is solved in the secular approximation for the density matrix, when the initial photonic distribution is binomial, while the atomic states obey the Boltzmann distribution. The atom-photon density matrix so calculated is then used to compute the negativity, as a measure of entanglement. The behavior of atom-photon entanglement is, consequently, determined as a function of time and temperature. To justify the behavior of atom-photon entanglement, moreover, we employ the total density matrix to compute and analyze the time evolution of the initial photonic binomial probability distribution. Our results, along with representative figures reveal that the atom-photon degree of entanglement exhibits oscillations while decaying with time and asymptotically vanishes. It is further demonstrated that an increase in the temperature gives rise to a decrease in the entanglement. The finer characteristics of the temporal behavior of the corresponding probability distribution and, consequently, the atom-photon entanglement is also given and discussed.Sensitivity Enhancement of Ring Laser Gyroscope Using Dielectric-Graphene Photonic Crystal
http://iranjournals.nlai.ir/1266/article_333032_46418.html
In a ring laser gyroscope, due to the rotation and the Sagnac effect, a phase difference between the two counter-propagating beams is generated. In this device, the higher phase difference between these two beams causes the better the interference pattern detection, and thus the sensitivity is increased. In this paper, the effect of inserting a dielectric-graphene photonic crystal inside a ring laser gyroscope on the interference pattern and the sensitivity of the device are studied and simulated using ABCD propagation matrix method. Results show that dielectric-graphene photonic crystal has a high transmission and therefore high efficiency in the wavelength of ring laser gyroscope. So it is a suitable choice to use in the ring laser gyroscope. Also, a comparison between ring laser gyroscope with and without dielectric-graphene photonic crystal shows that when the dielectric-graphene photonic crystal is in the system it is possible to build gyroscope with smaller lengths and high sensitivity.Plasmonic Solar Cells, a New Way to Enhance Energy Conversion Efficiency: Analysis and Modeling ...
http://iranjournals.nlai.ir/1266/article_333033_46418.html
In this article, the effect of plasmonic properties of metal nanoparticles with different shapes, and moreover, their plasmonic-photonic interaction, on solar cell performance were investigated and simulated. Because of low conversion efficiency and then high cost of solar cells, it is difficult to commercialize and replace them with conventional energy resources. But in recent years, the plasmonic solar cell has been very popular. In this study, it is shown that the enhancement of near-field electromagnetic waves severely affects the generation rate, which handles the carrier’s generation in the solar cell equations and causes alteration of the photocurrent. This means that by manipulating the plasmonic properties of nanoparticles (shape and density) and their interaction with photons in solar cell structure, distribution of electromagnetic fields will be altered. Hence, the optical power related to the poynting vector is changed. So, with the aim of improving the solar cell some important parameters such as alteration of nanoparticle shape and their inter-distance were investigated. Finally, a comparison between traditional solar cells and our improved structure was undertaken.Lattice-Plasmon Quantum Features
http://iranjournals.nlai.ir/1266/article_620296_46418.html
in this work, some of the lattice plasmon quantum features are examined. Initially, the interaction of the far-field photonic mode and the nanoparticle plasmon mode is investigated. We probe the optical properties of the array plasmon that are dramatically affected by the array geometry. It is notable to mention that the original goal of this work is to examine the quantum feature of the array plasmon. For this reason, we consider a system containing array of the plasmonic nanoparticles and quantum dots. For a complete understanding, we analyze the system with the full quantum theory. Notably, the full quantum analyzing enables us to investigate the quantum fluctuation of the array field. Here, for instance, we study the second-order correlation function and report its modeling results.