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Simulation and Optimization of Nonperiodic Plasmonic Nano-Particles
Majid Akhlaghi,Farzin Emami,Mokhtar Sha Sadeghi,Mohammad Yazdanypoor 한국광학회 2014 Current Optics and Photonics Vol.18 No.1
A binary-coupled dipole approximation (BCDA) is described for designing metal nanoparticles with nonperiodic structures in one, two, and three dimensions. This method can be used to simulate the variation of near- and far-field properties through the interactions of metal nanoparticles. An advantage of this method is in its combination with the binary particle swarm optimization (BPSO) algorithm to find the best array of nanoparticles from all possible arrays. The BPSO algorithm has been used to design an array of plasmonic nanospheres to achieve maximum absorption, scattering, and extinction coefficient spectra. In BPSO, a swarm consists of a matrix with binary entries controlling the presence (‘1’) or the absence (‘0’) of nanospheres in the array. This approach is useful in optical applications such as solar cells, biosensors, and plasmonic nanoantennae, and optical cloaking.
Fuzzy Adaptive Modified PSO-Algorithm Assisted to Design of Photonic Crystal Fiber Raman Amplifier
Majid Akhlaghi,Farzin Emami 한국광학회 2013 Current Optics and Photonics Vol.17 No.3
This paper presents an efficient evolutionary method to optimize the gain ripple of multi-pumps photonic crystal fiber Raman amplifier using the Fuzzy Adaptive Modified PSO (FAMPSO) algorithm. The original PSO has difficulties in premature convergence, performance and the diversity loss in optimization as well as appropriate tuning of its parameters. The feasibility and effectiveness of the proposed hybrid algorithm is demonstrated and results are compared with the PSO algorithm. It is shown that FAMPSO has a high quality solution, superior convergence characteristics and shorter computation time.
Mohammad Yazdanypoor,Farzin Emami 한국광학회 2014 Current Optics and Photonics Vol.18 No.2
A novel multi-oxide layer structure for vertical cavity surface emitting laser (VCSEL) structures is proposed to achieve higher single mode output power. The structure has four oxide layers with different aperture sizes and thicknesses. The oxide layer thicknesses are optimized simultaneously to reach the highest single mode output power. A heuristic method is proposed for plotting the influence of these variable changes on the operation of optical output power. A comprehensive optical-electrical thermal-gain self-consistent VCSEL model is used to simulate the continuous-wave operation of the multi-layer oxide VCSELs. A comparison between optimized VCSELs with different structures is presented. The results show that by using multi-oxide layers with different thicknesses, higher single-mode optical output power could be achieved in comparison with multi-oxide layer structures with the same thicknesses.
Azadeh Karimi,Farzin Emami,Najmeh Nozhat 한국광학회 2014 Current Optics and Photonics Vol.18 No.2
In this paper, four apodization functions are proposed for silicon-on-insulator (SOI) strip waveguides with sidewall-corrugated gratings. The effects of apodization functions on the full width at half maximum (FWHM), the side-lobe level, and the reflectivity of the reflection spectrum are studied using the coupled-mode theory (CMT) and the transfer-matrix method (TMM). The results show that applying proposed apodization functions creates very good filtering characteristics. Among investigated apodized waveguides, the apodization functions of Polynomial and z-power have the best performance in reducing side-lobes, where the side-lobe oscillations are entirely removed. Four functions are also used for precise adjustment of the bandwidth. Simulation results show that the minimum and maximum values of the FWHM are 0.74 nm and 8.48 nm respectively. In some investigated functions, changing the apodization parameters decreases the reflectivity which is compensated by increasing the grating length.