Showing 4 results for pourmahyabadi
Sh. Mohammad-Nejad, M. Pourmahyabadi, A. Lajevardizadeh,
Volume 2, Issue 3 (October 2006)
Abstract
In this paper, the performance of a Ring Laser Gyro based inertial navigation is
investigated. Dynamic and stochastic modeling are applied to gyro simulation and
performance evaluation. In the dynamic model, some parameters such as scale factor and
environmental sensitivity have been determined, whereas in the stochastic model, the other
parameters such as random drift and measurement noise have been computed. The
performance of the system is evaluated for several inputs. Also, the parameter variation of
output noise as a result of changing the dither characteristics is analyzed.
M. Pourmahyabadi, Sh. Mohammad Nejad,
Volume 5, Issue 3 (September 2009)
Abstract
In this article, perfectly matched layer (PML) for the boundary treatment and an efficient compact two dimensional finite-difference frequency-domain (2-D FDFD) method were combined to model photonic crystal fibers (PCF). For photonic crystal fibers, if we assume that the propagation constant along the propagation direction is fixed, three-dimensional hybrid guided modes can be calculated by using only a two-dimensional mesh. An index-guiding PCF with an array of air-holes surrounding the silica core region has special characteristics compared with conventional single-mode fibers (SMFs). Using this model, the fundamental characteristics of single mode photonic crystal fibers (SMPCFs) such as confinement loss, bending loss, effective mode area and chromatic dispersion are numerically investigated. The results revealed that low confinement loss and zero-flattened chromatic dispersion can be obtained by varying the air-holes diameter of each ring along the PCF radius. In this work, an especial PCF with nearly zero-flattened dispersion (1.3 ps/nm/km) over a wide wavelength range which covers O, E, S, C, L and U telecommunication wavelength bands and low confinement loss (0.06 dB/km at 1.55μm) is designed. Macro-bending loss performance of the designed PCF is also studied and it is found that the fiber shows low bending losses for the smallest feasible bending radius of 5 mm. Also, it is revealed that the temperature sensitivity of PCFs is very low in compared with the conventional fibers.
M. Pourmahyabadi,
Volume 11, Issue 1 (March 2015)
Abstract
In this article, Hill Climbing (HC) and Estimation of Distribution Algorithm (EDA) are integrated to produce a hybrid intelligent algorithm for design of endlessly Single Mode Photonic Crystal Fibers (SMPCFs) structure with desired properties over the C communication band. In order to analyzing the fiber components, Finite Difference Frequency Domain (FDFD) solver is applied. In addition, a special cost function which simultaneously includes the confinement loss, dispersion and its slope is considered in the proposed optimization algorithm. The results revealed that the proposed method is a powerful tool for solving this optimization problem. The optimized PCF exhibits an ultra-low confinement loss and low dispersion at 1.55 µm wavelength with a nearly zero dispersion slope over the C communication band.
R. Sanjari, M. Pourmahyabadi,
Volume 12, Issue 1 (March 2016)
Abstract
In this article, a novel structure of photonic crystal fiber with nearly zero ultra-flattened chromatic dispersion and ultra-low confinement loss is presented. By replacing the circular air-holes of two first rings with the elliptical air-holes, a fiber with outstanding features of chromatic dispersion and confinement loss is designed. The proposed structure is optimized for operating in a wide wavelength range covering S, C, and L communications bands. Finite Difference Frequency Domain (FDFD) solver is applied to analyze the proposed fiber components. The designed fiber exhibits a chromatic dispersion of -0.12 ps/nm/km at 1.55 µm along with a slope of 0.002 ps/nm2 /km. Also, the other remarkable feature of this fiber is ultra-low confinement loss in order of 10-5 dB/km around λ = 1.55 µm.
