Showing 8 results for Moradi
Dr. Esmaeil Shahriari, Dr. Mohammad Moradi, Dr. Mohsen Ghasemi Varnamkhasti,
Volume 9, Issue 2 (International Journal of Optics and Photonics (IJOP) Vol 9, No 2, Summer-Fall 2015)
Abstract
In this research, Ag nanoparticles were prepared by using g-radiation at concentration of 5.18×10-3 M and irradiated at different doses. A green laser was employed as excited source for measuring nonlinear refractive index and absorption coefficient. The measurements were done by z-scan method for both, closed and open aperture at temperature room. We deduced that with growth of size of Ag nanoparticles, nonlinear refractive index increased while absorption coefficient of samples decreased
Marjan Jafari, Fatemeh Moradi,
Volume 12, Issue 2 (International Journal of Optics and Photonics (IJOP) Vol 12, No 2, Summer-Fall 2018)
Abstract
A bi-isotropic magneto-electric metamaterials is modeled by two independent reservoirs. The reservoirs contain a continuum of three dimensional harmonic oscillators, which describe polarizability and magnetizability of the medium. The paper aimed to investigate the effect of electromagnetic field on bi-isotropic. Starting with a total Lagrangian and using Euler-Lagrange equation, researcher could obtain a quantum Langevin type dissipative equation for electromagnetic field. Generating functional of the system is obtained by the path integral method and based on the perturbative approach. By generating functional, a series expansion in terms of susceptibility function of the bi-isotropic metamaterials is obtained for correlation function or two-point Green’s function. In special case, the close relationship between statistical mechanics and quantum field theory,which was reflected in the path integral methods, could obtain free energy of electromagnetic field for isotropic metamaterial using two-point Green’s function. As an example, the Casimir force of two polarizable metamaterial spheres by Lorentz susceptibilities was studied. Furthermore, Casimir force of two polarizable-magnetizable metamaterials was calculated.
Forouzan Habibi, Mohammad Moradi,
Volume 13, Issue 2 (International Journal of Optics and Photonics (IJOP) Vol 13, No 2, Summer-Fall 2019)
Abstract
First, this study obtained the fields of an Airy beam (AiB) with optical vortex (OV) for a Fourier transform (FT) system and a fractional Fourier transform (fractional FT) system; thereafter, their intensity and phase patterns were simulated numerically. The splitting on each line of the phase pattern indicates the position of an OV. The results show that the OV position will change when the power of the fractional FT (p) changes. Moreover, the uniformity of the spot beam disappears for the beam with OV. Further, the characteristics of an AiB such as number, width, height, uniformity of the spot beam and the effective beam size will change when there is a change in the values of p and z.
Hamid Haghmoradi, Atoosa Sadat Arabanian, Reza Massudi,
Volume 14, Issue 1 (Winter-Spring 2020)
Abstract
In this paper, design and fabrication of an internal resonant enhanced frequency doubling of the continuous-wave ytterbium-doped fiber laser at 1064nm using a Fabry-Perot bow tie cavity inside the fiber laser cavity is presented. The 3.5W power coupled into the enhancement cavity is amplified to 163W by the intracavity passive locking technique. By placing an LBO crystal within this resonant enhancement cavity, conversion efficiency of the second harmonic generation of the laser in continuous regime is increased from 0.023% to 51.42% (i.e. about 2200 times) which results to generation of 1.8W light at 532nm.
Dr. Morteza Janfaza, Dr. Hamed Moradi, Mr. Morteza Maleki,
Volume 15, Issue 2 (Summer-Fall 2021)
Abstract
Graphene and molybdenum disulfide (MoS2), as two of the most attractive two-dimensional (2D) materials, are used to improve the temperature and strain sensing responses of the few-mode fibers (FMFs). The temperature and strain effects are detected based on distributed optical fiber sensors equations, where the Brillouin scattering (BS) is investigated for the FMF tapered region. For this purpose, the 2D materials were assumed as cover layers on the tapered FMF to enhance its sensitivity. Graphene and MoS2 are used as the cover layer on the FMF cladding at a distance of 10 μm from the core, and the impact of the number of material layers is investigated. By increasing the graphene layers, the temperature and strain sensitivities increase (3% and 16%, respectively) due to the rise of the inter-modal interference of the FMF. Moreover, the increasing of the MoS2 layer number improves the temperature sensitivity by 28% but shows a lower impact on strain sensitivity (about 13%). The advantage of MoS2 with respect to graphene originates from the imaginary part of the refractive index of graphene (assumed with chemical potential of 0.4 eV at the working wavelength of 1550 nm), which leads to a lower effective index of the tapered region, hence lower sensitivities. This sensitivity enhancement can improve the performance of the BS-based sensors for local detection of the parameters under-investigation in multi-parameter sensors.
Mohammad Moradi, Forouzan Habibi, Asieh Rafiee,
Volume 17, Issue 2 (Summer-Fall 2023)
Abstract
In this study, copper cobalt ferrite nanoparticles were synthesized by chemical formula Co1-xCuxFe2O4 and (x=0, 0.2, 0.4, 0.6, 0.8, 1) by co-precipitation method. The X-ray diffraction pattern of the samples confirmed the single-phase spinel structure of the fabricated nanoparticles and the average size of the crystals was calculated from the entire width of the diffraction peak with the highest intensity and Scherrer relationship. Using transmission electron microscope images, the nanoparticle size was about 10 nm. The magnetic properties of copper cobalt ferrite nanoparticles were measured by AGFM and it was seen that with increasing substitution of copper Cations instead of cobalt Cations in the samples, the amount of induction decreased and the saturation magnetization first increased and then decreased. In order to investigate the Faraday effect on copper cobalt ferrite nanoparticles, the transmittance values were measured using a laboratory experiment and their graphs were plotted in terms of the applied magnetic field, all of which were in agreement with the theory. In addition, transmittance was investigated for two angular positions of the analyzer at -45˚ and +45˚ in different fields.
Morteza Janfaza, Hamed Moradi, Arsalan Jalil,
Volume 17, Issue 2 (Summer-Fall 2023)
Abstract
In this study, we present the findings derived from our simulation and experimental investigation of a distributed optical fiber acoustic sensor. The proposed sensor operates by utilizing the self-interference of Rayleigh backscattering. When the optical pulse propagates through the optical fiber, the phase of the Rayleigh backscattered light changes at the location where the acoustic signal is present. This phase change is then amplified through the self-interference of two Rayleigh backscattered beams in the Michelson interferometer scheme. This study aims to present the Phase Generated Carrier (PGC) demodulation method along with the arctangent function (ATAN) and the Coordinate Rotation Digital Computer (CORDIC) algorithm. This method offers a simple and efficient algorithm for computing hyperbolic and trigonometric functions. The system allows for the detection of acoustic waves caused by sinusoidal disturbances with a spatial resolution of approximately 20 m.
Nastaran Kahrarian, Atoosa Sadat Arabanian, Zinab Moradi Alvand, Hasan Rafati, Reza Massudi,
Volume 18, Issue 1 (10-2024)
Abstract
The modification of cell surface structures has become a focal point in cell biology, with methods like drugs, chemicals, and non-destructive techniques such as laser light exposure being utilized. In particular, exposure to femtosecond laser pulses has been found to increase cell permeability to formulations without causing thermal damage. This study aimed to observe and document the changes in the structure of Staphylococcus aureus bacteria when they were optically trapped and subjected to femtosecond laser pulses, along with the application of a medicinal substance, over 20 minutes. The research successfully determined the optimal power and exposure time of the laser light on the bacterial surface and demonstrated the ability of femtosecond laser pulses to enhance the efficacy of the medicinal substance.
