Showing 15 results for Mir
Mehdi Miri, Sina Khorasani,
Volume 4, Issue 1 (International Journal of Optics and Photonics (IJOP) Vol. 4, No. 1, Winter-Spring 2010)
Abstract
We generalized the squeeze and displacement operators of the one-dimensional harmonic oscillator to the three-dimensional case and based on these operators we construct the corresponding coherent and squeezed states. We have also calculated the Wigner function for the three-dimensional harmonic oscillator and from the analysis of time evolution of this function, the quantum Liouville equation is also presented. Further properties of the quantum states including Mandel’s and quadrature squeezing parameters are discussed as well.
Mr. Amir Khodamohammadi, Mr. Ahmad Khayatjafary, Dr. Reza Aghbolaghi,
Volume 7, Issue 2 (International Journal of Optics and Photonics (IJOP) Vol 7, No 2, Summer-Fall 2013)
Abstract
In the present work, we investigate the tunability of the magnetic response of a new structure. A lattice of periodically arranged close-packed square conducting rings has been studied for this purpose. Here, instead of enhancing the magnetic activity via resonance, like in split-ring resonators, we concentrate on the analysis of the interactions between these rings. The core idea is to design an array with negligible capacity and to focus on inductive interactions between its building cells. In other words, in this structure, the enhancement of the microscopic process has been attained by the interaction of its building block, i.e. a collective feature has been considered. It is our goal to obtain a sizable magnetic response with this new approach. Our ultimate goal is to demonstrate that the relative magnetic permeability of this architecture could be less than one or even less than zero.
Dr. Roohollah Ghobadi, Ms Samira Gholizadeh, Dr. Mojtaba Mazaheri,
Volume 9, Issue 1 (International Journal of Optics and Photonics (IJOP) Vol 9, No 1, Winter-Spring 2015)
Abstract
One of the main milestones in the study of opto-mechanical system is to increase the sensitivity of weak forces measurement up to the standard quantum limit. We have studied the detection of weak force under a bistable condition in red detuned regime. In this case, dynamics of the system behaves asymptotically similar to stationary state and applying external force affects phase and fluctuation of the cavity field. Using the signal to noise ratio, we have found the sensitivity of the system to external force. The system show the maximum sensitivity in the region where bistability approaches zero. We also studied the destructive effects of thermal noise on the sensitivity. Our approach is based on the covariance matrix formalism which can be solved by first Lyapunov theorem.
Ms. Fatemeh Ghasemi, Dr. Parviz Parvin, Ms. Najme Alsadat Hosseini Motlagh, Ms. Fatemeh Mirzaee, Mr. Mohammad Keraji, Mr. Ali Bavali,
Volume 9, Issue 2 (International Journal of Optics and Photonics (IJOP) Vol 9, No 2, Summer-Fall 2015)
Abstract
Simultaneous laser induced- breakdown spectroscopy (LIBS) and acoustic response techniques as well as Laser induced fluorescence (LIF) are applied to investigate the abnormal lymph tissues due to Hodgkin disease. The spectral shift in the emissive fluorescence of the cancerous tissues has been observed respect to the normal ones. Regarding LIBS, the concentrations of Ca and Na trace elements have been identified to be higher in the cancerous samples. In addition, the acoustic response of cancerous tissues has been elevated against healthy ones. The distinct differences in the spectra are taken into account for early and the rapid identification and diagnosis.
Mr Amir Hossein Shahbazi, Prof. Khosro Madanipour, Prof. Ata Koohian,
Volume 9, Issue 2 (International Journal of Optics and Photonics (IJOP) Vol 9, No 2, Summer-Fall 2015)
Abstract
Defocusing effects in modulation transfer function (MTF) measurement of charge coupled device (CCD) cameras is the main focus of current paper. We introduce measuring Point-spread function (PSF) in order to calculate the MTF and further more we will study the shape of MTF and its cut-off frequency by adjusting the lens focusing in different locations. A collimated white light LED by broadband spectra is used as source and our results shows that the cut-off frequency is related to defocusing.
Dr Amin Ghadi, Prof Saeed Mirzanejhad,
Volume 10, Issue 1 (International Journal of Optics and Photonics (IJOP) Vol 10, No 1, Winter-Spring 2016)
Abstract
In this paper, we numerically simulated a glass-based all-optical 1×N power splitter with eleven different configurations using soliton breakup in a nonlinear medium. It is shown that in addition to reconfigurability of the proposed splitter, its power splitting ratio is tunable up to some extent values too. Nonlinear semivectorial iterative finite difference beam propagation method (IFD-BPM) with inclusion of two photon absorption (TPA) effects is applied to simulate the soliton propagation at different mode power. It is shown that operation of the proposed splitter depends on input mode power and an all-optical reconfigurable-tunable functional device is designed with nonlinear optical (NLO) property of a simple structure.
Dr. Mohammad Hossein Hekmatshoar, Ms. Samira Vafaei,
Volume 10, Issue 2 (International Journal of Optics and Photonics (IJOP) Vol 10, No 2, Summer-Fall 2016)
Abstract
Glassy samples with a composition of 40P2O5–30V2O5–(30-x)Li2O– xK2O, 0<x<30 (mol %) were prepared by the conventional melt quenching technique in two forms of bulk and blown film. X-ray diffraction patterns corroborated the amorphous feature of the samples. Density of samples was investigated by using Archimedes principle. Based on absorption and reflection spectra, indirect allowed optical gaps, Urbach energies, refractive index and dielectric coefficients were calculated. Study of FTIR spectra revealed that all of the samples mainly contain metaphosphate and pyrophosphate units. Glass transition temperatures were also evaluated using DSC curves. Non-linear variation of many physical properties by gradually substitution of Li ions with K, confirmed the existence of mixed alkali effect in glassy system.
Ms. Farkhondeh Allahverdi, Dr. Amirhossein Ahmadkhan Kordbacheh, Ms. Farideh Allahverdi,
Volume 10, Issue 2 (International Journal of Optics and Photonics (IJOP) Vol 10, No 2, Summer-Fall 2016)
Abstract
Due to sensitive and important applications of free-electron laser in industry and medicine, improvement of the power and efficiency of laser has always been emphasized. Therefore, understanding the created field and examining the properties of the field in waveguides with different shapes and studying the sustainability of electrons movement are particularly important. In this study, the behavior of electrons in free-electron laser in the wiggler field by square waveguide with central core is examined which is a new research. Due to the complexity of cross section, the equations governing the field are solved numerically, and magnetostatic fields are calculated and then the changes of Wiggler magnetic field are displayed. Finally, the properties of balanced electron circuits for the first and third harmonics are studied and the strong effect of the third space harmonic on the field is observed in the second magnetic resonance and the obtained results indicate greater volatility of transverse components of velocity.
Since the field intensity on the sides and center of the waveguide and the order of electrons motion are important in determining the laser power and efficiency
, studying the behavior of electrons in this research indicates that in the empty space between the two walls, Wiggler magnetic field is minimized and leads to the focus of electron beam. Therefore, the closer is the starting point of the movement of electron to the center of waveguide, the better will be the movement order.
Siamak Khademi, Samira Alipour,
Volume 11, Issue 1 (International Journal of Optics and Photonics (IJOP) Vol 11, No 1, Winter-Spring 2017 2017)
Abstract
The semi-classical model of atom-field interaction has been fully studied for some multilevel atoms, e.g. Vee, L, Cascade X , Y, and inverted Y and so on. This issue is developed into the full-quantum electrodynamics formalism, where the probe and coupling electromagnetic fields are quantized. In this article, we investigate the full-quantum model of absorption and dispersion spectrum of trapped four-levels inverted Y type atoms, interacting with a probe beam of photons as well as two-mode trapped coupling photons. It is shown that the measurement of the maximum of absorption of the probe field and its detuning gives us simply the number of two-mode coupling photons, individually. An experimental setup for this non-demolition photon counting method is proposed and the numbers of coupling photons are obtained analytically.
Amir Rahimian, Hossein Zahed,
Volume 13, Issue 2 (International Journal of Optics and Photonics (IJOP) Vol 13, No 2, Summer-Fall 2019)
Abstract
In this paper, we have simulated the excitation of wake fields in the interaction of an intensive laser pulses having Half-Sine and Gaussian time envelopes with a fully ionized cold plasma using particle in cell (PIC) method. We investigated the dependency of wake filed amplitude to different laser and plasma parameters such as laser wavelength, pulse duration and electron number density. In addition, the effect of employing a longitudinal magnetic field on the intensity of wake field is studied. It has been seen that the wake field intensity is enhanced in the presence of a magnetic field for both Half-Sine and Gaussian shape pulses. Our aim has been finding optimum values of different parameters for which higher accelerating wake electric fields can be obtained.
Abbas Hamooleh Alipour, Ali Mir,
Volume 13, Issue 2 (International Journal of Optics and Photonics (IJOP) Vol 13, No 2, Summer-Fall 2019)
Abstract
In this paper, an enhancement design of communication system using optical radio frequency (RF) waves in free space optical communication (FSO) system is presented. To our knowledge, it is the first time that the effect of Gamma-Gamma turbulent channel model on the performance of the proposed system is analyzed and simulated. To obtain an optical communication system with good performance and high spectrum efficiency, we proposed two types of optical RF waves including optical single sideband (OSSB) and optical double sideband (ODSB). This strategy that integrated an optical communication system with turbulent channel model can express an accurate model of optical and RF waves propagation in free space. Performance of the system under different regimes, weak, moderate and strong turbulent is studied considering several parameters like max quality factor, bit error rates (BER), and optical signal-to-noise ratio (OSNR). Also, a comparative study between two methods of optical RF waves is presented.
Mostafa Tarkashvand, Amir Hossein Farahbod, Seyed Ali Hashemizadeh,
Volume 14, Issue 1 (Winter-Spring 2020)
Abstract
In this paper, the mode structure and time behavior of a LED-pumped Ce:Nd:YAG laser have been studied. Four blue LED bars with total 128 LEDs at 460 nm are utilized to pump a 3 mm diameter laser rod. Using a Cr4+:YAG passive optical switch with 96% initial transmission, and a low loss stable optical resonator and 0.7 J pumping energy, a single 17 micro-joules Q-switched laser pulse with 240 ns pulse-width and nearly TEM00 mode profile was produced. By increasing the pumping energy Ep up to 0.8 J, the mode structure remained intact. Further increasing of Ep, the laser mode changed to TEM10. Numerical calculations show that the central high gain area of the laser rod and saturation mechanism of the passive Q-switch behaves like as a soft aperture to enforce the laser resonator to oscillate on a low order transverse mode. For laser free-running, the TEM00 mode has not been achieved and the optical resonator produced high order transverse mode patterns.
Mir Vahid Kazempour, Hamid Vahed,
Volume 14, Issue 2 (Summer-Fall 2020)
Abstract
In this paper, we propose a D-shaped plasmonic optical biosensor based on photonic crystal fiber (PCF) to detecting of the different materials such as water, blood plasma, Yd-10B and hemoglobin by using of the refractive index. The gold layer is coated on the polished surface of D-shaped fiber. To achieve the highest sensitivity of the proposed biosensor, we investigated the effects of variation of the gold layer thickness and the other structure parameters such as hole diameter (d) and the distance between two holes or Pitch (L). The results show that the most sensitivity of the proposed biosensor is 2506 nm per refractive index unit (nm/RIU) with the resolution of 1.25×10-5 RIU, when d=1.4 µm and Λ=1.9 µm with the gold layer thickness of 45nm.
Reza Pourahmad, Sheila Shahidi, Amirhossein Sari, Mohammadreza Hantezadeh,
Volume 17, Issue 1 (Winter-Spring 2023)
Abstract
In this research, an attempt is made to approach a specific type of carbon, such as graphene or carbon nanotubes by using pulsed laser ablation technique in deionized water environment with changing the laser factors such as wavelength and fluence. Nd:YAG laser with two wavelengths of 1064 and 532 nm and three fluence of 0.8, 1 and 1.2 J/cm2 were selected that number of pulses was 5000 with a frequency of 10 Hz to be irradiated on the graphite target at about 10 minutes. The medium was distilled water. Graphite was located in the 40 ml of distilled water.
The effects of wavelength and fluence of the laser have been experimentally investigated on types of carbon characteristics with different analysis such as Raman scattering spectrum, FE-SEM images, UV–Vis-NIR spectrum and X-ray diffraction (XRD). By using the mentioned analysis, the type of synthesized nano carbon is studied.
This study evaluates the effects of the pulse energy and laser wavelength on properties of synthesized carbon nanoparticle in laser ablation method in medium of distilled water.
Mr. Moein Golestanifar, Dr. Mohammad Ali Haddad, Mr. Amir Namiq Hassan, Dr. Fatemeh Ostovari,
Volume 17, Issue 2 (Summer-Fall 2023)
Abstract
The spatial self-phase modulation (SSPM) method was used to study the nonlinear optical responses of hydraulic oil containing dispersed nanosheets of reduced graphene oxide (rGO), hydroxylated rGO (rGO-OH), and carboxylated rGO (rGO-COOH). The intensity-dependent number of observed symmetric diffraction rings was analyzed to estimate the samples' thermally induced nonlinear refractive indexes and lead to estimated thermo-optical coefficients. Based on the observed symmetric diffraction rings, the nonlinear refraction coefficient and thermo-optical coefficient of samples were estimated to be in the order of magnitude of 10-6 cm2/W and 10-2 K-1, respectively. The results indicated that the presence of rGO derivatives significantly enhanced the optical nonlinearity of hydraulic oil.
