A. Bahrampour - Academia.edu (original) (raw)

Papers by A. Bahrampour

Optics and Photonics Society of Iran, 2016

Physical Review Letters, 2014

We analyze the impact of loss in lattices of coupled optical waveguides and find that in such cas... more We analyze the impact of loss in lattices of coupled optical waveguides and find that in such case, the hopping between adjacent waveguides is necessarily complex. This results not only in a transition of the light spreading from ballistic to diffusive, but also in a new kind of diffraction that is caused by loss dispersion. We prove our theoretical results with experimental observations.

Iranian Journal of Physics Research, 2016

Interferometry - Research and Applications in Science and Technology, 2012

We provide a physically motivated definition for the binding energy (or bond-dissociation) of a b... more We provide a physically motivated definition for the binding energy (or bond-dissociation) of a bipartite quantum system. We consider coherently applying an external field to cancel out the interaction between the subsystems, to break their bond and separate them as systems from which no work can be extracted coherently by any cyclic evolution. The minimum difference between the average energies of the initial and final states obtained this way is defined as the binding energy of the bipartite system. We show the final optimal state is a passive state. We also discuss how required evolution can be realized through a sequence of control pulses. We illustrate utility of our definition through two examples. In particular, we also show how quantum tunneling can assist or enhance bond-breaking process. This extends our definition to probabilistic events.

Journal of Modern Optics, 2015

The single-photon strong coupling in the deep-resolved sideband of the optomechanical system indu... more The single-photon strong coupling in the deep-resolved sideband of the optomechanical system induces photon blockade (PB) effect. For the PB cavity, an initial mechanical coherent state evolves into superposition of phonon cat states entangled with the cavity Fock states. Measurement of the cavity photon number states produces phonon even and odd cat states. The information leakage effect of two photon states on the fidelity of cat states is calculated, it is shown that for low average phonon number this effect is negligible and decreases by increasing the two photon cavity state. The Lindblad equation is solved numerically to obtain the environmental effects on the fidelity of cat states.

Journal of Modern Optics, 2016

It is shown that the asymmetry coupling between two coupled optomechanical cavities leads to spec... more It is shown that the asymmetry coupling between two coupled optomechanical cavities leads to special class of PT-symmetric model for optomechanical structure. Under these conditions, Hamiltonian is considered in blue and red sideband regime. In these cases, the asymmetric coupling between two cavities has been transferred such that the asymmetric beam-splitter or squeezing interaction is generated between optical and mechanical modes. Then, the amount of entanglement between the different optical and mechanical modes is calculated. The results define that PT-symmetry can improve the entanglement in special conditions. The proposed system provides good condition to investigate the nonreciprocal interaction between photon and phonon.

Iranian Journal of Physics Research, 2015

2014 Third Mediterranean Photonics Conference, 2014

ABSTRACT We propose a 10-fold photonic quasicrystal(QC)pattern as the cladding of modified index ... more ABSTRACT We propose a 10-fold photonic quasicrystal(QC)pattern as the cladding of modified index guiding quasi crystal fiber. We have studied the single-mode operation regime of the fiber by analyzing the effective V parameter. In this case it is presented an endlessly single mode regime due to V-parameter, and the result is in agreement with finite element method (FEM) simulation result. We present birefringence and electromagnetic field profiles using finite element method.

Signal, Image and Video Processing, 2008

This paper proposes a new method of estimating an orthogonal bounded spectrum wavelet from a give... more This paper proposes a new method of estimating an orthogonal bounded spectrum wavelet from a given signal. The method is based on minimizing the distance of the wavelet and the given signal in the sense of the metric of the L 2 space. In this method, the amplitude and phase of the mother wavelet are optimized simultaneously. The Lagrange multipliers

International Journal of Heat and Mass Transfer, 2013

ABSTRACT Oil leakage of transportation pipelines causes a change in its environmental temperature... more ABSTRACT Oil leakage of transportation pipelines causes a change in its environmental temperature. This effect is employed to detect the leakage and its positions. The Raman Optical Time Domain Reflectometer (ROTDR) and Brillouin Optical Time Domain Amplifier (BOTDA) sensors are two of the most precise oil pipeline leak detector systems operate based on this effect. The position of leakage is determined by the time difference between the sending and backscattered laser pulses. In this paper, the transient response of BOTDA and ROTDR sensors are obtained through solution of the mass, energy and heat transfer in soil and fiber cable. It is shown that the mechanical rise time is of the order of a few minutes, which is in agreement with the experimental results of BOTDA and ROTDR sensors. Ultimately, on the basis of the heat transfer results, a method for leak flow rate measurement by the optical fiber leak sensors is proposed.

International journal of preventive medicine, 2014

Tuberculosis (TB) can affect patients' life even after successful treatment. In this study, w... more Tuberculosis (TB) can affect patients' life even after successful treatment. In this study, we aimed to determine the survival rate of patients with smear positive TB after successful treatment and identify the predictors of mortality. This was a prospective study. The source of data was the TB registry system in Iran and 964 patients were eligible for the study. The life table was used to determine the annual survival rate. Survival curves were estimated using Kaplan-Meier and were compared using the log-rank test. In order to determine the predictors of survival, four models of Cox regression, exponential, Weibull and log-logistic fitted and finally exponential model with minimum akaike information criteria and Bayesian information criterion values were selected. Then, variables with significant levels <0.2 in univariate analysis were entered into the multivariate model. Hazard ratios with a confidence interval of 95% were used to measure the association. A total of 149 pat...

International journal of fertility & sterility, 2013

In many countries, 1 to 3% of newborn infants are conceived by assisted reproductive techniques (... more In many countries, 1 to 3% of newborn infants are conceived by assisted reproductive techniques (ART). Despite the success of ART, there is concern about the risk of congenital malformations among these infants. We report our experience to determine whether use of ART is associated with an increase in major congenital malformations or adverse pregnancy outcomes. Historical cohort study of major congenital malformations (MCM) was performed in 978 births from January 2008 to December 2010. The data for this analysis were derived from a Tehran's ART linked data file by simple sampling method. In our study, the risk of congenital malformations was compared in 326 ART infants and 652 naturally conceived (NC) infants. We also performed multiple logistic regression analyses to calculate the odds ratio (OR) and 95% confidence intervals (CI) for the independent association of ART on each outcome. We found 56 infants with major congenital malformations, these included 29 NC infants (4.4%)...

International Journal of Health Policy and Management, 2014

There are few quantitative documents about the seasonal incidence of tuberculosis (TB) among immi... more There are few quantitative documents about the seasonal incidence of tuberculosis (TB) among immigrant populations. Concerning the significant role of recognizing seasonal changes of TB in improving the TB control program, this study determines the trend and seasonal temporal changes of TB among immigrants entering Iran. In this longitudinal study, data from the Iranian TB register Program (from 2005 to 2011) was used. The aggregated number of monthly and seasonal TB cases was obtained by adding the daily counts. Data was analyzed by Chi-square, Independent T-test, ANOVA, and Poisson regression using Stata 11 and SPSS 20 software. Among 74,155 registered patients with TB, 14.3% (10,587) were non-Iranian who had immigrated to Iran from 29 different countries. The highest aggregated number of seasonal and monthly incidence of TB in immigrants was observed in spring (2824, P= 0.007) and in May (1037, P&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.001). The number of non-Iranian patients with TB increased significantly over the years (β= 0.016, P= 0.001). This study shows that immigrants constitute a significant portion of TB patients recorded in Iran and this trend is increasing. Also, the peak incidence of this disease is the second month of the spring.