Sharif Digital Repository

We investigate the Fano profile in an optomechanical system with two vibrating mirrors. The detuning between their mechanical frequency, leads to the occurrence of double Fano resonances. The Fano profile can be controlled by adjusting the cavity parameters  

In this paper, a new mechanism of heat transfer is introduced. It is shown that, without emission and absorption of photons, light can operate as a channel of heat transfer between nano- or micro-mechanical oscillators. We consider the dynamics of two vibrating mirrors coupled through one optical cavity mode in an optomechanical system. It is shown that light mediates heat transfer between two micro-mirrors. When the detuning frequency of the mechanical resonators is low, fluctuations flow through the light channel from the high temperature vibrating mirror toward the low temperature one. This behavior is named the resonance heat transfer effect. The rate of heat flow between the mechanical... 

In this paper, the effect of parametric amplifier pump phase noise on the cooling of a micromirror in an optomechanical system with an optical parametric amplifier inside the optical cavity is investigated theoretically. It has been demonstrated that the photon number distribution of a parametric amplifier near the threshold of instability leads to improved cooling of the micromirror. But due to the presence of the parametric amplifier, there is a resonance detuning frequency for transferring noise energy to the potential and kinetic energy fluctuations of the mirror which causes the mirror mechanical oscillation mode temperature to increase. In low quality factor cavities, this effect... 

Optomechanical and electromechanical cavities have been widely used in quantum memories and quantum transducers. We theoretically investigate the robustness of optomechanical and electromechanical quantum memories against the noise of the control laser. By solving the Langevin equations and using the covariance matrix formalism in the presence of laser noise, the storing fidelity of Gaussian states is obtained. It is shown that the destructive effect of phase noise is more significant in higher values of coupling laser amplitude and optomechanical coupling strength G. However, by further increasing the coupling coefficient, the interaction time between photons and phonons decreases below the... 

Orbital angular momentum (OAM) is one of the photon's degrees of freedom in infinite-dimensional Hilbert space. In this paper, we use this photon property to propose a modified version of the deterministic two-way quantum key distribution protocol, known as ping-pong protocol, based on the OAM of light. The advantage of the protocol is that it does not require Bell measurement for decoding the information being transmitted, which makes the protocol more flexible and feasible for practical applications. We propose an implementation setup and show how the channel capacity of the protocol can be easily increased. The security of the protocol is analyzed and the probability of detecting Eve in a... 

We propose a perturbation method for time division multiplexed (TDM) pumping fiber Raman amplifier (FRA). The method is based on the solution of Raman partial differential equations (PDEs) by a closed integral form. Taking the signals and pumps power as the interim solution and updating their values in an iterative process, Raman gain and pump/signal evolution can be calculated in any order of accuracy. In the first order of perturbation, some analytical formulas for the FRA dynamic control are obtained. Analytical formulas are employed for gain ripple minimization and also the gain clamping problem under channel reconfiguration. © 2009 Elsevier Inc. All rights reserved  

Microrings can have different hysteresis characteristics at their different resonance frequencies. They can be used as a multi-hysteresis optical component. In this paper an optical D-flip-flop circuit composed of a single nonlinear passive microring coupled to two straight waveguide based on the Kerr effect is proposed. The proposed circuit can operate as an optical digital circuit which synchronizes input DATA with the CLOCK of the circuit. A simple analytical model for hysteresis design and the transient analysis of the proposed D-flip-flop are presented. According to our model, the switching time of the flip-flop is in the order of 10 ps. Crown Copyright © 2008  

The electric field of the modes of semiconductor microring lasers (SMRLs) in the presence of bus waveguide reflections are linear combinations of the clock wise (CW) and the counter clock wise (CCW) electric fields. The mode structures can be controlled by the waveguide reflection coefficients. The power ratio and phase difference of the CW and CCW fields of one mode is proportional to the ratio of the reflection coefficients of the left and right waveguides. It is shown that the degenerate CW and CCW modes in the presence of bus waveguide reflections are split into two modes with different frequencies. Employing these new modes, SMRL can be used as an element to design flip-flops used in... 

In this paper, an optical fiber multi-intruder sensor based on polarization maintaining optical fiber (PMF), without any interferometric fiber loop, is introduced. To map the local coordinates of intruders on the beating spectrum of the output modes, radiation from a ramp frequency modulated laser is injected at the input of PMF optical fiber sensor. It is shown that the local coordinates and some characteristics of intruders can be obtained by the measurement of the frequencies and amplitudes of the output mode beating spectrum. Generally the number of beating frequencies is more than the number of intruders. Among the beating frequencies, a group with maximum signal to noise ratio is...