Hamed Saghaei | University of Alberta (original) (raw)

Papers by Hamed Saghaei

Research paper thumbnail of Comprehensive Evaluation of Using Solar Water Heater on a Household Scale in Canada P A P E R I N F O Paper history

Journal of Renewable Energy and Environment, 2019

Canadian researchers are now trying to exploit much more energy from solar sources, hydropower, w... more Canadian researchers are now trying to exploit much more energy from solar sources, hydropower, wind, and biomass. Given the fact that reducing the carbon pollutant level is a political priority in Canada, this paper studies the feasibility of providing sanitary hot water and space heating demands of a four-member family in 10 provinces in this country. The feasibility analysis was performed by T*SOL Pro 5.5 software, and radiation data were obtained by MeteoSyn software. Results indicated that the most suitable station in terms of using solar water heater was Regina, which supplied 35 % of the total heat load for space heating and sanitary hot water purposes. This accounted for 5074 kWh of heat for space heating (25 % of demand) and 3112 kWh energy for sanitary hot water (94 % of demand) using a 40 m 2 solar collector. In addition, results are indicative of an annual amount of saving up to 2080 kg of CO2 in the Regina station and an annual reduction of 984 m 3 in natural gas for this station. In conclusion, Canada has a potentially alluring market to utilize solar water heaters for providing sanitary hot water for the residential sector.

Research paper thumbnail of Comprehensive Evaluation of Using Solar Water Heater on a Household Scale in Canada

Journal of Renewable Energy and Environment, 2019

Canadian researchers are now trying to exploit much more energy from solar sources, hydropower, w... more Canadian researchers are now trying to exploit much more energy from solar sources, hydropower, wind, and biomass. Given the fact that reducing the carbon pollutant level is a political priority in Canada, this paper studies the feasibility of providing sanitary hot water and space heating demands of a four-member family in 10 provinces in this country. The feasibility analysis was performed by T*SOL Pro 5.5 software, and radiation data were obtained by MeteoSyn software. Results indicated that the most suitable station in terms of using solar water heater was Regina, which supplied 35 % of the total heat load for space heating and sanitary hot water purposes. This accounted for 5074 kWh of heat for space heating (25 % of demand) and 3112 kWh energy for sanitary hot water (94 % of demand) using a 40 m 2 solar collector. In addition, results are indicative of an annual amount of saving up to 2080 kg of CO2 in the Regina station and an annual reduction of 984 m 3 in natural gas for this station. In conclusion, Canada has a potentially alluring market to utilize solar water heaters for providing sanitary hot water for the residential sector.

Research paper thumbnail of A Novel Architecture for Antenna Arrangement in Wireless Cellular CDMASystems

Wise arrangement of antennas is critical in wireless cellular systems for both reduction of co-ch... more Wise arrangement of antennas is critical in wireless cellular systems for both reduction of co-channel interference (CCI) and increase the quality of service (QoS). In this paper, a novel architecture for antenna arrangement in CDMA wireless cellular systems is presented. In this architecture that we called microzone, every cell is divided into three (or more) zones and information transmission in downlink channel is done by an antenna which is placed at the outer region of the related zone. Also, the transmitting signal by the mobile station (MS) in uplink channel is received by all antennas of the related cell. Analytical calculations of the received signal to noise ratio (SIR) and outage probability for both microzone and used architectures show that proposed architecture has better performance in compared with the used architecture. Also, simulation results confirm lower outage probability in uplink channel for microzone architecture.

Research paper thumbnail of A systematic study of linear and nonlinear properties of photonic crystal fibers

Optik - International Journal for Light and Electron Optics, 2016

Research paper thumbnail of Visible Supercontinuum Generation Using honeycomb PCF

fs 4 ‫ر‬ 28 ‫ﺑﯿﺸﯿﻨﻪ‬ ‫و‬ ‫ي‬ ‫ﺗﻮان‬ kW 10 ‫ا‬ ‫ﯾﮏ‬ ‫ز‬ ‫زﻧﺒﻮري‬ ‫ﻻﻧﻪ‬ ‫ﻓﻮﺗﻮﻧﯽ‬ ‫ﺑﻠﻮر‬ ‫ﻓﯿﺒﺮ‬ ‫ﺑﻪ‬... more fs 4 ‫ر‬ 28 ‫ﺑﯿﺸﯿﻨﻪ‬ ‫و‬ ‫ي‬ ‫ﺗﻮان‬ kW 10 ‫ا‬ ‫ﯾﮏ‬ ‫ز‬ ‫زﻧﺒﻮري‬ ‫ﻻﻧﻪ‬ ‫ﻓﻮﺗﻮﻧﯽ‬ ‫ﺑﻠﻮر‬ ‫ﻓﯿﺒﺮ‬ ‫ﺑﻪ‬ ‫ﻃﻮل‬ 20 ‫ﻣﯿﻠﯽ‬ ‫ﻣﺘﺮ‬ ، ‫ﮐﻪ‬ ‫ﭘﺎﺷﻨﺪﮔﯽ‬ ‫ﻣﻨﺎﺳﺒﯽ‬ ‫ﻧﺤﻮ‬ ‫ﺑﻪ‬ ‫آن‬ ‫ﻣﻬﻨﺪﺳﯽ‬ ‫ﻣﯽ‬ ‫ﺑﺎﺷﺪ،‬ ‫ﺷﺪه‬ ‫ﺗﻮان‬ ‫ﻃﯿﻒ‬ ‫اﺑﺮﭘﯿﻮﺳﺘﺎر‬ ‫ﻣﺤﺪوده‬ ‫در‬ ‫ﯾﮑﻨﻮاﺧﺘﯽ‬ ‫ي‬ ‫ﻣﺮ‬ ‫ﻧﻮر‬ ‫ﺋ‬ ‫ﯽ‬ ‫ﮐﺮد‬ ‫ﺗﻮﻟﯿﺪ‬ . ‫ﺗﺎﺛﯿﺮ‬ ‫ﻫﻤﭽﻨﯿﻦ‬ ‫ﻗﻄﺮ‬ ‫ﻫﺴﺘﻪ‬ ‫ﻓﯿﺒﺮ‬ ‫ي‬ ‫ﻧﺤﻮه‬ ‫ﺑﺮ‬ ‫ﻟﯿﺰر‬ ‫ﻣﻮج‬ ‫ﻃﻮل‬ ‫اﻧﺘﺨﺎب‬ ‫و‬ ‫ﺷﮑﻞ‬ ‫ي‬ ‫ﻃﯿﻒ‬ ‫ﮔﯿﺮي‬ ‫اﺑﺮﭘﯿﻮﺳﺘﺎر‬ ‫رﻓﺘﺎر‬ ‫و‬ ‫ﺷﺪ.‬ ‫ﺧﻮاﻫﺪ‬ ‫ﺑﺤﺚ‬ ‫ﻓﯿﺒﺮ‬ ‫ﻧﻮع‬ ‫اﯾﻦ‬ ‫در‬ ‫ﻧﻮر‬ ‫واژه‬ ‫ﮐﻠﯿﺪ‬ -‫ﭘﺎﺷﻨﺪﮔﯽ،‬ ‫ﺳﻔﯿﺪ‬ ‫ﻧﻮر‬ ‫ﻓﻮﺗﻮﻧﯽ،‬ ‫ﺑﻠﻮر‬ ‫ﻓﯿﺒﺮ‬ ‫اﺑﺮﭘﯿﻮﺳﺘﺎر،‬ ‫ﻃﯿﻒ‬ .

Research paper thumbnail of Ultra-Wide Mid-Infrared Supercontinuum Generation in Αs<sub>40</sub>Se<sub>60</sub> Chalcogenide Fibers: Solid Core PCF versus SIF

IEEE Journal of Selected Topics in Quantum Electronics, 2015

Research paper thumbnail of Design and modeling of a five-channel all optical switch controlled with wavelength based on an asymmetric nonlinear Mach-Zehnder Waveguide

We present design procedure for a five-channel all optical asymmetric Mach-Zehnder switch based o... more We present design procedure for a five-channel all optical asymmetric Mach-Zehnder switch based on wavelength variation. Input signals with the same power but various wavelengths will, exit from the output desired channels. This switch is suitable for the wavelength range of 1.5 µm to 2.05 µm. Numerical simulations show that by increasing the wavelength of the input signal, the output channels will vary accordingly.

Research paper thumbnail of Visible supercontinuum generation in silica-based photonic crystal fiber in normal dispersion regime ‫ا

In this paper, we propose a silica-based photonic crystal fiber (PCF) for visible supercontinuum ... more In this paper, we propose a silica-based photonic crystal fiber (PCF) for visible supercontinuum generation. We, first engineer and optimize both dispersion and nonlinear parameters by varying the air-holes diameter, lattice constant and the number of air-holes rings. Then simulation results demonstrate that by launching an optical pulse with 50 fs time width, 60 kW peak power and center wavelength of 633 nm in normal dispersion region of the fiber into a 20-mm long PCF, a supercontinuum in visible region can be obtained at the end of the fiber.

Research paper thumbnail of Supercontinuum generation in square lattice photonic crystal fiber using optofluidic infiltration

The aim of this paper is to demonstrate the possibility of generating broad band optical supercon... more The aim of this paper is to demonstrate the possibility of generating broad band optical supercontinum, by means of infiltrating the air-holes adjacent to the core of the a square lattice photonic crystal fiber (PCF), by optical fluids of various refractive indices. First, by infiltrating the air holes adjacent to the core of a square lattice PCF its dispersion profile is engi-neered. Then, by launching optical pulses of various wavelengths into the infiltrated PCFs, their outputs are simulated. Simu-lations show that profiles of the dispersion and the effective mode area versus the input wavelength and hence the spectral characteristics of the resulting supercontinum are sensitive to the refractive index of the optical fluid.

Research paper thumbnail of Four-wave mixing based mid-span phase conjugation using slow light engineered chalcogenide and silicon photonic crystal waveguides

2011 Conference on Lasers and Electro-Optics Europe and 12th European Quantum Electronics Conference (CLEO EUROPE/EQEC), 2011

ABSTRACT The goal of this paper is to demonstrate numerically, the mid span phase conjugation usi... more ABSTRACT The goal of this paper is to demonstrate numerically, the mid span phase conjugation using slow light engineered 80 μm Chalcogenide PhC. Mid-span phase conjugation has significant advantages over other methods such as being independent of pulse shape, power, modulation format and bit-rate. We calculate the FWM efficiency for the various waveguides (3mm ridge (black dotted line), 80 μm Si PhC (blue line), and 80 μm Chalcogenide PhC (AMTIR) (red line)) when setting the pump wavelength in the middle of the flatband slow light window.

Research paper thumbnail of Midinfrared supercontinuum generation via As_2Se_3 chalcogenide photonic crystal fibers

Applied Optics, 2015

Using numerical analysis, we compare the results of optofluidic and rod filling techniques for th... more Using numerical analysis, we compare the results of optofluidic and rod filling techniques for the broadening of supercontinuum spectra generated by As2Se3 chalcogenide photonic crystal fibers (PCFs). The numerical results show that when air-holes constituting the innermost ring in a PCF made of As2Se3-based chalcogenide glass are filled with rods of As2Se3-based chalcogenide glass, over a wide range of mid-IR wavelengths, an ultra-flattened near-zero dispersion can be obtained, while the total loss is negligible and the PCF nonlinearity is very high. The simulations also show that when a 50 fs input optical pulse of 10 kW peak power and center wavelength of 4.6 μm is launched into a 50 mm long rod-filled chalcogenide PCF, a ripple-free spectral broadening as wide as 3.86 μm can be obtained.

Research paper thumbnail of New Approach to Closed-Loop Power Control in Cellular CDMA Systems under Multipath Fading

2008 4th International Conference on Wireless Communications, Networking and Mobile Computing, 2008

This paper proposes a new approach to the closed-loop power control algorithm with decision feedb... more This paper proposes a new approach to the closed-loop power control algorithm with decision feedback, called NAPC-DF algorithm. In this algorithm, the step size of the transmitting power by the mobile station (MS) in uplink channel is variable and adjusted by the received command from the base station (BS) and channel conditions. This algorithm is compared with fixed-step, variable step and adaptive step closed-loop power control with decision feedback (FSPC-DF, VSPC-DF and ASPC-DF, respectively). Numerical results indicate that NAPC-DF algorithm, under fading can significantly improve the radio network capacity without any increase in power control signaling. Also the speed of convergence and stability against loop delay can be increased and it decreases the outage probability and bit error rate (BER) of uplink channel in compared with the mentioned references algorithms.

Research paper thumbnail of Power Control with Diversity Antenna Arrays in CDMA Wireless Cellular Systems under Multipath Fading

2008 4th International Conference on Wireless Communications, Networking and Mobile Computing, 2008

In this paper, we present numerical results to show the performance of power control (PC) by usin... more In this paper, we present numerical results to show the performance of power control (PC) by using antenna arrays at the base station (BS). We show that the diversity generated by antenna array, decreases the outage probability, the bit error rate (BER), the fluctuations of the received signal to interference ratio (SIR) over the target SIR, the transmitted power level, and finally increases the speed of convergence of power control algorithms in compared without diversity. These results also increase the system capacity and the quality of service (QoS).

Research paper thumbnail of Variable Step Closed-Loop Power Control in Cellular Wireless CDMA Systems under Multipath Fading

2007 IEEE Pacific Rim Conference on Communications, Computers and Signal Processing, 2007

The Power control has been widely studied and shown to be crucial for the capacity and performanc... more The Power control has been widely studied and shown to be crucial for the capacity and performance of directsequence code-division multiple-access (DS-CDMA) systems. Practical implementations typically employ fast closed-loop power control, where transmitters adjust their transmit powers according to commands received in a feedback channel. The loop delay resulting from the measurements, processing, and transmission of the power control commands can result in oscillations of the transmission powers and lead to degradation in the system performance. In this paper We present new variable step closed-loop power control algorithm (VSPC) and fixed-step closed loop power control with information feedback (FSPC-IF), that are able to increase speed of convergence and alleviate the effect of the loop delay. We carried out computational experiments on a DS-CDMA network using these algorithms. Fixed-step power control with decision feedback (FSPC-DF) is reference algorithm. New algorithms are compared with it. The numerical results indicate that new algorithms can significantly improve the radio network capacity without any increase in power control signaling, also increase speed of convergence and decrease loop delay.

Research paper thumbnail of Minimizing the Connection Cost in a Real GSM Network

2010 International Conference on Computational Intelligence and Software Engineering, 2010

Wise resource allocation is necessary to increase the quality of service (QoS), the system capaci... more Wise resource allocation is necessary to increase the quality of service (QoS), the system capacity, the network performance, and also decrease the power consumption and connection cost. This paper, first, investigates the located global system for mobile (GSM) network in a region of Tehran province in Iran as a case of study and then proposes a novel approach to minimize the connection cost among different parts and components of the GSM network while considering our network practical constraints. The approach of this paper can also be used for the other network planning problems such as the universal mobile telecommunication system (UMTS) in the third generation of the mobile systems. In order to find an optimal solution for the total network connections cost, we use mathematical programming based on mixed integer programming (MIP) algorithm to minimize the connection cost. At the end, simulation and practical results show us that our proposed algorithm decreases the connection cost and improve the QoS of the GSM network.

Research paper thumbnail of A New Approach for Wireless Cellular Network Design

Int'l J. of Communications, Network and System Sciences, 2013

Wise arrangement of antennas is critical in wireless cellular systems for both reduction of co-ch... more Wise arrangement of antennas is critical in wireless cellular systems for both reduction of co-channel interference (CCI) and increase the quality of service (QoS). In this paper, a novel architecture for antenna arrangement in CDMA wireless cellular systems is presented. In this architecture that we called Microzone, every cell is divided into three (or more) zones and information transmission in downlink channel is done by an antenna which is placed at the outer region of the related zone. Also, the transmitting signal by the mobile station (MS) in uplink channel is received by all the antennas of the related cell. Analytical calculations of the received signal to noise ratio (SIR) and outage probability for both microzone and used architectures show that proposed architecture has better performance in compared with the used architecture. Also, simulation results confirm lower outage probability in uplink channel for microzone architecture.

Research paper thumbnail of Novel approach to adjust the step size for closed-loop power control in wireless cellular code division multiple access systems under flat fading

IET Communications, 2011

In this article, we study the power control (PC) process in wireless cellular code division-multi... more In this article, we study the power control (PC) process in wireless cellular code division-multiple access systems under flat fading and propose a novel approach to find an optimum step size for closed-loop power control algorithms. In this approach, an optimum step size will be computed from a proposed function. This function depends on system parameters such as, the number of co-channel users, processing gain, the period of PC, Doppler frequency, channel attenuation and the order of diversity. Based on this computation, the mobile station (MS) adjusts its transmit power optimally to decrease interference for other co-channel users. Simulation results for different sets of system parameters show that the proposed algorithm decreases the bit error rate, the outage probability at the base station (BS), and increases the battery life of the MS compared with other values of the step size. The performance of the proposed algorithm is compared with the fixed-step-size power control algorithm and superiority of its performance is confirmed by simulation results. Moreover, the upper and lower bounds of the outage probability and the received signal-to-interference ratio for the proposed algorithm at the BS will be calculated.

Research paper thumbnail of Minimizing the Total Connection Cost in a Real GSM

Research paper thumbnail of A Novel Architecture for Antenna Arrangement in Wireless Cellular CDMA Systems

Wise arrangement of antennas is critical in wireless cellular systems for both reduction of co-ch... more Wise arrangement of antennas is critical in wireless cellular systems for both reduction of co-channel interference (CCI) and increase the quality of service (QoS). In this paper, a novel architecture for antenna arrangement in CDMA wireless cellular systems is presented. In this architecture that we called microzone, every cell is divided into three (or more) zones and information transmission in downlink channel is done by an antenna which is placed at the outer region of the related zone. Also, the transmitting signal by the mobile station (MS) in uplink channel is received by all antennas of the related cell. Analytical calculations of the received signal to noise ratio (SIR) and outage probability for both microzone and used architectures show that proposed architecture has better performance in compared with the used architecture. Also, simulation results confirm lower outage probability in uplink channel for microzone architecture.

Research paper thumbnail of Proposal for Supercontinuum Generation by Optofluidic Infiltrated Photonic Crystal Fibers

IEEE Journal of Selected Topics in Quantum Electronics, 2000

ABSTRACT We propose a technique based on optofluidic infiltration to design a photonic crystal fi... more ABSTRACT We propose a technique based on optofluidic infiltration to design a photonic crystal fiber (PCF) to control chromatic dispersion for supercontinuum generation. Selectively infiltrating the PCF air-holes with an optical fluid having an appropriate refractive index, we have achieved a PCF with low confinement loss and ultra-flattened near zero dispersion centered about λZD ~ 1325 nm, without a need for nano-scale geometrical tuning. Numerical simulations show that femto-second pulses, with center wavelengths within the range of 1250 nm ≤ λ0 ≤ 1625 nm, can generate relatively flat supercontinuum spectra as wide as 640 to 1180 nm, passing through a 250 mm long PCF whose dispersion profile is engineered via selective optofluidic infiltra-tion. Simulations also show that optical fluid with refractive index of nF=1.32 for input signals having the aforementioned range of wavelengths result in the widest flat supercontinua. This is attributed to the smallest corresponding effective mode area as well as the smallest and flat corresponding dispersion both of which enhance the PCF nonlinearities.

Research paper thumbnail of Comprehensive Evaluation of Using Solar Water Heater on a Household Scale in Canada P A P E R I N F O Paper history

Journal of Renewable Energy and Environment, 2019

Canadian researchers are now trying to exploit much more energy from solar sources, hydropower, w... more Canadian researchers are now trying to exploit much more energy from solar sources, hydropower, wind, and biomass. Given the fact that reducing the carbon pollutant level is a political priority in Canada, this paper studies the feasibility of providing sanitary hot water and space heating demands of a four-member family in 10 provinces in this country. The feasibility analysis was performed by T*SOL Pro 5.5 software, and radiation data were obtained by MeteoSyn software. Results indicated that the most suitable station in terms of using solar water heater was Regina, which supplied 35 % of the total heat load for space heating and sanitary hot water purposes. This accounted for 5074 kWh of heat for space heating (25 % of demand) and 3112 kWh energy for sanitary hot water (94 % of demand) using a 40 m 2 solar collector. In addition, results are indicative of an annual amount of saving up to 2080 kg of CO2 in the Regina station and an annual reduction of 984 m 3 in natural gas for this station. In conclusion, Canada has a potentially alluring market to utilize solar water heaters for providing sanitary hot water for the residential sector.

Research paper thumbnail of Comprehensive Evaluation of Using Solar Water Heater on a Household Scale in Canada

Journal of Renewable Energy and Environment, 2019

Canadian researchers are now trying to exploit much more energy from solar sources, hydropower, w... more Canadian researchers are now trying to exploit much more energy from solar sources, hydropower, wind, and biomass. Given the fact that reducing the carbon pollutant level is a political priority in Canada, this paper studies the feasibility of providing sanitary hot water and space heating demands of a four-member family in 10 provinces in this country. The feasibility analysis was performed by T*SOL Pro 5.5 software, and radiation data were obtained by MeteoSyn software. Results indicated that the most suitable station in terms of using solar water heater was Regina, which supplied 35 % of the total heat load for space heating and sanitary hot water purposes. This accounted for 5074 kWh of heat for space heating (25 % of demand) and 3112 kWh energy for sanitary hot water (94 % of demand) using a 40 m 2 solar collector. In addition, results are indicative of an annual amount of saving up to 2080 kg of CO2 in the Regina station and an annual reduction of 984 m 3 in natural gas for this station. In conclusion, Canada has a potentially alluring market to utilize solar water heaters for providing sanitary hot water for the residential sector.

Research paper thumbnail of A Novel Architecture for Antenna Arrangement in Wireless Cellular CDMASystems

Wise arrangement of antennas is critical in wireless cellular systems for both reduction of co-ch... more Wise arrangement of antennas is critical in wireless cellular systems for both reduction of co-channel interference (CCI) and increase the quality of service (QoS). In this paper, a novel architecture for antenna arrangement in CDMA wireless cellular systems is presented. In this architecture that we called microzone, every cell is divided into three (or more) zones and information transmission in downlink channel is done by an antenna which is placed at the outer region of the related zone. Also, the transmitting signal by the mobile station (MS) in uplink channel is received by all antennas of the related cell. Analytical calculations of the received signal to noise ratio (SIR) and outage probability for both microzone and used architectures show that proposed architecture has better performance in compared with the used architecture. Also, simulation results confirm lower outage probability in uplink channel for microzone architecture.

Research paper thumbnail of A systematic study of linear and nonlinear properties of photonic crystal fibers

Optik - International Journal for Light and Electron Optics, 2016

Research paper thumbnail of Visible Supercontinuum Generation Using honeycomb PCF

fs 4 ‫ر‬ 28 ‫ﺑﯿﺸﯿﻨﻪ‬ ‫و‬ ‫ي‬ ‫ﺗﻮان‬ kW 10 ‫ا‬ ‫ﯾﮏ‬ ‫ز‬ ‫زﻧﺒﻮري‬ ‫ﻻﻧﻪ‬ ‫ﻓﻮﺗﻮﻧﯽ‬ ‫ﺑﻠﻮر‬ ‫ﻓﯿﺒﺮ‬ ‫ﺑﻪ‬... more fs 4 ‫ر‬ 28 ‫ﺑﯿﺸﯿﻨﻪ‬ ‫و‬ ‫ي‬ ‫ﺗﻮان‬ kW 10 ‫ا‬ ‫ﯾﮏ‬ ‫ز‬ ‫زﻧﺒﻮري‬ ‫ﻻﻧﻪ‬ ‫ﻓﻮﺗﻮﻧﯽ‬ ‫ﺑﻠﻮر‬ ‫ﻓﯿﺒﺮ‬ ‫ﺑﻪ‬ ‫ﻃﻮل‬ 20 ‫ﻣﯿﻠﯽ‬ ‫ﻣﺘﺮ‬ ، ‫ﮐﻪ‬ ‫ﭘﺎﺷﻨﺪﮔﯽ‬ ‫ﻣﻨﺎﺳﺒﯽ‬ ‫ﻧﺤﻮ‬ ‫ﺑﻪ‬ ‫آن‬ ‫ﻣﻬﻨﺪﺳﯽ‬ ‫ﻣﯽ‬ ‫ﺑﺎﺷﺪ،‬ ‫ﺷﺪه‬ ‫ﺗﻮان‬ ‫ﻃﯿﻒ‬ ‫اﺑﺮﭘﯿﻮﺳﺘﺎر‬ ‫ﻣﺤﺪوده‬ ‫در‬ ‫ﯾﮑﻨﻮاﺧﺘﯽ‬ ‫ي‬ ‫ﻣﺮ‬ ‫ﻧﻮر‬ ‫ﺋ‬ ‫ﯽ‬ ‫ﮐﺮد‬ ‫ﺗﻮﻟﯿﺪ‬ . ‫ﺗﺎﺛﯿﺮ‬ ‫ﻫﻤﭽﻨﯿﻦ‬ ‫ﻗﻄﺮ‬ ‫ﻫﺴﺘﻪ‬ ‫ﻓﯿﺒﺮ‬ ‫ي‬ ‫ﻧﺤﻮه‬ ‫ﺑﺮ‬ ‫ﻟﯿﺰر‬ ‫ﻣﻮج‬ ‫ﻃﻮل‬ ‫اﻧﺘﺨﺎب‬ ‫و‬ ‫ﺷﮑﻞ‬ ‫ي‬ ‫ﻃﯿﻒ‬ ‫ﮔﯿﺮي‬ ‫اﺑﺮﭘﯿﻮﺳﺘﺎر‬ ‫رﻓﺘﺎر‬ ‫و‬ ‫ﺷﺪ.‬ ‫ﺧﻮاﻫﺪ‬ ‫ﺑﺤﺚ‬ ‫ﻓﯿﺒﺮ‬ ‫ﻧﻮع‬ ‫اﯾﻦ‬ ‫در‬ ‫ﻧﻮر‬ ‫واژه‬ ‫ﮐﻠﯿﺪ‬ -‫ﭘﺎﺷﻨﺪﮔﯽ،‬ ‫ﺳﻔﯿﺪ‬ ‫ﻧﻮر‬ ‫ﻓﻮﺗﻮﻧﯽ،‬ ‫ﺑﻠﻮر‬ ‫ﻓﯿﺒﺮ‬ ‫اﺑﺮﭘﯿﻮﺳﺘﺎر،‬ ‫ﻃﯿﻒ‬ .

Research paper thumbnail of Ultra-Wide Mid-Infrared Supercontinuum Generation in Αs<sub>40</sub>Se<sub>60</sub> Chalcogenide Fibers: Solid Core PCF versus SIF

IEEE Journal of Selected Topics in Quantum Electronics, 2015

Research paper thumbnail of Design and modeling of a five-channel all optical switch controlled with wavelength based on an asymmetric nonlinear Mach-Zehnder Waveguide

We present design procedure for a five-channel all optical asymmetric Mach-Zehnder switch based o... more We present design procedure for a five-channel all optical asymmetric Mach-Zehnder switch based on wavelength variation. Input signals with the same power but various wavelengths will, exit from the output desired channels. This switch is suitable for the wavelength range of 1.5 µm to 2.05 µm. Numerical simulations show that by increasing the wavelength of the input signal, the output channels will vary accordingly.

Research paper thumbnail of Visible supercontinuum generation in silica-based photonic crystal fiber in normal dispersion regime ‫ا

In this paper, we propose a silica-based photonic crystal fiber (PCF) for visible supercontinuum ... more In this paper, we propose a silica-based photonic crystal fiber (PCF) for visible supercontinuum generation. We, first engineer and optimize both dispersion and nonlinear parameters by varying the air-holes diameter, lattice constant and the number of air-holes rings. Then simulation results demonstrate that by launching an optical pulse with 50 fs time width, 60 kW peak power and center wavelength of 633 nm in normal dispersion region of the fiber into a 20-mm long PCF, a supercontinuum in visible region can be obtained at the end of the fiber.

Research paper thumbnail of Supercontinuum generation in square lattice photonic crystal fiber using optofluidic infiltration

The aim of this paper is to demonstrate the possibility of generating broad band optical supercon... more The aim of this paper is to demonstrate the possibility of generating broad band optical supercontinum, by means of infiltrating the air-holes adjacent to the core of the a square lattice photonic crystal fiber (PCF), by optical fluids of various refractive indices. First, by infiltrating the air holes adjacent to the core of a square lattice PCF its dispersion profile is engi-neered. Then, by launching optical pulses of various wavelengths into the infiltrated PCFs, their outputs are simulated. Simu-lations show that profiles of the dispersion and the effective mode area versus the input wavelength and hence the spectral characteristics of the resulting supercontinum are sensitive to the refractive index of the optical fluid.

Research paper thumbnail of Four-wave mixing based mid-span phase conjugation using slow light engineered chalcogenide and silicon photonic crystal waveguides

2011 Conference on Lasers and Electro-Optics Europe and 12th European Quantum Electronics Conference (CLEO EUROPE/EQEC), 2011

ABSTRACT The goal of this paper is to demonstrate numerically, the mid span phase conjugation usi... more ABSTRACT The goal of this paper is to demonstrate numerically, the mid span phase conjugation using slow light engineered 80 μm Chalcogenide PhC. Mid-span phase conjugation has significant advantages over other methods such as being independent of pulse shape, power, modulation format and bit-rate. We calculate the FWM efficiency for the various waveguides (3mm ridge (black dotted line), 80 μm Si PhC (blue line), and 80 μm Chalcogenide PhC (AMTIR) (red line)) when setting the pump wavelength in the middle of the flatband slow light window.

Research paper thumbnail of Midinfrared supercontinuum generation via As_2Se_3 chalcogenide photonic crystal fibers

Applied Optics, 2015

Using numerical analysis, we compare the results of optofluidic and rod filling techniques for th... more Using numerical analysis, we compare the results of optofluidic and rod filling techniques for the broadening of supercontinuum spectra generated by As2Se3 chalcogenide photonic crystal fibers (PCFs). The numerical results show that when air-holes constituting the innermost ring in a PCF made of As2Se3-based chalcogenide glass are filled with rods of As2Se3-based chalcogenide glass, over a wide range of mid-IR wavelengths, an ultra-flattened near-zero dispersion can be obtained, while the total loss is negligible and the PCF nonlinearity is very high. The simulations also show that when a 50 fs input optical pulse of 10 kW peak power and center wavelength of 4.6 μm is launched into a 50 mm long rod-filled chalcogenide PCF, a ripple-free spectral broadening as wide as 3.86 μm can be obtained.

Research paper thumbnail of New Approach to Closed-Loop Power Control in Cellular CDMA Systems under Multipath Fading

2008 4th International Conference on Wireless Communications, Networking and Mobile Computing, 2008

This paper proposes a new approach to the closed-loop power control algorithm with decision feedb... more This paper proposes a new approach to the closed-loop power control algorithm with decision feedback, called NAPC-DF algorithm. In this algorithm, the step size of the transmitting power by the mobile station (MS) in uplink channel is variable and adjusted by the received command from the base station (BS) and channel conditions. This algorithm is compared with fixed-step, variable step and adaptive step closed-loop power control with decision feedback (FSPC-DF, VSPC-DF and ASPC-DF, respectively). Numerical results indicate that NAPC-DF algorithm, under fading can significantly improve the radio network capacity without any increase in power control signaling. Also the speed of convergence and stability against loop delay can be increased and it decreases the outage probability and bit error rate (BER) of uplink channel in compared with the mentioned references algorithms.

Research paper thumbnail of Power Control with Diversity Antenna Arrays in CDMA Wireless Cellular Systems under Multipath Fading

2008 4th International Conference on Wireless Communications, Networking and Mobile Computing, 2008

In this paper, we present numerical results to show the performance of power control (PC) by usin... more In this paper, we present numerical results to show the performance of power control (PC) by using antenna arrays at the base station (BS). We show that the diversity generated by antenna array, decreases the outage probability, the bit error rate (BER), the fluctuations of the received signal to interference ratio (SIR) over the target SIR, the transmitted power level, and finally increases the speed of convergence of power control algorithms in compared without diversity. These results also increase the system capacity and the quality of service (QoS).

Research paper thumbnail of Variable Step Closed-Loop Power Control in Cellular Wireless CDMA Systems under Multipath Fading

2007 IEEE Pacific Rim Conference on Communications, Computers and Signal Processing, 2007

The Power control has been widely studied and shown to be crucial for the capacity and performanc... more The Power control has been widely studied and shown to be crucial for the capacity and performance of directsequence code-division multiple-access (DS-CDMA) systems. Practical implementations typically employ fast closed-loop power control, where transmitters adjust their transmit powers according to commands received in a feedback channel. The loop delay resulting from the measurements, processing, and transmission of the power control commands can result in oscillations of the transmission powers and lead to degradation in the system performance. In this paper We present new variable step closed-loop power control algorithm (VSPC) and fixed-step closed loop power control with information feedback (FSPC-IF), that are able to increase speed of convergence and alleviate the effect of the loop delay. We carried out computational experiments on a DS-CDMA network using these algorithms. Fixed-step power control with decision feedback (FSPC-DF) is reference algorithm. New algorithms are compared with it. The numerical results indicate that new algorithms can significantly improve the radio network capacity without any increase in power control signaling, also increase speed of convergence and decrease loop delay.

Research paper thumbnail of Minimizing the Connection Cost in a Real GSM Network

2010 International Conference on Computational Intelligence and Software Engineering, 2010

Wise resource allocation is necessary to increase the quality of service (QoS), the system capaci... more Wise resource allocation is necessary to increase the quality of service (QoS), the system capacity, the network performance, and also decrease the power consumption and connection cost. This paper, first, investigates the located global system for mobile (GSM) network in a region of Tehran province in Iran as a case of study and then proposes a novel approach to minimize the connection cost among different parts and components of the GSM network while considering our network practical constraints. The approach of this paper can also be used for the other network planning problems such as the universal mobile telecommunication system (UMTS) in the third generation of the mobile systems. In order to find an optimal solution for the total network connections cost, we use mathematical programming based on mixed integer programming (MIP) algorithm to minimize the connection cost. At the end, simulation and practical results show us that our proposed algorithm decreases the connection cost and improve the QoS of the GSM network.

Research paper thumbnail of A New Approach for Wireless Cellular Network Design

Int'l J. of Communications, Network and System Sciences, 2013

Wise arrangement of antennas is critical in wireless cellular systems for both reduction of co-ch... more Wise arrangement of antennas is critical in wireless cellular systems for both reduction of co-channel interference (CCI) and increase the quality of service (QoS). In this paper, a novel architecture for antenna arrangement in CDMA wireless cellular systems is presented. In this architecture that we called Microzone, every cell is divided into three (or more) zones and information transmission in downlink channel is done by an antenna which is placed at the outer region of the related zone. Also, the transmitting signal by the mobile station (MS) in uplink channel is received by all the antennas of the related cell. Analytical calculations of the received signal to noise ratio (SIR) and outage probability for both microzone and used architectures show that proposed architecture has better performance in compared with the used architecture. Also, simulation results confirm lower outage probability in uplink channel for microzone architecture.

Research paper thumbnail of Novel approach to adjust the step size for closed-loop power control in wireless cellular code division multiple access systems under flat fading

IET Communications, 2011

In this article, we study the power control (PC) process in wireless cellular code division-multi... more In this article, we study the power control (PC) process in wireless cellular code division-multiple access systems under flat fading and propose a novel approach to find an optimum step size for closed-loop power control algorithms. In this approach, an optimum step size will be computed from a proposed function. This function depends on system parameters such as, the number of co-channel users, processing gain, the period of PC, Doppler frequency, channel attenuation and the order of diversity. Based on this computation, the mobile station (MS) adjusts its transmit power optimally to decrease interference for other co-channel users. Simulation results for different sets of system parameters show that the proposed algorithm decreases the bit error rate, the outage probability at the base station (BS), and increases the battery life of the MS compared with other values of the step size. The performance of the proposed algorithm is compared with the fixed-step-size power control algorithm and superiority of its performance is confirmed by simulation results. Moreover, the upper and lower bounds of the outage probability and the received signal-to-interference ratio for the proposed algorithm at the BS will be calculated.

Research paper thumbnail of Minimizing the Total Connection Cost in a Real GSM

Research paper thumbnail of A Novel Architecture for Antenna Arrangement in Wireless Cellular CDMA Systems

Wise arrangement of antennas is critical in wireless cellular systems for both reduction of co-ch... more Wise arrangement of antennas is critical in wireless cellular systems for both reduction of co-channel interference (CCI) and increase the quality of service (QoS). In this paper, a novel architecture for antenna arrangement in CDMA wireless cellular systems is presented. In this architecture that we called microzone, every cell is divided into three (or more) zones and information transmission in downlink channel is done by an antenna which is placed at the outer region of the related zone. Also, the transmitting signal by the mobile station (MS) in uplink channel is received by all antennas of the related cell. Analytical calculations of the received signal to noise ratio (SIR) and outage probability for both microzone and used architectures show that proposed architecture has better performance in compared with the used architecture. Also, simulation results confirm lower outage probability in uplink channel for microzone architecture.

Research paper thumbnail of Proposal for Supercontinuum Generation by Optofluidic Infiltrated Photonic Crystal Fibers

IEEE Journal of Selected Topics in Quantum Electronics, 2000

ABSTRACT We propose a technique based on optofluidic infiltration to design a photonic crystal fi... more ABSTRACT We propose a technique based on optofluidic infiltration to design a photonic crystal fiber (PCF) to control chromatic dispersion for supercontinuum generation. Selectively infiltrating the PCF air-holes with an optical fluid having an appropriate refractive index, we have achieved a PCF with low confinement loss and ultra-flattened near zero dispersion centered about λZD ~ 1325 nm, without a need for nano-scale geometrical tuning. Numerical simulations show that femto-second pulses, with center wavelengths within the range of 1250 nm ≤ λ0 ≤ 1625 nm, can generate relatively flat supercontinuum spectra as wide as 640 to 1180 nm, passing through a 250 mm long PCF whose dispersion profile is engineered via selective optofluidic infiltra-tion. Simulations also show that optical fluid with refractive index of nF=1.32 for input signals having the aforementioned range of wavelengths result in the widest flat supercontinua. This is attributed to the smallest corresponding effective mode area as well as the smallest and flat corresponding dispersion both of which enhance the PCF nonlinearities.