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Karim Abbasian

University of Tabriz, Faculty of Electrical and Computer Engineering, Faculty Member

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I am working on Nanophotonics&Nanoelectronics and Nanotechnology fields including solar cells, plasmonics, Bioelectromagnetics and so on. Also, I've started to work on Biomedicine subfields such as functional brain networks and their dynamicity.

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Rafael Abargues

Universitat de València

Prof.Dr. İbrahim USLU

Gazi University

Kenneth Vecchio

University of California, San Diego

University of Illinois at Urbana-Champaign

University of Sarajevo

University of Dr moulay taher

shivani R pandya

Parul university

Yalova University

Al-Azhar University

Jephias Gwamuri

National University of Sciences & Technology (NUST)

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Papers by Karim Abbasian

Electromagnetically induced transparency-based gas detector design using Michelson interferometer

International Nano Letters, May 14, 2013

In this paper, we have designed an all-optical controllable gas detector by doping 3-level Λ type... more In this paper, we have designed an all-optical controllable gas detector by doping 3-level Λ type nanocrystals in the moving arms' mirror of Michelson interferometer and used electromagnetically induced transparency (EIT) phenomenon to change its refractive index. By this means, we have created a controllable phase difference between light beams in two arms of the Michelson interferometer, where reflection phase of the EIT-based mirror changes about π radiant. Also, the signal reflection from EIT-based mirror changes between 0% and 100% approximately, while the second arm's signal is reflected completely. This EIT-based mirror's refractive index change can be a good alternative for conventional Michelson interferometer-based gas detector with one mechanical moving arm mirror (Undergraduate Instrumental Analysis, 6th edn. Marcel Dekker, New York, 2005), where long response time and unfix moving speed were its main drawbacks. While, in this scheme, not only these disadvantages are removed but also the response time can reach the electron transient time between the atomic energy levels. Then, by this all-optical tunable gas detector, we have achieved many modifications such as response time in sub-nanoseconds, high resolution, and high accuracy, or less cross sensitivity to other gas species.

Multiplexor 4 x 1 de alto rendimiento basado en un transistor de efecto de campo de nanotubos de carbono de pared simple con lógica de transistor de paso similar a CMOS

Ingeniería - Universidad de Carabobo, Facultad de Ingeniería, Dec 30, 2020

In the current research, the best property of Carbon Nanotube Field Effect Transistors (CNTFETs) ... more In the current research, the best property of Carbon Nanotube Field Effect Transistors (CNTFETs) exploited to propose a high performance 4-input 1-output (4 × 1) Multiplexer, using a CMOS-like Pass Transistor Logic (PTL) design style. To enhance a significant reduction in circuit complexity and a corresponding improvement in the performance envelope (power, area and speed) with respect to conventional CMOS equivalent circuit. The operating principles and experimental results for the PTL circuits using both p-FET and n-FET of CNTFETs presented. This property can be used in a multiplexer circuit, which transfers one of several input data to the output according to the control signal values. Results demonstrated that using of CNTFET can be achieved by constructing high performance carbon nanotube-based integrated circuits like logic Multiplexer based on a pass-transistor logic configuration. Further, this circuits can assembly with other circuits based on other Field effect transistors technology like GNR-FETs and improve ALU (Arithmetic Logic Unit) section of many processor ICs in high level of Nano-Scale VLSIs. The simulation results presented, and the power consumption compared with the conventional CMOS designs. The comparison of results approved that the CNTFET based design is capable of efficient power savings and high-speed performance.

Design of Optical Tunable CNOT (XOR) and XNOR Logic Gates Based on 2D-Photonic Crystal Cavity Using Electro-Optic Effect

arXiv: Optics, 2016

We have proposed optical tunable CNOT (XOR) and XNOR logic gates using two-dimensional photonic c... more We have proposed optical tunable CNOT (XOR) and XNOR logic gates using two-dimensional photonic crystal (2DPhC) cavities. Where, air rods with square lattice array have been embedded in Ag-Polymer substrate with refractive index of 1.59. In this work, we have enhanced speed of logic gates by applying two input signals with a phase difference at the same wavelength for 2DPhC cavities. Where, we have adjusted the phases of input and control signals equal with {\pi}/3 and zero, respectively. The response time of the structure and quality factor of the cavities are in the range of femtosecond and 2000, respectively. Then, we have used electro-optic property of the substrate material to change the cavities resonance wavelengths. By this means, we could design the logic gates and demonstrate a tunable range of 23nm for their operation wavelength. The quality factor and the response times of cavities remain constant in the tunable range of wavelength, approximately. The evaluated least ON ...

All-optical analog-to-digital converter based on Kerr effect in photonic crystal

Optics & Laser Technology, 2018

In this paper, a novel all-optical analog-to-digital converter (AOADC) is proposed and simulated ... more In this paper, a novel all-optical analog-to-digital converter (AOADC) is proposed and simulated for proof of principle. This AOADC is designed to operate in the range of telecom wavelength (1550 nm). A cavity made of nonlinear Kerr material in photonic crystal (PhC), is designed to achieve an optical analog-todigital conversion with 1 Tera sample per second (TS/s) and the total footprint of 42 lm 2 . The simulation is done using finite-difference time domain (FDTD) method.

Ultra-fast all-optical plasmonic switching in near infra-red spectrum using a Kerr nonlinear ring resonator

Optics Communications, 2018

In this paper, an all-optical plasmonic switch based on metal-insulator-metal (MIM) nanoplasmonic... more In this paper, an all-optical plasmonic switch based on metal-insulator-metal (MIM) nanoplasmonic waveguide with a Kerr nonlinear ring resonator is introduced and studied. Two-dimensional simulations utilizing the finite-difference time-domain algorithm are used to demonstrate an apparent optical bistability and significant switching mechanisms (in enabled-low condition: 𝑇 (ON/OFF) =21.9 and in enabled-high condition: 𝑇 (ON/OFF) =24.9) of the signal light arisen by altering the pump-light intensity. The proposed all-optical switching demonstrates femtosecond-scale feedback time (90 fs) and then ultra-fast switching can be achieved. The offered all-optical switch may recognize potential significant applications in integrated optical circuits.

Design of Hybrid Solar Cell Based on Dye-Sensitized TiO2Nanoparticles with Conjugated Polymer

Acta Physica Polonica A, 2012

In this paper, we have proposed dye-sensitized hybrid solar cell based on TiO 2 nanoparticles as ... more In this paper, we have proposed dye-sensitized hybrid solar cell based on TiO 2 nanoparticles as a medium for electron transport and conjugated polymers as hole-conductor, where dye molecules absorb solar radiation and create electron-hole pairs. This solar cell can be a better alternative to conventional electrolyte based dye-sensitized solar cells, because of enhanced characteristics of performance. We have simulated it numerically, to study essential characteristics of the structure such as electron, hole and their current densities and internal electric field in two operating conditions of open-circuit and short-circuit cases. Then current-voltage characteristic diagram has been plotted and energy conversion efficiency calculated.

Efficiency optimization in a rainbow quantum dot solar cell

In this paper, we have calculated the efficiency and I-V characteristic of a Quantum Dot (QD) Sol... more In this paper, we have calculated the efficiency and I-V characteristic of a Quantum Dot (QD) Solar Cell (SC) based on multi-stacked different-sized InGaN QDs on GaN substrate. In order to engineering the confinement states of QDs, we have inserted differentsized QDs in i-region of a p-i-n structure which includes different layers. This leads to Rainbow SCs.

Analytical Modeling of Quality Factor for Shell Type Microsphere Resonators

Progress In Electromagnetics Research B, 2011

In this paper, we have proposed a shell type dielectric microsphere resonator in order to enhance... more In this paper, we have proposed a shell type dielectric microsphere resonator in order to enhance its quality factor. In this work we have assumed that the radius of dielectric microsphere is 12 µm and that the interior metal layer radius is 11.5 µm. We have obtained analytic equations for Vector potentials, characteristic equation, quality factor, resonance frequency and resonance location of TE modes. We have plotted these characteristics by MATLAB software and compared them with the normal microsphere characteristics.

THz-Assisted Instantaneous Gain Switching in Quantum Dot Semiconductor Optical Amplifiers

IEEE Photonics Technology Letters, 2015

ABSTRACT A new concept of instantaneous gain switching in quantum dot semiconductor optical ampli... more ABSTRACT A new concept of instantaneous gain switching in quantum dot semiconductor optical amplifier (QD-SOA) is introduced in this letter. Based on numerical modeling, instantaneous gain dynamics of a QD-SOA due to modulation of quantum confinement potential of quantum dots with applied terahertz (THz) electric field is described and gain clamping phenomenon is discussed. The proposed gain switching mechanism is promising for THz to optical wavelength conversion in THz communication scenarios.

Developing a new pressure measurement mechanism based on squeeze film damping effect

The 2nd International Conference on Control, Instrumentation and Automation, 2011

This paper introduces a novel approach for measuring low pressures based on MEMS technology. In t... more This paper introduces a novel approach for measuring low pressures based on MEMS technology. In this technique the mechanism of squeeze film damping is used. A voltage is applied to a fixed-fixed MEMS beam and its step response is obtained; for each pressure there is a different response. Then the settling time is measured and we can relate each settling time with a defined pressure. Here, first we use some equations to relate pressure with the squeeze film damping effect; after that we use a micro beam model and relate its parameters with pressure. Then we use numerical analysis and simulation to show the procedure of pressure measuring. All simulation results are shown and discussed.

Long wavelength infrared photodetector design based on electromagnetically induced transparency

Optics Communications, 2008

A novel long-wavelength infrared (IR) photodetector based on Electromagnetically induced transpar... more A novel long-wavelength infrared (IR) photodetector based on Electromagnetically induced transparency (EIT) which is suitable for operation in about room temperature and THz range is proposed and analyzed in detail in this article. The main point in this paper for operation in room temperature is related to convert the incoming long-wavelength IR signal to short-wavelength or visible probe optical field through EIT phenomena. For realization of the idea, we used 4, 5- and 6-level atoms implemented by quantum wells or dots. In the proposed structure long-wavelength IR signal does not interact directly with electrons, but affects the absorption characteristics of short-wavelength or visible probe optical field. Therefore, the proposed structure reduces and cancels out the important thermionic dark current component. So, the proposed idea can operate as long wavelength photodetector.

Mode propagation in a double layer structure microsphere

2010 17th Iranian Conference of Biomedical Engineering (ICBME), 2010

ABSTRACT In this paper propagation of light in microsphere and using it as a powerful sensor is d... more ABSTRACT In this paper propagation of light in microsphere and using it as a powerful sensor is described. A new multilayer structure sphere is proposed and its characteristic equation would be obtained. With this structure quality factor (Q) would be improved. Recent improvement in utilizing this powerful sensor with very high quality factor (Q) in biomedical and specially biophotonic is reported.

Spectrum envelope analysis of sampled gratings with different sampling segments

International Conference On Photonics 2010, 2010

An analytical method for reflection-spectrum envelope calculation of sampled gratings with differ... more An analytical method for reflection-spectrum envelope calculation of sampled gratings with different sampling periods and phase shifts is presented. In this paper we study the effects of different phase shifts and sampling lengths on the reflection spectrum envelope. The optimum values for phase shift and sampling segments length in order to achieve flat top reflection and maximum 3-dB bandwidth have been suggested.

Effect of charge carriers and excitons mobility on transport in an organic solar cell

2012 International Conference on Optical Engineering (ICOE), 2012

Effect of charge carriers and excitons mobility on transport in an organic solar cell In: N.B. Wh... more

An organic solar cell: Investigation of band offset effect on transport and the validity of reciprocity theorem between electroluminescence and quantum efficiency

2012 International Conference on Optical Engineering (ICOE), 2012

ABSTRACT The paper on hand shows an organic solar cell that combines the Shockley Queisser (SQ) t... more ABSTRACT The paper on hand shows an organic solar cell that combines the Shockley Queisser (SQ) theory with the classical diode theory to describe the microscopic processes which exist inside a cell. The photon recycling term is used to connect these two existing theories of solar cells. So this model can describe the interactions of electrons, holes and excitons and also reproduces the maximum SQ quantum efficiency. We show that how conduction band offset affect the short circuit current density and the operation modes of solar cell. Also we determine a relation that links the photovoltaic quantum efficiency and electroluminescence emission. We use this relation to calculate the quantum efficiency from electroluminescence (EL) and to compare with the directly calculated quantum efficiency.

Charge carriers and excitons transport in an organic solar cell-theory and simulation

Electronic Materials Letters, 2012

An organic solar cell model is developed that consists of both excitonic and classical bipolar as... more An organic solar cell model is developed that consists of both excitonic and classical bipolar aspects of solar cells. In order to achieve this goal, the photon recycling term is imported into the equations to connect the Shockley-Queisser theory and the classical diode theory. This model for excitonic and classical bipolar solar cells can describe the combined transport and interaction of electrons, holes and excitons. For high mobilities this model reproduces the Shockley Queisser efficiency limit. We show how varying the respective mobilities of the different species changes the operation mode of the solar cell path between excitonic and bipolar. Then, the effect of conduction band offset on transport will be described in this paper. Finally, validity of reciprocity theorem between quantum efficiency and electroluminescence in this model will be discussed.

EIT Based Gas Detector Design by Using Michelson Interferometer

AIP Conference Proceedings, 2011

ABSTRACT Electromagnetically induced transparency (EIT) is one of the interesting phenomena of li... more ABSTRACT Electromagnetically induced transparency (EIT) is one of the interesting phenomena of light-matter interaction which modifies matter properties for propagation of light. In other words, we can change the absorption and refractive index (RI) in neighborhood of the resonant frequency using EIT. In this paper, we have doped 3-level quantum dots in one of the Michelson Interferometer&#39;s mirror and used EIT to change its RI. So, a controllable phase difference between lights in two arms of interferometer is created. Long response time is the main drawback of Michelson interferometer based sensor, which is resolved by this technique.

All-optical loadable and erasable memory cell design based on inversionless lasing and electromagnetically induced transparency effects

Quantum Electronics, 2011

Star clusters have long been used to illuminate both stellar evolution and Galactic evolution. Th... more Star clusters have long been used to illuminate both stellar evolution and Galactic evolution. They also hold clues to the chemical and nucleosynthetic processes throughout the history of the Galaxy. We have taken high signal-tonoise (S/N), high-resolution spectra of 11 solar-type stars in the Praesepe open cluster to determine the chemical abundances of 16 elements: Li, C, O, Na, Mg, Al, Si, Ca, Sc, Ti, V, Cr, Fe, Ni, Y, and Ba. We have determined Fe from Fe i and Fe ii lines and find [Fe/H] = +0.12 ±0.04. We find that Li decreases with temperature due to increasing Li depletion in cooler stars; it matches the Li-temperature pattern found in the Hyades. The [C/Fe] and [O/Fe] abundances are below solar and lower than the field star samples due to the younger age of Praesepe (0.7 Gyr) than the field stars. The alpha-elements, Mg, Si, Ca, and Ti, have solar ratios with respect to Fe, and are also lower than the field star samples. The Fe-peak elements, Cr and Ni, track Fe and have solar values. The neutron capture element [Y/Fe] is found to be solar, but [Ba/Fe] is enhanced relative to solar and to the field stars. Three Praesepe giants were studied by Carrera and Pancino; they are apparently enhanced in Na, Mg, and Ba relative to the Praesepe dwarfs. The Na enhancement may indicate proton-capture nucleosynthesis in the Ne → Na cycling with dredge-up into the atmospheres of the red giants.

WITHDRAWN: Ultrasmall and tunable all-optical photonic crystal-based demultiplexer for DWDM systems

Photonics and Nanostructures - Fundamentals and Applications, 2009

WITHDRAWN: Ultrasmall and tunable all-optical photonic crystalbased demultiplexer for DWDM system... more WITHDRAWN: Ultrasmall and tunable all-optical photonic crystalbased demultiplexer for DWDM systems H. Habibiyan , H. Ghafoori-Fard , K. Abbasian , A. Rostami b,c a Faculty of Electrical Engineering, Amirkabir University of Technology, Tehran 15914, Iran b Photonics and Nanocrystal Research Laboratory (PNRL), Faculty of Electrical and Computer Engineering, University of Tabriz, Tabriz 51664, Iran c School of Engineering Emerging Technologies, University of Tabriz, Tabriz 51664, Iran

Design of an ultrafast all-optical NOR logic gate based on Mach-Zehnder interferometer using quantum-dot SOA

Optik, 2014

This paper proposes a design for all-optical NOR logic gate, based on Mach-Zehnder interferometer... more This paper proposes a design for all-optical NOR logic gate, based on Mach-Zehnder interferometer (MZI) using quantum-dot semiconductor optical amplifier (QD-SOA). In this regard, a theoretical model for an ultrafast all-optical signal processor is developed using QD-SOA to achieve high bit rate operation. We have demonstrated the NOR gate operation in two cases of with and without an optical control pulse. Simulations have been carried out at data bit rates 160 Gb/s, 200 Gb/s, and 250 Gb/s for the case that control pulse is not applied, and also at data bit rates 1 Tb/s and 2 Tb/s in presence of control pulse which leads to improvement of gain recovery time and ultrafast NOR logic operation. In addition, quality factors of the output signals in presence and without the control pulse at different bit rates with different bias currents have been investigated for pseudo-random binary sequence (PRBS) of word length 2 8 -1.

Electromagnetically induced transparency-based gas detector design using Michelson interferometer

International Nano Letters, May 14, 2013

In this paper, we have designed an all-optical controllable gas detector by doping 3-level Λ type... more In this paper, we have designed an all-optical controllable gas detector by doping 3-level Λ type nanocrystals in the moving arms' mirror of Michelson interferometer and used electromagnetically induced transparency (EIT) phenomenon to change its refractive index. By this means, we have created a controllable phase difference between light beams in two arms of the Michelson interferometer, where reflection phase of the EIT-based mirror changes about π radiant. Also, the signal reflection from EIT-based mirror changes between 0% and 100% approximately, while the second arm's signal is reflected completely. This EIT-based mirror's refractive index change can be a good alternative for conventional Michelson interferometer-based gas detector with one mechanical moving arm mirror (Undergraduate Instrumental Analysis, 6th edn. Marcel Dekker, New York, 2005), where long response time and unfix moving speed were its main drawbacks. While, in this scheme, not only these disadvantages are removed but also the response time can reach the electron transient time between the atomic energy levels. Then, by this all-optical tunable gas detector, we have achieved many modifications such as response time in sub-nanoseconds, high resolution, and high accuracy, or less cross sensitivity to other gas species.

Multiplexor 4 x 1 de alto rendimiento basado en un transistor de efecto de campo de nanotubos de carbono de pared simple con lógica de transistor de paso similar a CMOS

Ingeniería - Universidad de Carabobo, Facultad de Ingeniería, Dec 30, 2020

In the current research, the best property of Carbon Nanotube Field Effect Transistors (CNTFETs) ... more In the current research, the best property of Carbon Nanotube Field Effect Transistors (CNTFETs) exploited to propose a high performance 4-input 1-output (4 × 1) Multiplexer, using a CMOS-like Pass Transistor Logic (PTL) design style. To enhance a significant reduction in circuit complexity and a corresponding improvement in the performance envelope (power, area and speed) with respect to conventional CMOS equivalent circuit. The operating principles and experimental results for the PTL circuits using both p-FET and n-FET of CNTFETs presented. This property can be used in a multiplexer circuit, which transfers one of several input data to the output according to the control signal values. Results demonstrated that using of CNTFET can be achieved by constructing high performance carbon nanotube-based integrated circuits like logic Multiplexer based on a pass-transistor logic configuration. Further, this circuits can assembly with other circuits based on other Field effect transistors technology like GNR-FETs and improve ALU (Arithmetic Logic Unit) section of many processor ICs in high level of Nano-Scale VLSIs. The simulation results presented, and the power consumption compared with the conventional CMOS designs. The comparison of results approved that the CNTFET based design is capable of efficient power savings and high-speed performance.

Design of Optical Tunable CNOT (XOR) and XNOR Logic Gates Based on 2D-Photonic Crystal Cavity Using Electro-Optic Effect

arXiv: Optics, 2016

We have proposed optical tunable CNOT (XOR) and XNOR logic gates using two-dimensional photonic c... more We have proposed optical tunable CNOT (XOR) and XNOR logic gates using two-dimensional photonic crystal (2DPhC) cavities. Where, air rods with square lattice array have been embedded in Ag-Polymer substrate with refractive index of 1.59. In this work, we have enhanced speed of logic gates by applying two input signals with a phase difference at the same wavelength for 2DPhC cavities. Where, we have adjusted the phases of input and control signals equal with {\pi}/3 and zero, respectively. The response time of the structure and quality factor of the cavities are in the range of femtosecond and 2000, respectively. Then, we have used electro-optic property of the substrate material to change the cavities resonance wavelengths. By this means, we could design the logic gates and demonstrate a tunable range of 23nm for their operation wavelength. The quality factor and the response times of cavities remain constant in the tunable range of wavelength, approximately. The evaluated least ON ...

All-optical analog-to-digital converter based on Kerr effect in photonic crystal

Optics & Laser Technology, 2018

In this paper, a novel all-optical analog-to-digital converter (AOADC) is proposed and simulated ... more In this paper, a novel all-optical analog-to-digital converter (AOADC) is proposed and simulated for proof of principle. This AOADC is designed to operate in the range of telecom wavelength (1550 nm). A cavity made of nonlinear Kerr material in photonic crystal (PhC), is designed to achieve an optical analog-todigital conversion with 1 Tera sample per second (TS/s) and the total footprint of 42 lm 2 . The simulation is done using finite-difference time domain (FDTD) method.

Ultra-fast all-optical plasmonic switching in near infra-red spectrum using a Kerr nonlinear ring resonator

Optics Communications, 2018

In this paper, an all-optical plasmonic switch based on metal-insulator-metal (MIM) nanoplasmonic... more In this paper, an all-optical plasmonic switch based on metal-insulator-metal (MIM) nanoplasmonic waveguide with a Kerr nonlinear ring resonator is introduced and studied. Two-dimensional simulations utilizing the finite-difference time-domain algorithm are used to demonstrate an apparent optical bistability and significant switching mechanisms (in enabled-low condition: 𝑇 (ON/OFF) =21.9 and in enabled-high condition: 𝑇 (ON/OFF) =24.9) of the signal light arisen by altering the pump-light intensity. The proposed all-optical switching demonstrates femtosecond-scale feedback time (90 fs) and then ultra-fast switching can be achieved. The offered all-optical switch may recognize potential significant applications in integrated optical circuits.

Design of Hybrid Solar Cell Based on Dye-Sensitized TiO2Nanoparticles with Conjugated Polymer

Acta Physica Polonica A, 2012

In this paper, we have proposed dye-sensitized hybrid solar cell based on TiO 2 nanoparticles as ... more In this paper, we have proposed dye-sensitized hybrid solar cell based on TiO 2 nanoparticles as a medium for electron transport and conjugated polymers as hole-conductor, where dye molecules absorb solar radiation and create electron-hole pairs. This solar cell can be a better alternative to conventional electrolyte based dye-sensitized solar cells, because of enhanced characteristics of performance. We have simulated it numerically, to study essential characteristics of the structure such as electron, hole and their current densities and internal electric field in two operating conditions of open-circuit and short-circuit cases. Then current-voltage characteristic diagram has been plotted and energy conversion efficiency calculated.

Efficiency optimization in a rainbow quantum dot solar cell

In this paper, we have calculated the efficiency and I-V characteristic of a Quantum Dot (QD) Sol... more In this paper, we have calculated the efficiency and I-V characteristic of a Quantum Dot (QD) Solar Cell (SC) based on multi-stacked different-sized InGaN QDs on GaN substrate. In order to engineering the confinement states of QDs, we have inserted differentsized QDs in i-region of a p-i-n structure which includes different layers. This leads to Rainbow SCs.

Analytical Modeling of Quality Factor for Shell Type Microsphere Resonators

Progress In Electromagnetics Research B, 2011

In this paper, we have proposed a shell type dielectric microsphere resonator in order to enhance... more In this paper, we have proposed a shell type dielectric microsphere resonator in order to enhance its quality factor. In this work we have assumed that the radius of dielectric microsphere is 12 µm and that the interior metal layer radius is 11.5 µm. We have obtained analytic equations for Vector potentials, characteristic equation, quality factor, resonance frequency and resonance location of TE modes. We have plotted these characteristics by MATLAB software and compared them with the normal microsphere characteristics.

THz-Assisted Instantaneous Gain Switching in Quantum Dot Semiconductor Optical Amplifiers

IEEE Photonics Technology Letters, 2015

ABSTRACT A new concept of instantaneous gain switching in quantum dot semiconductor optical ampli... more ABSTRACT A new concept of instantaneous gain switching in quantum dot semiconductor optical amplifier (QD-SOA) is introduced in this letter. Based on numerical modeling, instantaneous gain dynamics of a QD-SOA due to modulation of quantum confinement potential of quantum dots with applied terahertz (THz) electric field is described and gain clamping phenomenon is discussed. The proposed gain switching mechanism is promising for THz to optical wavelength conversion in THz communication scenarios.

Developing a new pressure measurement mechanism based on squeeze film damping effect

The 2nd International Conference on Control, Instrumentation and Automation, 2011

This paper introduces a novel approach for measuring low pressures based on MEMS technology. In t... more This paper introduces a novel approach for measuring low pressures based on MEMS technology. In this technique the mechanism of squeeze film damping is used. A voltage is applied to a fixed-fixed MEMS beam and its step response is obtained; for each pressure there is a different response. Then the settling time is measured and we can relate each settling time with a defined pressure. Here, first we use some equations to relate pressure with the squeeze film damping effect; after that we use a micro beam model and relate its parameters with pressure. Then we use numerical analysis and simulation to show the procedure of pressure measuring. All simulation results are shown and discussed.

Long wavelength infrared photodetector design based on electromagnetically induced transparency

Optics Communications, 2008

A novel long-wavelength infrared (IR) photodetector based on Electromagnetically induced transpar... more A novel long-wavelength infrared (IR) photodetector based on Electromagnetically induced transparency (EIT) which is suitable for operation in about room temperature and THz range is proposed and analyzed in detail in this article. The main point in this paper for operation in room temperature is related to convert the incoming long-wavelength IR signal to short-wavelength or visible probe optical field through EIT phenomena. For realization of the idea, we used 4, 5- and 6-level atoms implemented by quantum wells or dots. In the proposed structure long-wavelength IR signal does not interact directly with electrons, but affects the absorption characteristics of short-wavelength or visible probe optical field. Therefore, the proposed structure reduces and cancels out the important thermionic dark current component. So, the proposed idea can operate as long wavelength photodetector.

Mode propagation in a double layer structure microsphere

2010 17th Iranian Conference of Biomedical Engineering (ICBME), 2010

ABSTRACT In this paper propagation of light in microsphere and using it as a powerful sensor is d... more ABSTRACT In this paper propagation of light in microsphere and using it as a powerful sensor is described. A new multilayer structure sphere is proposed and its characteristic equation would be obtained. With this structure quality factor (Q) would be improved. Recent improvement in utilizing this powerful sensor with very high quality factor (Q) in biomedical and specially biophotonic is reported.

Spectrum envelope analysis of sampled gratings with different sampling segments

International Conference On Photonics 2010, 2010

An analytical method for reflection-spectrum envelope calculation of sampled gratings with differ... more An analytical method for reflection-spectrum envelope calculation of sampled gratings with different sampling periods and phase shifts is presented. In this paper we study the effects of different phase shifts and sampling lengths on the reflection spectrum envelope. The optimum values for phase shift and sampling segments length in order to achieve flat top reflection and maximum 3-dB bandwidth have been suggested.

Effect of charge carriers and excitons mobility on transport in an organic solar cell

2012 International Conference on Optical Engineering (ICOE), 2012

Effect of charge carriers and excitons mobility on transport in an organic solar cell In: N.B. Wh... more

An organic solar cell: Investigation of band offset effect on transport and the validity of reciprocity theorem between electroluminescence and quantum efficiency

2012 International Conference on Optical Engineering (ICOE), 2012

ABSTRACT The paper on hand shows an organic solar cell that combines the Shockley Queisser (SQ) t... more ABSTRACT The paper on hand shows an organic solar cell that combines the Shockley Queisser (SQ) theory with the classical diode theory to describe the microscopic processes which exist inside a cell. The photon recycling term is used to connect these two existing theories of solar cells. So this model can describe the interactions of electrons, holes and excitons and also reproduces the maximum SQ quantum efficiency. We show that how conduction band offset affect the short circuit current density and the operation modes of solar cell. Also we determine a relation that links the photovoltaic quantum efficiency and electroluminescence emission. We use this relation to calculate the quantum efficiency from electroluminescence (EL) and to compare with the directly calculated quantum efficiency.

Charge carriers and excitons transport in an organic solar cell-theory and simulation

Electronic Materials Letters, 2012

An organic solar cell model is developed that consists of both excitonic and classical bipolar as... more An organic solar cell model is developed that consists of both excitonic and classical bipolar aspects of solar cells. In order to achieve this goal, the photon recycling term is imported into the equations to connect the Shockley-Queisser theory and the classical diode theory. This model for excitonic and classical bipolar solar cells can describe the combined transport and interaction of electrons, holes and excitons. For high mobilities this model reproduces the Shockley Queisser efficiency limit. We show how varying the respective mobilities of the different species changes the operation mode of the solar cell path between excitonic and bipolar. Then, the effect of conduction band offset on transport will be described in this paper. Finally, validity of reciprocity theorem between quantum efficiency and electroluminescence in this model will be discussed.

EIT Based Gas Detector Design by Using Michelson Interferometer

AIP Conference Proceedings, 2011

ABSTRACT Electromagnetically induced transparency (EIT) is one of the interesting phenomena of li... more ABSTRACT Electromagnetically induced transparency (EIT) is one of the interesting phenomena of light-matter interaction which modifies matter properties for propagation of light. In other words, we can change the absorption and refractive index (RI) in neighborhood of the resonant frequency using EIT. In this paper, we have doped 3-level quantum dots in one of the Michelson Interferometer&#39;s mirror and used EIT to change its RI. So, a controllable phase difference between lights in two arms of interferometer is created. Long response time is the main drawback of Michelson interferometer based sensor, which is resolved by this technique.

All-optical loadable and erasable memory cell design based on inversionless lasing and electromagnetically induced transparency effects

Quantum Electronics, 2011

Star clusters have long been used to illuminate both stellar evolution and Galactic evolution. Th... more Star clusters have long been used to illuminate both stellar evolution and Galactic evolution. They also hold clues to the chemical and nucleosynthetic processes throughout the history of the Galaxy. We have taken high signal-tonoise (S/N), high-resolution spectra of 11 solar-type stars in the Praesepe open cluster to determine the chemical abundances of 16 elements: Li, C, O, Na, Mg, Al, Si, Ca, Sc, Ti, V, Cr, Fe, Ni, Y, and Ba. We have determined Fe from Fe i and Fe ii lines and find [Fe/H] = +0.12 ±0.04. We find that Li decreases with temperature due to increasing Li depletion in cooler stars; it matches the Li-temperature pattern found in the Hyades. The [C/Fe] and [O/Fe] abundances are below solar and lower than the field star samples due to the younger age of Praesepe (0.7 Gyr) than the field stars. The alpha-elements, Mg, Si, Ca, and Ti, have solar ratios with respect to Fe, and are also lower than the field star samples. The Fe-peak elements, Cr and Ni, track Fe and have solar values. The neutron capture element [Y/Fe] is found to be solar, but [Ba/Fe] is enhanced relative to solar and to the field stars. Three Praesepe giants were studied by Carrera and Pancino; they are apparently enhanced in Na, Mg, and Ba relative to the Praesepe dwarfs. The Na enhancement may indicate proton-capture nucleosynthesis in the Ne → Na cycling with dredge-up into the atmospheres of the red giants.

WITHDRAWN: Ultrasmall and tunable all-optical photonic crystal-based demultiplexer for DWDM systems

Photonics and Nanostructures - Fundamentals and Applications, 2009

WITHDRAWN: Ultrasmall and tunable all-optical photonic crystalbased demultiplexer for DWDM system... more WITHDRAWN: Ultrasmall and tunable all-optical photonic crystalbased demultiplexer for DWDM systems H. Habibiyan , H. Ghafoori-Fard , K. Abbasian , A. Rostami b,c a Faculty of Electrical Engineering, Amirkabir University of Technology, Tehran 15914, Iran b Photonics and Nanocrystal Research Laboratory (PNRL), Faculty of Electrical and Computer Engineering, University of Tabriz, Tabriz 51664, Iran c School of Engineering Emerging Technologies, University of Tabriz, Tabriz 51664, Iran

Design of an ultrafast all-optical NOR logic gate based on Mach-Zehnder interferometer using quantum-dot SOA

Optik, 2014

This paper proposes a design for all-optical NOR logic gate, based on Mach-Zehnder interferometer... more This paper proposes a design for all-optical NOR logic gate, based on Mach-Zehnder interferometer (MZI) using quantum-dot semiconductor optical amplifier (QD-SOA). In this regard, a theoretical model for an ultrafast all-optical signal processor is developed using QD-SOA to achieve high bit rate operation. We have demonstrated the NOR gate operation in two cases of with and without an optical control pulse. Simulations have been carried out at data bit rates 160 Gb/s, 200 Gb/s, and 250 Gb/s for the case that control pulse is not applied, and also at data bit rates 1 Tb/s and 2 Tb/s in presence of control pulse which leads to improvement of gain recovery time and ultrafast NOR logic operation. In addition, quality factors of the output signals in presence and without the control pulse at different bit rates with different bias currents have been investigated for pseudo-random binary sequence (PRBS) of word length 2 8 -1.