In this paper we will try to create, propose and analyze structure of a slow light device, based on plasmonic induced transparency in a metal-dielectric-metal based ring resonator. Group index by first design about 37...In this paper we will try to create, propose and analyze structure of a slow light device, based on plasmonic induced transparency in a metal-dielectric-metal based ring resonator. Group index by first design about 37 and second design about 35 earned. The proposed dielectric material is Poly Methyl Meta Acrylate (PMMA) sandwiched by gold metal cladding. Finite Element Method-con- ducted Electromagnetic simulations are employed to evaluate the plasmonic designs for behavior of slow light. The signal and pump wavelength are assumed to be 830 nm and 1550 nm respectively in the systems. The overall length of the plasmonic slow light system is 600 nm. In a wide range of frequency bands, the optical properties of metals can be described with a plasma model. The optical signal can be achieved with the use of surface waves on the boundary between the insulating materials and metals with dimensions smaller than the diffraction limit. The main goal, is estimation of optical characteristics such as bandwidth, the Real and Imaginary parts of refractive index, group velocity and slow down factor in such optical devices. The obtained results and observations, can be useful in basic research and the production of highly integrated plasmonic devices.展开更多
In this paper human face machine identification is experienced using optical correlation techniques in spatial frequency domain. This approach is tested on ORL dataset of faces which includes face images of 40 subject...In this paper human face machine identification is experienced using optical correlation techniques in spatial frequency domain. This approach is tested on ORL dataset of faces which includes face images of 40 subjects, each in 10 different positions. The examined optical setup relies on optical correlation based on developing optical Vanderlugt filters and its basics are described in this article. With the limitation of face database of 40 persons, the recognition is examined successfully with nearly 100% of accuracy in matching the input images with their respective Vanderlugt synthesized filters. Software simulation is implemented by using MATLAB for face identification.展开更多
In this paper we simulate and analyze a sample of slow light semiconducting device with quantum dot structure based on coherent population oscillation (CPO). The simulation is conducted to enhance the main parameters ...In this paper we simulate and analyze a sample of slow light semiconducting device with quantum dot structure based on coherent population oscillation (CPO). The simulation is conducted to enhance the main parameters of slow light device and a method is presented for setting the output specifications of this kind of devices. In this paper, we deal with changing the size of quantum dot to find the ideal size. The simulation results indicate that as the size of quantum dot changes properly (with reducing more than 50 percent of quantum dots both radius and height), then the slope of diagram of the real part of refractive index increases significantly so that the Slow Down Factor (SDF) predicted to be18 times greater. Analysis and simulations based on cylinderical quantum dots structure slow light devices based on exitonic cpo.展开更多
We propose and analyze a submicron stub-assisted ultrafast all-optical plasmonic switch based on nonlinear MIM waveguide. It is constructed by two silicon stub filters sandwiched by silver cladding. The signal wavelen...We propose and analyze a submicron stub-assisted ultrafast all-optical plasmonic switch based on nonlinear MIM waveguide. It is constructed by two silicon stub filters sandwiched by silver cladding. The signal wavelength is assumed to be 1550 nm. The simulation results show a ?14.66 dB extinction ratio. Downscaling the silicon waveguide in MIM structure leads to enhancement of the effective Kerr nonlinearity due to tight mode confinement. Also, using O+ ions implanted into silicon, the switching time less than 10 ps and a delay time less than 8 fs are achieved. The overall length of the switch is 550 nm.展开更多
In this study we investigate strain effect in barriers of 1.3 μm AlCalnAs-InP uncooled multiple quantum well lasers. Single effective mass and Kohn-Luttinger Harniltonian equations have been solved to obtain quantum ...In this study we investigate strain effect in barriers of 1.3 μm AlCalnAs-InP uncooled multiple quantum well lasers. Single effective mass and Kohn-Luttinger Harniltonian equations have been solved to obtain quantum states and envelope wave functions in the structure. In the case of unstrained barriers, our simulations results have good agreement with a real device fabricated and presented in one of the references. Our main work is proposal of 0.2% compressive strain in the structure Barriers that causes significant reduction in Leakage current density and Auger current density characteristics in 85 ℃. 20% improvement in mode gain-current density characteristic is also obtained in 85 ℃.展开更多
This paper investigates the effects of quantum well size changes on center frequency and slow down factor of an slow light device. In this way, we consider the quantum well size alteration effects on oscillator streng...This paper investigates the effects of quantum well size changes on center frequency and slow down factor of an slow light device. In this way, we consider the quantum well size alteration effects on oscillator strength and binding energy of exciton. First, we investigate the variations in oscillator strength of exciton due to different quantum well size. Second, exciton binding energy level shift due to size of quantum well is investigated. According to this analysis, we have developed a new method for tuning slow light device bandwidth center frequency and slow down factor. Analysis and simulation of a basic GaAs/AlGaAs quantum wells optical slow light device based on excitonic population oscillation shows that size of quantum wells could tune both of the frequency properties and slow down factor of an optical slow light device. In our simulation with 34 quantum wells each with the width of 60?, we have received the slow down factor of more than 60,000. These achievements are useful in optical nonlinearity enhancements, all-optical signal processing applications and optical communications.展开更多
In this paper we investigate the effects of base width variation on performance of long wavelength transistor laser. In our structure with increasing the base width, the cut off frequency increases until 367 nm with 2...In this paper we investigate the effects of base width variation on performance of long wavelength transistor laser. In our structure with increasing the base width, the cut off frequency increases until 367 nm with 24.5 GHz and then abruptly fall. In 100 nm base width, we have 17.5 GHz cut off frequency, and overall ac performances become optimized, although, other parameters like optical losses and threshold current density are not optimized.展开更多
In this paper, an optical waveguide junction is introduced to reduce crosstalk based on a hexagonal structure of photonic crystals for TE modes. The wavelength is 1330 nm which is an important wavelength for optical f...In this paper, an optical waveguide junction is introduced to reduce crosstalk based on a hexagonal structure of photonic crystals for TE modes. The wavelength is 1330 nm which is an important wavelength for optical fiber data transmission. Simulation results show that the proposed design exhibits a reduction of -50 dB in crosstalk. It translates to a considerable isolation improvement between two crossover waveguides. FDTD method is used to obtain the transmission coefficient.展开更多
We analyze an integrated electrically pumped opto-electronic mixer, which consists of two InP/GalnAs hetero junction bipolar transistors （HBT）, in a cascode configuration. A new HBT with modified physical structure ...We analyze an integrated electrically pumped opto-electronic mixer, which consists of two InP/GalnAs hetero junction bipolar transistors （HBT）, in a cascode configuration. A new HBT with modified physical structure is proposed and simulated to improve the frequency characteristics of a cascode mixer. For the verification and calibrating software simulator, we compare the simulation results of a typical HBT, before modifying it and com paring it with empirical reported experiments. Then we examine the simulator on our modified proposed HBT to prove its wider frequency characteristics with better flatness and acceptable down conversion gain. Although the idea is examined in several GHz modulation, it may easily be extended to state of the art HBT cascode mixers in much higher frequency range.展开更多
In order to improve the performance of a pre-designed direct conversion terahertz detector which is implemented in a 0.25 μm-SiGe-BiCMOS process, we propose some slight modifications in the bipolar section of the SiG...In order to improve the performance of a pre-designed direct conversion terahertz detector which is implemented in a 0.25 μm-SiGe-BiCMOS process, we propose some slight modifications in the bipolar section of the SiGe device physical design. Comparison of our new proposed device and the previously reported device is done by SILVACO TCAD software simulation and we have used previous experimentally reported data to confirm our software simulations. Our proposed modifications in device structural design show a present device responsivity improvement of about 10% from 1 to 1.1 A/W while the bandwidth improvement is about 218 GHz. The minimum noise equivalent power at detector output is increased by about 14.3% and finally power consumption per pixel at the maximum responsivity is decreased by about 5%.展开更多
In this paper, four optical filter topologies based on metal–insulator–metal waveguides are proposed and the designed structures are investigated numerically using finite-difference timedomain method. Triangular-sha...In this paper, four optical filter topologies based on metal–insulator–metal waveguides are proposed and the designed structures are investigated numerically using finite-difference timedomain method. Triangular-shaped adjunctions have been added to the filter structures to improve their transmission spectrum. These improved structures consist of air as the insulator and silver as the metal. The relative permittivity of metal has been described via the Drude,Drude–Lorentz, and Palik models. The first filter’s transmission spectrum shows an acceptable transmittance. In the second optimized filter, the transmission spectrum has been improved. The transmittance spectrum can be tuned through adjusting the edge of the triangle in these four optimized filters. As a result, the bandwidths of resonance spectra can be adjusted. The theory of such tapered structures will be investigated by the tapered transmission line and will be solved with the transfer matrix method. This method shows a better performance and higher transmission efficiency in comparison with the basic structures. On the other hand, the final filter has been chosen as the best one because of its hexagonal resonator. The main reason for having a better result is due to a longer interaction length in comparison with the circular resonator. This in turn creates much better energy coupling and results in higher transmission.展开更多
A novel ultrahigh-speed all-optical demultiplexer （DMUX） with polarization-shift-keying （PolSK） modula- tion input signals is proposed. This design is based on four-wave mixing （FWM） in a semiconductor optical a...A novel ultrahigh-speed all-optical demultiplexer （DMUX） with polarization-shift-keying （PolSK） modula- tion input signals is proposed. This design is based on four-wave mixing （FWM） in a semiconductor optical amplifier （SOA）. For analyzing each amplifier, we use finite-difference method （FDM） based on solution of the traveling wave coupled equations. Using numerical simulation, the all-optical DMUX is theoretically realized at 40 Gb/s. We also study the relation between optical confinement factor and thickness of active layer of the SOA section successfully, and investigate the increasing effect of confinement factor on the DMUX optical output power. With this work, the confinement factor is increased from 0.3 to 0.48, and as a result, the output power approximately twice of its initial value is achieved. Moreover, the effects of polarization dependence of SOA on the output performance of all-optical DMUX for PolSK signal are theoretically investigated in detail.展开更多
An optical bandwidth analysis of a quantum-well （16 nm） transistor laser with 150-μm cavity length using a charge control model is reported in order to modify the quantum-well location through the base region. At c...An optical bandwidth analysis of a quantum-well （16 nm） transistor laser with 150-μm cavity length using a charge control model is reported in order to modify the quantum-well location through the base region. At constant bias current, the simulation shows significant enhancement in optical bandwidth due to moving the quantum well in the direction of collector-base junction. No remarkable resonance peak, limiting factor in laser diodes, is observed during this modification in transistor laser structure. The method can be utilized for transistor laser structure design.展开更多
A new configuration of the confinement structure is utilized to improve optoelectronic performance, including threshold current, ac current gain, optical bandwidth, and optical output power of a single quantum well tr...A new configuration of the confinement structure is utilized to improve optoelectronic performance, including threshold current, ac current gain, optical bandwidth, and optical output power of a single quantum well transistor laser. Considering the drift component in addition to the diffusion term in electron current density, a new continuity equation is developed to analyze the proposed structures. Physical parameters, including electron mobility, recombination lifetime, optical confinement factor, electron capture time, and photon lifetime, are calculated for new structures. Based on solving the continuity equation in separate confinement heterostructures, the threshold current reduces 67%, the optical output power increases 37%, and the-3 d B optical bandwidth increases to 21 GHz（compared to 19.5 GHz in the original structure） when the graded index layers of AlξGa1-ξAs（ξ：0.05 → 0 in the left side of quantum well, ξ：0 → 0.02 in the right side of quantum well） are used instead of uniform Ga As in the base region.展开更多
文摘In this paper we will try to create, propose and analyze structure of a slow light device, based on plasmonic induced transparency in a metal-dielectric-metal based ring resonator. Group index by first design about 37 and second design about 35 earned. The proposed dielectric material is Poly Methyl Meta Acrylate (PMMA) sandwiched by gold metal cladding. Finite Element Method-con- ducted Electromagnetic simulations are employed to evaluate the plasmonic designs for behavior of slow light. The signal and pump wavelength are assumed to be 830 nm and 1550 nm respectively in the systems. The overall length of the plasmonic slow light system is 600 nm. In a wide range of frequency bands, the optical properties of metals can be described with a plasma model. The optical signal can be achieved with the use of surface waves on the boundary between the insulating materials and metals with dimensions smaller than the diffraction limit. The main goal, is estimation of optical characteristics such as bandwidth, the Real and Imaginary parts of refractive index, group velocity and slow down factor in such optical devices. The obtained results and observations, can be useful in basic research and the production of highly integrated plasmonic devices.
文摘In this paper human face machine identification is experienced using optical correlation techniques in spatial frequency domain. This approach is tested on ORL dataset of faces which includes face images of 40 subjects, each in 10 different positions. The examined optical setup relies on optical correlation based on developing optical Vanderlugt filters and its basics are described in this article. With the limitation of face database of 40 persons, the recognition is examined successfully with nearly 100% of accuracy in matching the input images with their respective Vanderlugt synthesized filters. Software simulation is implemented by using MATLAB for face identification.
文摘In this paper we simulate and analyze a sample of slow light semiconducting device with quantum dot structure based on coherent population oscillation (CPO). The simulation is conducted to enhance the main parameters of slow light device and a method is presented for setting the output specifications of this kind of devices. In this paper, we deal with changing the size of quantum dot to find the ideal size. The simulation results indicate that as the size of quantum dot changes properly (with reducing more than 50 percent of quantum dots both radius and height), then the slope of diagram of the real part of refractive index increases significantly so that the Slow Down Factor (SDF) predicted to be18 times greater. Analysis and simulations based on cylinderical quantum dots structure slow light devices based on exitonic cpo.
文摘We propose and analyze a submicron stub-assisted ultrafast all-optical plasmonic switch based on nonlinear MIM waveguide. It is constructed by two silicon stub filters sandwiched by silver cladding. The signal wavelength is assumed to be 1550 nm. The simulation results show a ?14.66 dB extinction ratio. Downscaling the silicon waveguide in MIM structure leads to enhancement of the effective Kerr nonlinearity due to tight mode confinement. Also, using O+ ions implanted into silicon, the switching time less than 10 ps and a delay time less than 8 fs are achieved. The overall length of the switch is 550 nm.
文摘In this study we investigate strain effect in barriers of 1.3 μm AlCalnAs-InP uncooled multiple quantum well lasers. Single effective mass and Kohn-Luttinger Harniltonian equations have been solved to obtain quantum states and envelope wave functions in the structure. In the case of unstrained barriers, our simulations results have good agreement with a real device fabricated and presented in one of the references. Our main work is proposal of 0.2% compressive strain in the structure Barriers that causes significant reduction in Leakage current density and Auger current density characteristics in 85 ℃. 20% improvement in mode gain-current density characteristic is also obtained in 85 ℃.
文摘This paper investigates the effects of quantum well size changes on center frequency and slow down factor of an slow light device. In this way, we consider the quantum well size alteration effects on oscillator strength and binding energy of exciton. First, we investigate the variations in oscillator strength of exciton due to different quantum well size. Second, exciton binding energy level shift due to size of quantum well is investigated. According to this analysis, we have developed a new method for tuning slow light device bandwidth center frequency and slow down factor. Analysis and simulation of a basic GaAs/AlGaAs quantum wells optical slow light device based on excitonic population oscillation shows that size of quantum wells could tune both of the frequency properties and slow down factor of an optical slow light device. In our simulation with 34 quantum wells each with the width of 60?, we have received the slow down factor of more than 60,000. These achievements are useful in optical nonlinearity enhancements, all-optical signal processing applications and optical communications.
文摘In this paper we investigate the effects of base width variation on performance of long wavelength transistor laser. In our structure with increasing the base width, the cut off frequency increases until 367 nm with 24.5 GHz and then abruptly fall. In 100 nm base width, we have 17.5 GHz cut off frequency, and overall ac performances become optimized, although, other parameters like optical losses and threshold current density are not optimized.
文摘In this paper, an optical waveguide junction is introduced to reduce crosstalk based on a hexagonal structure of photonic crystals for TE modes. The wavelength is 1330 nm which is an important wavelength for optical fiber data transmission. Simulation results show that the proposed design exhibits a reduction of -50 dB in crosstalk. It translates to a considerable isolation improvement between two crossover waveguides. FDTD method is used to obtain the transmission coefficient.
文摘We analyze an integrated electrically pumped opto-electronic mixer, which consists of two InP/GalnAs hetero junction bipolar transistors （HBT）, in a cascode configuration. A new HBT with modified physical structure is proposed and simulated to improve the frequency characteristics of a cascode mixer. For the verification and calibrating software simulator, we compare the simulation results of a typical HBT, before modifying it and com paring it with empirical reported experiments. Then we examine the simulator on our modified proposed HBT to prove its wider frequency characteristics with better flatness and acceptable down conversion gain. Although the idea is examined in several GHz modulation, it may easily be extended to state of the art HBT cascode mixers in much higher frequency range.
文摘In order to improve the performance of a pre-designed direct conversion terahertz detector which is implemented in a 0.25 μm-SiGe-BiCMOS process, we propose some slight modifications in the bipolar section of the SiGe device physical design. Comparison of our new proposed device and the previously reported device is done by SILVACO TCAD software simulation and we have used previous experimentally reported data to confirm our software simulations. Our proposed modifications in device structural design show a present device responsivity improvement of about 10% from 1 to 1.1 A/W while the bandwidth improvement is about 218 GHz. The minimum noise equivalent power at detector output is increased by about 14.3% and finally power consumption per pixel at the maximum responsivity is decreased by about 5%.
文摘In this paper, four optical filter topologies based on metal–insulator–metal waveguides are proposed and the designed structures are investigated numerically using finite-difference timedomain method. Triangular-shaped adjunctions have been added to the filter structures to improve their transmission spectrum. These improved structures consist of air as the insulator and silver as the metal. The relative permittivity of metal has been described via the Drude,Drude–Lorentz, and Palik models. The first filter’s transmission spectrum shows an acceptable transmittance. In the second optimized filter, the transmission spectrum has been improved. The transmittance spectrum can be tuned through adjusting the edge of the triangle in these four optimized filters. As a result, the bandwidths of resonance spectra can be adjusted. The theory of such tapered structures will be investigated by the tapered transmission line and will be solved with the transfer matrix method. This method shows a better performance and higher transmission efficiency in comparison with the basic structures. On the other hand, the final filter has been chosen as the best one because of its hexagonal resonator. The main reason for having a better result is due to a longer interaction length in comparison with the circular resonator. This in turn creates much better energy coupling and results in higher transmission.
文摘A novel ultrahigh-speed all-optical demultiplexer （DMUX） with polarization-shift-keying （PolSK） modula- tion input signals is proposed. This design is based on four-wave mixing （FWM） in a semiconductor optical amplifier （SOA）. For analyzing each amplifier, we use finite-difference method （FDM） based on solution of the traveling wave coupled equations. Using numerical simulation, the all-optical DMUX is theoretically realized at 40 Gb/s. We also study the relation between optical confinement factor and thickness of active layer of the SOA section successfully, and investigate the increasing effect of confinement factor on the DMUX optical output power. With this work, the confinement factor is increased from 0.3 to 0.48, and as a result, the output power approximately twice of its initial value is achieved. Moreover, the effects of polarization dependence of SOA on the output performance of all-optical DMUX for PolSK signal are theoretically investigated in detail.
文摘An optical bandwidth analysis of a quantum-well （16 nm） transistor laser with 150-μm cavity length using a charge control model is reported in order to modify the quantum-well location through the base region. At constant bias current, the simulation shows significant enhancement in optical bandwidth due to moving the quantum well in the direction of collector-base junction. No remarkable resonance peak, limiting factor in laser diodes, is observed during this modification in transistor laser structure. The method can be utilized for transistor laser structure design.
文摘A new configuration of the confinement structure is utilized to improve optoelectronic performance, including threshold current, ac current gain, optical bandwidth, and optical output power of a single quantum well transistor laser. Considering the drift component in addition to the diffusion term in electron current density, a new continuity equation is developed to analyze the proposed structures. Physical parameters, including electron mobility, recombination lifetime, optical confinement factor, electron capture time, and photon lifetime, are calculated for new structures. Based on solving the continuity equation in separate confinement heterostructures, the threshold current reduces 67%, the optical output power increases 37%, and the-3 d B optical bandwidth increases to 21 GHz（compared to 19.5 GHz in the original structure） when the graded index layers of AlξGa1-ξAs（ξ：0.05 → 0 in the left side of quantum well, ξ：0 → 0.02 in the right side of quantum well） are used instead of uniform Ga As in the base region.
