This study investigates the properties of exciton-polaritons in a two-dimensional(2D)hybrid organic-inorganic perovskite microcavity in the presence of optical Stark effect.Through both steady and dynamic state analys...This study investigates the properties of exciton-polaritons in a two-dimensional(2D)hybrid organic-inorganic perovskite microcavity in the presence of optical Stark effect.Through both steady and dynamic state analyses,strong coupling between excitons of perovskite and cavity photons is revealed,indicating the formation of polaritons in the perovskite microcavity.Besides,it is found that an external optical Stark pulse can induce energy shifts of excitons proportional to the pulse intensity,which modifies the dispersion characteristics of the polaritons.展开更多
The purpose is to explore the effect of the spatial distribution of ground control points （GCPs） on the accuracy of imagery rectification. Both area-distributed and linearly distributed GCPs were used to rectify a L...The purpose is to explore the effect of the spatial distribution of ground control points （GCPs） on the accuracy of imagery rectification. Both area-distributed and linearly distributed GCPs were used to rectify a Landsat TM image of a coastal zone. Rectification accuracy was checked against 99 independent points over the intertidal mudflats with no ground control. Results indicate that the root-mean-square error of residuals over these areas is several times larger than its GCPs-measured counterpart. If the GCPs are spatially dispersed over an area, residuals fluctuate but increase steadily with distance to the source of control in easting （R^2= 0. 827）. in northing they fluctuate around 150 m until 15 km, beyond which they rise steadily at a small range of fluctuation. These residuals are less predictable from distance to the source of control than in easting （R^2= 0.517 ）. If the GCPs are distributed along a control line, residuals rise with distance to it linearly and predictably （R^2 = 0. 877） in the direction perpendicular to it. In a direction parallel to it, the distance has little impact on rectification residuals.展开更多
This paper presents the single element dual band switched beam textile antenna.The antenna can operate at frequencies of 0.7 and 2.6 GHz using for 5G wireless communication applications.Textile fabric is considered to...This paper presents the single element dual band switched beam textile antenna.The antenna can operate at frequencies of 0.7 and 2.6 GHz using for 5G wireless communication applications.Textile fabric is considered to be used for substrate layer at the parts of a microstrip antenna for wireless body area network.The beam pattern of antenna can be switched into two directions by changing the position of shorted-circuit points at each edge of antenna.The main beam direction is 45°/225°when corner A is shorted while it steers at 135°/315°when corner B is shorted circuit.The advantage of the proposed antenna is the decrease of the problems like interference,light weight,flexibility and ability to switch beam easily.In addition,the results of the fabricated antenna are compared with the simulated ones.Moreover,the antenna is bent with curvature radius of 6 mm in forward direction.The effects of the bent antenna are studied.The results can confirm that radiation patterns of the bending antenna can be pointed into two directions when changing the positions of shorted circuit.Therefore,the proposed antenna can switch beam patterns,it is flexible,and it can operate at dual-band frequency on textile.展开更多
This work presents,design and specific absorption rate(SAR)analysis of a 37GHz antenna,for 5th Generation(5G)applications.The proposed antenna comprises of 4-elements of rectangular patch and an even distribution.The ...This work presents,design and specific absorption rate(SAR)analysis of a 37GHz antenna,for 5th Generation(5G)applications.The proposed antenna comprises of 4-elements of rectangular patch and an even distribution.The radiating element is composed of copper material supported by Rogers RT5880 substrate of thickness,0.254 mm,dielectric constant(εr),2.2,and loss tangent,0.0009.The 4-elements array antenna is compact in size with a dimension of 8mm×20mm in length and width.The radiating patch is excited with a 50 ohms connector i.e.,K-type.The antenna resonates in the frequency band of 37 GHz,that covers the 5G applications.The antenna behavior is studied both in free space and in the proximity of the human body.Three models of the human body,i.e.,belly,hand,and head(contain skin,fat,muscles,and bone)are considered for on-body simulations.At resonant frequency,the antenna gives a boresight gain of 11.6 dB.The antenna radiates efficiently with a radiated efficiency of more than 90%.Also,it is observed that the antenna detunes to the lowest in the proximity of the human body,but still a good impedance matching is achieved considering the−10 dB criteria.Moreover,SAR is also being presented.The safe limit of 2 W/kg for any 10 g of biological tissue,specified by the European International Electro Technical Commission(IEC)has been considered.The calculated values of SAR for human body models,i.e.,belly,hand and head are 1.82,1.81 and 1.09 W/kg,respectively.The SAR values are less than the international recommendations for the three models.Furthermore,the simulated and measured results of the antenna are in close agreement,which makes it,a potential candidate for the fifth-generation smart phones and other handheld devices.展开更多
We have demonstrated the first carrier density model for AlGaN channel with AlN buffer using spontaneous and piezoelectric polarization comparison with experimental and theoretical results. From the results we proved ...We have demonstrated the first carrier density model for AlGaN channel with AlN buffer using spontaneous and piezoelectric polarization comparison with experimental and theoretical results. From the results we proved that the formation of 2DEG in undoped structure relied both on spontaneous and piezoelectric polarization. The electron distribution of Al concentration (0 < x < 0.5) was measured for both AlGaN channel and barrier. Barrier thickness assumed between 20 and 25 nm for validating the experimental results. The carrier concentration was observed at the specific interface of the N- and Ga-face by assuming x1, x2 = 0. The model results are verified with previously reported experimental data.展开更多
We present a measurement campaign to characterize an indoor massive multiple-input multiple-output (MIMO) channel system, using a 64-element virtual linear array, a 64-element virtual planar array, and a 128-element v...We present a measurement campaign to characterize an indoor massive multiple-input multiple-output (MIMO) channel system, using a 64-element virtual linear array, a 64-element virtual planar array, and a 128-element virtual planar array. The array topologies are generated using a 3D mechanical turntable. The measurements are conducted at 2, 4, 6, 11, 15, and 22 GHz, with a large bandwidth of 200 MHz. Both line-of-sight (LOS) and non-LOS (NLOS) propagation scenarios are considered. The typical channel parameters are extracted, including path loss,shadow fading, power delay profile, and root mean square (RMS) delay spread. The frequency dependence of these channel parameters is analyzed. The correlation between shadow fading and RMS delay spread is discussed. In addition, the performance of the standard linear precoder—the matched filter, which can be used for intersymbol interference (ISI) mitigation by shortening the RMS delay spread, is investigated. Other performance measures,such as entropy capacity, Demmel condition number, and channel ellipticity, are analyzed. The measured channels,which are in a rich-scattering indoor environment, are found to achieve a performance close to that in independent and identically distributed Rayleigh channels even in an LOS scenario.展开更多
A novel DOIND logic approach is proposed for domino logic, which reduces the leakage current with a minimum delay penalty. Simulation is performed at 70 nm technology node with supply voltage 1V for domino logic and D...A novel DOIND logic approach is proposed for domino logic, which reduces the leakage current with a minimum delay penalty. Simulation is performed at 70 nm technology node with supply voltage 1V for domino logic and DOIND logic based AND, OR, XOR and Half Adder circuits using the tanner EDA tool. Simulation results show that the proposed DOIND approach decreases the average leakage current by 68.83%, 66.6%, 77.86% and 74.34% for 2 input AND, OR, XOR and Half Adder respectively. The proposed approach also has 47.76% improvement in PDAP for the buffer circuit as compared to domino logic.展开更多
We investigate the performance of an 18 nm gate length AIInN/GaN heterostructure underlap double gate MOSFET, using 2D Sentaurus TCAD simulation. The device uses lattice-matched wideband Al0.83In0.17N and narrowband G...We investigate the performance of an 18 nm gate length AIInN/GaN heterostructure underlap double gate MOSFET, using 2D Sentaurus TCAD simulation. The device uses lattice-matched wideband Al0.83In0.17N and narrowband GaN layers, along with high-k Al2O3 as the gate dielectric. The device has an ultrathin body and is designed according to the ITRS specifications. The simulation is done using the hydrodynamic model and interface traps are also considered. Due to the large two-dimensional electron gas （2DEG） density and high velocity, the maximal drain current density achieved is very high. Extensive device simulation of the major device performance metrics such as drain induced barrier lowering （DIBL）, subthreshold slope （SS）, delay, threshold voltage （Vt）, Ion/Ioff ratio and energy delay product have been done for a wide range of gate and underlap lengths. Encouraging results for delay, Ion, DIBL and energy delay product are obtained. The results indicate that there is a need to optimize theIoff and SS values for specific logic design. The proposed AlInN/GaN heterostructure underlap DG MOSFET shows excellent promise as one of the candidates to substitute currently used MOSFETs for future high speed applications.展开更多
We propose an analytical model for drain current and inversion charge in the subthreshold region for an underlap DG FinFET by using the minimum channel potential method, i.e., the virtual source. The flicker and therm...We propose an analytical model for drain current and inversion charge in the subthreshold region for an underlap DG FinFET by using the minimum channel potential method, i.e., the virtual source. The flicker and thermal noise spectral density models are also developed using these charge and current models expression. The model is validated with already published experimental results of flicker noise for DG FinFETs. For an ultrathin body, the degradation of effective mobility and variation of the scattering parameter are considered. The effect of device parameters like gate length Lg and underlap length Lun on both flicker and thermal noise spectral densities are also analyzed. Increasing Lg and Lun, increases the effective gate length, which reduces drain current, resulting in decreased flicker and thermal noise density. A decrease of flicker noise is observed for an increase of frequency, which indicates that the device can be used for wide range of frequency applications.展开更多
In analog circuit design an important parameter, from the perspective of superior device performance, is linearity. The DG MOSFET in asymmetric mode operation has been found to present a better linearity. In addi- tio...In analog circuit design an important parameter, from the perspective of superior device performance, is linearity. The DG MOSFET in asymmetric mode operation has been found to present a better linearity. In addi- tion to that it provides, at the discretion of analog circuit designer, an additional degree of freedom, by providing independent bias control for the front and the back gates. Here a non-quasi-static （NQS） small signal model for DGMOSFET with asymmetric gate bias is proposed for extracting the parameters of the device using TCAD sim- ulations. The parameters extracted here for analysis are the intrinsic front and back gate to drain capacitance, Cgal and Cgd2, the intrinsic front and back distributed channel resistance, Rgdl and Rgd2 respectively, the transport de- lay, rm, and the inductance, Lsd. The parameter extraction model for an asymmetric DG MOSFET is validated with pre-established extracted parameter data, for symmetric DG MOSFET devices, from the available literature. The device simulation is performed with respect to frequency up to 100 GHz.展开更多
This paper has designed 2-channel dense wavelength division multiplexing （DWDM） chaotic sys- tem at the frequencies of 193.1 and 193,2THz, respec- tively. The optical chaotic signals were produced by using the semic...This paper has designed 2-channel dense wavelength division multiplexing （DWDM） chaotic sys- tem at the frequencies of 193.1 and 193,2THz, respec- tively. The optical chaotic signals were produced by using the semiconductor laser that is numerically modeled by employing laser rate equations. These two channels were multiplexed and then propagated through single mode optical fiber （SMF） of 80kin length with dispersion compensating fiber of 16 km length. Erbium doped fiber amplifier （EDFA） was used to compensate the power losses in the SMF. In lhis paper, we investigated the effects of polarization mode dispersion （PMD） and nonlinearities especially stimulated Raman scattering （SRS） on 2 channel DWDM chaotic communication system by varying the length of the SMF and value of differential group delay （DGD）.展开更多
In this paper, a technique was numerically implemented to generate a frequency shift keying （FSK） radio-over-fiber （RoF） signal in optical domain. Due to the oscillator free generation of FSK signal, this scheme i...In this paper, a technique was numerically implemented to generate a frequency shift keying （FSK） radio-over-fiber （RoF） signal in optical domain. Due to the oscillator free generation of FSK signal, this scheme is highly stable with reduced complexity and extremely cost effective. The remote heterodyne detection method was used to detect the signal, where beating occurs to detect the FSK signal. With this scheme, it is able to efficiently generate FSK signal in the range of 60 and 75 GHz at 8 Gbit/s and effectively transmit it over 80 km link without degrading the signal shape and quality. The nonlinear threshold （NLT） point of the system has also been numerically analyzed to estimate the nonlinear tolerance of the system. Besides, the impact of transmission distance and polarization mode dispersion （PMD） was evaluated. Furthermore, the wavelength reuse for the uplink was implemented in the scheme by reusing the same wave- length for uplink that was used for signal generation at downlink. The whole process was performed in optical domain. Thus this scheme is very cost effective as the overall architecture of RoF system is simplified.展开更多
We present a two-dimensional electron gas （2DEG） charge-control mobility variation based drain cur- rent model for sheet carrier density in the channel. The model was developed for the AIInGaN/A1N/GaN high- electron...We present a two-dimensional electron gas （2DEG） charge-control mobility variation based drain cur- rent model for sheet carrier density in the channel. The model was developed for the AIInGaN/A1N/GaN high- electron-mobility transistor. The sheet carrier density model used here accounts for the independence between the Fermi levels Ef and ns along with mobility for various AI and In molefractions. This physics based ns model fully depends upon the variation of El, u0, the first subband E0, the second subband El, and as. We present a physics based analytical drain current model using ns with the minimum set of parameters. The analytical resuks obtained are compared with the experimental results for four samples with various molefraction and barrier thickness. A good agreement between the results is obtained, thus validating the model.展开更多
In this paper,we report on the performance comparison of all-optical signal processing methodologies to compensate fiber transmission impairments,namely chromatic dispersion and nonlinear distortion caused by the Ker...In this paper,we report on the performance comparison of all-optical signal processing methodologies to compensate fiber transmission impairments,namely chromatic dispersion and nonlinear distortion caused by the Kerr effect,in a coherent 112 Gbit∕s dual-polarization 64 bit quadrature amplitude modulation system over 800 km standard single-mode fiber.We numerically compare optical backward propagation(OBP)with optical phase conjugation(OPC)techniques,namely.mid-link spectral inversion,predispersed spectral inversion,and OPC with nonlinearity module.We also evaluate a self-phase-modulation-based optical limiter with an appropriate prechirping to compensate for the intensity fluctuations as a hybrid approach with OBP.The results depict improvement in system performance by a factor of∼4 dB of signal input power by all-optical signal processing methods,which is comparative with ideal digital backward propagation where the high complexity is the intrinsic impediment in the real-time implementation of the technique with coherent receivers.展开更多
A stable mode-locked laser was demonstrated using a newly developed zinc phthalocyanine(ZnPc)thin film as passive saturable absorber(SA)in ytterbium-doped fiber laser(YDFL).The ZnPc thin film was obtained using a cast...A stable mode-locked laser was demonstrated using a newly developed zinc phthalocyanine(ZnPc)thin film as passive saturable absorber(SA)in ytterbium-doped fiber laser(YDFL).The ZnPc thin film was obtained using a casting method and then inserted between the two fiber ferrules of a YDFL ring cavity to generate mode-locked pulses.The resulting pulsed laser operated at a wavelength of 1034.5 nm having a repetition rate of 3.3 MHz.At pump power of 277 mW,the maximum output power and pulse energy are achieved at 4.92 mW and 1.36 nJ,respectively.ZnPc has a high chemical and photochemical stability,and its significance for use as a potential SA in a mode-locked laser is reported in this work.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11974071 and 62375040)the Sichuan Science and Technology Program(Grant Nos.2022ZYD0108 and 2023JDRC0030).
文摘This study investigates the properties of exciton-polaritons in a two-dimensional(2D)hybrid organic-inorganic perovskite microcavity in the presence of optical Stark effect.Through both steady and dynamic state analyses,strong coupling between excitons of perovskite and cavity photons is revealed,indicating the formation of polaritons in the perovskite microcavity.Besides,it is found that an external optical Stark pulse can induce energy shifts of excitons proportional to the pulse intensity,which modifies the dispersion characteristics of the polaritons.
基金financially supported by a grant from the joint key project of National Natural Science Foundation of China under contract(No.50339010)the National"211"Key Project of China.
文摘The purpose is to explore the effect of the spatial distribution of ground control points （GCPs） on the accuracy of imagery rectification. Both area-distributed and linearly distributed GCPs were used to rectify a Landsat TM image of a coastal zone. Rectification accuracy was checked against 99 independent points over the intertidal mudflats with no ground control. Results indicate that the root-mean-square error of residuals over these areas is several times larger than its GCPs-measured counterpart. If the GCPs are spatially dispersed over an area, residuals fluctuate but increase steadily with distance to the source of control in easting （R^2= 0. 827）. in northing they fluctuate around 150 m until 15 km, beyond which they rise steadily at a small range of fluctuation. These residuals are less predictable from distance to the source of control than in easting （R^2= 0.517 ）. If the GCPs are distributed along a control line, residuals rise with distance to it linearly and predictably （R^2 = 0. 877） in the direction perpendicular to it. In a direction parallel to it, the distance has little impact on rectification residuals.
基金This work is funded from the Thailand Science Research and Innovation through the research grant No.036/2564,https://www.tsri.or.th/.
文摘This paper presents the single element dual band switched beam textile antenna.The antenna can operate at frequencies of 0.7 and 2.6 GHz using for 5G wireless communication applications.Textile fabric is considered to be used for substrate layer at the parts of a microstrip antenna for wireless body area network.The beam pattern of antenna can be switched into two directions by changing the position of shorted-circuit points at each edge of antenna.The main beam direction is 45°/225°when corner A is shorted while it steers at 135°/315°when corner B is shorted circuit.The advantage of the proposed antenna is the decrease of the problems like interference,light weight,flexibility and ability to switch beam easily.In addition,the results of the fabricated antenna are compared with the simulated ones.Moreover,the antenna is bent with curvature radius of 6 mm in forward direction.The effects of the bent antenna are studied.The results can confirm that radiation patterns of the bending antenna can be pointed into two directions when changing the positions of shorted circuit.Therefore,the proposed antenna can switch beam patterns,it is flexible,and it can operate at dual-band frequency on textile.
文摘This work presents,design and specific absorption rate(SAR)analysis of a 37GHz antenna,for 5th Generation(5G)applications.The proposed antenna comprises of 4-elements of rectangular patch and an even distribution.The radiating element is composed of copper material supported by Rogers RT5880 substrate of thickness,0.254 mm,dielectric constant(εr),2.2,and loss tangent,0.0009.The 4-elements array antenna is compact in size with a dimension of 8mm×20mm in length and width.The radiating patch is excited with a 50 ohms connector i.e.,K-type.The antenna resonates in the frequency band of 37 GHz,that covers the 5G applications.The antenna behavior is studied both in free space and in the proximity of the human body.Three models of the human body,i.e.,belly,hand,and head(contain skin,fat,muscles,and bone)are considered for on-body simulations.At resonant frequency,the antenna gives a boresight gain of 11.6 dB.The antenna radiates efficiently with a radiated efficiency of more than 90%.Also,it is observed that the antenna detunes to the lowest in the proximity of the human body,but still a good impedance matching is achieved considering the−10 dB criteria.Moreover,SAR is also being presented.The safe limit of 2 W/kg for any 10 g of biological tissue,specified by the European International Electro Technical Commission(IEC)has been considered.The calculated values of SAR for human body models,i.e.,belly,hand and head are 1.82,1.81 and 1.09 W/kg,respectively.The SAR values are less than the international recommendations for the three models.Furthermore,the simulated and measured results of the antenna are in close agreement,which makes it,a potential candidate for the fifth-generation smart phones and other handheld devices.
文摘We have demonstrated the first carrier density model for AlGaN channel with AlN buffer using spontaneous and piezoelectric polarization comparison with experimental and theoretical results. From the results we proved that the formation of 2DEG in undoped structure relied both on spontaneous and piezoelectric polarization. The electron distribution of Al concentration (0 < x < 0.5) was measured for both AlGaN channel and barrier. Barrier thickness assumed between 20 and 25 nm for validating the experimental results. The carrier concentration was observed at the specific interface of the N- and Ga-face by assuming x1, x2 = 0. The model results are verified with previously reported experimental data.
基金supported by the National Natural Science Foundation of China(Nos.61501020 and U1334202)the State Key Laboratory of Rail Traffic Control and Safety(No.RCS2016ZJ005)+5 种基金the National Key Research and Development Program(No.2016YFB1200102-04)the China Postdoctoral Science Foundation(No.2016M591355)the Fundamental Research Funds for the Central Universities(No.2016JBZ006)the National HighTech R&D Program(863)of China(No.2014AA01A706)the National S&T Major Project(No.2016ZX03001021-003)the Key Laboratory of Wireless Sensor Network and Communication,Chinese Academy of Sciences(No.2013005)
文摘We present a measurement campaign to characterize an indoor massive multiple-input multiple-output (MIMO) channel system, using a 64-element virtual linear array, a 64-element virtual planar array, and a 128-element virtual planar array. The array topologies are generated using a 3D mechanical turntable. The measurements are conducted at 2, 4, 6, 11, 15, and 22 GHz, with a large bandwidth of 200 MHz. Both line-of-sight (LOS) and non-LOS (NLOS) propagation scenarios are considered. The typical channel parameters are extracted, including path loss,shadow fading, power delay profile, and root mean square (RMS) delay spread. The frequency dependence of these channel parameters is analyzed. The correlation between shadow fading and RMS delay spread is discussed. In addition, the performance of the standard linear precoder—the matched filter, which can be used for intersymbol interference (ISI) mitigation by shortening the RMS delay spread, is investigated. Other performance measures,such as entropy capacity, Demmel condition number, and channel ellipticity, are analyzed. The measured channels,which are in a rich-scattering indoor environment, are found to achieve a performance close to that in independent and identically distributed Rayleigh channels even in an LOS scenario.
文摘A novel DOIND logic approach is proposed for domino logic, which reduces the leakage current with a minimum delay penalty. Simulation is performed at 70 nm technology node with supply voltage 1V for domino logic and DOIND logic based AND, OR, XOR and Half Adder circuits using the tanner EDA tool. Simulation results show that the proposed DOIND approach decreases the average leakage current by 68.83%, 66.6%, 77.86% and 74.34% for 2 input AND, OR, XOR and Half Adder respectively. The proposed approach also has 47.76% improvement in PDAP for the buffer circuit as compared to domino logic.
文摘We investigate the performance of an 18 nm gate length AIInN/GaN heterostructure underlap double gate MOSFET, using 2D Sentaurus TCAD simulation. The device uses lattice-matched wideband Al0.83In0.17N and narrowband GaN layers, along with high-k Al2O3 as the gate dielectric. The device has an ultrathin body and is designed according to the ITRS specifications. The simulation is done using the hydrodynamic model and interface traps are also considered. Due to the large two-dimensional electron gas （2DEG） density and high velocity, the maximal drain current density achieved is very high. Extensive device simulation of the major device performance metrics such as drain induced barrier lowering （DIBL）, subthreshold slope （SS）, delay, threshold voltage （Vt）, Ion/Ioff ratio and energy delay product have been done for a wide range of gate and underlap lengths. Encouraging results for delay, Ion, DIBL and energy delay product are obtained. The results indicate that there is a need to optimize theIoff and SS values for specific logic design. The proposed AlInN/GaN heterostructure underlap DG MOSFET shows excellent promise as one of the candidates to substitute currently used MOSFETs for future high speed applications.
文摘We propose an analytical model for drain current and inversion charge in the subthreshold region for an underlap DG FinFET by using the minimum channel potential method, i.e., the virtual source. The flicker and thermal noise spectral density models are also developed using these charge and current models expression. The model is validated with already published experimental results of flicker noise for DG FinFETs. For an ultrathin body, the degradation of effective mobility and variation of the scattering parameter are considered. The effect of device parameters like gate length Lg and underlap length Lun on both flicker and thermal noise spectral densities are also analyzed. Increasing Lg and Lun, increases the effective gate length, which reduces drain current, resulting in decreased flicker and thermal noise density. A decrease of flicker noise is observed for an increase of frequency, which indicates that the device can be used for wide range of frequency applications.
文摘In analog circuit design an important parameter, from the perspective of superior device performance, is linearity. The DG MOSFET in asymmetric mode operation has been found to present a better linearity. In addi- tion to that it provides, at the discretion of analog circuit designer, an additional degree of freedom, by providing independent bias control for the front and the back gates. Here a non-quasi-static （NQS） small signal model for DGMOSFET with asymmetric gate bias is proposed for extracting the parameters of the device using TCAD sim- ulations. The parameters extracted here for analysis are the intrinsic front and back gate to drain capacitance, Cgal and Cgd2, the intrinsic front and back distributed channel resistance, Rgdl and Rgd2 respectively, the transport de- lay, rm, and the inductance, Lsd. The parameter extraction model for an asymmetric DG MOSFET is validated with pre-established extracted parameter data, for symmetric DG MOSFET devices, from the available literature. The device simulation is performed with respect to frequency up to 100 GHz.
文摘This paper has designed 2-channel dense wavelength division multiplexing （DWDM） chaotic sys- tem at the frequencies of 193.1 and 193,2THz, respec- tively. The optical chaotic signals were produced by using the semiconductor laser that is numerically modeled by employing laser rate equations. These two channels were multiplexed and then propagated through single mode optical fiber （SMF） of 80kin length with dispersion compensating fiber of 16 km length. Erbium doped fiber amplifier （EDFA） was used to compensate the power losses in the SMF. In lhis paper, we investigated the effects of polarization mode dispersion （PMD） and nonlinearities especially stimulated Raman scattering （SRS） on 2 channel DWDM chaotic communication system by varying the length of the SMF and value of differential group delay （DGD）.
文摘In this paper, a technique was numerically implemented to generate a frequency shift keying （FSK） radio-over-fiber （RoF） signal in optical domain. Due to the oscillator free generation of FSK signal, this scheme is highly stable with reduced complexity and extremely cost effective. The remote heterodyne detection method was used to detect the signal, where beating occurs to detect the FSK signal. With this scheme, it is able to efficiently generate FSK signal in the range of 60 and 75 GHz at 8 Gbit/s and effectively transmit it over 80 km link without degrading the signal shape and quality. The nonlinear threshold （NLT） point of the system has also been numerically analyzed to estimate the nonlinear tolerance of the system. Besides, the impact of transmission distance and polarization mode dispersion （PMD） was evaluated. Furthermore, the wavelength reuse for the uplink was implemented in the scheme by reusing the same wave- length for uplink that was used for signal generation at downlink. The whole process was performed in optical domain. Thus this scheme is very cost effective as the overall architecture of RoF system is simplified.
文摘We present a two-dimensional electron gas （2DEG） charge-control mobility variation based drain cur- rent model for sheet carrier density in the channel. The model was developed for the AIInGaN/A1N/GaN high- electron-mobility transistor. The sheet carrier density model used here accounts for the independence between the Fermi levels Ef and ns along with mobility for various AI and In molefractions. This physics based ns model fully depends upon the variation of El, u0, the first subband E0, the second subband El, and as. We present a physics based analytical drain current model using ns with the minimum set of parameters. The analytical resuks obtained are compared with the experimental results for four samples with various molefraction and barrier thickness. A good agreement between the results is obtained, thus validating the model.
文摘In this paper,we report on the performance comparison of all-optical signal processing methodologies to compensate fiber transmission impairments,namely chromatic dispersion and nonlinear distortion caused by the Kerr effect,in a coherent 112 Gbit∕s dual-polarization 64 bit quadrature amplitude modulation system over 800 km standard single-mode fiber.We numerically compare optical backward propagation(OBP)with optical phase conjugation(OPC)techniques,namely.mid-link spectral inversion,predispersed spectral inversion,and OPC with nonlinearity module.We also evaluate a self-phase-modulation-based optical limiter with an appropriate prechirping to compensate for the intensity fluctuations as a hybrid approach with OBP.The results depict improvement in system performance by a factor of∼4 dB of signal input power by all-optical signal processing methods,which is comparative with ideal digital backward propagation where the high complexity is the intrinsic impediment in the real-time implementation of the technique with coherent receivers.
基金This work was supported in part by the Airlangga University(Grant No.804/UN3.15/PT/2021)the University of Malaya(Grant No.ML001-2017).
文摘A stable mode-locked laser was demonstrated using a newly developed zinc phthalocyanine(ZnPc)thin film as passive saturable absorber(SA)in ytterbium-doped fiber laser(YDFL).The ZnPc thin film was obtained using a casting method and then inserted between the two fiber ferrules of a YDFL ring cavity to generate mode-locked pulses.The resulting pulsed laser operated at a wavelength of 1034.5 nm having a repetition rate of 3.3 MHz.At pump power of 277 mW,the maximum output power and pulse energy are achieved at 4.92 mW and 1.36 nJ,respectively.ZnPc has a high chemical and photochemical stability,and its significance for use as a potential SA in a mode-locked laser is reported in this work.
