Future inter-satellite clock comparison on high orbit will require optical time and frequency transmission technology between moving objects.Here,we demonstrate robust optical frequency transmission under the conditio...Future inter-satellite clock comparison on high orbit will require optical time and frequency transmission technology between moving objects.Here,we demonstrate robust optical frequency transmission under the condition of variable link distance.This variable link is accomplished by the relative motion of a single telescope fixed on the experimental platform to a corner-cube reflector(CCR)installed on a sliding guide.Two acousto–optic modulators with different frequencies are used to separate forward signal from backward signal.With active phase noise suppression,when the CCR moves back and forth at a constant velocity of 20 cm/s and an acceleration of 20 cm/s^(2),we achieve the best frequency stability of 1.9×10^(-16) at 1 s and 7.9×10^(-19) at 1000 s indoors.This work paves the way for future studying optical frequency transfer between ultra-high-orbit satellites.展开更多
An 8×10 GHz receiver optical sub-assembly (ROSA) consisting of an 8-channel arrayed waveguide grating (AWG) and an 8-channel PIN photodetector (PD) array is designed and fabricated based on silica hybrid in...An 8×10 GHz receiver optical sub-assembly (ROSA) consisting of an 8-channel arrayed waveguide grating (AWG) and an 8-channel PIN photodetector (PD) array is designed and fabricated based on silica hybrid integration technology. Multimode output waveguides in the silica AWG with 2% refractive index difference are used to obtain fiat-top spectra. The output waveguide facet is polished to 45° bevel to change the light propagation direction into the mesa-type PIN PD, which simplifies the packaging process. The experimentM results show that the single channel I dB bandwidth of AWG ranges from 2.12nm to 3.06nm, the ROSA responsivity ranges from 0.097 A/W to 0.158A/W, and the 3dB bandwidth is up to 11 GHz. It is promising to be applied in the eight-lane WDM transmission system in data center interconnection.展开更多
This paper presents a 26-Gb/s CMOS optical receiver that is fabricated in 65-nm technology. It consists of a tripleinductive transimpedance amplifier(TIA), direct current(DC) offset cancellation circuits, 3-stage gm-T...This paper presents a 26-Gb/s CMOS optical receiver that is fabricated in 65-nm technology. It consists of a tripleinductive transimpedance amplifier(TIA), direct current(DC) offset cancellation circuits, 3-stage gm-TIA variable-gain amplifiers(VGA), and a reference-less clock and data recovery(CDR) circuit with built-in equalization technique. The TIA/VGA frontend measurement results demonstrate 72-dB? transimpedance gain, 20.4-GHz-3-dB bandwidth, and 12-dB DC gain tuning range. The measurements of the VGA’s resistive networks also demonstrate its efficient capability of overcoming the voltage and temperature variations. The CDR adopts a full-rate topology with 12-dB imbedded equalization tuning range. Optical measurements of this chipset achieve a 10-12 BER at 26 Gb/s for a 2;-1 PRBS input with a-7.3-dBm input sensitivity. The measurement results with a 10-dB @ 13 GHz attenuator also demonstrate the effectiveness of the gain tuning capability and the built-in equalization. The entire system consumes 140 mW from a 1/1.2-V supply.展开更多
This study develops an optimal performance monitoring metric for a hybrid free space optical and radio wireless network, the Outage Capacity Objective Function. The objective function—the dependence of hybrid channel...This study develops an optimal performance monitoring metric for a hybrid free space optical and radio wireless network, the Outage Capacity Objective Function. The objective function—the dependence of hybrid channel outage capacity upon the error rate, jointly quantifies the effects of atmospheric optical impairments on the performance of the free space optical segment as well as the effect of RF channel impairments on the radio frequency segment. The objective function is developed from the basic information-theoretic capacity of the optical and radio channels using the gamma-gamma model for optical fading and Ricean statistics for the radio channel fading. A simulation is performed by using the hybrid network. The objective function is shown to provide significantly improved sensitivity to degrading performance trends and supports of proactive link failure prediction and mitigation when compared to current thresholding techniques for signal quality metrics.展开更多
In this letter, we present the generation, the balanced detection, and the transmission performance evaluation of dual polarization differential quadrature phase shift keying (DP-DQPSK) signals in optical access syste...In this letter, we present the generation, the balanced detection, and the transmission performance evaluation of dual polarization differential quadrature phase shift keying (DP-DQPSK) signals in optical access system integrated with fiber and free-space downlink. Polarization-multip- lexed (POLMUX) technique is introduced in the system for high spectral efficiency access utilization. 10 Gb/s DP-DQPSK downlink signals are successfully transmitted over 50 km SMF-28 and a 800 m wireless optical channel under the bad weather condition, such as fog and haze. The results show that the potentiality of DP-DQPSK optical access system is integrated with fiber and free- space downlink for providing flexible user access with high bandwidth efficiency.展开更多
With the capacities of self-learning,acquainted capacities,high-speed looking for ideal arrangements,solid nonlin-ear fitting,and mapping self-assertively complex nonlinear relations,neural systems have made incredibl...With the capacities of self-learning,acquainted capacities,high-speed looking for ideal arrangements,solid nonlin-ear fitting,and mapping self-assertively complex nonlinear relations,neural systems have made incredible advances and accomplished broad application over the final half-century.As one of the foremost conspicuous methods for fake insights,neural systems are growing toward high computational speed and moo control utilization.Due to the inborn impediments of electronic gadgets,it may be troublesome for electronic-implemented neural systems to make the strides these two exhibitions encourage.Optical neural systems can combine optoelectronic procedures and neural organization models to provide ways to break the bottleneck.This paper outlines optical neural networks of feedforward repetitive and spiking models to give a clearer picture of history,wildernesses,and future optical neural systems.The framework demonstrates neural systems in optic communication with the serial and parallel setup.The graphene-based laser structure for fiber optic communication is discussed.The comparison of different balance plans for photonic neural systems is made within the setting of hereditary calculation and molecule swarm optimization.In expansion,the execution comparison of routine photonic neural,time-domain with and without extending commotion is additionally expounded.The challenges and future patterns of optical neural systems on the growing scale and applications of in situ preparing nonlinear computing will hence be uncovered.展开更多
Visible light communication(VLC),which is a prominent emerging solution that complements the radio frequency(RF)technology,exhibits the potential to meet the demands of fifth-generation(5G)and beyond technologies.The ...Visible light communication(VLC),which is a prominent emerging solution that complements the radio frequency(RF)technology,exhibits the potential to meet the demands of fifth-generation(5G)and beyond technologies.The random movement of mobile terminals in the indoor environment is a challenge in the VLC system.The model of optical attocells has a critical role in the uniform distribution and the quality of communication links in terms of received power and signal-to-noise ratio(SNR).As such,the optical attocells positions were optimized in this study with a developed try and error(TE)algorithm.The optimized optical attocells were examined and compared with previous models.This novel approach had successfully increased minimum received power from−1.29 to−0.225 dBm,along with enhanced SNR performance by 2.06 dB.The bit error rate(BER)was reduced to 4.42×10−8 and 6.63×10−14 by utilizing OOK-NRZ and BPSK modulation techniques,respectively.The optimized attocells positions displayed better uniform distribution,as both received power and SNR performances improved by 0.45 and 0.026,respectively.As the results of the proposed model are optimal,it is suitable for standard office and room model applications.展开更多
This paper studies in detail the interaction of two edge dislocations nested in a Gaussian beam propagating in free space. It shows that in free-space propagation the edge dislocations are unstable and vanish, and two...This paper studies in detail the interaction of two edge dislocations nested in a Gaussian beam propagating in free space. It shows that in free-space propagation the edge dislocations are unstable and vanish, and two noncanonical vortices with opposite topological charge take place when off-axis distances cl and c2 of two edge dislocations are nonzero, and the condition k2w08+ 32c1c2(w02- 2C1C2)Z2 〉 0 is fulfilled (k-wave number, w0-waist width). A noncanonical vortex appears when one off-axis distance is zero. However, one edge dislocation is stable when two edge dislocations are perpendicular and one off-axis distance is zero. Two perpendicular edge dislocations both with zero off-axis distance are also stable. The analytical results are illustrated by numerical examples.展开更多
This work presents a high-gain broadband inverter-based cascode transimpedance amplifier fabricated in a 65-nm CMOS process.Multiple bandwidth enhancement techniques,including input bonding wire,input series on-chip i...This work presents a high-gain broadband inverter-based cascode transimpedance amplifier fabricated in a 65-nm CMOS process.Multiple bandwidth enhancement techniques,including input bonding wire,input series on-chip inductive peak-ing and negative capacitance compensation,are adopted to overcome the large off-chip photodiode capacitive loading and the miller capacitance of the input device,achieving an overall bandwidth enhancement ratio of 8.5.The electrical measure-ment shows TIA achieves 58 dBΩup to 12.7 GHz with a 180-fF off-chip photodetector.The optical measurement demonstrates a clear open eye of 20 Gb/s.The TIA dissipates 4 mW from a 1.2-V supply voltage.展开更多
The design, production and characterization of tailored printable optical filters for visible optical communications are demonstrated. As result, the average color difference between the specified and the produced fil...The design, production and characterization of tailored printable optical filters for visible optical communications are demonstrated. As result, the average color difference between the specified and the produced filters is 32.6, quantified in terms of CIELAB coordinates.展开更多
This paper utilizes uniquely decodable codes[UDCs]in an M-to-1 free-space optical[FSO]system.Benefiting from UDCs’nonorthogonal nature,the sum throughput is improved.We first prove that the uniquely decodable propert...This paper utilizes uniquely decodable codes[UDCs]in an M-to-1 free-space optical[FSO]system.Benefiting from UDCs’nonorthogonal nature,the sum throughput is improved.We first prove that the uniquely decodable property still holds,even in optical fading channels.It is further discovered that the receiver can extract each source’s data from superimposed symbols with only one processing unit.According to theoretical analysis and simulation results,the throughput gain is up to the normalized UDC’s sum rate in high signal-to-noise ratio cases.An equivalent desktop experiment is also implemented to show the feasibility of the UDC-FSO structure.展开更多
The spot-diffusing technique provides better performance compared to conventional diffuse system for indoor optical-wireless communication (OWC) system. In this paper, the performance of an OW spot-diffusing communica...The spot-diffusing technique provides better performance compared to conventional diffuse system for indoor optical-wireless communication (OWC) system. In this paper, the performance of an OW spot-diffusing communication system using Neuro-Fuzzy (NF) adaptive multi-beam transmitter configuration has been proposed. The multi-beam transmitter generates multiple spots pointed in different directions, hence, forming a matrix of diffusing spots based on position of the receiver and receiver mobility. Regardless of the position of the transmitter and receiver, NF controller target the spots adaptively at the best locations and allocates optimal power to the spots and beam angle are adapted in order to achieve better signal-to-noise plus interference ratio (SNIR). Maximum ratio combining (MRC) is used in the imaging receiver. The proposed OW spot-diffusing communication system is compared with other spot-beam diffusion methods proposed in literature. Performance evaluation revels that the proposed NF based OW spot-diffusing communication system outperforms other spot-beam diffusion methods.展开更多
Unmanned aerial vehicle(UAV)relaying is promising to overcome the challenge of signal blockage in free-space optical(FSO)communications for users in dense urban area.Existing works on UAV relay placement are mostly ba...Unmanned aerial vehicle(UAV)relaying is promising to overcome the challenge of signal blockage in free-space optical(FSO)communications for users in dense urban area.Existing works on UAV relay placement are mostly based on simplified line-of-sight(LOS)channel models or probabilistic channel models,and thus fail to capture the actual LOS status of the optical communication link.By contrast,this paper studies three-dimensional(3D)online placement for a UAV to construct relay links to two ground users in deep shadow with LOS guarantees.By analyzing the properties of the UAV relay placement problem,it is found that searching on a plane that approximates the equipotential surface can achieve a good performance and complexity trade-off for a good placement of the UAV relay in 3D.Based on these insights,a two-stage online search algorithm on an equipotential plane(TOSEP)is developed for a special case where the equipotential surface turns out to be an equipotential plane.For the general case,a strategy called gradient projected online search algorithm on an approximated equipotential plane(GOSAEP)is developed,which approximates the equipotential surface with a perpendicular plane using the gradient projection method.Numerical experiments are conducted over a real-world city topology,and it is shown that the GOSAEP achieves over 95%of the performance of the exhaustive 3D search scheme within a 300-m search length.展开更多
基金Project supported by the National Key Research and Development Program of China(Grant No.2020YFB0408300)the National Natural Science Foundation of China(Grant No.62175246)+2 种基金the Natural Science Foundation of Shanghai,China(Grant No.22ZR1471100)the Youth Innovation Promotion Association of Chinese Academy of Sciences(Grant No.YIPA2021244)the Innovation Program for Quantum Science and Technology(Grant No.2021ZD0300701).
文摘Future inter-satellite clock comparison on high orbit will require optical time and frequency transmission technology between moving objects.Here,we demonstrate robust optical frequency transmission under the condition of variable link distance.This variable link is accomplished by the relative motion of a single telescope fixed on the experimental platform to a corner-cube reflector(CCR)installed on a sliding guide.Two acousto–optic modulators with different frequencies are used to separate forward signal from backward signal.With active phase noise suppression,when the CCR moves back and forth at a constant velocity of 20 cm/s and an acceleration of 20 cm/s^(2),we achieve the best frequency stability of 1.9×10^(-16) at 1 s and 7.9×10^(-19) at 1000 s indoors.This work paves the way for future studying optical frequency transfer between ultra-high-orbit satellites.
基金Supported by the National High Technology Research and Development Program of China under Grant No 2015AA016902the National Natural Science Foundation of China under Grant Nos 61435013 and 61405188the K.C.Wong Education Foundation
文摘An 8×10 GHz receiver optical sub-assembly (ROSA) consisting of an 8-channel arrayed waveguide grating (AWG) and an 8-channel PIN photodetector (PD) array is designed and fabricated based on silica hybrid integration technology. Multimode output waveguides in the silica AWG with 2% refractive index difference are used to obtain fiat-top spectra. The output waveguide facet is polished to 45° bevel to change the light propagation direction into the mesa-type PIN PD, which simplifies the packaging process. The experimentM results show that the single channel I dB bandwidth of AWG ranges from 2.12nm to 3.06nm, the ROSA responsivity ranges from 0.097 A/W to 0.158A/W, and the 3dB bandwidth is up to 11 GHz. It is promising to be applied in the eight-lane WDM transmission system in data center interconnection.
基金supported in part by Research and Development Program in Key Areas of Guangdong Province under Grant 2019B010116002in part by the National Natural Science Foundation of China under Grant 62074074in part by the Science and Technology Plan of Shenzhen under Grants JCYJ20190809142017428 and JCYJ20200109141225025。
文摘This paper presents a 26-Gb/s CMOS optical receiver that is fabricated in 65-nm technology. It consists of a tripleinductive transimpedance amplifier(TIA), direct current(DC) offset cancellation circuits, 3-stage gm-TIA variable-gain amplifiers(VGA), and a reference-less clock and data recovery(CDR) circuit with built-in equalization technique. The TIA/VGA frontend measurement results demonstrate 72-dB? transimpedance gain, 20.4-GHz-3-dB bandwidth, and 12-dB DC gain tuning range. The measurements of the VGA’s resistive networks also demonstrate its efficient capability of overcoming the voltage and temperature variations. The CDR adopts a full-rate topology with 12-dB imbedded equalization tuning range. Optical measurements of this chipset achieve a 10-12 BER at 26 Gb/s for a 2;-1 PRBS input with a-7.3-dBm input sensitivity. The measurement results with a 10-dB @ 13 GHz attenuator also demonstrate the effectiveness of the gain tuning capability and the built-in equalization. The entire system consumes 140 mW from a 1/1.2-V supply.
文摘This study develops an optimal performance monitoring metric for a hybrid free space optical and radio wireless network, the Outage Capacity Objective Function. The objective function—the dependence of hybrid channel outage capacity upon the error rate, jointly quantifies the effects of atmospheric optical impairments on the performance of the free space optical segment as well as the effect of RF channel impairments on the radio frequency segment. The objective function is developed from the basic information-theoretic capacity of the optical and radio channels using the gamma-gamma model for optical fading and Ricean statistics for the radio channel fading. A simulation is performed by using the hybrid network. The objective function is shown to provide significantly improved sensitivity to degrading performance trends and supports of proactive link failure prediction and mitigation when compared to current thresholding techniques for signal quality metrics.
文摘In this letter, we present the generation, the balanced detection, and the transmission performance evaluation of dual polarization differential quadrature phase shift keying (DP-DQPSK) signals in optical access system integrated with fiber and free-space downlink. Polarization-multip- lexed (POLMUX) technique is introduced in the system for high spectral efficiency access utilization. 10 Gb/s DP-DQPSK downlink signals are successfully transmitted over 50 km SMF-28 and a 800 m wireless optical channel under the bad weather condition, such as fog and haze. The results show that the potentiality of DP-DQPSK optical access system is integrated with fiber and free- space downlink for providing flexible user access with high bandwidth efficiency.
基金Supported by the Natural Science Foundation of Jiangsu Province ( BK2010411 ) and the National International Cooperation Project of China-Korea (2011DFA11310).
基金extend their appreciation to the Deputyship for Research&Innovation,Ministry of Education in Saudi Arabia for funding this research work through Project Number RI-44-0345.
文摘With the capacities of self-learning,acquainted capacities,high-speed looking for ideal arrangements,solid nonlin-ear fitting,and mapping self-assertively complex nonlinear relations,neural systems have made incredible advances and accomplished broad application over the final half-century.As one of the foremost conspicuous methods for fake insights,neural systems are growing toward high computational speed and moo control utilization.Due to the inborn impediments of electronic gadgets,it may be troublesome for electronic-implemented neural systems to make the strides these two exhibitions encourage.Optical neural systems can combine optoelectronic procedures and neural organization models to provide ways to break the bottleneck.This paper outlines optical neural networks of feedforward repetitive and spiking models to give a clearer picture of history,wildernesses,and future optical neural systems.The framework demonstrates neural systems in optic communication with the serial and parallel setup.The graphene-based laser structure for fiber optic communication is discussed.The comparison of different balance plans for photonic neural systems is made within the setting of hereditary calculation and molecule swarm optimization.In expansion,the execution comparison of routine photonic neural,time-domain with and without extending commotion is additionally expounded.The challenges and future patterns of optical neural systems on the growing scale and applications of in situ preparing nonlinear computing will hence be uncovered.
基金the grant names“ProfessionalDevelopment Research University Grant”(“UTM Vot No.05E69”and“TDR grant Vot No.05G27”).
文摘Visible light communication(VLC),which is a prominent emerging solution that complements the radio frequency(RF)technology,exhibits the potential to meet the demands of fifth-generation(5G)and beyond technologies.The random movement of mobile terminals in the indoor environment is a challenge in the VLC system.The model of optical attocells has a critical role in the uniform distribution and the quality of communication links in terms of received power and signal-to-noise ratio(SNR).As such,the optical attocells positions were optimized in this study with a developed try and error(TE)algorithm.The optimized optical attocells were examined and compared with previous models.This novel approach had successfully increased minimum received power from−1.29 to−0.225 dBm,along with enhanced SNR performance by 2.06 dB.The bit error rate(BER)was reduced to 4.42×10−8 and 6.63×10−14 by utilizing OOK-NRZ and BPSK modulation techniques,respectively.The optimized attocells positions displayed better uniform distribution,as both received power and SNR performances improved by 0.45 and 0.026,respectively.As the results of the proposed model are optimal,it is suitable for standard office and room model applications.
基金Project supported by the National Natural Science Foundation of China(Grant No.10874125)
文摘This paper studies in detail the interaction of two edge dislocations nested in a Gaussian beam propagating in free space. It shows that in free-space propagation the edge dislocations are unstable and vanish, and two noncanonical vortices with opposite topological charge take place when off-axis distances cl and c2 of two edge dislocations are nonzero, and the condition k2w08+ 32c1c2(w02- 2C1C2)Z2 〉 0 is fulfilled (k-wave number, w0-waist width). A noncanonical vortex appears when one off-axis distance is zero. However, one edge dislocation is stable when two edge dislocations are perpendicular and one off-axis distance is zero. Two perpendicular edge dislocations both with zero off-axis distance are also stable. The analytical results are illustrated by numerical examples.
基金supported in part by the National NaturalScience Foundation of China under Grant 62074074in part by Natural Science Foundation of Guangdong Province under Grant 2021A1515011266in part by the Science and Technology Plan of Shenzhen under Grants JCYJ20190809142017428 and JCYJ20200109141225025。
文摘This work presents a high-gain broadband inverter-based cascode transimpedance amplifier fabricated in a 65-nm CMOS process.Multiple bandwidth enhancement techniques,including input bonding wire,input series on-chip inductive peak-ing and negative capacitance compensation,are adopted to overcome the large off-chip photodiode capacitive loading and the miller capacitance of the input device,achieving an overall bandwidth enhancement ratio of 8.5.The electrical measure-ment shows TIA achieves 58 dBΩup to 12.7 GHz with a 180-fF off-chip photodetector.The optical measurement demonstrates a clear open eye of 20 Gb/s.The TIA dissipates 4 mW from a 1.2-V supply voltage.
基金The financial support of“Scientific and technological collaboration Portugal/China 2010/2012.Proc.0 441.00”is gratefully acknowledged.
文摘The design, production and characterization of tailored printable optical filters for visible optical communications are demonstrated. As result, the average color difference between the specified and the produced filters is 32.6, quantified in terms of CIELAB coordinates.
基金supported in part by the National Natural Science Foundation of China(No.62101527)in part by the Funding Program of Innovation Labs by CIOMP。
文摘This paper utilizes uniquely decodable codes[UDCs]in an M-to-1 free-space optical[FSO]system.Benefiting from UDCs’nonorthogonal nature,the sum throughput is improved.We first prove that the uniquely decodable property still holds,even in optical fading channels.It is further discovered that the receiver can extract each source’s data from superimposed symbols with only one processing unit.According to theoretical analysis and simulation results,the throughput gain is up to the normalized UDC’s sum rate in high signal-to-noise ratio cases.An equivalent desktop experiment is also implemented to show the feasibility of the UDC-FSO structure.
文摘The spot-diffusing technique provides better performance compared to conventional diffuse system for indoor optical-wireless communication (OWC) system. In this paper, the performance of an OW spot-diffusing communication system using Neuro-Fuzzy (NF) adaptive multi-beam transmitter configuration has been proposed. The multi-beam transmitter generates multiple spots pointed in different directions, hence, forming a matrix of diffusing spots based on position of the receiver and receiver mobility. Regardless of the position of the transmitter and receiver, NF controller target the spots adaptively at the best locations and allocates optimal power to the spots and beam angle are adapted in order to achieve better signal-to-noise plus interference ratio (SNIR). Maximum ratio combining (MRC) is used in the imaging receiver. The proposed OW spot-diffusing communication system is compared with other spot-beam diffusion methods proposed in literature. Performance evaluation revels that the proposed NF based OW spot-diffusing communication system outperforms other spot-beam diffusion methods.
基金supported in part by the National Key R&D Program of China(No.2018YFB1800800)the Basic Research Project of Hetao Shenzhen-HK S&T Cooperation Zone(No.HZQB-KCZYZ-2021067)+3 种基金National Natural Science Foundation of China(Nos.62171398 and 92067202)the Shenzhen Science and Technology Program(Nos.JCYJ20210324134612033 and KQTD20200909114730003)Guangdong Research(Nos.2019QN01X895 and 2017ZT07X152)Guangdong Provincial Key Laboratory of Future Networks of Intelligence(No.2022B1212010001).
文摘Unmanned aerial vehicle(UAV)relaying is promising to overcome the challenge of signal blockage in free-space optical(FSO)communications for users in dense urban area.Existing works on UAV relay placement are mostly based on simplified line-of-sight(LOS)channel models or probabilistic channel models,and thus fail to capture the actual LOS status of the optical communication link.By contrast,this paper studies three-dimensional(3D)online placement for a UAV to construct relay links to two ground users in deep shadow with LOS guarantees.By analyzing the properties of the UAV relay placement problem,it is found that searching on a plane that approximates the equipotential surface can achieve a good performance and complexity trade-off for a good placement of the UAV relay in 3D.Based on these insights,a two-stage online search algorithm on an equipotential plane(TOSEP)is developed for a special case where the equipotential surface turns out to be an equipotential plane.For the general case,a strategy called gradient projected online search algorithm on an approximated equipotential plane(GOSAEP)is developed,which approximates the equipotential surface with a perpendicular plane using the gradient projection method.Numerical experiments are conducted over a real-world city topology,and it is shown that the GOSAEP achieves over 95%of the performance of the exhaustive 3D search scheme within a 300-m search length.