The linear transmission impairments,such as the timing offset(TO),frequency offset(FO),and chromatic dispersion(CD),are major factors of signal degradations in coherent optical fiber communication systems.The estimati...The linear transmission impairments,such as the timing offset(TO),frequency offset(FO),and chromatic dispersion(CD),are major factors of signal degradations in coherent optical fiber communication systems.The estimation and compensation of such impairments play significant roles in the receiver side digital signal processing(DSP)unit.In this paper,we propose to combat the linear impairments systematically(including TO,FO and CD)with a joint timefrequency signal processing by taking the advantage of fractional Fourier transform(FrFT).In view of geometrical analysis,TO/FO induces a shift in time/frequency coordinate and the CD leads to the rotation in the fractional domain.Both mathematical derivations and geometrical interpretations have been established to unveil the relationships between impairments and linear frequency modulated(LFM)training symbols(TSs).By considering a typical coherent optical orthogonal frequency-division multiplexing(COOFDM)transmission system,three kinds of linear impairments have been jointly estimated by simple geometric calculations using appropriately designed TS based on FrFTs.Simulation and experimental results confirmed the feasibility of time-frequency techniques with better accuracy,less complexity,and improved spectral efficiency.展开更多
The integrated waveguide polarizer is essential for photonic integrated circuits,and various designs of waveguide polarizers have been developed.As the demand for dense photonic integration increases rapidly,new strat...The integrated waveguide polarizer is essential for photonic integrated circuits,and various designs of waveguide polarizers have been developed.As the demand for dense photonic integration increases rapidly,new strategies to minimize the device size are needed.In this paper,we have inversely designed an integrated transverse electric pass(TE-pass)polarizer with a footprint of 2.88μm×2.88μm,which is the smallest footprint ever achieved.A direct binary search algorithm is used to inversely design the device for maximizing the transverse electric(TE)transmission while minimizing transverse magnetic(TM)transmission.Finally,the inverse-designed device provides an average insertion loss of 0.99 dB and an average extinction ratio of 33 dB over a wavelength range of 100 nm.展开更多
A microfiber with large evanescent field encapsulated in PDMS is proposed and demonstrated for ultrasound sensing.The compact size and large evanescent field of microfiber provide an excellent platform for the interac...A microfiber with large evanescent field encapsulated in PDMS is proposed and demonstrated for ultrasound sensing.The compact size and large evanescent field of microfiber provide an excellent platform for the interaction between optical signal and ultrasound wave,exhibiting a high sensitivity of 3.5 mV/kPa,which is approximately 10 times higher than the single-mode fiber sensor.Meanwhile,a phase feedback stabilization module is introduced into the coherent demodulation system for long-term stable measurement.In addition,a photoacoustic tomography experiment with the microfiber ultrasound sensor is implemented to verify the excellent performance on imaging,with the depth of 12 mm,the highest lateral resolution of 65μm and axial resolution of 250μm,respectively.The highly sensitive microfiber ultrasound sensor provides a competitive alternative for various applications,such as industrial non-destructive testing,biomedical ultrasound and photoacoustic imaging.展开更多
We propose a side-core holey fiber （SCHF）-based surface plasmon resonance （SPR） sensor to achieve high refractive index （RI） sensitivity. The SCHF structure can facilitate analyte filling and enhance the overlap...We propose a side-core holey fiber （SCHF）-based surface plasmon resonance （SPR） sensor to achieve high refractive index （RI） sensitivity. The SCHF structure can facilitate analyte filling and enhance the overlapping area of the core mode and surface plasmon polariton （SPP） mode. The coupling properties of the sensor are analyzed by numerical simulation. The maximum sensitivity of 5000 nm/RIU in an RI range of 1.33-1.44, and the average sensitivity of 9295 nm/RIU in an RI range from 1.44 to 1.54 can be obtained.展开更多
Multicore fiber(MCF)which contains more than one core in a single fiber cladding has attracted ever increasing attention for application in optical sensing systems owing to its unique capability of independent light t...Multicore fiber(MCF)which contains more than one core in a single fiber cladding has attracted ever increasing attention for application in optical sensing systems owing to its unique capability of independent light transmission in multiple spatial channels.Different from the situation in standard single mode fiber(SMF),the fiber bending gives rise to tangential strain in off-center cores,and this unique feature has been employed for directional bending and shape sensing,where strain measurement is achieved by using either fiber Bragg gratings(FBGs),optical frequency-domain reflectometry(OFDR)or Brillouin distributed sensing technique.On the other hand,the parallel spatial cores enable space-division multiplexed(SDM)system configuration that allows for the multiplexing of multiple distributed sensing techniques.As a result,multi-parameter sensing or performance enhanced sensing can be achieved by using MCF.In this paper,we review the research progress in MCF based distributed fiber sensors.Brief introductions of MCF and the multiplexing/de-multiplexing methods are presented.The bending sensitivity of off-center cores is analyzed.Curvature and shape sensing,as well as various SDM distributed sensing using MCF are summarized,and the working principles of diverse MCF sensors are discussed.Finally,we present the challenges and prospects of MCF for distributed sensing applications.展开更多
The requirement for guaranteed Quality of Service (QoS) have become very essential since there are numerous network base application is available such as video conferencing, data streaming, data transfer and many more...The requirement for guaranteed Quality of Service (QoS) have become very essential since there are numerous network base application is available such as video conferencing, data streaming, data transfer and many more. This has led to the multi-class switch architecture to cater for the needs for different QoS requirements. The introduction of threshold in multi-class switch to solve the starvation problems in loss sensitive class has increased the mean delay for delay sensitive class. In this research, a new scheduling architecture is introduced to improve mean delay in delay sensitive class when the threshold is active. The proposed architecture has been simulated under uniform and non-uniform traffic to show performance of the switch in terms of mean delay. The results show that the proposed architecture has achieved better performance as compared to Weighted Fair Queueing (WFQ) and Priority Queue (PQ).展开更多
This paper presents a novel way to improve Transmission Control Protocol (TCP) performance of the users at the edge areas of the macro cells in Long Term Evolution Advanced (LTE-A) systems. Previous works on improving...This paper presents a novel way to improve Transmission Control Protocol (TCP) performance of the users at the edge areas of the macro cells in Long Term Evolution Advanced (LTE-A) systems. Previous works on improving wireless TCP performance are reviewed and current considerations on TCP in LTE-A are explained. However, those solutions are neither too complex nor limited to some presuppositions which are too restricting for the deployment of LTE-A networks. In this paper a substituted TCP acknowledgement transmission scheme based on Automatic Repeat reQuest (ARQ) information in layer 2 is proposed. The simulation result shows that the proposed method can reduce the delay and improve the throughput of the edging users of the cell, as well as reducing radio resources in LTE-A macro cells.展开更多
Optical fiber technology has changed the world by enabling extraordinary growth in world-wide communications and sensing.The rapid development and wide deployment of optical fiber sensors are driven by their excellent...Optical fiber technology has changed the world by enabling extraordinary growth in world-wide communications and sensing.The rapid development and wide deployment of optical fiber sensors are driven by their excellent sensing performance with outstanding flexibility,functionality,and versatility.Notably,the research on specialty optical fibers is playing a critical role in enabling and proliferating the optical fiber sensing applications.This paper overviews recent developments in specialty optical fibers and their sensing applications.The specialty optical fibers are reviewed based on their innovations in special structures,special materials,and technologies to realize lab in/on a fiber.An overview of sensing applications in various fields is presented.The prospects and emerging research areas of specialty optical fibers are also discussed.展开更多
A new hybrid WDM/TDM passive optical network （PON） implemented by using all-optical wavelength converters （AOWCs） is proposed. The AOWCs are based on the cross-gain modulation （XGM） effect of the semiconductor o...A new hybrid WDM/TDM passive optical network （PON） implemented by using all-optical wavelength converters （AOWCs） is proposed. The AOWCs are based on the cross-gain modulation （XGM） effect of the semiconductor optical amplifier （SOA）. Moreover, the feasibility of this sys- tem is experimentally demonstrated by evaluating the impacts of the optical wavelength conversion, time domain waveforms, eye diagrams and bit-error-rate （BER） in AOWC. The results show that the proposal will be a promising solution for the next generation access networks.展开更多
The detection of the state of polarization(SOP)of light is essential for many optical applications.However,cost-effective SOP measurement is a challenge due to the complexity of conventional methods and the poor trans...The detection of the state of polarization(SOP)of light is essential for many optical applications.However,cost-effective SOP measurement is a challenge due to the complexity of conventional methods and the poor transferability of new methods.We propose a straightforward,low-cost,and portable SOP measurement system based on the multimode fiber speckle.A convolutional neural network is utilized to establish the mapping relationship between speckle and Stokes parameters.The lowest root-mean-square error of the estimated SOP on the Poincarésphere can be 0.0042.This method is distinguished by its low cost,clear structure,and applicability to different wavelengths with high precision.The proposed method is of great value in polarization-related applications.展开更多
We proposed an optical 4-ary frequency shift keying （FSK） modulation scheme applying dual-parallel Mach-Zehnder （MZ） modulator. The 4-ary FSK based on the single-side-band modulation scheme can greatly lower the t...We proposed an optical 4-ary frequency shift keying （FSK） modulation scheme applying dual-parallel Mach-Zehnder （MZ） modulator. The 4-ary FSK based on the single-side-band modulation scheme can greatly lower the transmission speed in each sub-carriers and increase the transmission performance, comparing with the 2-FSK signal. The transmission performance of the 4-ary FSK was demonstrated after a 50 km single mode fiber. The results showed that the 4-ary FSK can realize error-free transmission. Moreover, we analyzed the influence of factors （such as disperse compensation and demodulation bandwidth） on the transmission performance in this paper. The analysis of the influenced factors can provide a theoretical basic for experiment.展开更多
A distributed access scheme using optical add/drop multiplexers （OADMs） for long reach hybrid wavelength division multiplexing and time division multiplexing passive optical networks （WDM-TDM PONs） is proposed and...A distributed access scheme using optical add/drop multiplexers （OADMs） for long reach hybrid wavelength division multiplexing and time division multiplexing passive optical networks （WDM-TDM PONs） is proposed and demonstrated. Colorless operations are implemented by using commercially available reflective semiconductor optical amplifiers （RSOAs） at both the center office （CO） and the customer side. Four 1.25-Gb/s channels are successfully transmitted over 80-km single-mode fiber with four OADMs. The dynamic input power range of the RSOA is also investigated. Compared with traditional access schemes, the proposed scheme could cover the area along the feed fiber with no blind zone. The experimental results show that it could be an ideal solution for the next generation access networks.展开更多
Imaging flow cytometry(IFC)combines the imaging capabilities of microscopy with the high throughput of flow cytometry,offering a promising solution for high-precision and high-throughput cell analysis in fields such a...Imaging flow cytometry(IFC)combines the imaging capabilities of microscopy with the high throughput of flow cytometry,offering a promising solution for high-precision and high-throughput cell analysis in fields such as biomedicine,green energy,and environmental monitoring.However,due to limitations in imaging framerate and realtime data processing,the real-time throughput of existing IFC systems has been restricted to approximately 1000-10,000 events per second(eps),which is insufficient for large-scale cell analysis.In this work,we demonstrate IFC with real-time throughput exceeding 1,000,000 eps by integrating optical time-stretch(OTS)imaging,microfluidic-based cell manipulation,and online image processing.Cells flowing at speeds up to 15 m/s are clearly imaged with a spatial resolution of 780 nm,and images of each individual cell are captured,stored,and analyzed.The capabilities and performance of our system are validated through the identification of malignancies in clinical colorectal samples.This work sets a new record for throughput in imaging flow cytometry,and we believe it has the potential to revolutionize cell analysis by enabling highly efficient,accurate,and intelligent measurement.展开更多
We propose and validate a novel optical semantic transmission scheme using multimode fiber(MMF).By leveraging the frequency sensitivity of intermodal dispersion in MMFs,we achieve high-dimensional semantic encoding an...We propose and validate a novel optical semantic transmission scheme using multimode fiber(MMF).By leveraging the frequency sensitivity of intermodal dispersion in MMFs,we achieve high-dimensional semantic encoding and decoding in the frequency domain.Our system maps symbols to 128 distinct frequencies spaced at 600 kHz intervals,demonstrating a seven-fold increase in capacity compared to conventional communication encoding.We further enhance spectral efficiency by implementing 4-level pulse amplitude modulation(PAM-4),achieving 9.12 bits/s/Hz without decoding errors.Additionally,we explore the application of this system for sentiment analysis using the IMDb movie review dataset.By encoding semantically similar symbols to adjacent frequencies,the system's noise tolerance is effectively improved,facilitating accurate sentiment analysis.This work highlights the potential of MMF-based semantic communication to enhance both capacity and robustness in optical communication systems,offering promising applications in bandwidth-constrained and noisy environments.展开更多
We propose a novel waveguide design of polarization-maintaining few mode fiber(PM-FMF) supporting ≥10non-degenerate modes, utilizing a central circular air hole and a circumjacent elliptical-ring core. The structure ...We propose a novel waveguide design of polarization-maintaining few mode fiber(PM-FMF) supporting ≥10non-degenerate modes, utilizing a central circular air hole and a circumjacent elliptical-ring core. The structure endows a new degree of freedom to adjust the birefringence of all the guided modes, including the fundamental polarization mode. Numerical simulations demonstrate that, by optimizing the air hole and elliptical-ring core,a PM-FMF supporting 10 distinctive polarization modes has been achieved, and the effective index difference Δn_(eff) between the adjacent guided modes could be kept larger than 1.32 × 10^(-4) over the whole C +L band. The proposed fiber structure can flexibly tailored to support an even larger number of modes in PM-FMF(14-mode PM-FMF has been demonstrated as an example), which can be readily applicable to a scalable mode division multiplexing system.展开更多
Distributed optical fiber Brillouin sensors detect the temperature and strain along a fiber according to the local Brillouin frequency shift(BFS),which is usually calculated by the measured Brillouin spectrum using Lo...Distributed optical fiber Brillouin sensors detect the temperature and strain along a fiber according to the local Brillouin frequency shift(BFS),which is usually calculated by the measured Brillouin spectrum using Lorentzian curve fitting.In addition,cross-correlation,principal component analysis,and machine learning methods have been proposed for the more efficient extraction of BFS.However,existing methods only process the Brillouin spectrum individually,ignoring the correlation in the time domain,indicating that there is still room for improvement.Here,we propose and experimentally demonstrate a BFS extraction convolutional neural network(BFSCNN)to retrieve the distributed BFS directly from the measured two-dimensional data.Simulated ideal Brillouin spectra with various parameters are used to train the BFSCNN.Both the simulation and experimental results show that the extraction accuracy of the BFSCNN is better than that of the traditional curve fitting algorithm with a much shorter processing time.The BFSCNN has good universality and robustness and can effectively improve the performances of existing Brillouin sensors.展开更多
Continuous pulse wave signals monitoring is the essential basis for clinical cardiovascular diagnosis and treatment.Recent researches show the majority of current electronic pulse sensors usually face challenges in el...Continuous pulse wave signals monitoring is the essential basis for clinical cardiovascular diagnosis and treatment.Recent researches show the majority of current electronic pulse sensors usually face challenges in electrical safety concern,poor durability and demanding precision in position alignment.Thus,a highly sensitive,inherently electrical safe,robust and alignment-free device is highly desired.Here,we present a wearable alignment-free microfber-based sensor chip(AFMSC)for precise vital signs monitoring and cardiovascular health assessment.The AFMSC comprises an optical micro/nano fber sensor(MNF)and a fexible soft liquid sac while the MNF sensor is used to perceive the physiological signals and the liquid sac is used to eliminate the misalignment.The real-time and accurate monitoring of the pulse signals was realized by tracking the optical power variation of transmitted light from MNF.Then,the cardiovascular vital signs extracted from radial artery pulse signals were used to evaluate cardiovascular health condition and the results were in accordance with human physiological characteristics.Moreover,the pulse signals from diferent arterial area,the respiration signals from chest and the radial pulse signals before and after exercise were detected and analyzed.The non-invasive,continuous and accurate monitoring of cardiovascular health based on the reported wearable and alignment-free device is promising in both ftness monitoring and medical diagnostics for cardiovascular disease prevention and diagnosis.展开更多
We propose and experimentally demonstrate a novel physical layer encryption scheme for high-speed optical communication. A 10 Gb/s on-off keying signal is secretly transmitted over 100 km standard single-mode fiber.Th...We propose and experimentally demonstrate a novel physical layer encryption scheme for high-speed optical communication. A 10 Gb/s on-off keying signal is secretly transmitted over 100 km standard single-mode fiber.The intensity-modulated message is secured by the encryption mechanism, which is composed of an external noise source and an internal time-delayed feedback loop. The external noise serves as an entropy source with sufficient randomness. The feedback loop structure in the transmitter introduces a time-domain encryption key space, and a corresponding open-loop configuration at the receiver side is used for synchronization and decryption.Experiment results show the effectiveness of the proposed scheme. For a legitimate terminal, bit error rate below10-8 can be obtained. Decryption degradations with the mismatch of different hardware parameters are researched. The time delay in the feedback loop provides a sensitive encryption key. For other hardware parameters,the system is robust enough for synchronization. Meanwhile, the time-delay signature of the loop is able to be well concealed by the external noise. Moreover, the proposed scheme can support density wavelength division multiplexing transmission with a relatively simple structure. This work also provides a new concept to establish optical secure communication by combining a time-delayed feedback chaotic system and random noise.展开更多
The recent research progress in the key device and technology of the fiber optic sensor network （FOSN） is introduced in this paper. An architecture of the sensor optical passive network （SPON）, by employing hybrid...The recent research progress in the key device and technology of the fiber optic sensor network （FOSN） is introduced in this paper. An architecture of the sensor optical passive network （SPON）, by employing hybrid wavelength division multiplexing/time division multiplexing （WDM/TDM） techniques similar to the fiber communication passive optical network （PON）, is proposed. The network topology scheme of a hybrid TDM/WDM/FDM （frequency division multiplexing） three-dimension fiber optic sensing system for achieving ultra-large capacity, long distance, and high resolution sensing performance is performed and analyzed. As the most important device of the FOSN, several kinds of light source are developed, including the wideband multi-wavelength fiber laser operating at C band, switchable and tunable 2 μm multi-wavelength fiber lasers, ultra-fast mode-locked fiber laser, as well as the optical wideband chaos source, which have very good application prospects in the FOSN. Meanwhile, intelligent management techniques for the FOSN including wideband spectrum demodulation of the sensing signals and real-time fault monitoring of fiber links are presented. Moreover, several typical applications of the FOSN are also discussed, such as the fiber optic gas sensing network, fiber optic acoustic sensing network, and strain/dynamic strain sensing network.展开更多
In this Letter, a low-frequency acoustic sensor based on an extrinsic Fabry–Pérot(FP) interferometer with a silicon nitride(Si3N4) membrane is demonstrated. Using micromachining techniques, the 800 nm thick Si3N...In this Letter, a low-frequency acoustic sensor based on an extrinsic Fabry–Pérot(FP) interferometer with a silicon nitride(Si3N4) membrane is demonstrated. Using micromachining techniques, the 800 nm thick Si3N4 membrane is deposited on an 8 mm × 8 mm × 400 μm silicon(Si) substrate. All the assembly procedures of the sensor are focused on the substrate to avoid any damage to the membrane itself, compared to general membrane transfer methods. The frequency response of the proposed sensor is discussed theoretically and experimentally demonstrated. The sensor exhibits an excellent flat response to the tested acoustic frequency range of 1 Hz to 250 Hz. The phase sensitivity is around-152 dB re 1 rad/μPa with sensitivity fluctuation less than 0.8 dB.The frequency response characteristic shows a promising potential of the sensor in low-frequency acoustic signal sensing applications.展开更多
文摘The linear transmission impairments,such as the timing offset(TO),frequency offset(FO),and chromatic dispersion(CD),are major factors of signal degradations in coherent optical fiber communication systems.The estimation and compensation of such impairments play significant roles in the receiver side digital signal processing(DSP)unit.In this paper,we propose to combat the linear impairments systematically(including TO,FO and CD)with a joint timefrequency signal processing by taking the advantage of fractional Fourier transform(FrFT).In view of geometrical analysis,TO/FO induces a shift in time/frequency coordinate and the CD leads to the rotation in the fractional domain.Both mathematical derivations and geometrical interpretations have been established to unveil the relationships between impairments and linear frequency modulated(LFM)training symbols(TSs).By considering a typical coherent optical orthogonal frequency-division multiplexing(COOFDM)transmission system,three kinds of linear impairments have been jointly estimated by simple geometric calculations using appropriately designed TS based on FrFTs.Simulation and experimental results confirmed the feasibility of time-frequency techniques with better accuracy,less complexity,and improved spectral efficiency.
基金supported by the National Natural Science Foundation of China(Nos.62175076,62105028,62475085)the Natural Science Foundation of Hubei Province of China(Nos.2024AFA016,2024AFB612)the Open Project Program of Hubei Optical Fundamental Research Center.
文摘The integrated waveguide polarizer is essential for photonic integrated circuits,and various designs of waveguide polarizers have been developed.As the demand for dense photonic integration increases rapidly,new strategies to minimize the device size are needed.In this paper,we have inversely designed an integrated transverse electric pass(TE-pass)polarizer with a footprint of 2.88μm×2.88μm,which is the smallest footprint ever achieved.A direct binary search algorithm is used to inversely design the device for maximizing the transverse electric(TE)transmission while minimizing transverse magnetic(TM)transmission.Finally,the inverse-designed device provides an average insertion loss of 0.99 dB and an average extinction ratio of 33 dB over a wavelength range of 100 nm.
基金financial supports from National Natural Science Foundation of China (NSFC)(No.61922033)Foundation for Innovative Research Groups of Hubei Province of China (2018CFA004)Innovation Fund of WNLO
文摘A microfiber with large evanescent field encapsulated in PDMS is proposed and demonstrated for ultrasound sensing.The compact size and large evanescent field of microfiber provide an excellent platform for the interaction between optical signal and ultrasound wave,exhibiting a high sensitivity of 3.5 mV/kPa,which is approximately 10 times higher than the single-mode fiber sensor.Meanwhile,a phase feedback stabilization module is introduced into the coherent demodulation system for long-term stable measurement.In addition,a photoacoustic tomography experiment with the microfiber ultrasound sensor is implemented to verify the excellent performance on imaging,with the depth of 12 mm,the highest lateral resolution of 65μm and axial resolution of 250μm,respectively.The highly sensitive microfiber ultrasound sensor provides a competitive alternative for various applications,such as industrial non-destructive testing,biomedical ultrasound and photoacoustic imaging.
基金Project supported by the Major Projects of the National Natural Science Foundation of China(Grant No.61290315)the National Natural Science Foundation of China(Grant No.61340057)the Special Program of the National Modern Service Industrial Development Foundation of China(Grant No.[2012]14)
文摘We propose a side-core holey fiber （SCHF）-based surface plasmon resonance （SPR） sensor to achieve high refractive index （RI） sensitivity. The SCHF structure can facilitate analyte filling and enhance the overlapping area of the core mode and surface plasmon polariton （SPP） mode. The coupling properties of the sensor are analyzed by numerical simulation. The maximum sensitivity of 5000 nm/RIU in an RI range of 1.33-1.44, and the average sensitivity of 9295 nm/RIU in an RI range from 1.44 to 1.54 can be obtained.
文摘Multicore fiber(MCF)which contains more than one core in a single fiber cladding has attracted ever increasing attention for application in optical sensing systems owing to its unique capability of independent light transmission in multiple spatial channels.Different from the situation in standard single mode fiber(SMF),the fiber bending gives rise to tangential strain in off-center cores,and this unique feature has been employed for directional bending and shape sensing,where strain measurement is achieved by using either fiber Bragg gratings(FBGs),optical frequency-domain reflectometry(OFDR)or Brillouin distributed sensing technique.On the other hand,the parallel spatial cores enable space-division multiplexed(SDM)system configuration that allows for the multiplexing of multiple distributed sensing techniques.As a result,multi-parameter sensing or performance enhanced sensing can be achieved by using MCF.In this paper,we review the research progress in MCF based distributed fiber sensors.Brief introductions of MCF and the multiplexing/de-multiplexing methods are presented.The bending sensitivity of off-center cores is analyzed.Curvature and shape sensing,as well as various SDM distributed sensing using MCF are summarized,and the working principles of diverse MCF sensors are discussed.Finally,we present the challenges and prospects of MCF for distributed sensing applications.
文摘The requirement for guaranteed Quality of Service (QoS) have become very essential since there are numerous network base application is available such as video conferencing, data streaming, data transfer and many more. This has led to the multi-class switch architecture to cater for the needs for different QoS requirements. The introduction of threshold in multi-class switch to solve the starvation problems in loss sensitive class has increased the mean delay for delay sensitive class. In this research, a new scheduling architecture is introduced to improve mean delay in delay sensitive class when the threshold is active. The proposed architecture has been simulated under uniform and non-uniform traffic to show performance of the switch in terms of mean delay. The results show that the proposed architecture has achieved better performance as compared to Weighted Fair Queueing (WFQ) and Priority Queue (PQ).
基金Partly supported by the Key Project of National Natural Science Foundation of China(No.61231007)863 Hi Tech R&D Program of China(No.2012AA121604)ISTCP(No.2012DFG12010)
文摘This paper presents a novel way to improve Transmission Control Protocol (TCP) performance of the users at the edge areas of the macro cells in Long Term Evolution Advanced (LTE-A) systems. Previous works on improving wireless TCP performance are reviewed and current considerations on TCP in LTE-A are explained. However, those solutions are neither too complex nor limited to some presuppositions which are too restricting for the deployment of LTE-A networks. In this paper a substituted TCP acknowledgement transmission scheme based on Automatic Repeat reQuest (ARQ) information in layer 2 is proposed. The simulation result shows that the proposed method can reduce the delay and improve the throughput of the edging users of the cell, as well as reducing radio resources in LTE-A macro cells.
基金We are grateful for financial supports from Special Funds for the Major Fields of Colleges and Universities by the Department of Education of Guangdong Province(2021ZDZX1023)Natural Science Foundation of Guangdong Province(No.2022A1515011434)+4 种基金Stable Support Program for Higher Education Institutions from Shenzhen Science,Technology&Innovation Commission(20200925162216001)Guangdong Basic and Applied Basic Research Foundation(2021B1515120013)Open Fund of State Key Laboratory of Information Photonics and Optical Communications(Beijing University of Posts and Telecommunications,No.IPOC2020A002)The Open Projects Foundation of State Key Laboratory of Optical Fiber and Cable Manufacture Technology(No.SKLD2105)General Program of Shenzhen Science,Technology&Innovation Commission(JCYJ20220530113811026).
文摘Optical fiber technology has changed the world by enabling extraordinary growth in world-wide communications and sensing.The rapid development and wide deployment of optical fiber sensors are driven by their excellent sensing performance with outstanding flexibility,functionality,and versatility.Notably,the research on specialty optical fibers is playing a critical role in enabling and proliferating the optical fiber sensing applications.This paper overviews recent developments in specialty optical fibers and their sensing applications.The specialty optical fibers are reviewed based on their innovations in special structures,special materials,and technologies to realize lab in/on a fiber.An overview of sensing applications in various fields is presented.The prospects and emerging research areas of specialty optical fibers are also discussed.
文摘A new hybrid WDM/TDM passive optical network （PON） implemented by using all-optical wavelength converters （AOWCs） is proposed. The AOWCs are based on the cross-gain modulation （XGM） effect of the semiconductor optical amplifier （SOA）. Moreover, the feasibility of this sys- tem is experimentally demonstrated by evaluating the impacts of the optical wavelength conversion, time domain waveforms, eye diagrams and bit-error-rate （BER） in AOWC. The results show that the proposal will be a promising solution for the next generation access networks.
基金supported by the National Key Research and Development Program of China(Grant No.2021YFB2800902)the National Natural Science Foundation of China(Grant No.62225110)+1 种基金the Key Research and Development Program of Hubei Province(No.2022BAA001)the Innovation Fund of WNLO.
文摘The detection of the state of polarization(SOP)of light is essential for many optical applications.However,cost-effective SOP measurement is a challenge due to the complexity of conventional methods and the poor transferability of new methods.We propose a straightforward,low-cost,and portable SOP measurement system based on the multimode fiber speckle.A convolutional neural network is utilized to establish the mapping relationship between speckle and Stokes parameters.The lowest root-mean-square error of the estimated SOP on the Poincarésphere can be 0.0042.This method is distinguished by its low cost,clear structure,and applicability to different wavelengths with high precision.The proposed method is of great value in polarization-related applications.
基金This work was supported by the National Natural Science Foundation of China （Grant Nos. 61471179 and 61301226）, and the High Technology Research and Development Program of China （No. 2015AA016904）.
文摘We proposed an optical 4-ary frequency shift keying （FSK） modulation scheme applying dual-parallel Mach-Zehnder （MZ） modulator. The 4-ary FSK based on the single-side-band modulation scheme can greatly lower the transmission speed in each sub-carriers and increase the transmission performance, comparing with the 2-FSK signal. The transmission performance of the 4-ary FSK was demonstrated after a 50 km single mode fiber. The results showed that the 4-ary FSK can realize error-free transmission. Moreover, we analyzed the influence of factors （such as disperse compensation and demodulation bandwidth） on the transmission performance in this paper. The analysis of the influenced factors can provide a theoretical basic for experiment.
基金supported by the National "863" program of China (No. 2007AA01Z229)the National Basic Research Program of China (No. 2010CB328300)
文摘A distributed access scheme using optical add/drop multiplexers （OADMs） for long reach hybrid wavelength division multiplexing and time division multiplexing passive optical networks （WDM-TDM PONs） is proposed and demonstrated. Colorless operations are implemented by using commercially available reflective semiconductor optical amplifiers （RSOAs） at both the center office （CO） and the customer side. Four 1.25-Gb/s channels are successfully transmitted over 80-km single-mode fiber with four OADMs. The dynamic input power range of the RSOA is also investigated. Compared with traditional access schemes, the proposed scheme could cover the area along the feed fiber with no blind zone. The experimental results show that it could be an ideal solution for the next generation access networks.
基金supported by the National Key R&D Program of China(2023YFF0723300)National Natural Science Foundation of China(62475198,62075200,12374295)+8 种基金Fundamental Research Funds for the Central Universities(2042024kf0003,2042024kf1010,2042023kf0105)Hubei Provincial Natural Science Foundation of China(2023AFB133)Jiangsu Science and Technology Program(BK20221257)Shenzhen Science and Technology Program(JCYJ20220530140601003,JCYJ20230807090207014)Translational Medicine and Multidisciplinary Research Project of Zhongnan Hospital of Wuhan University(ZNJC202217,ZNJC202232)The Interdisciplinary Innovative Talents Foundation from Renmin Hospital of Wuhan University(JCRCYR-2022-006)Hubei Province Young Science and Technology Talent Morning Hight Lift Project(202319)The Fund of National Key Laboratory of Plasma Physics(6142A04230201)We gratefully acknowledge Serendipity Lab for facilitating collaboration opportunities.
文摘Imaging flow cytometry(IFC)combines the imaging capabilities of microscopy with the high throughput of flow cytometry,offering a promising solution for high-precision and high-throughput cell analysis in fields such as biomedicine,green energy,and environmental monitoring.However,due to limitations in imaging framerate and realtime data processing,the real-time throughput of existing IFC systems has been restricted to approximately 1000-10,000 events per second(eps),which is insufficient for large-scale cell analysis.In this work,we demonstrate IFC with real-time throughput exceeding 1,000,000 eps by integrating optical time-stretch(OTS)imaging,microfluidic-based cell manipulation,and online image processing.Cells flowing at speeds up to 15 m/s are clearly imaged with a spatial resolution of 780 nm,and images of each individual cell are captured,stored,and analyzed.The capabilities and performance of our system are validated through the identification of malignancies in clinical colorectal samples.This work sets a new record for throughput in imaging flow cytometry,and we believe it has the potential to revolutionize cell analysis by enabling highly efficient,accurate,and intelligent measurement.
基金supported by the National Key Research and Development Program of China(2023YFB2906300)National Natural Science Foundation of China(61931010,62225110)JD project of Hubei province(2023BAA013).
文摘We propose and validate a novel optical semantic transmission scheme using multimode fiber(MMF).By leveraging the frequency sensitivity of intermodal dispersion in MMFs,we achieve high-dimensional semantic encoding and decoding in the frequency domain.Our system maps symbols to 128 distinct frequencies spaced at 600 kHz intervals,demonstrating a seven-fold increase in capacity compared to conventional communication encoding.We further enhance spectral efficiency by implementing 4-level pulse amplitude modulation(PAM-4),achieving 9.12 bits/s/Hz without decoding errors.Additionally,we explore the application of this system for sentiment analysis using the IMDb movie review dataset.By encoding semantically similar symbols to adjacent frequencies,the system's noise tolerance is effectively improved,facilitating accurate sentiment analysis.This work highlights the potential of MMF-based semantic communication to enhance both capacity and robustness in optical communication systems,offering promising applications in bandwidth-constrained and noisy environments.
基金National Natural Science Foundation of China(NSFC)(61331010,61205063)863 High Technology plan(2015AA016904)Program for New Century Excellent Talents in University(NCET)(NCET-13-0235)
文摘We propose a novel waveguide design of polarization-maintaining few mode fiber(PM-FMF) supporting ≥10non-degenerate modes, utilizing a central circular air hole and a circumjacent elliptical-ring core. The structure endows a new degree of freedom to adjust the birefringence of all the guided modes, including the fundamental polarization mode. Numerical simulations demonstrate that, by optimizing the air hole and elliptical-ring core,a PM-FMF supporting 10 distinctive polarization modes has been achieved, and the effective index difference Δn_(eff) between the adjacent guided modes could be kept larger than 1.32 × 10^(-4) over the whole C +L band. The proposed fiber structure can flexibly tailored to support an even larger number of modes in PM-FMF(14-mode PM-FMF has been demonstrated as an example), which can be readily applicable to a scalable mode division multiplexing system.
基金National Key Research and Development Program of China(2018YFB1801002)National Natural Science Foundation of China(61722108,61931010)Innovation Fund of WNLO。
文摘Distributed optical fiber Brillouin sensors detect the temperature and strain along a fiber according to the local Brillouin frequency shift(BFS),which is usually calculated by the measured Brillouin spectrum using Lorentzian curve fitting.In addition,cross-correlation,principal component analysis,and machine learning methods have been proposed for the more efficient extraction of BFS.However,existing methods only process the Brillouin spectrum individually,ignoring the correlation in the time domain,indicating that there is still room for improvement.Here,we propose and experimentally demonstrate a BFS extraction convolutional neural network(BFSCNN)to retrieve the distributed BFS directly from the measured two-dimensional data.Simulated ideal Brillouin spectra with various parameters are used to train the BFSCNN.Both the simulation and experimental results show that the extraction accuracy of the BFSCNN is better than that of the traditional curve fitting algorithm with a much shorter processing time.The BFSCNN has good universality and robustness and can effectively improve the performances of existing Brillouin sensors.
基金This work was supported by the National Science Fund of China for Excellent Young Scholars(No.61922033)the Science Found for Creative Research Groups of the Natural Science Foundation of Hubei(No.2018CFA004)the Innovation Fund of WNLO.
文摘Continuous pulse wave signals monitoring is the essential basis for clinical cardiovascular diagnosis and treatment.Recent researches show the majority of current electronic pulse sensors usually face challenges in electrical safety concern,poor durability and demanding precision in position alignment.Thus,a highly sensitive,inherently electrical safe,robust and alignment-free device is highly desired.Here,we present a wearable alignment-free microfber-based sensor chip(AFMSC)for precise vital signs monitoring and cardiovascular health assessment.The AFMSC comprises an optical micro/nano fber sensor(MNF)and a fexible soft liquid sac while the MNF sensor is used to perceive the physiological signals and the liquid sac is used to eliminate the misalignment.The real-time and accurate monitoring of the pulse signals was realized by tracking the optical power variation of transmitted light from MNF.Then,the cardiovascular vital signs extracted from radial artery pulse signals were used to evaluate cardiovascular health condition and the results were in accordance with human physiological characteristics.Moreover,the pulse signals from diferent arterial area,the respiration signals from chest and the radial pulse signals before and after exercise were detected and analyzed.The non-invasive,continuous and accurate monitoring of cardiovascular health based on the reported wearable and alignment-free device is promising in both ftness monitoring and medical diagnostics for cardiovascular disease prevention and diagnosis.
基金National Key R&D Program of China(2018YFB1801304)State Key Laboratory of Advanced Optical Communication Systems and Networks(2019GZKF7)+1 种基金National Natural Science Foundation of China(61505061,61675083)Key Project of RD Program of Hubei Province(2017AAA046)
文摘We propose and experimentally demonstrate a novel physical layer encryption scheme for high-speed optical communication. A 10 Gb/s on-off keying signal is secretly transmitted over 100 km standard single-mode fiber.The intensity-modulated message is secured by the encryption mechanism, which is composed of an external noise source and an internal time-delayed feedback loop. The external noise serves as an entropy source with sufficient randomness. The feedback loop structure in the transmitter introduces a time-domain encryption key space, and a corresponding open-loop configuration at the receiver side is used for synchronization and decryption.Experiment results show the effectiveness of the proposed scheme. For a legitimate terminal, bit error rate below10-8 can be obtained. Decryption degradations with the mismatch of different hardware parameters are researched. The time delay in the feedback loop provides a sensitive encryption key. For other hardware parameters,the system is robust enough for synchronization. Meanwhile, the time-delay signature of the loop is able to be well concealed by the external noise. Moreover, the proposed scheme can support density wavelength division multiplexing transmission with a relatively simple structure. This work also provides a new concept to establish optical secure communication by combining a time-delayed feedback chaotic system and random noise.
基金These works are supported by a grant from the Sub-Project of the Major Program of the National Natural Science Foundation of China （No. 61290315）, the National Natural Science Foundation of China （No. 61275083, 61275004, and 61404056）, the National Key Foundation of Exploring Scientific Instrument of China （No. 2013YQ16048707）, and the Fundamental Research Funds for the Central Universities （HUST： No. 2014CG002, and 2014QNRC005）. Much appreciation should be given to the students, Zhinlin Xu, Yiyang Luo, Fan Ai, Wei Yang, Enci Chen, Shun Wang ,Shui Zhao, Li Liu, Hao Liao, Xin Fu, Shun Wang, Wei Yang, Wang Yang, and Mingren Su.
文摘The recent research progress in the key device and technology of the fiber optic sensor network （FOSN） is introduced in this paper. An architecture of the sensor optical passive network （SPON）, by employing hybrid wavelength division multiplexing/time division multiplexing （WDM/TDM） techniques similar to the fiber communication passive optical network （PON）, is proposed. The network topology scheme of a hybrid TDM/WDM/FDM （frequency division multiplexing） three-dimension fiber optic sensing system for achieving ultra-large capacity, long distance, and high resolution sensing performance is performed and analyzed. As the most important device of the FOSN, several kinds of light source are developed, including the wideband multi-wavelength fiber laser operating at C band, switchable and tunable 2 μm multi-wavelength fiber lasers, ultra-fast mode-locked fiber laser, as well as the optical wideband chaos source, which have very good application prospects in the FOSN. Meanwhile, intelligent management techniques for the FOSN including wideband spectrum demodulation of the sensing signals and real-time fault monitoring of fiber links are presented. Moreover, several typical applications of the FOSN are also discussed, such as the fiber optic gas sensing network, fiber optic acoustic sensing network, and strain/dynamic strain sensing network.
基金supported by the National Key R&D Program of China (No. 2018YFF01011800)the National Natural Science Foundation of China (No. 61775070)the Fundamental Research Funds for the Central Universities (Nos. 2017KFYXJJ032 and 2019kfyXMBZ052)
文摘In this Letter, a low-frequency acoustic sensor based on an extrinsic Fabry–Pérot(FP) interferometer with a silicon nitride(Si3N4) membrane is demonstrated. Using micromachining techniques, the 800 nm thick Si3N4 membrane is deposited on an 8 mm × 8 mm × 400 μm silicon(Si) substrate. All the assembly procedures of the sensor are focused on the substrate to avoid any damage to the membrane itself, compared to general membrane transfer methods. The frequency response of the proposed sensor is discussed theoretically and experimentally demonstrated. The sensor exhibits an excellent flat response to the tested acoustic frequency range of 1 Hz to 250 Hz. The phase sensitivity is around-152 dB re 1 rad/μPa with sensitivity fluctuation less than 0.8 dB.The frequency response characteristic shows a promising potential of the sensor in low-frequency acoustic signal sensing applications.
