In this paper, the influencing factors that affect few-mode and multi core optical fiber channel are analyzed in a comprehensive way. The theoretical modeling and computer simulation of the information channel are car...In this paper, the influencing factors that affect few-mode and multi core optical fiber channel are analyzed in a comprehensive way. The theoretical modeling and computer simulation of the information channel are carried out and then the modeling scheme of few-mode multicore optical fiber channel based on non-uniform mode field distribution is put forward. The proposed modeling scheme can not only exponentially increases the system capacity through fewmode multi-core optical fiber channel, but has better transmission performance compared to the channel of the same type to the uniform channel revealing from the simulation results.展开更多
We propose and experimentally validate an optical true time delay beamforming scheme with straightforward integration into hybrid optical/millimeter（mm）-wave access networks. In the proposed approach, the most compl...We propose and experimentally validate an optical true time delay beamforming scheme with straightforward integration into hybrid optical/millimeter（mm）-wave access networks. In the proposed approach, the most complex functions, including the beamforming network, are implemented in a central office, reducing the complexity and cost of remote antenna units. Different cores in a multi-core fiber are used to distribute the modulated signals to high-speed photodetectors acting as heterodyne mixers. The mm-wave carrier frequency is fixed to 50 GHz（VBand）, thereby imposing a progressive delay between antenna elements of a few picoseconds. That true time delay is achieved with an accuracy lower than 1 ps and low phase noise.展开更多
Iced transmission line galloping poses a significant threat to the safety and reliability of power systems,leading directly to line tripping,disconnections,and power outages.Existing early warning methods of iced tran...Iced transmission line galloping poses a significant threat to the safety and reliability of power systems,leading directly to line tripping,disconnections,and power outages.Existing early warning methods of iced transmission line galloping suffer from issues such as reliance on a single data source,neglect of irregular time series,and lack of attention-based closed-loop feedback,resulting in high rates of missed and false alarms.To address these challenges,we propose an Internet of Things(IoT)empowered early warning method of transmission line galloping that integrates time series data from optical fiber sensing and weather forecast.Initially,the method applies a primary adaptive weighted fusion to the IoT empowered optical fiber real-time sensing data and weather forecast data,followed by a secondary fusion based on a Back Propagation(BP)neural network,and uses the K-medoids algorithm for clustering the fused data.Furthermore,an adaptive irregular time series perception adjustment module is introduced into the traditional Gated Recurrent Unit(GRU)network,and closed-loop feedback based on attentionmechanism is employed to update network parameters through gradient feedback of the loss function,enabling closed-loop training and time series data prediction of the GRU network model.Subsequently,considering various types of prediction data and the duration of icing,an iced transmission line galloping risk coefficient is established,and warnings are categorized based on this coefficient.Finally,using an IoT-driven realistic dataset of iced transmission line galloping,the effectiveness of the proposed method is validated through multi-dimensional simulation scenarios.展开更多
Optogenetic has been widely applied in various pathogenesis investigations of neuropathic diseases since its accurate and targeted regulation of neuronal activity.However,due to the mismatch between the soft tissues a...Optogenetic has been widely applied in various pathogenesis investigations of neuropathic diseases since its accurate and targeted regulation of neuronal activity.However,due to the mismatch between the soft tissues and the optical waveguide,the long-term neural regulation within soft tissue(such as brain and spinal cord)by implantable optical fibers is a large challenge.Herein,we designed a modulus selfadaptive hydrogel optical fiber(MSHOF)with tunable mechanical properties(Young’modulus was tunable in the range of 0.32-10.56MPa)and low light attenuation(0.12-0.21 dB/cm,472nm laser light),which adapts to light transmission under soft tissues.These advantages of MSHOF can ensure the effectiveness of optogenetic stimulation meanwhile safeguarding the safety of the brain/materials interaction interface.In addition,this work provides more design possibilities of MSHOF for photogenetic stimuli and has significant application prospects in photomedical therapy.展开更多
In this paper,a double-effect DNN-based Digital Back-Propagation(DBP)scheme is proposed and studied to achieve the Integrated Communication and Sensing(ICS)ability,which can not only realize nonlinear damage mitigatio...In this paper,a double-effect DNN-based Digital Back-Propagation(DBP)scheme is proposed and studied to achieve the Integrated Communication and Sensing(ICS)ability,which can not only realize nonlinear damage mitigation but also monitor the optical power and dispersion profile over multi-span links.The link status information can be extracted by the characteristics of the learned optical fiber parameters without any other measuring instruments.The efficiency and feasibility of this method have been investigated in different fiber link conditions,including various launch power,transmission distance,and the location and the amount of the abnormal losses.A good monitoring performance can be obtained while the launch optical power is 2 dBm which does not affect the normal operation of the optical communication system and the step size of DBP is 20 km which can provide a better distance resolution.This scheme successfully detects the location of single or multiple optical attenuators in long-distance multi-span fiber links,including different abnormal losses of 2 dB,4 dB,and 6 dB in 360 km and serval combinations of abnormal losses of(1 dB,5 dB),(3 dB,3 dB),(5 dB,1 dB)in 360 km and 760 km.Meanwhile,the transfer relationship of the estimated coefficient values with different step sizes is further investigated to reduce the complexity of the fiber nonlinear damage compensation.These results provide an attractive approach for precisely sensing the optical fiber link status information and making correct strategies timely to ensure optical communication system operations.展开更多
Soft polymer optical fiber(SPOF)has shown great potential in optical-based wearable and implantable biosensors due to its excellent mechanical properties and optical guiding characteristics.However,the multimodality c...Soft polymer optical fiber(SPOF)has shown great potential in optical-based wearable and implantable biosensors due to its excellent mechanical properties and optical guiding characteristics.However,the multimodality characteristics of SPOF limit their integration with traditional fiber optic sensors.This article introduces for the first time a flexible fiber optic vibration sensor based on laser interference technology,which can be applied to vibration measurement under high stretch conditions.This sensor utilizes elastic optical fibers made of polydimethylsiloxane(PDMS)as sensing elements,combined with phase generating carrier technology,to achieve vibration measurement at 50−260 Hz within the stretch range of 0−42%.展开更多
This paper examines the design and optimization of optical fibers for high-speed data transmission, emphasizing advancements that maximize efficiency in modern communication networks. Optical fibers, core components o...This paper examines the design and optimization of optical fibers for high-speed data transmission, emphasizing advancements that maximize efficiency in modern communication networks. Optical fibers, core components of global communication infrastructure, are capable of transmitting data over long distances with minimal loss through principles like total internal reflection. This study explores single-mode and multi-mode fiber designs, providing an overview of key parameters such as core diameter, refractive index profile, and numerical aperture. Mathematical modeling using Maxwell’s equations plays a central role in optimizing fiber performance, helping engineers mitigate challenges like attenuation and dispersion. The paper also discusses advanced techniques, including dense wavelength division multiplexing (DWDM), which enables terabit-per-second data rates. Case studies in practical applications, such as fiber-to-the-home (FTTH) networks and transoceanic cables, highlight the impact of optimized designs on network performance. Looking forward, innovations in photonic crystal fibers and hollow-core fibers are expected to drive further improvements, enabling ultra-high-speed data transmission. The paper concludes by underscoring the significance of continuous research and development to address challenges in optical fiber technology and support the increasing demands of global communication systems.展开更多
Embedding optical fiber sensors into composite materials offers the advantage of real-time structural monitoring.However,there is an order-of-magnitude difference in diameter between optical fibers and reinforcing fib...Embedding optical fiber sensors into composite materials offers the advantage of real-time structural monitoring.However,there is an order-of-magnitude difference in diameter between optical fibers and reinforcing fibers,and the detailed mechanism of how embedded optical fibers affect the micromechanical behavior and damage failure processes within composite materials remains unclear.This paper presents a micromechanical simulation analysis of composite materials embedded with optical fibers.By constructing representative volume elements(RVEs)with randomly distributed reinforcing fibers,the optical fiber,the matrix,and the interface phase,the micromechanical behavior and damage evolution under transverse tensile and compressive loads are explored.The study finds that the presence of embedded optical fibers significantly influences the initiation and propagation of microscopic damage within the composites.Under transverse tension,the fiber-matrix interface cracks first,followed by plastic cracking in the matrix surrounding the fibers,forming micro-cracks.Eventually,these cracks connect with the debonded areas at the fiber-matrix interface to form a dominant crack that spans the entire model.Under transverse compression,plastic cracking first occurs in the resin surrounding the optical fibers,connecting with the interface debonding areas between the optical fibers and the matrix to form two parallel shear bands.Additionally,it is observed that the strength of the interface between the optical fiber and the matrix critically affects the simulation results.The simulated damage morphologies align closely with those observed using scanning electron microscopy(SEM).These findings offer theoretical insights that can inform the design and fabrication of smart composite materials with embedded optical fiber sensors for advanced structural health monitoring.展开更多
As a laser passes through a scattering medium,the light interacts with the irregular reflections within the medium,resulting in light scattering and the formation of speckles.In this paper,an image sensor based on the...As a laser passes through a scattering medium,the light interacts with the irregular reflections within the medium,resulting in light scattering and the formation of speckles.In this paper,an image sensor based on the combination of a coreless optical fiber and a digital camera is proposed for liquid refractive index sensing applications.The coreless fiber is used as a sensing unit,and the change in the speckle pattern is measured using the digital correlation method to detect the magnitude of the liquid's refractive index.The experimental results indicate that the laser image sensing technique is capable of effectively distinguishing liquid samples with refractive indices ranging from 1.332 8 to1.390 8,with a sensing sensitivity of-1.306 RIU-l.Moreover,the laser image sensing technique,with its advantages of high experimental reproducibility,simple system design,remote over-control,holds great research significance and potential application in laser communication and sensor integration.展开更多
To achieve a low-complexity nonlinearity compensation(NLC)in high-symbol-rate(HSR)systems,we propose a modified weighted digital backpropagation(M-W-DBP)by jointly shifting the calculated position of nonlinear phase n...To achieve a low-complexity nonlinearity compensation(NLC)in high-symbol-rate(HSR)systems,we propose a modified weighted digital backpropagation(M-W-DBP)by jointly shifting the calculated position of nonlinear phase noise and considering the correlation of neighboring symbols in the NLC section of DBP.Based on this model,with the aid of neural network optimization,a learned version of M-W-DBP(M-W-LDBP)is also proposed and explored.Furthermore,enough technical details are revealed for the first time,including the principle of our proposed M-W-DBP and M-W-LDBP,the training process,and the complexity analysis of different DBPclass NLC algorithms.Evaluated numerically with QPSK,16QAM,and PS-64QAM modulation formats,1-step-per-span(1-StPS)M-W-DBP/LDBP achieves up to 1.29/1.49 dB and 0.63/0.74 dB signal-to-noise ratio improvement compared to chromatic dispersion compensation(CDC)in 90-GBaud and 128-GBaud 1000-km single-channel transmission systems,respectively.Moreover,1-StPS M-W-DBP/LDBP provides a more powerful NLC ability than 2-StPS LDBP but only needs about 60%of the complexity.The effectiveness of the proposed M-W-DBP and M-W-LDBP in the presence of laser phase noise is also verified and the necessity of using the learned version of M-WDBP is also discussed.This work is a comprehensive study of M-W-DBP/LDBP and other DBP-class NLC algorithms in HSR systems.展开更多
The principle of optical time-domain reflection localization limits the sensing spatial resolution of Raman distributed optical fiber sensing.We provide a solution for a Raman distributed optical fiber sensing system ...The principle of optical time-domain reflection localization limits the sensing spatial resolution of Raman distributed optical fiber sensing.We provide a solution for a Raman distributed optical fiber sensing system with kilometer-level sensing distance and submeter spatial resolution.Based on this,we propose a Raman distributed optical fiber sensing scheme based on chaotic pulse cluster demodulation.Chaotic pulse clusters are used as the probe signal,in preference to conventional pulsed or chaotic single-pulse lasers.Furthermore,the accurate positioning of the temperature variety region along the sensing fiber can be realized using chaotic pulse clusters.The proposed demodulation scheme can enhance the signal-to-noise ratio by improving the correlation between the chaotic reference and the chaotic Raman anti-Stokes scattering signals.The experiment achieved a sensing spatial resolution of 30 cm at a distributed temperature-sensing distance of∼6.0 km.Furthermore,we explored the influence of chaotic pulse width and detector bandwidth on the sensing spatial resolution.In addition,the theoretical experiments proved that the sensing spatial resolution in the proposed scheme was independent of the pulse width and sensing distance.展开更多
Reverse design of highly GeO2-doped silica optical fibers with broadband and flat dispersion profiles is proposed using a neural network(NN) combined with a particle swarm optimization(PSO) algorithm.Firstly,the NN mo...Reverse design of highly GeO2-doped silica optical fibers with broadband and flat dispersion profiles is proposed using a neural network(NN) combined with a particle swarm optimization(PSO) algorithm.Firstly,the NN model designed to predict optical fiber dispersion is trained with an appropriate choice of hyperparameters,achieving a root mean square error(RMSE) of 9.47×10-7on the test dataset,with a determination coefficient(R2) of 0.999.Secondly,the NN is combined with the PSO algorithm for the inverse design of dispersion-flattened optical fibers.To expand the search space and avoid particles becoming trapped in local optimal solutions,the PSO algorithm incorporates adaptive inertia weight updating and a simulated annealing algorithm.Finally,by using a suitable fitness function,the designed fibers exhibit flat group velocity dispersion(GVD) profiles at 1 400—2 400 nm,where the GVD fluctuations and minimum absolute GVD values are below 18 ps·nm-1·km-1and 7 ps·nm-1·km-1,respectively.展开更多
The method for self diagnose and self repair of composite materials using hollow optical fiber with injected adhesive is first put forward. The investigation and analysis of pass light mechanism of hollow optical ...The method for self diagnose and self repair of composite materials using hollow optical fiber with injected adhesive is first put forward. The investigation and analysis of pass light mechanism of hollow optical fiber are made in detail. The measurement principle, method and experimental research on self diagnose of the rupture place in composite materials by using hollow optical fiber are also put forward. Experiments on composite materials with or without embedded optical fiber are performed according to Chinese test standards in order to find out the comparable characters. Based on the experimental results, it is found that there is only little difference on the mechanical behavior of composite materials with or without embedded hollow optical fibers. In other words, this method can be used in engineering practice, such as in smart structures and other fields. Finally the general scheme of the entire system is given.展开更多
This paper presents an optical sensor technique used in the damage evaluation which is formed by structurally integrated fiber optic reticulate sensors embedded in the composite materials. The fibers are processed by ...This paper presents an optical sensor technique used in the damage evaluation which is formed by structurally integrated fiber optic reticulate sensors embedded in the composite materials. The fibers are processed by chemical method and their outsides are peeled to form particles of irregular distribution and they differ in size, so the slight disturbance range of stochastic wall are formed in fibers. According to the characteristics of power loss of waveguide mode caused by slight disturbance of stochastic wall and radiative mode transmission, the range of slight disturbance of stochastic wall may be served as the sensitive range of the sensor. On the basis of theory of slight disturbance of stochastic wall of planar optical waveguide, the relation between the corrosion time and the opposite power loss by experiments is investigated. In this paper, the measurement results of object of SIFORS are also presented. The results show that the optical sensor technique may be used in the damage evaluation of an aircraft.展开更多
Novel 2×2 torsion-mirror optical switch arrays are fabricated by using the mixed micromachining based on the surface and bulk silicon microelectronics,then are investigated electromechanically in applied direct a...Novel 2×2 torsion-mirror optical switch arrays are fabricated by using the mixed micromachining based on the surface and bulk silicon microelectronics,then are investigated electromechanically in applied direct and alternating electric fields.When the thickness of the elastic torsion beams suspending the aluminum coated polysilicon micro-mirrors of the switches in the arrays is about 1μm,the electrostatic yielding voltages for driving the mirrors to achieve their ON-state are in the range of 270～290V,and the minimum holding voltages for mirrors ON-state are found as 55V or so.Theoretical analysis manifests that the yielding voltage is more sensitive to beam thickness than other design parameters do about the torsion-mirror switch structures.The lifetime can reach 10 8 times.The estimated shortest switching time of the switches at least lasts for less than 2ms.The force analysis on the two kinds of new fiber self-holding structures integrated monolithically in the chip of the optical switch arrays indicates that the structures can feature self-fixing and self-aligning of optical fibers.展开更多
2.5 Gbit/s monolithic integrated circuits （ICs） for optical fiber transmitter and receiver in 0.35 μm CMOS （complementary metal-oxide-semiconductor transistor） process are presented. The transmitter, which includ...2.5 Gbit/s monolithic integrated circuits （ICs） for optical fiber transmitter and receiver in 0.35 μm CMOS （complementary metal-oxide-semiconductor transistor） process are presented. The transmitter, which includes a 4： 1 multiplexer and a laser diode driver （LDD）, has four 622 Mbit/s random signals as its inputs and gets a 2.5 Gbit/s driving signal as its output; the receiver detects a 2.5 Gbit/s random signal and gets four 622 Mbit/s signals at the output. The main circuits include a trans-impedance amplifier （TIA）, a limiting amplifier, a clock and data recovery （CDR） unit, and a 1： 4 demultiplexer （DEMUX）. Test results prove the logic functions of the transmitter to be right, and the 10% to 90% rise and fall times of transmitter＇s output data eye diagram are 211.1 ps and 200 ps, respectively. The sensitivity of the receiver is measured to be better than 20 mV. The root mean square jitter of the DEMUX＇s output data is 15.6 ps and that of the clock after 1： 4 frequency dividing is 1.9 ps. Two chips are both applicable to 2.5 Gbit/s optical fiber communication systems.展开更多
This paper investigated the continuous measurement of a refractive index(RI)sensor based on macrobending microoptical plastic fiber(m-POF).The sensing properties of the RI sensor depend on the structure parameter,whic...This paper investigated the continuous measurement of a refractive index(RI)sensor based on macrobending microoptical plastic fiber(m-POF).The sensing properties of the RI sensor depend on the structure parameter,which is the ratio of macrobending radius of m-POF to the radius of fiber itself.The ratio changes with the measurement time increasing because of the water absorption,which introduces an maximum measurement deviation of 7.3×10^(-5) RIU when the immersion time exceeds 40 h.This work indicates that for the sensors based on POF,the measurement time must be taken into consideration for continuous measurement.展开更多
Optical fiber coil winding model is used to guide proper and high precision coil winding for fiber optic gyroscope （FOG） application. Based on the large-deformation theory of elasticity, stress analysis of optical f...Optical fiber coil winding model is used to guide proper and high precision coil winding for fiber optic gyroscope （FOG） application. Based on the large-deformation theory of elasticity, stress analysis of optical fiber free end has been made and balance equation of infinitesimal fiber is deduced, then deformation equation is derived by substituting terminal conditions. On condition that only axial tensile force exists, approximate curve equation has been built in small angle deformation scope. The comparison of tangent point longitudinal coordinate result between theory and approximation gives constant of integration, and expression with tangent point as origin of coordinate is readjusted. Analyzing the winding parameters of an example, it is clear that the horizontal distance from the highest point of wheel to fiber tangent point has millimeter order of magnitude and significant difference with fiber tension variation, and maintains invariant when wheel radius changes. The height of tension and accurate position of tangent point are defined for proper fiber guide. For application to fiber optic gyroscope, spiral-disc winding method and nonideal deformation of straddle section are analyzed, and then spiral-disc quadrupole pattern winding method has been introduced and realized by winding system. The winding results approve that the winding model is applicable.展开更多
Based on gravity frequency shift effect predicted by general relativity theory, this study discusses an approach for determining the gravity potential(geopotential) difference between arbitrary two points P and Q by r...Based on gravity frequency shift effect predicted by general relativity theory, this study discusses an approach for determining the gravity potential(geopotential) difference between arbitrary two points P and Q by remote comparison of two precise optical clocks via optical fiber frequency transfer. After synchronization, by measuring the signal's frequency shift based upon the comparison of bidirectional frequency signals from P and Q oscillators connected with two optical atomic clocks via remote optical fiber frequency transfer technique, the geopotential difference between the two points could be determined, and its accuracy depends on the stabilities of the optical clocks and the frequency transfer comparison technique. Due to the fact that the present stability of optical clocks achieves 1.6×10-18 and the present frequency transfer comparison via optical fiber provides stabilities as high as 10-19 level, this approach is prospective to determine geopotential difference with an equivalent accuracy of 1.5 cm. In addition, since points P and Q are quite arbitrary, this approach may provide an alternative way to determine the geopotential over a continent, and prospective potential to unify a regional height datum system.展开更多
In order to analyze the effect of wavelength-dependent radiation-induced attenuation （RIA） on the mean trans- mission wavelength in optical fiber and the scale factor of interferometric fiber optic gyroscopes （IFOG...In order to analyze the effect of wavelength-dependent radiation-induced attenuation （RIA） on the mean trans- mission wavelength in optical fiber and the scale factor of interferometric fiber optic gyroscopes （IFOGs）, three types of polarization-maintaining （PM） fibers are tested by using a 60Co γ-radiation source. The observed different mean wave- length shift （MWS） behaviors for different fibers are interpreted by color-center theory involving dose rate-dependent absorption bands in ultraviolet and visible ranges and total dose-dependent near-infrared absorption bands. To evaluate the mean wavelength variation in a fiber coil and the induced scale factor change for space-borne IFOGs under low radiation doses in a space environment, the influence of dose rate on the mean wavelength is investigated by testing four germanium （Ge） doped fibers and two germanium-phosphorus （Ge-P） codoped fibers irradiated at different dose rates. Experimental results indicate that the Ge-doped fibers show the least mean wavelength shift during irradiation and their mean wavelength of optical signal transmission in fibers will shift to a shorter wavelength in a low-dose-rate radiation environment. Finally, the change in the scale factor of IFOG resulting from the mean wavelength shift is estimated and tested, and it is found that the significant radiation-induced scale factor variation must be considered during the design of space-borne IFOGs.展开更多
基金supports from National High Technology 863 Program of China(No.2013AA013403,2015AA015501,2015AA015502,2015AA015504)National NSFC(No.61425022/61522501/61307086/61475024/61275158/61201151/61275074/61372109)+4 种基金Beijing Nova Program(No.Z141101001814048)Beijing Excellent Ph.D.Thesis Guidance Foundation(No.20121001302)the Universities Ph.D.Special Research Funds(No.20120005110003/20120005120007)Fund of State Key Laboratory of IPOC(BUPT)P.R.China
文摘In this paper, the influencing factors that affect few-mode and multi core optical fiber channel are analyzed in a comprehensive way. The theoretical modeling and computer simulation of the information channel are carried out and then the modeling scheme of few-mode multicore optical fiber channel based on non-uniform mode field distribution is put forward. The proposed modeling scheme can not only exponentially increases the system capacity through fewmode multi-core optical fiber channel, but has better transmission performance compared to the channel of the same type to the uniform channel revealing from the simulation results.
基金founded by H2020 ITN CELTA under Grant No.675683 of Call:H2020-MSCA-ITN-2015
文摘We propose and experimentally validate an optical true time delay beamforming scheme with straightforward integration into hybrid optical/millimeter（mm）-wave access networks. In the proposed approach, the most complex functions, including the beamforming network, are implemented in a central office, reducing the complexity and cost of remote antenna units. Different cores in a multi-core fiber are used to distribute the modulated signals to high-speed photodetectors acting as heterodyne mixers. The mm-wave carrier frequency is fixed to 50 GHz（VBand）, thereby imposing a progressive delay between antenna elements of a few picoseconds. That true time delay is achieved with an accuracy lower than 1 ps and low phase noise.
基金research was funded by Science and Technology Project of State Grid Corporation of China under grant number 5200-202319382A-2-3-XG.
文摘Iced transmission line galloping poses a significant threat to the safety and reliability of power systems,leading directly to line tripping,disconnections,and power outages.Existing early warning methods of iced transmission line galloping suffer from issues such as reliance on a single data source,neglect of irregular time series,and lack of attention-based closed-loop feedback,resulting in high rates of missed and false alarms.To address these challenges,we propose an Internet of Things(IoT)empowered early warning method of transmission line galloping that integrates time series data from optical fiber sensing and weather forecast.Initially,the method applies a primary adaptive weighted fusion to the IoT empowered optical fiber real-time sensing data and weather forecast data,followed by a secondary fusion based on a Back Propagation(BP)neural network,and uses the K-medoids algorithm for clustering the fused data.Furthermore,an adaptive irregular time series perception adjustment module is introduced into the traditional Gated Recurrent Unit(GRU)network,and closed-loop feedback based on attentionmechanism is employed to update network parameters through gradient feedback of the loss function,enabling closed-loop training and time series data prediction of the GRU network model.Subsequently,considering various types of prediction data and the duration of icing,an iced transmission line galloping risk coefficient is established,and warnings are categorized based on this coefficient.Finally,using an IoT-driven realistic dataset of iced transmission line galloping,the effectiveness of the proposed method is validated through multi-dimensional simulation scenarios.
基金supported by the National Key Research and Development Program of China(Nos.2021YFA1201302 and 2021YFA1201300)the National Natural Science Foundation of China(Nos.52303033,52173029)+1 种基金Shanghai Sailing Program(No.23YF1400400)the Natural Science Foundation of Shanghai(No.21ZR1400500).
文摘Optogenetic has been widely applied in various pathogenesis investigations of neuropathic diseases since its accurate and targeted regulation of neuronal activity.However,due to the mismatch between the soft tissues and the optical waveguide,the long-term neural regulation within soft tissue(such as brain and spinal cord)by implantable optical fibers is a large challenge.Herein,we designed a modulus selfadaptive hydrogel optical fiber(MSHOF)with tunable mechanical properties(Young’modulus was tunable in the range of 0.32-10.56MPa)and low light attenuation(0.12-0.21 dB/cm,472nm laser light),which adapts to light transmission under soft tissues.These advantages of MSHOF can ensure the effectiveness of optogenetic stimulation meanwhile safeguarding the safety of the brain/materials interaction interface.In addition,this work provides more design possibilities of MSHOF for photogenetic stimuli and has significant application prospects in photomedical therapy.
基金supported by the National Key Research and Development Program of China (2019YFB1803905)the National Natural Science Foundation of China (No.62171022)+2 种基金Beijing Natural Science Foundation (4222009)Guangdong Basic and Applied Basic Research Foundation (2021B1515120057)the Scientific and Technological Innovation Foundation of Shunde Graduate School,USTB (No.BK19AF005)。
文摘In this paper,a double-effect DNN-based Digital Back-Propagation(DBP)scheme is proposed and studied to achieve the Integrated Communication and Sensing(ICS)ability,which can not only realize nonlinear damage mitigation but also monitor the optical power and dispersion profile over multi-span links.The link status information can be extracted by the characteristics of the learned optical fiber parameters without any other measuring instruments.The efficiency and feasibility of this method have been investigated in different fiber link conditions,including various launch power,transmission distance,and the location and the amount of the abnormal losses.A good monitoring performance can be obtained while the launch optical power is 2 dBm which does not affect the normal operation of the optical communication system and the step size of DBP is 20 km which can provide a better distance resolution.This scheme successfully detects the location of single or multiple optical attenuators in long-distance multi-span fiber links,including different abnormal losses of 2 dB,4 dB,and 6 dB in 360 km and serval combinations of abnormal losses of(1 dB,5 dB),(3 dB,3 dB),(5 dB,1 dB)in 360 km and 760 km.Meanwhile,the transfer relationship of the estimated coefficient values with different step sizes is further investigated to reduce the complexity of the fiber nonlinear damage compensation.These results provide an attractive approach for precisely sensing the optical fiber link status information and making correct strategies timely to ensure optical communication system operations.
文摘Soft polymer optical fiber(SPOF)has shown great potential in optical-based wearable and implantable biosensors due to its excellent mechanical properties and optical guiding characteristics.However,the multimodality characteristics of SPOF limit their integration with traditional fiber optic sensors.This article introduces for the first time a flexible fiber optic vibration sensor based on laser interference technology,which can be applied to vibration measurement under high stretch conditions.This sensor utilizes elastic optical fibers made of polydimethylsiloxane(PDMS)as sensing elements,combined with phase generating carrier technology,to achieve vibration measurement at 50−260 Hz within the stretch range of 0−42%.
文摘This paper examines the design and optimization of optical fibers for high-speed data transmission, emphasizing advancements that maximize efficiency in modern communication networks. Optical fibers, core components of global communication infrastructure, are capable of transmitting data over long distances with minimal loss through principles like total internal reflection. This study explores single-mode and multi-mode fiber designs, providing an overview of key parameters such as core diameter, refractive index profile, and numerical aperture. Mathematical modeling using Maxwell’s equations plays a central role in optimizing fiber performance, helping engineers mitigate challenges like attenuation and dispersion. The paper also discusses advanced techniques, including dense wavelength division multiplexing (DWDM), which enables terabit-per-second data rates. Case studies in practical applications, such as fiber-to-the-home (FTTH) networks and transoceanic cables, highlight the impact of optimized designs on network performance. Looking forward, innovations in photonic crystal fibers and hollow-core fibers are expected to drive further improvements, enabling ultra-high-speed data transmission. The paper concludes by underscoring the significance of continuous research and development to address challenges in optical fiber technology and support the increasing demands of global communication systems.
基金funded by the National Key Research and Development Program of China(Grant No.2022YFB3402500)the National Natural Science Foundation of China(Grant No.12372129).
文摘Embedding optical fiber sensors into composite materials offers the advantage of real-time structural monitoring.However,there is an order-of-magnitude difference in diameter between optical fibers and reinforcing fibers,and the detailed mechanism of how embedded optical fibers affect the micromechanical behavior and damage failure processes within composite materials remains unclear.This paper presents a micromechanical simulation analysis of composite materials embedded with optical fibers.By constructing representative volume elements(RVEs)with randomly distributed reinforcing fibers,the optical fiber,the matrix,and the interface phase,the micromechanical behavior and damage evolution under transverse tensile and compressive loads are explored.The study finds that the presence of embedded optical fibers significantly influences the initiation and propagation of microscopic damage within the composites.Under transverse tension,the fiber-matrix interface cracks first,followed by plastic cracking in the matrix surrounding the fibers,forming micro-cracks.Eventually,these cracks connect with the debonded areas at the fiber-matrix interface to form a dominant crack that spans the entire model.Under transverse compression,plastic cracking first occurs in the resin surrounding the optical fibers,connecting with the interface debonding areas between the optical fibers and the matrix to form two parallel shear bands.Additionally,it is observed that the strength of the interface between the optical fiber and the matrix critically affects the simulation results.The simulated damage morphologies align closely with those observed using scanning electron microscopy(SEM).These findings offer theoretical insights that can inform the design and fabrication of smart composite materials with embedded optical fiber sensors for advanced structural health monitoring.
文摘As a laser passes through a scattering medium,the light interacts with the irregular reflections within the medium,resulting in light scattering and the formation of speckles.In this paper,an image sensor based on the combination of a coreless optical fiber and a digital camera is proposed for liquid refractive index sensing applications.The coreless fiber is used as a sensing unit,and the change in the speckle pattern is measured using the digital correlation method to detect the magnitude of the liquid's refractive index.The experimental results indicate that the laser image sensing technique is capable of effectively distinguishing liquid samples with refractive indices ranging from 1.332 8 to1.390 8,with a sensing sensitivity of-1.306 RIU-l.Moreover,the laser image sensing technique,with its advantages of high experimental reproducibility,simple system design,remote over-control,holds great research significance and potential application in laser communication and sensor integration.
基金supported in part by National Natural Science Foundation of China(No.62271080)in part by Fund of State Key Laboratory of IPOC(BUPT)(No.IPOC2022ZT06)in part by BUPT Excellent Ph.D Students Foundation(No.CX2022102).
文摘To achieve a low-complexity nonlinearity compensation(NLC)in high-symbol-rate(HSR)systems,we propose a modified weighted digital backpropagation(M-W-DBP)by jointly shifting the calculated position of nonlinear phase noise and considering the correlation of neighboring symbols in the NLC section of DBP.Based on this model,with the aid of neural network optimization,a learned version of M-W-DBP(M-W-LDBP)is also proposed and explored.Furthermore,enough technical details are revealed for the first time,including the principle of our proposed M-W-DBP and M-W-LDBP,the training process,and the complexity analysis of different DBPclass NLC algorithms.Evaluated numerically with QPSK,16QAM,and PS-64QAM modulation formats,1-step-per-span(1-StPS)M-W-DBP/LDBP achieves up to 1.29/1.49 dB and 0.63/0.74 dB signal-to-noise ratio improvement compared to chromatic dispersion compensation(CDC)in 90-GBaud and 128-GBaud 1000-km single-channel transmission systems,respectively.Moreover,1-StPS M-W-DBP/LDBP provides a more powerful NLC ability than 2-StPS LDBP but only needs about 60%of the complexity.The effectiveness of the proposed M-W-DBP and M-W-LDBP in the presence of laser phase noise is also verified and the necessity of using the learned version of M-WDBP is also discussed.This work is a comprehensive study of M-W-DBP/LDBP and other DBP-class NLC algorithms in HSR systems.
基金supported by the National Natural Science Foundation of China(Grant Nos.U23A20375 and 62075151)the National Key Research and Development Program of China(Grant No.202103021223042).
文摘The principle of optical time-domain reflection localization limits the sensing spatial resolution of Raman distributed optical fiber sensing.We provide a solution for a Raman distributed optical fiber sensing system with kilometer-level sensing distance and submeter spatial resolution.Based on this,we propose a Raman distributed optical fiber sensing scheme based on chaotic pulse cluster demodulation.Chaotic pulse clusters are used as the probe signal,in preference to conventional pulsed or chaotic single-pulse lasers.Furthermore,the accurate positioning of the temperature variety region along the sensing fiber can be realized using chaotic pulse clusters.The proposed demodulation scheme can enhance the signal-to-noise ratio by improving the correlation between the chaotic reference and the chaotic Raman anti-Stokes scattering signals.The experiment achieved a sensing spatial resolution of 30 cm at a distributed temperature-sensing distance of∼6.0 km.Furthermore,we explored the influence of chaotic pulse width and detector bandwidth on the sensing spatial resolution.In addition,the theoretical experiments proved that the sensing spatial resolution in the proposed scheme was independent of the pulse width and sensing distance.
基金supported by the Fundamental Research Funds for the Central Universities (No.2024JBZY021)the National Natural Science Foundation of China (No.61575018)。
文摘Reverse design of highly GeO2-doped silica optical fibers with broadband and flat dispersion profiles is proposed using a neural network(NN) combined with a particle swarm optimization(PSO) algorithm.Firstly,the NN model designed to predict optical fiber dispersion is trained with an appropriate choice of hyperparameters,achieving a root mean square error(RMSE) of 9.47×10-7on the test dataset,with a determination coefficient(R2) of 0.999.Secondly,the NN is combined with the PSO algorithm for the inverse design of dispersion-flattened optical fibers.To expand the search space and avoid particles becoming trapped in local optimal solutions,the PSO algorithm incorporates adaptive inertia weight updating and a simulated annealing algorithm.Finally,by using a suitable fitness function,the designed fibers exhibit flat group velocity dispersion(GVD) profiles at 1 400—2 400 nm,where the GVD fluctuations and minimum absolute GVD values are below 18 ps·nm-1·km-1and 7 ps·nm-1·km-1,respectively.
文摘The method for self diagnose and self repair of composite materials using hollow optical fiber with injected adhesive is first put forward. The investigation and analysis of pass light mechanism of hollow optical fiber are made in detail. The measurement principle, method and experimental research on self diagnose of the rupture place in composite materials by using hollow optical fiber are also put forward. Experiments on composite materials with or without embedded optical fiber are performed according to Chinese test standards in order to find out the comparable characters. Based on the experimental results, it is found that there is only little difference on the mechanical behavior of composite materials with or without embedded hollow optical fibers. In other words, this method can be used in engineering practice, such as in smart structures and other fields. Finally the general scheme of the entire system is given.
文摘This paper presents an optical sensor technique used in the damage evaluation which is formed by structurally integrated fiber optic reticulate sensors embedded in the composite materials. The fibers are processed by chemical method and their outsides are peeled to form particles of irregular distribution and they differ in size, so the slight disturbance range of stochastic wall are formed in fibers. According to the characteristics of power loss of waveguide mode caused by slight disturbance of stochastic wall and radiative mode transmission, the range of slight disturbance of stochastic wall may be served as the sensitive range of the sensor. On the basis of theory of slight disturbance of stochastic wall of planar optical waveguide, the relation between the corrosion time and the opposite power loss by experiments is investigated. In this paper, the measurement results of object of SIFORS are also presented. The results show that the optical sensor technique may be used in the damage evaluation of an aircraft.
文摘Novel 2×2 torsion-mirror optical switch arrays are fabricated by using the mixed micromachining based on the surface and bulk silicon microelectronics,then are investigated electromechanically in applied direct and alternating electric fields.When the thickness of the elastic torsion beams suspending the aluminum coated polysilicon micro-mirrors of the switches in the arrays is about 1μm,the electrostatic yielding voltages for driving the mirrors to achieve their ON-state are in the range of 270～290V,and the minimum holding voltages for mirrors ON-state are found as 55V or so.Theoretical analysis manifests that the yielding voltage is more sensitive to beam thickness than other design parameters do about the torsion-mirror switch structures.The lifetime can reach 10 8 times.The estimated shortest switching time of the switches at least lasts for less than 2ms.The force analysis on the two kinds of new fiber self-holding structures integrated monolithically in the chip of the optical switch arrays indicates that the structures can feature self-fixing and self-aligning of optical fibers.
基金The National High Technology Research and Develop-ment Program of China (863 Program) (No.2001AA312010).
文摘2.5 Gbit/s monolithic integrated circuits （ICs） for optical fiber transmitter and receiver in 0.35 μm CMOS （complementary metal-oxide-semiconductor transistor） process are presented. The transmitter, which includes a 4： 1 multiplexer and a laser diode driver （LDD）, has four 622 Mbit/s random signals as its inputs and gets a 2.5 Gbit/s driving signal as its output; the receiver detects a 2.5 Gbit/s random signal and gets four 622 Mbit/s signals at the output. The main circuits include a trans-impedance amplifier （TIA）, a limiting amplifier, a clock and data recovery （CDR） unit, and a 1： 4 demultiplexer （DEMUX）. Test results prove the logic functions of the transmitter to be right, and the 10% to 90% rise and fall times of transmitter＇s output data eye diagram are 211.1 ps and 200 ps, respectively. The sensitivity of the receiver is measured to be better than 20 mV. The root mean square jitter of the DEMUX＇s output data is 15.6 ps and that of the clock after 1： 4 frequency dividing is 1.9 ps. Two chips are both applicable to 2.5 Gbit/s optical fiber communication systems.
基金National Natural Science Foundation of China(No.61405127)Key Program for International S&T Cooperation Projects of China(No.2013DFR10150)
文摘This paper investigated the continuous measurement of a refractive index(RI)sensor based on macrobending microoptical plastic fiber(m-POF).The sensing properties of the RI sensor depend on the structure parameter,which is the ratio of macrobending radius of m-POF to the radius of fiber itself.The ratio changes with the measurement time increasing because of the water absorption,which introduces an maximum measurement deviation of 7.3×10^(-5) RIU when the immersion time exceeds 40 h.This work indicates that for the sensors based on POF,the measurement time must be taken into consideration for continuous measurement.
基金Fundamental Research Funds for the Central Universities (YWF-10-01-B30)
文摘Optical fiber coil winding model is used to guide proper and high precision coil winding for fiber optic gyroscope （FOG） application. Based on the large-deformation theory of elasticity, stress analysis of optical fiber free end has been made and balance equation of infinitesimal fiber is deduced, then deformation equation is derived by substituting terminal conditions. On condition that only axial tensile force exists, approximate curve equation has been built in small angle deformation scope. The comparison of tangent point longitudinal coordinate result between theory and approximation gives constant of integration, and expression with tangent point as origin of coordinate is readjusted. Analyzing the winding parameters of an example, it is clear that the horizontal distance from the highest point of wheel to fiber tangent point has millimeter order of magnitude and significant difference with fiber tension variation, and maintains invariant when wheel radius changes. The height of tension and accurate position of tangent point are defined for proper fiber guide. For application to fiber optic gyroscope, spiral-disc winding method and nonideal deformation of straddle section are analyzed, and then spiral-disc quadrupole pattern winding method has been introduced and realized by winding system. The winding results approve that the winding model is applicable.
基金supported by the National Natural Science Foundation of China (Nos. 41631072, 41721003, 41574007, and 41429401)the Discipline Innovative Engineering Plan of Modern Geodesy and Geodynamics (No. B17033)+1 种基金the DAAD Thematic Network Project (No. 57173947)the International Space Science Institute (ISSI) 2017–2019
文摘Based on gravity frequency shift effect predicted by general relativity theory, this study discusses an approach for determining the gravity potential(geopotential) difference between arbitrary two points P and Q by remote comparison of two precise optical clocks via optical fiber frequency transfer. After synchronization, by measuring the signal's frequency shift based upon the comparison of bidirectional frequency signals from P and Q oscillators connected with two optical atomic clocks via remote optical fiber frequency transfer technique, the geopotential difference between the two points could be determined, and its accuracy depends on the stabilities of the optical clocks and the frequency transfer comparison technique. Due to the fact that the present stability of optical clocks achieves 1.6×10-18 and the present frequency transfer comparison via optical fiber provides stabilities as high as 10-19 level, this approach is prospective to determine geopotential difference with an equivalent accuracy of 1.5 cm. In addition, since points P and Q are quite arbitrary, this approach may provide an alternative way to determine the geopotential over a continent, and prospective potential to unify a regional height datum system.
基金Project supported by the National Natural Science Foundation of China (Grant No. 61007040)
文摘In order to analyze the effect of wavelength-dependent radiation-induced attenuation （RIA） on the mean trans- mission wavelength in optical fiber and the scale factor of interferometric fiber optic gyroscopes （IFOGs）, three types of polarization-maintaining （PM） fibers are tested by using a 60Co γ-radiation source. The observed different mean wave- length shift （MWS） behaviors for different fibers are interpreted by color-center theory involving dose rate-dependent absorption bands in ultraviolet and visible ranges and total dose-dependent near-infrared absorption bands. To evaluate the mean wavelength variation in a fiber coil and the induced scale factor change for space-borne IFOGs under low radiation doses in a space environment, the influence of dose rate on the mean wavelength is investigated by testing four germanium （Ge） doped fibers and two germanium-phosphorus （Ge-P） codoped fibers irradiated at different dose rates. Experimental results indicate that the Ge-doped fibers show the least mean wavelength shift during irradiation and their mean wavelength of optical signal transmission in fibers will shift to a shorter wavelength in a low-dose-rate radiation environment. Finally, the change in the scale factor of IFOG resulting from the mean wavelength shift is estimated and tested, and it is found that the significant radiation-induced scale factor variation must be considered during the design of space-borne IFOGs.
