Optical transmission technologies have gone through several generations of development.Spectral efficiency has significant ly improved,and industry has begun to search for an answer to a basic question：What are the f...Optical transmission technologies have gone through several generations of development.Spectral efficiency has significant ly improved,and industry has begun to search for an answer to a basic question：What are the fundamental linear and nonlin ear signal channel limitations of the Shannon theory when there is no compensation in an optical fiber transmission system？Next-generation technologies should exceed the 100G transmis sion capability of coherent systems in order to approach the Shannon limit.Spectral efficiency first needs to be improved be fore overall transmission capability can be improved.The means to improve spectral efficiency include more complex modulation formats and channel encoding/decoding algorithms,prefiltering with multisymbol detection,optical OFDM and Ny quist WDM multicarrier technologies,and nonlinearity compen sation.With further optimization,these technologies will most likely be incorporated into beyond-100G optical transport sys tems to meet bandwidth demand.展开更多
Doppler cooling of^(88)Sr atoms is studied in the presence of off-resonant red-detuned fluctuating laser fields.Using a semi-classical approach,we show that the relevant physical quantities in the cooling process,such...Doppler cooling of^(88)Sr atoms is studied in the presence of off-resonant red-detuned fluctuating laser fields.Using a semi-classical approach,we show that the relevant physical quantities in the cooling process,such as optical forces,the damping coefficient,Doppler temperature,and atom number in the trap,are strongly affected by the laser amplitude and phase fluctuations.We find that the Doppler cooling limit is higher than the predicted Doppler theory for non-fluctuating lasers.This implies an additional heating mechanism exists due to the laser fluctuations.Furthermore,our numerical analysis shows that the effect of laser power stability on reducing the number of trapped atoms in a magneto-optical trap is more substantial than the effect of laser linewidth.展开更多
In this paper, we investigate advanced digital signal process ing （DSP） at the transmitter and receiver side for signal pre equalization and postequalization in order to improve spec trum efficiency （SE） and trans...In this paper, we investigate advanced digital signal process ing （DSP） at the transmitter and receiver side for signal pre equalization and postequalization in order to improve spec trum efficiency （SE） and transmission distance in an optical access network. A novel DSP scheme for this optical super Nyquist filtering 9 Quadrature Amplitude Modulation （9 QAM） like signals based on muhimodulus equalization with out post filtering is proposed. This scheme recovers the Ny quist filtered Quadrature PhaseShift Keying （QPSK） signal to a 9QAMlike one. With this technique, SE can be increased to 4 b/s/Hz for QPSK signals. A novel digital superNyquist signal generation scheme is also proposed to further suppress the Nyquist signal bandwidth and reduce channel crosstalk without the need for optical prefiltering. Only optical cou plers are needed for superNyquist wavelengthdivisionmulti plexing （WDM） channel multiplexing. We extend the DSP for shorthaul optical transmission networks by using highorder QAMs. We propose a highspeed Can＇ierless Amplitude/Phase 64 QAM （CAP64 QAM） system using directly modulated la ser （DML） based on direct detection and digital equalization. Decisiondirected least mean square is used to equalize the CAP64QAM. Using this scheme, we generate and transmit up to 60 Gbit/s CAP64QAM over 20 km standard single mode fiber based on the DML and direct detection. Finally, several key problems are solved for real time orthogonalfre quencydivisionmultiplexing （OFDM） signal transmission aml processing. With coherent detection, up to 100 Glfit/s 16 QAMOFDM realtime transmission is possible.展开更多
Energy and environmental stuff are two of the main worries for humanity,and nanoscience plays a key role in providing the solution.Huge nanoresearch activities have attracted lot of attention in the current scenario.H...Energy and environmental stuff are two of the main worries for humanity,and nanoscience plays a key role in providing the solution.Huge nanoresearch activities have attracted lot of attention in the current scenario.However,designing the material with enhanced optoelectronic properties remains the foremost challenge.In the present work,the Li doped CuO nanosheets are synthesized by the chemical route and examined in photovoltaics and environmental remediation applications.The crystallographic and optical study reveals that crystallite size and bandgap decrease with an increase in lithium-doping concentration up to 5 mole%and beyond that a reverse trend is observed.Additionally,impedance study has shown the significant contribution of lithium-ions to the total capacitance and resistivity.Further,the photoactivity of Cu_(1-x)Li_(x)O nanosheets(optimum concentration of Cu_(1-x)Li_(x)O NSs(x=0.05))is projected to the degradation of methylene blue(MB)and used to fabricate bulk heterojunction solar cell together with P3HT and PCBM blend,respectively.The ITO/PEDOT:PSS/P3 HT:PC_(70)BM:Cu_(1-x)Li_(x)O(x=0.05)/Li F/Al solar cell realized higher power-conversion efficiencyη~3.91 than their corresponding pristine deviceη~2.98 with enhanced photocurrent density from 9.026 to 11.56 m A cm^(-2).The proliferation in photocatalysts and solar cells efficiency of Cu_(1-x)Li_(x)O(x=0.05)is mainly attributed to the higher light absorption and lesser electron-hole recombination.The approach for the synthesis of Cu_(1-x)Li_(x)O NSs as potential donor material and device prototypes fabricated is completely safe and cost-effective.展开更多
The phenomenon of photothermally induced transparency(PTIT)arises from the nonlinear behavior of an optical cavity,resulting from the heating of mirrors.By introducing a coupling field in the form of a standing wave,P...The phenomenon of photothermally induced transparency(PTIT)arises from the nonlinear behavior of an optical cavity,resulting from the heating of mirrors.By introducing a coupling field in the form of a standing wave,PTIT can be transitioned into photothermally induced grating(PTIG).A two-dimensional(2D)diffraction pattern is achieved through the adjustment of key parameters such as coupling strength and effective detuning.Notably,we observe first,second,and third-order intensity distributions,with the ability to transfer probe energy predominantly to the third order by fine-tuning the coupling strength.The intensity distribution is characterized by(±m,±n),where m,n=1,2,3.This proposed 2D grating system offers a novel platform for manipulating PTIG,presenting unique possibilities for enhanced functionality and control.展开更多
Copper oxide nanoflowers(CuO-NFs)have been synthesized through a novel green route using Tulsi leaves-extracted eugenol(4-allyl-2-methoxyphenol)as reducing agent.Characterizations results reveal the growth of crystall...Copper oxide nanoflowers(CuO-NFs)have been synthesized through a novel green route using Tulsi leaves-extracted eugenol(4-allyl-2-methoxyphenol)as reducing agent.Characterizations results reveal the growth of crystalline singlephase CuO-NFs with monoclinic structure.The prepared CuO-NFs can effectively degrade methylene blue with 90%efficiency.They also show strong barrier against E.coli(27±2 mm)at the concentration of 100μg mL−1,while at the concentration of 25μg mL−1 weak barrier has been found against all examined bacterial organisms.The results provide important evidence that CuO-NFs have sustainable performance in methylene blue degradation as well as bacterial organisms.展开更多
Rotationally symmetric triangulation(RST)sensor has more flexibility and less uncertainty limits because of the abaxial rotationally symmetric optical system.But if the incident laser is eccentric,the symmetry of the ...Rotationally symmetric triangulation(RST)sensor has more flexibility and less uncertainty limits because of the abaxial rotationally symmetric optical system.But if the incident laser is eccentric,the symmetry of the image will descend,and it will result in the eccentric error especially when some part of the imaged ring is blocked.The model of rotationally symmetric triangulation that meets the Schimpflug condition is presented in this paper.The error from eccentric incident laser is analysed.It is pointed out that the eccentric error is composed of two parts,one is a cosine in circumference and proportional to the eccentric departure factor,and the other is a much smaller quadric factor of the departure.When the ring is complete,the first error factor is zero because it is integrated in whole ring, but if some part of the ring is blocked,the first factor will be the main error.Simulation verifies the result of the a- nalysis.At last,a compensation method to the error when some part of the ring is lost is presented based on neural network.The results of experiment show that the compensation will make the absolute maximum error descend to half,and the standard deviation of error descends to 1/3.展开更多
Recently,the increasing interest in wearable technology for personal healthcare and smart virtual/augmented reality applications has led to the development of facile fabrication methods.Lasers have long been used to d...Recently,the increasing interest in wearable technology for personal healthcare and smart virtual/augmented reality applications has led to the development of facile fabrication methods.Lasers have long been used to develop original solutions to such challenging technological problems due to their remote,sterile,rapid,and site-selective processing of materials.In this review,recent developments in relevant laser processes are summarized under two separate categories.First,transformative approaches,such as for laser-induced graphene,are introduced.In addition to design optimization and the alteration of a native substrate,the latest advances under a transformative approach now enable more complex material compositions and multilayer device configurations through the simultaneous transformation of heterogeneous precursors,or the sequential addition of functional layers coupled with other electronic elements.In addition,the more conventional laser techniques,such as ablation,sintering,and synthesis,can still be used to enhance the functionality of an entire system through the expansion of applicable materials and the adoption of new mechanisms.Later,various wearable device components developed through the corresponding laser processes are discussed,with an emphasis on chemical/physical sensors and energy devices.In addition,special attention is given to applications that use multiple laser sources or processes,which lay the foundation for the all-laser fabrication of wearable devices.展开更多
In this paper, we examine the transmission of a probe field through a one dimensional photonic crystal (1DPC) when the sixth layer of the crystal is doped with four level atoms. We analyze effects of the external driv...In this paper, we examine the transmission of a probe field through a one dimensional photonic crystal (1DPC) when the sixth layer of the crystal is doped with four level atoms. We analyze effects of the external driving field on the passage of weak probe field across the photonic crystal. It is found that for the phase time delay of the probe photons, intensity of the driving field switches the Hartman effect from sub to superluminal character. It is interesting to note that in our model, the superluminal transmission of the probe pulse is accompanied by a negligibly small absorption of the incident beam. It ensures that the probe field does not attenuate while passing through the photonic crystal. A similar switching of the Hartman effect may be obtained by adjusting detuning of the probe field related to the excited states of the four-level doping atoms.展开更多
We study the tunneling time of ultracold V-type atoms interacting a high quality microwave cavity. Here atomic coherence is introduced in the system by a strong driving field which couples the two lower states of the ...We study the tunneling time of ultracold V-type atoms interacting a high quality microwave cavity. Here atomic coherence is introduced in the system by a strong driving field which couples the two lower states of the three-level atom. It is found that in the presence of coherence, mazer action or the scattering like nature of the interaction may be examined for extended energies of the incident cold atoms. Our results show that position and amplitudes of the peak values of the phase time(traversal time) may be very effectively controlled by the coherent driving field. Further, here we obtained superclassical values of the phase time corresponding to much higher values of the transmission amplitudes of the tunneling atoms which may be advantageous in the possible experimental realization of the superclassical tunneling time of the traversing cold atoms. In addition, we examine a mirror reflection type symmetry in the phase time curve for a judicious choice of the external driving field.展开更多
We investigate the time evolution of quantum correlations of a hybrid qubit-qutrit system under the classical Ornstein-Uhlenbeck(OU) noise. Here we consider two different one-parameter families of qubit-qutrit states ...We investigate the time evolution of quantum correlations of a hybrid qubit-qutrit system under the classical Ornstein-Uhlenbeck(OU) noise. Here we consider two different one-parameter families of qubit-qutrit states which independently interact with the non-Markovian reservoirs. A comparison with the Markovian dynamics reveals that for the same set of initial condition parameters, the non-Markovian behavior of the environment plays an important role in the enhancement of the survival time of quantum correlations. In addition, it is observed that the non-Markovian strength(γ/Γ) has a positive impact on the correlations time. For the initial separable states it is found that there is a finite time interval in which the geometric quantum discord is frozen despite the presence of a noisy environment and that interval can be further prolonged by using the non-Markovian property. Moreover, its decay can be significantly delayed.展开更多
Large-scale indoor 3D reconstruction with multiple robots faces challenges in core enabling technologies.This work contributes to a framework addressing localization,coordination,and vision processing for multi-agent ...Large-scale indoor 3D reconstruction with multiple robots faces challenges in core enabling technologies.This work contributes to a framework addressing localization,coordination,and vision processing for multi-agent reconstruction.A system architecture fusing visible light positioning,multi-agent path finding via reinforcement learning,and 360°camera techniques for 3D reconstruction is proposed.Our visible light positioning algorithm leverages existing lighting for centimeter-level localization without additional infrastructure.Meanwhile,a decentralized reinforcement learning approach is developed to solve the multi-agent path finding problem,with communications among agents optimized.Our 3D reconstruction pipeline utilizes equirectangular projection from 360°cameras to facilitate depth-independent reconstruction from posed monocular images using neural networks.Experimental validation demonstrates centimeter-level indoor navigation and 3D scene reconstruction capabilities of our framework.The challenges and limitations stemming from the above enabling technologies are discussed at the end of each corresponding section.In summary,this research advances fundamental techniques for multi-robot indoor 3D modeling,contributing to automated,data-driven applications through coordinated robot navigation,perception,and modeling.展开更多
Ground penetrating radar (GPR) is a remote sensing technique used to obtain information on subsurface features from data collected over the surface. We propose an automatic algorithm for estimating object depth using...Ground penetrating radar (GPR) is a remote sensing technique used to obtain information on subsurface features from data collected over the surface. We propose an automatic algorithm for estimating object depth using f-k migration and velocity scanning methods in a homogeneous medium. To improve the accuracy of the algorithm, the formula used to calculate the GPR valid lateral aperture is also presented. Experimental results show that the relative estimating error of depth is as low as 5% in a homogeneous medium.展开更多
The emission and Fourier transformation infrared spectra of freshly prepared porous silicon(PS) and the silicon wafer were examined. Increasing temperature generally led to a decrease in the emission intensities of th...The emission and Fourier transformation infrared spectra of freshly prepared porous silicon(PS) and the silicon wafer were examined. Increasing temperature generally led to a decrease in the emission intensities of the PS samples, however, the freshly prepared sample showed an unusually large and sudden increase in its emission intensity at the specific temperature at which the hydrogen ion conductivity in the silicon wafer increased. The O-H vibrations of the silicon wafer also showed a sudden decrease at the same temperature. These results are consistent with the assumption that the luminescence of fresh PS comes from the carrier bound exciton in its confined nanostructure.展开更多
A simple WDM Add-Drop Multiplexer (ADM) Consisting of a set of Er-doped fibers (EDF) and a shared pump is proposed. The chief benefit of the module is that the interchannel power spread does not accumulate from stage ...A simple WDM Add-Drop Multiplexer (ADM) Consisting of a set of Er-doped fibers (EDF) and a shared pump is proposed. The chief benefit of the module is that the interchannel power spread does not accumulate from stage to stage in a cascaded WDM system. Moreover, the power differences caused by different component losses existing in the WDM networks can be automatically compressed. The cost will not increase a lot since the pump source is shared in the module. The performance of a cascaded system constructed from the modules has been carefully studied by computer simulation.展开更多
We propose a method to implement electromagnetically induced grating in a phaseonium medium that has been coherently generated via atomic mechanisms.Phaseonium atoms have aΛ-type structure and three distinct energy l...We propose a method to implement electromagnetically induced grating in a phaseonium medium that has been coherently generated via atomic mechanisms.Phaseonium atoms have aΛ-type structure and three distinct energy levels;such atoms are originally generated in a coherent superposition of two lower levels.The phaseonium system is comprised of three-level atoms with aΛ-type configuration,which are initially prepared in a coherent superposition of two lower levels.To accomplish this spatial modulation based on the susceptibility of phaseonium medium,a standingwave field is used.By looking at how an optical field diffracts at different relative phases,we find that the zeroth and first order diffraction intensities increase as the relative phase changes.We also investigate the impact of the Rabi frequency of the field on diffraction intensity and notice that an increasing strength of the Rabi frequency leads to amplification in the intensity of both central zeroth order and first-order diffraction.Furthermore,it has been observed that a significant rise in diffraction intensity occurs at longer interaction lengths between external fields and the atomic medium.展开更多
In this work, we focus on enhancing the network reach in terabit superchannel transmission by using a noise-suppressed Nyquist wavelength division multiplexing （NS-N-WDM） technique for polarization multiplexing quad...In this work, we focus on enhancing the network reach in terabit superchannel transmission by using a noise-suppressed Nyquist wavelength division multiplexing （NS-N-WDM） technique for polarization multiplexing quadrature phase-shift keying （PM-QPSK） subchannels at different symbol-rate-to-subchannel-spacing ratios up to 1.28. For the first time, we experimentally compare the transmission reach of this emerging technique with that of no-guard-interval coherent optical orthogonal frequency-division multiplexing （NGI-CO-OFDM） on the same testbed. At BER of 2 x 10 3 and 100 Gbit/s per channel, an NGI-CO-OFDM terabit superchannel can transmit over a maximum of 3200 km SMF-28 with EDFA-only amplification, and an NS-N-WDM terabit superchannel can transmit over a maximum of 2800 km SMF-28 with EDFA-only amplification. Assuming different coding gain, 11 x 112 Gbit/s per channel with hard-decision （HD） forward-error correction （FEC） and 11 × 128 Gbit/s per channel NS-N-WDM transmission with soft-decision （SD） FEC can be achieved over a maximum of 2100 km and 2170 km, respectively. These are almost equal and were achieved using digital noise filtering and one-bit maximum likelihood sequence estimation （MLSE） at the receiver DSP. Characteristics including the back-to-back （BTB） curves, the ADC bandwidth requirement, and the tolerance to unequal subchannel power of an NS-N-WDM superchannel were also evaluated.展开更多
We propose an effective surface plasmon resonance system designed to achieve both negative and positive Goos–H??nchen shifts in reflected light.This system comprises a metal film and an underlying medium,where the re...We propose an effective surface plasmon resonance system designed to achieve both negative and positive Goos–H??nchen shifts in reflected light.This system comprises a metal film and an underlying medium,where the real part of the permittivity of the underlying medium must be less than unity.Surface plasmon polaritons can be excited at the lower surface of the metal when light is incident from the air onto the upper surface of the metal.The excitation of surface plasmon polaritons leads to the exploration of the Goos–H??nchen shift(G–HS).Control over the negative and positive(G–HS)is investigated via the wavelength of the incident light.The magnitude of the G–HS is strongly dependent on the incident wavelength.A remarkable enhancement of both negative and positive G–HS in the reflected light is achieved at certain wavelengths and incident angles.Our system paves the way for exploring different characteristics of optical switching and micro-sensors with very high precision.展开更多
基金supported by National High-Tech Research and Development Program of China under Grant No.2013AA010501
文摘Optical transmission technologies have gone through several generations of development.Spectral efficiency has significant ly improved,and industry has begun to search for an answer to a basic question：What are the fundamental linear and nonlin ear signal channel limitations of the Shannon theory when there is no compensation in an optical fiber transmission system？Next-generation technologies should exceed the 100G transmis sion capability of coherent systems in order to approach the Shannon limit.Spectral efficiency first needs to be improved be fore overall transmission capability can be improved.The means to improve spectral efficiency include more complex modulation formats and channel encoding/decoding algorithms,prefiltering with multisymbol detection,optical OFDM and Ny quist WDM multicarrier technologies,and nonlinearity compen sation.With further optimization,these technologies will most likely be incorporated into beyond-100G optical transport sys tems to meet bandwidth demand.
文摘Doppler cooling of^(88)Sr atoms is studied in the presence of off-resonant red-detuned fluctuating laser fields.Using a semi-classical approach,we show that the relevant physical quantities in the cooling process,such as optical forces,the damping coefficient,Doppler temperature,and atom number in the trap,are strongly affected by the laser amplitude and phase fluctuations.We find that the Doppler cooling limit is higher than the predicted Doppler theory for non-fluctuating lasers.This implies an additional heating mechanism exists due to the laser fluctuations.Furthermore,our numerical analysis shows that the effect of laser power stability on reducing the number of trapped atoms in a magneto-optical trap is more substantial than the effect of laser linewidth.
基金supported by the High Technology Research and Development Program of China("863"Program)under Grant No.2012AA011303 and 2013AA010501National Nature Science Foundation of China under Grant No.61325002
文摘In this paper, we investigate advanced digital signal process ing （DSP） at the transmitter and receiver side for signal pre equalization and postequalization in order to improve spec trum efficiency （SE） and transmission distance in an optical access network. A novel DSP scheme for this optical super Nyquist filtering 9 Quadrature Amplitude Modulation （9 QAM） like signals based on muhimodulus equalization with out post filtering is proposed. This scheme recovers the Ny quist filtered Quadrature PhaseShift Keying （QPSK） signal to a 9QAMlike one. With this technique, SE can be increased to 4 b/s/Hz for QPSK signals. A novel digital superNyquist signal generation scheme is also proposed to further suppress the Nyquist signal bandwidth and reduce channel crosstalk without the need for optical prefiltering. Only optical cou plers are needed for superNyquist wavelengthdivisionmulti plexing （WDM） channel multiplexing. We extend the DSP for shorthaul optical transmission networks by using highorder QAMs. We propose a highspeed Can＇ierless Amplitude/Phase 64 QAM （CAP64 QAM） system using directly modulated la ser （DML） based on direct detection and digital equalization. Decisiondirected least mean square is used to equalize the CAP64QAM. Using this scheme, we generate and transmit up to 60 Gbit/s CAP64QAM over 20 km standard single mode fiber based on the DML and direct detection. Finally, several key problems are solved for real time orthogonalfre quencydivisionmultiplexing （OFDM） signal transmission aml processing. With coherent detection, up to 100 Glfit/s 16 QAMOFDM realtime transmission is possible.
基金Syed Maqbool Husain,Sha-Shib Group of Institutions for their support
文摘Energy and environmental stuff are two of the main worries for humanity,and nanoscience plays a key role in providing the solution.Huge nanoresearch activities have attracted lot of attention in the current scenario.However,designing the material with enhanced optoelectronic properties remains the foremost challenge.In the present work,the Li doped CuO nanosheets are synthesized by the chemical route and examined in photovoltaics and environmental remediation applications.The crystallographic and optical study reveals that crystallite size and bandgap decrease with an increase in lithium-doping concentration up to 5 mole%and beyond that a reverse trend is observed.Additionally,impedance study has shown the significant contribution of lithium-ions to the total capacitance and resistivity.Further,the photoactivity of Cu_(1-x)Li_(x)O nanosheets(optimum concentration of Cu_(1-x)Li_(x)O NSs(x=0.05))is projected to the degradation of methylene blue(MB)and used to fabricate bulk heterojunction solar cell together with P3HT and PCBM blend,respectively.The ITO/PEDOT:PSS/P3 HT:PC_(70)BM:Cu_(1-x)Li_(x)O(x=0.05)/Li F/Al solar cell realized higher power-conversion efficiencyη~3.91 than their corresponding pristine deviceη~2.98 with enhanced photocurrent density from 9.026 to 11.56 m A cm^(-2).The proliferation in photocatalysts and solar cells efficiency of Cu_(1-x)Li_(x)O(x=0.05)is mainly attributed to the higher light absorption and lesser electron-hole recombination.The approach for the synthesis of Cu_(1-x)Li_(x)O NSs as potential donor material and device prototypes fabricated is completely safe and cost-effective.
文摘The phenomenon of photothermally induced transparency(PTIT)arises from the nonlinear behavior of an optical cavity,resulting from the heating of mirrors.By introducing a coupling field in the form of a standing wave,PTIT can be transitioned into photothermally induced grating(PTIG).A two-dimensional(2D)diffraction pattern is achieved through the adjustment of key parameters such as coupling strength and effective detuning.Notably,we observe first,second,and third-order intensity distributions,with the ability to transfer probe energy predominantly to the third order by fine-tuning the coupling strength.The intensity distribution is characterized by(±m,±n),where m,n=1,2,3.This proposed 2D grating system offers a novel platform for manipulating PTIG,presenting unique possibilities for enhanced functionality and control.
文摘Copper oxide nanoflowers(CuO-NFs)have been synthesized through a novel green route using Tulsi leaves-extracted eugenol(4-allyl-2-methoxyphenol)as reducing agent.Characterizations results reveal the growth of crystalline singlephase CuO-NFs with monoclinic structure.The prepared CuO-NFs can effectively degrade methylene blue with 90%efficiency.They also show strong barrier against E.coli(27±2 mm)at the concentration of 100μg mL−1,while at the concentration of 25μg mL−1 weak barrier has been found against all examined bacterial organisms.The results provide important evidence that CuO-NFs have sustainable performance in methylene blue degradation as well as bacterial organisms.
基金Supported by China Scholarship Council(CSC),Deutscher Akademischer Austausch Dienst(DAAD),National Natural Science Foundation of China(60375011,60575028)Natural Science Foundation of Anhui Province(04042044)Supported by Program for New Century Excellent Talents in University(NCET-04-0560)
文摘Rotationally symmetric triangulation(RST)sensor has more flexibility and less uncertainty limits because of the abaxial rotationally symmetric optical system.But if the incident laser is eccentric,the symmetry of the image will descend,and it will result in the eccentric error especially when some part of the imaged ring is blocked.The model of rotationally symmetric triangulation that meets the Schimpflug condition is presented in this paper.The error from eccentric incident laser is analysed.It is pointed out that the eccentric error is composed of two parts,one is a cosine in circumference and proportional to the eccentric departure factor,and the other is a much smaller quadric factor of the departure.When the ring is complete,the first error factor is zero because it is integrated in whole ring, but if some part of the ring is blocked,the first factor will be the main error.Simulation verifies the result of the a- nalysis.At last,a compensation method to the error when some part of the ring is lost is presented based on neural network.The results of experiment show that the compensation will make the absolute maximum error descend to half,and the standard deviation of error descends to 1/3.
基金supported by the Basic Research Program through the National Research Foundation of Korea(NRF)(Nos.2022R1C1C1006593,2022R1A4A3031263,and RS-2023-00271166)the National Science Foundation(Nos.2054098 and 2213693)+1 种基金the National Natural Science Foundation of China(No.52105593)Zhejiang Provincial Natural Science Foundation of China(No.LDQ24E050001).EH acknowledges a fellowship from the Hyundai Motor Chung Mong-Koo Foundation.
文摘Recently,the increasing interest in wearable technology for personal healthcare and smart virtual/augmented reality applications has led to the development of facile fabrication methods.Lasers have long been used to develop original solutions to such challenging technological problems due to their remote,sterile,rapid,and site-selective processing of materials.In this review,recent developments in relevant laser processes are summarized under two separate categories.First,transformative approaches,such as for laser-induced graphene,are introduced.In addition to design optimization and the alteration of a native substrate,the latest advances under a transformative approach now enable more complex material compositions and multilayer device configurations through the simultaneous transformation of heterogeneous precursors,or the sequential addition of functional layers coupled with other electronic elements.In addition,the more conventional laser techniques,such as ablation,sintering,and synthesis,can still be used to enhance the functionality of an entire system through the expansion of applicable materials and the adoption of new mechanisms.Later,various wearable device components developed through the corresponding laser processes are discussed,with an emphasis on chemical/physical sensors and energy devices.In addition,special attention is given to applications that use multiple laser sources or processes,which lay the foundation for the all-laser fabrication of wearable devices.
基金Supported in part by the National Natural Science Foundation of China under Grant Nos.11274132 and 11750110411
文摘In this paper, we examine the transmission of a probe field through a one dimensional photonic crystal (1DPC) when the sixth layer of the crystal is doped with four level atoms. We analyze effects of the external driving field on the passage of weak probe field across the photonic crystal. It is found that for the phase time delay of the probe photons, intensity of the driving field switches the Hartman effect from sub to superluminal character. It is interesting to note that in our model, the superluminal transmission of the probe pulse is accompanied by a negligibly small absorption of the incident beam. It ensures that the probe field does not attenuate while passing through the photonic crystal. A similar switching of the Hartman effect may be obtained by adjusting detuning of the probe field related to the excited states of the four-level doping atoms.
基金Supported by the National Natural Science Foundation of China under Grant Nos.11750110411 and 11274132
文摘We study the tunneling time of ultracold V-type atoms interacting a high quality microwave cavity. Here atomic coherence is introduced in the system by a strong driving field which couples the two lower states of the three-level atom. It is found that in the presence of coherence, mazer action or the scattering like nature of the interaction may be examined for extended energies of the incident cold atoms. Our results show that position and amplitudes of the peak values of the phase time(traversal time) may be very effectively controlled by the coherent driving field. Further, here we obtained superclassical values of the phase time corresponding to much higher values of the transmission amplitudes of the tunneling atoms which may be advantageous in the possible experimental realization of the superclassical tunneling time of the traversing cold atoms. In addition, we examine a mirror reflection type symmetry in the phase time curve for a judicious choice of the external driving field.
基金Supported by the National Natural Science Foundation of China under Grant Nos.11274132 and 11550110180
文摘We investigate the time evolution of quantum correlations of a hybrid qubit-qutrit system under the classical Ornstein-Uhlenbeck(OU) noise. Here we consider two different one-parameter families of qubit-qutrit states which independently interact with the non-Markovian reservoirs. A comparison with the Markovian dynamics reveals that for the same set of initial condition parameters, the non-Markovian behavior of the environment plays an important role in the enhancement of the survival time of quantum correlations. In addition, it is observed that the non-Markovian strength(γ/Γ) has a positive impact on the correlations time. For the initial separable states it is found that there is a finite time interval in which the geometric quantum discord is frozen despite the presence of a noisy environment and that interval can be further prolonged by using the non-Markovian property. Moreover, its decay can be significantly delayed.
基金supported by Bright Dream Robotics and the HKUSTBDR Joint Research Institute Funding Scheme under Project HBJRI-FTP-005(Automated 3D Reconstruction using Robot-mounted 360-Degree Camera with Visible Light Positioning Technology for Building Information Modelling Applications,OKT22EG06).
文摘Large-scale indoor 3D reconstruction with multiple robots faces challenges in core enabling technologies.This work contributes to a framework addressing localization,coordination,and vision processing for multi-agent reconstruction.A system architecture fusing visible light positioning,multi-agent path finding via reinforcement learning,and 360°camera techniques for 3D reconstruction is proposed.Our visible light positioning algorithm leverages existing lighting for centimeter-level localization without additional infrastructure.Meanwhile,a decentralized reinforcement learning approach is developed to solve the multi-agent path finding problem,with communications among agents optimized.Our 3D reconstruction pipeline utilizes equirectangular projection from 360°cameras to facilitate depth-independent reconstruction from posed monocular images using neural networks.Experimental validation demonstrates centimeter-level indoor navigation and 3D scene reconstruction capabilities of our framework.The challenges and limitations stemming from the above enabling technologies are discussed at the end of each corresponding section.In summary,this research advances fundamental techniques for multi-robot indoor 3D modeling,contributing to automated,data-driven applications through coordinated robot navigation,perception,and modeling.
文摘Ground penetrating radar (GPR) is a remote sensing technique used to obtain information on subsurface features from data collected over the surface. We propose an automatic algorithm for estimating object depth using f-k migration and velocity scanning methods in a homogeneous medium. To improve the accuracy of the algorithm, the formula used to calculate the GPR valid lateral aperture is also presented. Experimental results show that the relative estimating error of depth is as low as 5% in a homogeneous medium.
基金Supported by the National Natural Science Foundation of China(No.2 0 1730 73)
文摘The emission and Fourier transformation infrared spectra of freshly prepared porous silicon(PS) and the silicon wafer were examined. Increasing temperature generally led to a decrease in the emission intensities of the PS samples, however, the freshly prepared sample showed an unusually large and sudden increase in its emission intensity at the specific temperature at which the hydrogen ion conductivity in the silicon wafer increased. The O-H vibrations of the silicon wafer also showed a sudden decrease at the same temperature. These results are consistent with the assumption that the luminescence of fresh PS comes from the carrier bound exciton in its confined nanostructure.
基金Supported by State Science and Technology Commission of China
文摘A simple WDM Add-Drop Multiplexer (ADM) Consisting of a set of Er-doped fibers (EDF) and a shared pump is proposed. The chief benefit of the module is that the interchannel power spread does not accumulate from stage to stage in a cascaded WDM system. Moreover, the power differences caused by different component losses existing in the WDM networks can be automatically compressed. The cost will not increase a lot since the pump source is shared in the module. The performance of a cascaded system constructed from the modules has been carefully studied by computer simulation.
基金the financial support provided by Hubei University of Automotive Technology in the form of a startup research grant(BK202212)。
文摘We propose a method to implement electromagnetically induced grating in a phaseonium medium that has been coherently generated via atomic mechanisms.Phaseonium atoms have aΛ-type structure and three distinct energy levels;such atoms are originally generated in a coherent superposition of two lower levels.The phaseonium system is comprised of three-level atoms with aΛ-type configuration,which are initially prepared in a coherent superposition of two lower levels.To accomplish this spatial modulation based on the susceptibility of phaseonium medium,a standingwave field is used.By looking at how an optical field diffracts at different relative phases,we find that the zeroth and first order diffraction intensities increase as the relative phase changes.We also investigate the impact of the Rabi frequency of the field on diffraction intensity and notice that an increasing strength of the Rabi frequency leads to amplification in the intensity of both central zeroth order and first-order diffraction.Furthermore,it has been observed that a significant rise in diffraction intensity occurs at longer interaction lengths between external fields and the atomic medium.
基金supported by National High Technology Research and Development Program of China (No. 2012AA011303)
文摘In this work, we focus on enhancing the network reach in terabit superchannel transmission by using a noise-suppressed Nyquist wavelength division multiplexing （NS-N-WDM） technique for polarization multiplexing quadrature phase-shift keying （PM-QPSK） subchannels at different symbol-rate-to-subchannel-spacing ratios up to 1.28. For the first time, we experimentally compare the transmission reach of this emerging technique with that of no-guard-interval coherent optical orthogonal frequency-division multiplexing （NGI-CO-OFDM） on the same testbed. At BER of 2 x 10 3 and 100 Gbit/s per channel, an NGI-CO-OFDM terabit superchannel can transmit over a maximum of 3200 km SMF-28 with EDFA-only amplification, and an NS-N-WDM terabit superchannel can transmit over a maximum of 2800 km SMF-28 with EDFA-only amplification. Assuming different coding gain, 11 x 112 Gbit/s per channel with hard-decision （HD） forward-error correction （FEC） and 11 × 128 Gbit/s per channel NS-N-WDM transmission with soft-decision （SD） FEC can be achieved over a maximum of 2100 km and 2170 km, respectively. These are almost equal and were achieved using digital noise filtering and one-bit maximum likelihood sequence estimation （MLSE） at the receiver DSP. Characteristics including the back-to-back （BTB） curves, the ADC bandwidth requirement, and the tolerance to unequal subchannel power of an NS-N-WDM superchannel were also evaluated.
基金Hubei University of Automotive Technology through the start-up research grant(BK202212),located in Shiyan 442002,China。
文摘We propose an effective surface plasmon resonance system designed to achieve both negative and positive Goos–H??nchen shifts in reflected light.This system comprises a metal film and an underlying medium,where the real part of the permittivity of the underlying medium must be less than unity.Surface plasmon polaritons can be excited at the lower surface of the metal when light is incident from the air onto the upper surface of the metal.The excitation of surface plasmon polaritons leads to the exploration of the Goos–H??nchen shift(G–HS).Control over the negative and positive(G–HS)is investigated via the wavelength of the incident light.The magnitude of the G–HS is strongly dependent on the incident wavelength.A remarkable enhancement of both negative and positive G–HS in the reflected light is achieved at certain wavelengths and incident angles.Our system paves the way for exploring different characteristics of optical switching and micro-sensors with very high precision.
