In this paper, we propose a scheme for the generation of low phase noise tunable mm-wave signal by bearing two lightwaves in a photodiode. These two lightwaves are made phase coherent by an optoelectronic phase locked...In this paper, we propose a scheme for the generation of low phase noise tunable mm-wave signal by bearing two lightwaves in a photodiode. These two lightwaves are made phase coherent by an optoelectronic phase locked loop. Calculated mm-wave power at a frequency of 60 GHz is found to be -4 dBm.展开更多
A new device of two parallel distributed feedback （DFB） lasers integrated monolithically with Y-branch waveguide coupler was fabricated by means of quantum well intermixing. Optical microwave signal was generated in...A new device of two parallel distributed feedback （DFB） lasers integrated monolithically with Y-branch waveguide coupler was fabricated by means of quantum well intermixing. Optical microwave signal was generated in the Y-branch waveguide coupler through frequency beating of the two laser modes coming from two DFB laser in parallel, which had a small difference in frequency. Continuous rapid tuning of optical microwave signal from 13 to 42 GHz were realized by adjusting independently the driving currents injected into the two DFB lasers.展开更多
A 194-nm cw laser is an essential part in the mercury ion optical frequency standard. We report the generation of over 2mW continuous-wave radiation at 194nm in a beta barium borate crystal using a simple sum frequenc...A 194-nm cw laser is an essential part in the mercury ion optical frequency standard. We report the generation of over 2mW continuous-wave radiation at 194nm in a beta barium borate crystal using a simple sum frequency mixing （SFM） system. One source beams at 718nm is resonantly enhanced with a cavity and the other at 266mn makes a single pass. Considering the walk-off effect in SFM, the source beam waists are designed to be elliptical, thus the conversion efficiency can be promoted. The 266-nm beam produced by frequency doubling of 532-nm laser is shaped close to the diffraction limit to achieve better mode matching.展开更多
An environmentally friendly,low power consuming,sensitive and compact mercury analyzer was developed for the determination of mercury in water samples by integrating a thin film dielectric barrier discharge induced co...An environmentally friendly,low power consuming,sensitive and compact mercury analyzer was developed for the determination of mercury in water samples by integrating a thin film dielectric barrier discharge induced cold vapor reactor and a dielectric barrier discharge optical emission spectrometer into a small polymethyl methacrylate plate（10.5 cm length×8.0 cm width×1.2 cm height）.Mercury cold vapor was generated when standard or sample solutions with or without formic acid were introduced to the reactor to form thin film liquid and exposed to microplasma irradiation and subsequently separated from the liquid phase for transport to the microplasma and detection of its atomic emission.Limits of detection of 0.20 μg L^-1 and 2.6 μg L^-1 were obtained for the proposed system using or not using formic acid,respectively.Compared to the conventional microplasma optical emission spectrometry used for mercury analysis,this system not only retains the good limit of detection amenable to the determination of mercury in real samples,but also reduces power consumption,eliminates the generation of hydrogen and avoids the use of toxic or unstable reductant.Method validation was demonstrated by analysis of a certified reference material of water sample and three real water samples with good spike recoveries（88-102%）.展开更多
We propose and demonstrate a silicon-on-insulator （SOI） on-chip optical pulse shaper based on four-tap finite impulse response. Due to different width designs in phase region of each tap, the phase differences for a...We propose and demonstrate a silicon-on-insulator （SOI） on-chip optical pulse shaper based on four-tap finite impulse response. Due to different width designs in phase region of each tap, the phase differences for all taps are controlled by an external thermal source, resulting in an optical pulse shaper. We further demonstrate optical arbitrary waveform generation based on the optical pulse shaper assisted by an optical frequency comb injection. Four different optical waveforms are generated when setting the central wavelengths at 1533.78 nm and 1547.1 nm and setting the thermal source temperatures at 23 ℃ and 33 ℃, respectively. Our scheme has distinct advantages of compactness, capability for integrating with electronics since the integrated silicon waveguide is employed.展开更多
A general theory of optical parametric generation that accounts for pump depletion, loss, phase mismatch, group-velocity mismatch among the pump, signal and idler pulses, and intrapulse group-velocity dispersion is pr...A general theory of optical parametric generation that accounts for pump depletion, loss, phase mismatch, group-velocity mismatch among the pump, signal and idler pulses, and intrapulse group-velocity dispersion is proposed for coherent ultrashort pulses with arbitrary shapes and carrier chirps. The coupled differential equations are numerically solved using a symmetric split step beam-propagation method. The general solutions of these equations are obtained and the optical parametric generation process is theoretically investigated. Results show that the major factors, which remarkably affect the optical parametric conversion efficiency and durations of the pulses in phase-matched structure, are the group velocity mismatch and the intrapulse group velocity dispersion.展开更多
We propos e a cos t-effective multi-carrier generation technique which minimizes the passive optical access network(PON) costs. In this study replacement of laser array with multi-carrier source at optical line termin...We propos e a cos t-effective multi-carrier generation technique which minimizes the passive optical access network(PON) costs. In this study replacement of laser array with multi-carrier source at optical line terminal(OLT) side in PON is addressed. With 25-GHz frequency spacing, the generated optical multi-carriers exhibit good tone to noise ratio(TNR) i. e. above 20 d B, and least amplitude difference i. e. 1.5d B. At the OLT, multi-carriers signal based multiplexed differential phase shift keying(DPSK) data from all the channels each having 10 Gbps for downlink is transmitted through 25 km single mode fiber. While the transmitted information is retrieved at optical network unit(ONU), part of the downlink signal is re-modulated using intensity modulated(IM) on-off keying(OOK) for upstream transmission at 10-Gbps. Simulation results are in good agreement with the theoretical analysis, showing error free transmission in downlink and uplink with 10 Gbps symmetric data rate at each channel. The receivedpower, both for uplink and downlink transmission, is adequate for all channels at BER of 10-9 with minimum power penalties. Power budget is calculated for different splitting ratios showing excellent system margins for any unseen losses. The proposed setup provides a cost-effective way minimizing transmission losses, and providing greater system's margin in PON architecture.展开更多
In order to generate high quality regular optical vortex array(OVA),we present an experimental method for generating OVA using phase only liquid crystal spatial light modulator(LC-SLM)assisted two gratings.In the sche...In order to generate high quality regular optical vortex array(OVA),we present an experimental method for generating OVA using phase only liquid crystal spatial light modulator(LC-SLM)assisted two gratings.In the scheme,holograms of two grating are displayed on the screen of two LC-SLMs respectively;the diffraction optical fields are captured by a CCD camera.The simulated and experimental results show that the regular OVA can be generated by using double diffraction gratings.The generated OVAs have a constant topological charge of±1.The method can provide a useful pathway to produce regular OVA for some applications in optical communication,particle trapping and optical metrology.展开更多
An optical modulation format generation scheme based on spectral filtering and frequency-to-time mapping is experimentally demonstrated. Many modulation formats with continuously adjustable duty radio and bit rate can...An optical modulation format generation scheme based on spectral filtering and frequency-to-time mapping is experimentally demonstrated. Many modulation formats with continuously adjustable duty radio and bit rate can be formed by changing the dispersion of dispersion element and the bandwidth of shaped spectrum in this scheme. In the experiment, non-return-to-zero(NRZ) signal with bit rate of 29.41 Gbit/s and 1/2 duty ratio return-to-zero(RZ) signal with bit rate of 13.51 Gbit/s are obtained. The maximum bit rate of modulation format signal is also analyzed.展开更多
In order to study the correlation between the cracking of rice (Oryza sativa L.) kernels and the molecular structure of the amylopectin in them, we attempted optical sum frequency generation (SFG) spectroscopy in the ...In order to study the correlation between the cracking of rice (Oryza sativa L.) kernels and the molecular structure of the amylopectin in them, we attempted optical sum frequency generation (SFG) spectroscopy in the C-H stretching vibration region for normal and cracked japonica non-glutinous rice kernels. The samples were Koshihikari and Nipponbare. In Nipponbare, the width of the SFG spectrum peak at 2915 cm<sup>- 1</sup> of the cracked rice kernels was broader than that of the normal ones, while for Koshihikari there was no clear difference. The width of the 2915 cm<sup>- 1</sup> peak is suggested to originate from the variety of the higher-order structure of the saccharide chains in amylopectin. Although this is a tentative result, this method is shown to have a potential of serving for preventing the cracking of the rice kernels.展开更多
We propose a scheme to generate isolated attosecond pulses in the water-window spectral region. Based on the numerical solutions of the single active electron model, we investigate high-order harmonic generation in he...We propose a scheme to generate isolated attosecond pulses in the water-window spectral region. Based on the numerical solutions of the single active electron model, we investigate high-order harmonic generation in helium atoms driven by a multi-cycle two-colour optical field synthesized by an intense 2000 nm, 20 fs pulse and its frequency-doubled pulse. When the latter is slightly detuned and properly phase shifted with respect to the fundamental laser pulse, an ultra-broad extreme ultraviolet supercontinuum with a spectral width of 130 eV can be generated in the 270 400 eV spectral regions. A supercontinuum from 280-340 eV in the water window can be selected to yield an isolated 67 attosecond pulse without employing any phase compensation. This water window coherent x-ray pulse with less than 100 attosecond duration is a potential tool for studying the ultrafast electronic dynamics of biological samples in water.展开更多
From the viewpoint of quantum information, this paper proposes a concept and a definition of the atomic optimal entropy squeezing sudden generation （AOESSG） for the system of an effective two-level moving atom which...From the viewpoint of quantum information, this paper proposes a concept and a definition of the atomic optimal entropy squeezing sudden generation （AOESSG） for the system of an effective two-level moving atom which entangles with the two-mode coherent fields. It also researches the relationship between the AOESSG and entanglement sudden death of the atom-fields, and discusses the influences of atomic initial state on the AOESSG and obtains the system parameter which controls the AOESSG.展开更多
Highly efficient nonlinear optical（NLO） materials with well-defined architectures in the wavelength and subwavelength length scales are of particular importance for next generation of integrated photonic circuits. F...Highly efficient nonlinear optical（NLO） materials with well-defined architectures in the wavelength and subwavelength length scales are of particular importance for next generation of integrated photonic circuits. Fluorenone analogues have been demonstrated to be promising candidates as building blocks for assembly of organic NLO materials thanks to their synergistic supramolecular interactions and brilliant optical properties. Here we have studied the polymorphs of a phenylethynyl functionalized fluorenone derivative, and their controlled self-assembly for microstructures with different morphologies. These polymorphic microcrystals exhibit very distinctive NLO properties, highly related to their supramolecular and electronic structures.展开更多
The conventional way of generating optical waveforms relies on in-phase and quadrature(IQ)modulation of a continuous-wave(CW)laser tone.In this case,the bandwidth of the resulting optical waveform is limited by the un...The conventional way of generating optical waveforms relies on in-phase and quadrature(IQ)modulation of a continuous-wave(CW)laser tone.In this case,the bandwidth of the resulting optical waveform is limited by the underlying electronic components,in particular by the digital-to-analog converters(DACs)generating the drive signals for the IQ modulator.This bandwidth bottleneck can be overcome by using a concept known as optical arbitrary waveform generation(OAWG),where multiple IQ modulators and DACs are operated in parallel to first synthesize individual spectral slices,which are subsequently combined to form a single ultra-broadband arbitrary optical waveform.However,targeted synthesis of arbitrary optical waveforms from multiple spectral slices has so far been hampered by difficulties to maintain the correct optical phase relationship between the slices.In this paper,we propose and demonstrate spectrally sliced OAWG with active phase stabilization,which permits targeted synthesis of truly arbitrary optical waveforms.We demonstrate the viability of the scheme by synthesizing optical waveforms with record-high bandwidths of up to 325 GHz from four individually generated optical tributaries.In a proof-of-concept experiment,we use the OAWG system to generate 32QAM data signals at symbol rates of up to 320 GBd,which we transmit over 87 km of single-mode fiber and receive by a two-channel non-sliced optical arbitrary waveform measurement(OAWM)system,achieving excellent signal quality.We believe that our scheme can unlock the full potential of OAWG and disrupt a wide range of applications in high-speed optical communications,photonic-electronic digital-to-analog conversion,as well as advanced test and measurement in science and industry.展开更多
Antiferromagnetism has become a promising candidate for the next generation electronic devices due to its thermal stability,low energy consumption,and fast switching speed.However,the canceling of the net magnetic mom...Antiferromagnetism has become a promising candidate for the next generation electronic devices due to its thermal stability,low energy consumption,and fast switching speed.However,the canceling of the net magnetic moment in antiferromagnetic order presents great challenge on quantitative characterization and modulation,hindering its investigation and application.In this work,utilizing the optical second harmonic generation(SHG)in a wide temperature range,the integrated differential phase contrast scanning transmission electron microscopy,and firstprinciples calculations,we performed a quantitative study on the evolution of non-collinear antiferromagnetic order in BiFeO_(3)films with a series of strains.We found that the antiferromagnetic coupling was significantly enhanced,featured by the increase of Néel temperature from 428 K to 646 K,and by one order of enhancement of SHG intensity contributed from the G-type antiferromagnetic order by strain manipulation from-2.4%to+0.6%.We attributed the enhancement of the antiferromagnetic coupling to the enhancement of the superexchange interaction as the Fe-O-Fe bond angle approaches 180°when the in-plane lattice constants increase,which might also result in a tendency from a non-collinear antiferromagnetic order to a collinear one.Our work not only bridges the antiferromagnetic order and the strain manipulation in epitaxial multiferroics,more importantly,also paves a way for quantitative characterization by SHG technology and the precise manipulation of antiferromagnetism.展开更多
Artificial neural networks with internal dynamics exhibit remarkable capability in processing information.Reservoir computing(RC)is a canonical example that features rich computing expressivity and compatibility with ...Artificial neural networks with internal dynamics exhibit remarkable capability in processing information.Reservoir computing(RC)is a canonical example that features rich computing expressivity and compatibility with physical implementations for enhanced efficiency.Recently,a new RC paradigm known as next generation reservoir computing(NGRC)further improves expressivity but compromises its physical openness,posing challenges for realizations in physical systems.Here we demonstrate optical NGRC with computations performed by light scattering through disordered media.In contrast to conventional optical RC implementations,we directly and solely drive our optical reservoir with time-delayed inputs.Much like digital NGRC that relies on polynomial features of delayed inputs,our optical reservoir also implicitly generates these polynomial features for desired functionalities.By leveraging the domain knowledge of the reservoir inputs,we show that the optical NGRC not only predicts the short-term dynamics of the low-dimensional Lorenz63 and large-scale Kuramoto-Sivashinsky chaotic time series,but also replicates their long-term ergodic properties.Optical NGRC shows superiority in shorter training length and fewer hyperparameters compared to conventional optical RC based on scattering media,while achieving better forecasting performance.Our optical NGRC framework may inspire the realization of NGRC in other physical RC systems,new applications beyond time-series processing,and the development of deep and parallel architectures broadly.展开更多
A high-efficiency technique for optical vortex(OV) generation is proposed and demonstrated. The technique is based on liquid crystal fork gratings with space-variant azimuthal orientations, which are locally controlle...A high-efficiency technique for optical vortex(OV) generation is proposed and demonstrated. The technique is based on liquid crystal fork gratings with space-variant azimuthal orientations, which are locally controlled via polarization-sensitive alignment layers. Thanks to the optical rewritability of the alignment agent and the dynamic image generation of the digital micro-mirror device, fork gratings can be instantly and arbitrarily reconfigured.Corresponding optical vortices carrying arbitrary azimuthal and radial indices are demonstrated with a conversion efficiency of 98.5%, exhibiting features of polarization control and electrical switching. The technique may pave a bright road toward OV generation, manipulation, and detection.展开更多
A novel scheme is proposed to transform a Gaussian optical pulse to a millimeter-wave （mm-wave） frequency modulation pulse by using a Fabry-Perot interferometer （FPI） for radio-over-fiber （ROF） system. It is sho...A novel scheme is proposed to transform a Gaussian optical pulse to a millimeter-wave （mm-wave） frequency modulation pulse by using a Fabry-Perot interferometer （FPI） for radio-over-fiber （ROF） system. It is shown that modulation frequency of mm-wave is determined by the optical path of the Fabry-Perot （F-P） cavity, and amplitude decay time and energy transfer efficiency axe related to the reflectivity of the F-P cavity mirror. The effect of pulse train extension on inter-symbol interference is also discussed.展开更多
This paper reviews recent progresses on optical arbitrary waveform generation （AWG） techniques, which could be used to break the speed and bandwidth bottle- necks of electronics technologies for waveform generation....This paper reviews recent progresses on optical arbitrary waveform generation （AWG） techniques, which could be used to break the speed and bandwidth bottle- necks of electronics technologies for waveform generation. The main enabling techniques for optically generating optical and microwave waveforms are introduced and reviewed in this paper, such as wavelength-to-time mapping techniques, space-to-time mapping techniques, temporal pulse shaping （TPS） system, optoelectronics oscillator （OEO）, programmable optical filters, optical differentiator and integrator and versatile electro-optic modulation implementations. The main advantages and challenges of these optical AWG techniques are also discussed.展开更多
The rapid development of emerging technologies observed in recent years,such as artificial intelligence, machine learning, mobile internet, big data,cloud computing, and the Internet of Everything, are generating esca...The rapid development of emerging technologies observed in recent years,such as artificial intelligence, machine learning, mobile internet, big data,cloud computing, and the Internet of Everything, are generating escalatingdemands for expanding the capacity density, and speed in next-generation opticalcommunications. This poses a significant challenge to existing communicationtechniques. Within this context, the integration of near-infraredbroadband, tunable, and high-gain luminescent materials into silicon opticalcircuits or fiber architectures to transmit and modulate light shows enormouspotential for advancing next-generation communication techniques. Here, thisreview provides an overview of the recent breakthroughs in near-infrared luminescentepitaxial/colloidal quantum dots, and metal-active-center-doped materialsfor broadband optical amplifiers and tunable lasers. We also expound onefforts to enhance the bandwidth and gain of these materials-based amplifiersand lasers, exploring the challenges associate with developing ultra-broadbandand high-speed optical communication systems. Additionally, the potentialapplications in Fifth Generation Fixed Networks, integration with 5G and 6Gwireless networks, compensation for current Si electronic based CMOS forhigh computing capability, and the prospects of these light sources for nextgenerationoptoelectronic devices are discussed.展开更多
文摘In this paper, we propose a scheme for the generation of low phase noise tunable mm-wave signal by bearing two lightwaves in a photodiode. These two lightwaves are made phase coherent by an optoelectronic phase locked loop. Calculated mm-wave power at a frequency of 60 GHz is found to be -4 dBm.
基金Project supported by the National Natural Science Foundation of China （Grant No 90401025）. Acknowledgments The authors are grateful to the Multiple-function 0ptoelectronic Integration group, Institute of Semiconductors, CAS for sponsoring this project. We extend our thanks to Professor Wang Zi-Yu of Peking University for microwave signal testing.
文摘A new device of two parallel distributed feedback （DFB） lasers integrated monolithically with Y-branch waveguide coupler was fabricated by means of quantum well intermixing. Optical microwave signal was generated in the Y-branch waveguide coupler through frequency beating of the two laser modes coming from two DFB laser in parallel, which had a small difference in frequency. Continuous rapid tuning of optical microwave signal from 13 to 42 GHz were realized by adjusting independently the driving currents injected into the two DFB lasers.
基金Supported by the National Natural Science Foundation of China under Grant Nos 91436103 and 11204374
文摘A 194-nm cw laser is an essential part in the mercury ion optical frequency standard. We report the generation of over 2mW continuous-wave radiation at 194nm in a beta barium borate crystal using a simple sum frequency mixing （SFM） system. One source beams at 718nm is resonantly enhanced with a cavity and the other at 266mn makes a single pass. Considering the walk-off effect in SFM, the source beam waists are designed to be elliptical, thus the conversion efficiency can be promoted. The 266-nm beam produced by frequency doubling of 532-nm laser is shaped close to the diffraction limit to achieve better mode matching.
基金the National Natural Science Foundation of China(No.21575092)for financial support
文摘An environmentally friendly,low power consuming,sensitive and compact mercury analyzer was developed for the determination of mercury in water samples by integrating a thin film dielectric barrier discharge induced cold vapor reactor and a dielectric barrier discharge optical emission spectrometer into a small polymethyl methacrylate plate（10.5 cm length×8.0 cm width×1.2 cm height）.Mercury cold vapor was generated when standard or sample solutions with or without formic acid were introduced to the reactor to form thin film liquid and exposed to microplasma irradiation and subsequently separated from the liquid phase for transport to the microplasma and detection of its atomic emission.Limits of detection of 0.20 μg L^-1 and 2.6 μg L^-1 were obtained for the proposed system using or not using formic acid,respectively.Compared to the conventional microplasma optical emission spectrometry used for mercury analysis,this system not only retains the good limit of detection amenable to the determination of mercury in real samples,but also reduces power consumption,eliminates the generation of hydrogen and avoids the use of toxic or unstable reductant.Method validation was demonstrated by analysis of a certified reference material of water sample and three real water samples with good spike recoveries（88-102%）.
基金supported by the National Basic Research Program of China(Grant No.2011CB301704)the Program for New Century Excellent Talents in Ministryof Education of China(Grant No.NCET-11-0168)+1 种基金the Foundation for the Author of National Excellent Doctoral Dissertation of China(Grant No.201139)the National Natural Science Foundation of China(Grant Nos.60901006 and 11174096)
文摘We propose and demonstrate a silicon-on-insulator （SOI） on-chip optical pulse shaper based on four-tap finite impulse response. Due to different width designs in phase region of each tap, the phase differences for all taps are controlled by an external thermal source, resulting in an optical pulse shaper. We further demonstrate optical arbitrary waveform generation based on the optical pulse shaper assisted by an optical frequency comb injection. Four different optical waveforms are generated when setting the central wavelengths at 1533.78 nm and 1547.1 nm and setting the thermal source temperatures at 23 ℃ and 33 ℃, respectively. Our scheme has distinct advantages of compactness, capability for integrating with electronics since the integrated silicon waveguide is employed.
文摘A general theory of optical parametric generation that accounts for pump depletion, loss, phase mismatch, group-velocity mismatch among the pump, signal and idler pulses, and intrapulse group-velocity dispersion is proposed for coherent ultrashort pulses with arbitrary shapes and carrier chirps. The coupled differential equations are numerically solved using a symmetric split step beam-propagation method. The general solutions of these equations are obtained and the optical parametric generation process is theoretically investigated. Results show that the major factors, which remarkably affect the optical parametric conversion efficiency and durations of the pulses in phase-matched structure, are the group velocity mismatch and the intrapulse group velocity dispersion.
基金National High Technology 863 Program of China(No.2013AA013403,2013AA013301/02,2015AA015501/02)National NSFC(No.61425022/61307086/61475024/61275158/61201151/61275074/61205066)+4 种基金NITC(No.2012DFG12110)Beijing Nova Program(No.Z141101001814048)Beijing Excellent Ph.D.Thesis Guidance Foundation(No.20121001302)are gratefully acknowledgedsupported by the Universities Ph.D.Special Research Funds(No.20120005110003/20120005120007)fund of State Key Laboratory of IPOC(BUPT)
文摘We propos e a cos t-effective multi-carrier generation technique which minimizes the passive optical access network(PON) costs. In this study replacement of laser array with multi-carrier source at optical line terminal(OLT) side in PON is addressed. With 25-GHz frequency spacing, the generated optical multi-carriers exhibit good tone to noise ratio(TNR) i. e. above 20 d B, and least amplitude difference i. e. 1.5d B. At the OLT, multi-carriers signal based multiplexed differential phase shift keying(DPSK) data from all the channels each having 10 Gbps for downlink is transmitted through 25 km single mode fiber. While the transmitted information is retrieved at optical network unit(ONU), part of the downlink signal is re-modulated using intensity modulated(IM) on-off keying(OOK) for upstream transmission at 10-Gbps. Simulation results are in good agreement with the theoretical analysis, showing error free transmission in downlink and uplink with 10 Gbps symmetric data rate at each channel. The receivedpower, both for uplink and downlink transmission, is adequate for all channels at BER of 10-9 with minimum power penalties. Power budget is calculated for different splitting ratios showing excellent system margins for any unseen losses. The proposed setup provides a cost-effective way minimizing transmission losses, and providing greater system's margin in PON architecture.
基金supported by the National Natural Science Foundation of China(Nos.61975099 and 11902317)the Natural Science Foundation of Shandong Province of China(Nos.ZR201702090137 and ZR2017LA010)。
文摘In order to generate high quality regular optical vortex array(OVA),we present an experimental method for generating OVA using phase only liquid crystal spatial light modulator(LC-SLM)assisted two gratings.In the scheme,holograms of two grating are displayed on the screen of two LC-SLMs respectively;the diffraction optical fields are captured by a CCD camera.The simulated and experimental results show that the regular OVA can be generated by using double diffraction gratings.The generated OVAs have a constant topological charge of±1.The method can provide a useful pathway to produce regular OVA for some applications in optical communication,particle trapping and optical metrology.
基金supported by the National Natural Science Foundation of China(No.61377075)the Tianjin Natural Science Foundation(No.17JCYBJC16600)
文摘An optical modulation format generation scheme based on spectral filtering and frequency-to-time mapping is experimentally demonstrated. Many modulation formats with continuously adjustable duty radio and bit rate can be formed by changing the dispersion of dispersion element and the bandwidth of shaped spectrum in this scheme. In the experiment, non-return-to-zero(NRZ) signal with bit rate of 29.41 Gbit/s and 1/2 duty ratio return-to-zero(RZ) signal with bit rate of 13.51 Gbit/s are obtained. The maximum bit rate of modulation format signal is also analyzed.
文摘In order to study the correlation between the cracking of rice (Oryza sativa L.) kernels and the molecular structure of the amylopectin in them, we attempted optical sum frequency generation (SFG) spectroscopy in the C-H stretching vibration region for normal and cracked japonica non-glutinous rice kernels. The samples were Koshihikari and Nipponbare. In Nipponbare, the width of the SFG spectrum peak at 2915 cm<sup>- 1</sup> of the cracked rice kernels was broader than that of the normal ones, while for Koshihikari there was no clear difference. The width of the 2915 cm<sup>- 1</sup> peak is suggested to originate from the variety of the higher-order structure of the saccharide chains in amylopectin. Although this is a tentative result, this method is shown to have a potential of serving for preventing the cracking of the rice kernels.
基金Project supported by the National Basic Research Program of China (Grant No. 2006CB806000)the Knowledge Innovation Program of Chinese Academy of Sciencesthe National Natural Science Foundation of China (Grant Nos. 10734080, 60578049 and 10523003)
文摘We propose a scheme to generate isolated attosecond pulses in the water-window spectral region. Based on the numerical solutions of the single active electron model, we investigate high-order harmonic generation in helium atoms driven by a multi-cycle two-colour optical field synthesized by an intense 2000 nm, 20 fs pulse and its frequency-doubled pulse. When the latter is slightly detuned and properly phase shifted with respect to the fundamental laser pulse, an ultra-broad extreme ultraviolet supercontinuum with a spectral width of 130 eV can be generated in the 270 400 eV spectral regions. A supercontinuum from 280-340 eV in the water window can be selected to yield an isolated 67 attosecond pulse without employing any phase compensation. This water window coherent x-ray pulse with less than 100 attosecond duration is a potential tool for studying the ultrafast electronic dynamics of biological samples in water.
基金Project supported by the National Natural Science Foundation of China (Grant No 19874020)the Natural Science Foundation of Hunan Province,China (Grant No 09JJ3012)the Scientific Research Fund of the Education Department of Hunan Province of China (Grant No 07c543)
文摘From the viewpoint of quantum information, this paper proposes a concept and a definition of the atomic optimal entropy squeezing sudden generation （AOESSG） for the system of an effective two-level moving atom which entangles with the two-mode coherent fields. It also researches the relationship between the AOESSG and entanglement sudden death of the atom-fields, and discusses the influences of atomic initial state on the AOESSG and obtains the system parameter which controls the AOESSG.
基金the financial supports from the National Natural Science Foundation of China(NSFC) (Nos.21773168, 51503143 and 21761132007)the Tianjin Natural Science Foundation(No. 16JCQNJC05000)+5 种基金the Innovation Foundation of Tianjin University (No. 2016XRX-0017)the China International Science and Technology Projects(No. S2016G3413)The Netherlands Organization for Scientific Research (NWO) with the Veni Grant (No. 680-47-437)The Royal Netherlands Academy of Arts and Sciences(KNAW) with the China-Exchange Program (No. 530-4CDPO2)the Tianjin 1000 Youth Talents Planthe Chinese Scholarship Council (CSC)
文摘Highly efficient nonlinear optical（NLO） materials with well-defined architectures in the wavelength and subwavelength length scales are of particular importance for next generation of integrated photonic circuits. Fluorenone analogues have been demonstrated to be promising candidates as building blocks for assembly of organic NLO materials thanks to their synergistic supramolecular interactions and brilliant optical properties. Here we have studied the polymorphs of a phenylethynyl functionalized fluorenone derivative, and their controlled self-assembly for microstructures with different morphologies. These polymorphic microcrystals exhibit very distinctive NLO properties, highly related to their supramolecular and electronic structures.
基金supported by the ERC Consolidator Grant TeraSHAPE(#773248)by the associated ERC Proof-of-Concept Grant TeraGear(#101123567)+11 种基金by the EU H2020 project TeraSlice(#863322)by the DFG projects PACE(#403188360)GOSPEL(#403187440)by the joint DFG-ANR projects HybridCombs(#491234846)Quad-Combs(#505515860)by the DFG Collaborative Research Centers(CRC)WavePhenomena(SFB 1173,#258734477)HyPERION(SFB 1527,#454252029)by the BMBF project Open6GHub(#16KISK010)by the Horizon Europe EIC transition program with the projects CombTools(#101136978)MAGNIFY(#101113302)HDLN(#101113260)by the Alfried Krupp von Bohlen und Halbach Foundation,by the MaxPlanck School of Photonics(MPSP),and by the Karlsruhe School of Optics&Photonics(KSOP).
文摘The conventional way of generating optical waveforms relies on in-phase and quadrature(IQ)modulation of a continuous-wave(CW)laser tone.In this case,the bandwidth of the resulting optical waveform is limited by the underlying electronic components,in particular by the digital-to-analog converters(DACs)generating the drive signals for the IQ modulator.This bandwidth bottleneck can be overcome by using a concept known as optical arbitrary waveform generation(OAWG),where multiple IQ modulators and DACs are operated in parallel to first synthesize individual spectral slices,which are subsequently combined to form a single ultra-broadband arbitrary optical waveform.However,targeted synthesis of arbitrary optical waveforms from multiple spectral slices has so far been hampered by difficulties to maintain the correct optical phase relationship between the slices.In this paper,we propose and demonstrate spectrally sliced OAWG with active phase stabilization,which permits targeted synthesis of truly arbitrary optical waveforms.We demonstrate the viability of the scheme by synthesizing optical waveforms with record-high bandwidths of up to 325 GHz from four individually generated optical tributaries.In a proof-of-concept experiment,we use the OAWG system to generate 32QAM data signals at symbol rates of up to 320 GBd,which we transmit over 87 km of single-mode fiber and receive by a two-channel non-sliced optical arbitrary waveform measurement(OAWM)system,achieving excellent signal quality.We believe that our scheme can unlock the full potential of OAWG and disrupt a wide range of applications in high-speed optical communications,photonic-electronic digital-to-analog conversion,as well as advanced test and measurement in science and industry.
基金supported by the National Key Basic Research Program of China(Grant No.2019YFA0308500,2020YFA0309100,and 2021YFA1400701)the National Natural Science Foundation of China(Grant No.12174437,No.12222414,No.12074416,and No.12104054)+4 种基金the Strategic Priority Research Program(B)of the Chinese Academy of Sciences(Grant No.XDB33030200)the Youth Innovation Promotion Association of the Chinese Academy of Sciences(Grant No.Y2022003)the China Postdoctoral Innovative Talent Support Program(Grant No.BX20240409)the China Postdoctoral Science Foundation(Grant No.2024M763507)the Beijing Natural Science Foundation(Grant No.1222035).
文摘Antiferromagnetism has become a promising candidate for the next generation electronic devices due to its thermal stability,low energy consumption,and fast switching speed.However,the canceling of the net magnetic moment in antiferromagnetic order presents great challenge on quantitative characterization and modulation,hindering its investigation and application.In this work,utilizing the optical second harmonic generation(SHG)in a wide temperature range,the integrated differential phase contrast scanning transmission electron microscopy,and firstprinciples calculations,we performed a quantitative study on the evolution of non-collinear antiferromagnetic order in BiFeO_(3)films with a series of strains.We found that the antiferromagnetic coupling was significantly enhanced,featured by the increase of Néel temperature from 428 K to 646 K,and by one order of enhancement of SHG intensity contributed from the G-type antiferromagnetic order by strain manipulation from-2.4%to+0.6%.We attributed the enhancement of the antiferromagnetic coupling to the enhancement of the superexchange interaction as the Fe-O-Fe bond angle approaches 180°when the in-plane lattice constants increase,which might also result in a tendency from a non-collinear antiferromagnetic order to a collinear one.Our work not only bridges the antiferromagnetic order and the strain manipulation in epitaxial multiferroics,more importantly,also paves a way for quantitative characterization by SHG technology and the precise manipulation of antiferromagnetism.
基金supported by Swiss National Science Foundation(SNF)projects LION,ERC SMARTIES and Institut Universitaire de France.H.W.acknowledges China Scholarship Council and National Natural Science Foundation of China(623B2064 and 62275137)J.H.acknowledges SNF fellowship(P2ELP2_199825)+3 种基金Y.B.acknowledges the support from Basic Science Research Program through the National Research Foundation of Korea(NRF)funded by the Ministry of Education(2022R1A6A3A03072108)European Union’s Horizon Europe research and innovation program(N.101105899)Q.L.acknowledges National Natural Science Foundation of China(62275137)the Tsinghua University(Department of Precision Instrument)-North Laser Research Institute Co.,Ltd Joint Research Center for Advanced Laser Technology(20244910194).
文摘Artificial neural networks with internal dynamics exhibit remarkable capability in processing information.Reservoir computing(RC)is a canonical example that features rich computing expressivity and compatibility with physical implementations for enhanced efficiency.Recently,a new RC paradigm known as next generation reservoir computing(NGRC)further improves expressivity but compromises its physical openness,posing challenges for realizations in physical systems.Here we demonstrate optical NGRC with computations performed by light scattering through disordered media.In contrast to conventional optical RC implementations,we directly and solely drive our optical reservoir with time-delayed inputs.Much like digital NGRC that relies on polynomial features of delayed inputs,our optical reservoir also implicitly generates these polynomial features for desired functionalities.By leveraging the domain knowledge of the reservoir inputs,we show that the optical NGRC not only predicts the short-term dynamics of the low-dimensional Lorenz63 and large-scale Kuramoto-Sivashinsky chaotic time series,but also replicates their long-term ergodic properties.Optical NGRC shows superiority in shorter training length and fewer hyperparameters compared to conventional optical RC based on scattering media,while achieving better forecasting performance.Our optical NGRC framework may inspire the realization of NGRC in other physical RC systems,new applications beyond time-series processing,and the development of deep and parallel architectures broadly.
基金sponsored by the 973 programs (Nos. 2011CBA00200 and 2012CB921803)the NSFC programs (Nos. 61490714, 11304151, 61435008, and 61225026)+2 种基金the Ph.D. Programs Foundation of the Ministry of Education of China (No.20120091120020)the support from the Program for Changjiang Scholars and Innovative Research Team in University (No.IRT13021)PAPD
文摘A high-efficiency technique for optical vortex(OV) generation is proposed and demonstrated. The technique is based on liquid crystal fork gratings with space-variant azimuthal orientations, which are locally controlled via polarization-sensitive alignment layers. Thanks to the optical rewritability of the alignment agent and the dynamic image generation of the digital micro-mirror device, fork gratings can be instantly and arbitrarily reconfigured.Corresponding optical vortices carrying arbitrary azimuthal and radial indices are demonstrated with a conversion efficiency of 98.5%, exhibiting features of polarization control and electrical switching. The technique may pave a bright road toward OV generation, manipulation, and detection.
文摘A novel scheme is proposed to transform a Gaussian optical pulse to a millimeter-wave （mm-wave） frequency modulation pulse by using a Fabry-Perot interferometer （FPI） for radio-over-fiber （ROF） system. It is shown that modulation frequency of mm-wave is determined by the optical path of the Fabry-Perot （F-P） cavity, and amplitude decay time and energy transfer efficiency axe related to the reflectivity of the F-P cavity mirror. The effect of pulse train extension on inter-symbol interference is also discussed.
基金Acknowledgements We would like to thank our colleagues for their contributions in these works, such as Reza Ashrafi, Chao Wang, Tae-Jung Ahn, Ze Li, Wei Li, Ningbo Huang, Ye Deng, Yi Hu, Roberto Morandotti, Yichen Han, Shilong Pan, Maria Rosario and Wangzhe Li. This work was supported by the National Natural Science Foundation of China （Grant Nos. 61377002, 61321063, and 61090391）. This work was also supported by the Natural Sciences and Engineering Research Council of Canada （NSERC）. Ming Li was supported in part by the ＂Thousand Young Talent＂ program.
文摘This paper reviews recent progresses on optical arbitrary waveform generation （AWG） techniques, which could be used to break the speed and bandwidth bottle- necks of electronics technologies for waveform generation. The main enabling techniques for optically generating optical and microwave waveforms are introduced and reviewed in this paper, such as wavelength-to-time mapping techniques, space-to-time mapping techniques, temporal pulse shaping （TPS） system, optoelectronics oscillator （OEO）, programmable optical filters, optical differentiator and integrator and versatile electro-optic modulation implementations. The main advantages and challenges of these optical AWG techniques are also discussed.
基金National Key Research and Development Program of China,Grant/Award Number:2021YFB2800500National Natural Science Foundation of China,Grant/Award Numbers:62375243,61574138,61974131,62035013,62105281+2 种基金Natural Science Foundation of ZhejiangProvince, Grant/Award Numbers:LD22E010001, LR23E030002,LGJ21F050001Major Scientific Project ofZhejiang LabEngineering and PhysicalSciences Research Council (EPSRC),Grant/Award Numbers: EP/P006973/1,EP/R029075/1, EP/T028475/1, EP/V036327/1, EP/V048732/1, EP/X015300/1。
文摘The rapid development of emerging technologies observed in recent years,such as artificial intelligence, machine learning, mobile internet, big data,cloud computing, and the Internet of Everything, are generating escalatingdemands for expanding the capacity density, and speed in next-generation opticalcommunications. This poses a significant challenge to existing communicationtechniques. Within this context, the integration of near-infraredbroadband, tunable, and high-gain luminescent materials into silicon opticalcircuits or fiber architectures to transmit and modulate light shows enormouspotential for advancing next-generation communication techniques. Here, thisreview provides an overview of the recent breakthroughs in near-infrared luminescentepitaxial/colloidal quantum dots, and metal-active-center-doped materialsfor broadband optical amplifiers and tunable lasers. We also expound onefforts to enhance the bandwidth and gain of these materials-based amplifiersand lasers, exploring the challenges associate with developing ultra-broadbandand high-speed optical communication systems. Additionally, the potentialapplications in Fifth Generation Fixed Networks, integration with 5G and 6Gwireless networks, compensation for current Si electronic based CMOS forhigh computing capability, and the prospects of these light sources for nextgenerationoptoelectronic devices are discussed.
