Full-Stokes polarimeters can detect the polarization states of light,which is critical for the next-generation optical and optoelectronic systems.Traditional full-Stokes polarimeters are either based on bulky optical ...Full-Stokes polarimeters can detect the polarization states of light,which is critical for the next-generation optical and optoelectronic systems.Traditional full-Stokes polarimeters are either based on bulky optical systems or complex metasurface structures,which cause the system complexity with unessential energy loss.Recently,filterless on-chip full-Stokes polarimeters have been demonstrated by using optical anisotropic materials which are able to detect the circularly polarized light.Nevertheless,those on-chip full-Stokes polarimeters have either the limited detection wavelength range or relatively poor device performance that need to be further improved.Here,we report the high performance broadband full-Stokes polarimeters based on rhenium disulfide(ReS_(2)).While the anisotropic structure of the ReS_(2)introduces the in-plane optical anisotropy for linearly polarized light(LP)detection,Schottky contacts formed by the ReS_(2)-Au could break the symmetry,which can detect circularly polarized(CP)light.By building a proper model,all four Stokes parameters can be extracted by using the ReS_(2)nanobelt device.The device delivers a photoresponsivity of 181 A/W,a detectivity of 6.8×10^(10)Jones and can sense the four Stokes parameters of incident light within a wide range of wavelength from 565-800 nm with reasonable average errors.We believe our study provides an alternative strategy to develop high performance broadband on-chip full-Stokes polarimeters.展开更多
Dual-comb interferometric systems with high time accuracy have been realized for various applications.The flourishing ultralow noise dual-comb system promotes the measurement and characterization of relative timing ji...Dual-comb interferometric systems with high time accuracy have been realized for various applications.The flourishing ultralow noise dual-comb system promotes the measurement and characterization of relative timing jitter,thus improving time accuracy.With optical solutions,introducing an optical reference enables 105 harmonics measurements,thereby breaking the limit set by electrical methods;nonlinear processes or spectral interference schemes were also employed to track the relative timing jitter.However,such approaches operating in the time domain either require additional continuous references or impose stringent requirements on the amount of timing jitter.We propose a scheme to correct the relative timing jitter of a free-running dual-comb interferometry assisted by a Fabry-Pérot(F-P)cavity in the frequency domain.With high wavelength thermal stability provided by the F-P cavity,the absolute wavelength deviation in the operating bandwidth is compressed to<0.4 pm,corresponding to a subpicosecond sensitivity of pulse-to-pulse relative timing jitter.Also,Allan deviation of 10^(-10) is obtained under multiple coherent averaging,which lays the foundation for mode-resolved molecular spectroscopic applications.The spectral absorption features of hydrogen cyanide gas molecules at ambient temperature were measured and matched to the HITRAN database.Our scheme promises to provide new ideas on sensitive measurements of relative timing jitter.展开更多
The microring resonator(MRR)plays an important role in signal processing because high-quality bandpass filtering can be obtained at its drop port.To promote the signal-to-noise ratio,a high rejection ratio is signific...The microring resonator(MRR)plays an important role in signal processing because high-quality bandpass filtering can be obtained at its drop port.To promote the signal-to-noise ratio,a high rejection ratio is significantly demanded.However,it is still challenging to promote the rejection ratio of the MRR-based bandpass filter.To solve this problem,we propose to use an all-pass filter to enhance the rejection ratio of the MRR-based bandpass filter.Experimental results show that the improved rejection ratio is as high as 47.7 dB,which is improved by 23.6 dB compared with that of the MRR.Meanwhile,the bandwidth of the MRR-based bandpass filter is reduced from 2.61 to 1.14 GHz due to the constructive interference in the passband.In addition,the center frequency of this ultrahigh rejection MRR can be continuously tuned from 6.26 to 46.25 GHz.The quality factor(Q)of the MRR is improved from 7.4×10^(4) to 1.7×10^(5).During the adjustment,the rejection ratio of the bandpass filter exceeds 40 dB.The proposed approach can be used to achieve optical bandpass filters with high performance.展开更多
Optical pulse processor meets the urgent demand for high-speed,ultra wideband devices,which can avoid electrical confinements in various fields,e.g.,alloptical communication,optical computing technology,cohcrcnt contr...Optical pulse processor meets the urgent demand for high-speed,ultra wideband devices,which can avoid electrical confinements in various fields,e.g.,alloptical communication,optical computing technology,cohcrcnt control and microwave fields.To date,great efforts have been madc particularly in on-chip programmable pulse proccessing.Here,we experimentally demonstrate a programmable pulse proceesor employing 16cascaded Mach-Zehnder interferometer coupled microring resonator(MZI-MRR)structure based on silicon-oninsulator wafer.With micro-heaters loaded to the device,both amplitude and frequency tunings can be realized in each MZI-MRR unit.Thanks to its reconfigurability and integration ability,First,it can serve as a fractional differentiator whose tuning range is 0.51-2.23 with deviation no more than 7%.Second,the device can be tuned into a programmable optical filter whose bandwidth varies from 0.15to 0.97nm.The optical filter is also shape tunable.Especially,15-channel wavelength selective switches are generated.展开更多
Applications of optical switches,such as signal routing and data-intensive computing,are critical in optical interconnects and optical computing.Integrated optical switches enabled by two-dimensional(2D)materials and ...Applications of optical switches,such as signal routing and data-intensive computing,are critical in optical interconnects and optical computing.Integrated optical switches enabled by two-dimensional(2D)materials and beyond,such as graphene and black phosphorus,have demonstrated many advantages in terms of speed and energy consumption compared to their conventional silicon-based counterparts.Here we review the state-of-the-art of optical switches enabled by 2D materials and beyond and organize them into several tables.The performance tables and future projections show the frontiers of optical switches fabricated from 2D materials and beyond,providing researchers with an overview of this field and enabling them to identify existing challenges and predict promising research directions.展开更多
Molecules with long preserved magnetic moments are perceived as the smallest units for storing bytes,which could bring a new revolution for information technology.However,the rational design of such molecules remains ...Molecules with long preserved magnetic moments are perceived as the smallest units for storing bytes,which could bring a new revolution for information technology.However,the rational design of such molecules remains challenging.Here two rigid adamantanol ligand based dysprosium(III)complexes([Dy(1-AdO)_(2)(py)_(5)]BPh_(4)-1 and[Dy(2-AdO)_(2)(py)_(5)]BPh_(4)-2)with pentagonal-bipyramidal coordination geometry and local D5h symmetry were successfully prepared,which display excellent single-molecule magnet(SMM)behavior(U_(eff)≈1835 K,T_(B)_(ZFC)≈24 K,T_(B)^(100s)≈17 K and T_(B)^(H)=23 K for 1;U_(eff)≈1756 K,T_(B)^(ZFC)≈20 K,T_(B)^(100s)≈16 K and T_(B)^(H)=23 K for 2)due to the much weakened vibration in low energy regimes.Remarkably,the large energy barriers and high blocking temperatures for these two complexes in solid states are well preserved in solution.This is never observed in previous studies of SMMs,indicating that the adamantanol is rigid and can be introduced to make the composed molecules stable enough to maintain the solid state magnetic property in solution.展开更多
Polaritons are quasi-particles that combine light with matter,enabling precise control of light at deep subwavelength scales.The excitation and propagation of polaritons are closely linked to the structural symmetries...Polaritons are quasi-particles that combine light with matter,enabling precise control of light at deep subwavelength scales.The excitation and propagation of polaritons are closely linked to the structural symmetries of the host materials,resulting in symmetrical polariton propagation in high-symmetry materials.However,in low-symmetry crystals,symmetry-broken polaritons exist,exhibiting enhanced directionality of polariton propagation for nanoscale light manipulation and steering.Here,we theoretically propose and experimentally demonstrate the existence of symmetry-broken polaritons,with hyperbolic dispersion,in a high-symmetry crystal.We show that an optical disk-antenna positioned on the crystal surface can act as an in-plane polarized excitation source,enabling dynamic tailoring of the asymmetry of hyperbolic polariton propagation in the high-symmetry crystal over a broad frequency range.Additionally,we provide an intuitive analysis model that predicts the condition under which the asymmetric polaritonic behavior is maximized,which is corroborated by our simulations and experiments.Our results demonstrate that the directionality of polariton propagation can be conveniently configured,independent of the structure symmetry of crystals,providing a tuning knob for the polaritonic response and in-plane anisotropy in nanophotonic applications.展开更多
The servo-motor possesses a strongly nonlinear property due to the effect of the stimulating input voltage, load-torque and environmental operating conditions. So it is rather difficult to derive a traditional mathema...The servo-motor possesses a strongly nonlinear property due to the effect of the stimulating input voltage, load-torque and environmental operating conditions. So it is rather difficult to derive a traditional mathematical model which is capable of expressing both its dynamics and steady-state characteristics. A neural network-based adaptive control strategy is proposed in this paper. In this method, two neural networks have been adopted for system identification （NNI） and control （NNC）, respectively. Then, the commonly-used specialized learning has been modified, by taking the NNI output as the approximation output of the servo-motor during the weights training to get sensitivity information. Moreover, the rule for choosing the learning rate is given on the basis of the analysis of Lyapunov stability. Finally, an example of applying the proposed control strategy on a servo-motor is presented to show its effectiveness.展开更多
Encircling an exceptional point(EP) in a parity-time(PT) symmetric system has shown great potential for chiral optical devices,such as chiral mode switching for symmetric and antisymmetric modes.However,to our best kn...Encircling an exceptional point(EP) in a parity-time(PT) symmetric system has shown great potential for chiral optical devices,such as chiral mode switching for symmetric and antisymmetric modes.However,to our best knowledge,chiral switching for polarization states has never been reported,although chiral polarization manipulation has significant applications in imaging,sensing,communication,etc.Here,inspired by the anti-PT symmetry,we demonstrate,for the first time to our best knowledge,an on-chip chiral polarizer by constructing a polarization-coupled anti-PT symmetric system.The transmission axes of the chiral polarizer are different for forward and backward propagation.A polarization extinction ratio of over 10 dB is achieved for both propagating directions.Moreover,a telecommunication experiment is performed to demonstrate the potential applications in polarization encoding signals.It provides a novel functionality for encircling-an-EP parametric evolution and offers a new approach for on-chip chiral polarization manipulation.展开更多
All-optical modulation based on the photothermal effect of two-dimensional(2 D)materials shows great promise for all-optical signal processing and communication.In this work,an all-optical modulator with a 2 D Pt Se2-...All-optical modulation based on the photothermal effect of two-dimensional(2 D)materials shows great promise for all-optical signal processing and communication.In this work,an all-optical modulator with a 2 D Pt Se2-onsilicon structure based on a microring resonator is proposed and demonstrated utilizing the photothermal effect of Pt Se2.A tuning efficiency of 0.0040 nm·m W-1 is achieved,and the 10%–90%rise and decay times are 304μs and 284μs,respectively.The fabricated device exhibits a long-term air stability of more than 3 months.The experimental results prove that 2 D Pt Se2 has great potential for optical modulation on a silicon photonic platform.展开更多
Integrated photonics is widely regarded as an important post-Moore’s law research direction.However,it suffers from intrinsic limitations,such as lack of control and satisfactory photonic memory,that cannot be solved...Integrated photonics is widely regarded as an important post-Moore’s law research direction.However,it suffers from intrinsic limitations,such as lack of control and satisfactory photonic memory,that cannot be solved in the optical domain and must be combined with electronics for practical use.Inevitably,electronics and photonics will converge.The photonic fabrication and integration technology is gradually maturing and electronics-photonics convergence(EPC)is experiencing a transition from device integration to circuit design.We derive a conceptual framework consisting of regulator,oscillator,and memory for scalable integrated circuits based on the fundamental concepts of purposeful behavior in cybernetics,entropy in information theory,and symmetry breaking in physics.Leveraging this framework and emulating the successes experienced by electronic integrated circuits,we identify the key building blocks for the integrated circuits for EPC and review the recent advances.展开更多
Parity‐time(PT)symmetry breaking offers mode selection capability for facilitating single‐mode oscillation in the optoelectronic oscillator(OEO)loop.However,most OEO implementations depend on discrete devices,which ...Parity‐time(PT)symmetry breaking offers mode selection capability for facilitating single‐mode oscillation in the optoelectronic oscillator(OEO)loop.However,most OEO implementations depend on discrete devices,which impedes proliferation due to size,weight,power consumption,and cost.In this work,we propose and experimentally demonstrate an on-chip tunable PT‐symmetric OEO.A tunable microwave photonic filter,a PT‐symmetric mode‐selective architecture,and two photodetectors are integrated on a silicon‐on‐insulator chip.By exploiting an on‐chip Mach–Zehnder interferometer to match the gain and loss of two mutually coupled optoelectronic loops,single‐mode oscillation can be obtained.In the experiment,the oscillation frequency of the on-chip tunable PT‐symmetric OEO can be tuned from 0 to 20 GHz.To emulate the integrated case,the OEO loop length is minimized,and no extra-long fiber is used in the experiment.When the oscillation frequency is 13.67 GHz,the single‐sideband phase noise at 10-kHz offset frequency is−80.96 dBc∕Hz and the side mode suppression ratio is 46 dB.The proposed on-chip tunable PT‐symmetric OEO significantly reduces the footprint of the system and enhances mode selection.展开更多
Silicon nitride(Si3N4)waveguides with high confinement and low loss have been widely used in integrated nonlinear photonics.Indeed,state-of-the-art ultralow-loss Si3N4 waveguides are all fabricated using complex fabri...Silicon nitride(Si3N4)waveguides with high confinement and low loss have been widely used in integrated nonlinear photonics.Indeed,state-of-the-art ultralow-loss Si3N4 waveguides are all fabricated using complex fabrication processes,and all of those reported that high Q microring resonators(MRRs)are fabricated in laboratories.We propose and demonstrate an ultralow-loss Si3N4 racetrack MRR by shaping the mode using a uniform multimode structure to reduce its overlap with the waveguide.The MRR is fabricated by the standard multi project wafer(MPW)foundry process.It consists of two multimode straight waveguides(MSWs)connected by two multimode waveguide bends(MWBs).In particular,the MWBs are based on modified Euler bends,and an MSW directional coupler is used to avoid higher-order mode excitation.In this way,although a multimode waveguide is used in the MRR,only the fundamental mode is excited and transmitted with ultralow loss.Meanwhile,thanks to the 180 deg Euler bend,a compact chip footprint of 2.226 mm perimeter with an effective radius as small as 195μm and a waveguide width of 3μm is achieved.Results show that based on the widely used MPW process,a propagation loss of only 3.3 dB∕m and a mean intrinsic Q of around 10.8 million are achieved for the first time.展开更多
The increasing amount of data exchange requires higher-capacity optical communication links.Mode division multiplexing(MDM)is considered as a promising technology to support the higher data throughput.In an MDM system...The increasing amount of data exchange requires higher-capacity optical communication links.Mode division multiplexing(MDM)is considered as a promising technology to support the higher data throughput.In an MDM system,the mode generator and sorter are the backbone.However,most of the current schemes lack the programmability and universality,which makes the MDM link susceptible to the mode crosstalk and environmental disturbances.In this paper,we propose an intelligent multimode optical communication link using universal mode processing(generation and sorting)chips.The mode processor consists of a programmable 4×4 Mach Zehnder interferometer(MZI)network and can be intelligently configured to generate or sort both quasi linearly polarized(LP)modes and orbital angular momentum(OAM)modes in any desired routing state.We experimentally establish a chip-to-chip MDM communication system.The mode basis can be freely switched between four LP modes and four OAM modes.We also demonstrate the multimode optical communication capability at a data rate of 25 Gbit/s.The proposed scheme shows significant advantages in terms of universality,intelligence,programmability and resistance to mode crosstalk,environmental disturbances,and fabrication errors,demonstrating that the MZI-based reconfigurable mode processor chip has great potential in longdistance chip-to-chip multimode optical communication systems.展开更多
The characteristic property of white Gaussian noise (WGN) is derived in S-transformation domain. The results show that the distribution of normalized S-spectrum of WGN follows X2?distribution with two degrees of freed...The characteristic property of white Gaussian noise (WGN) is derived in S-transformation domain. The results show that the distribution of normalized S-spectrum of WGN follows X2?distribution with two degrees of freedom. The conclusion has been confirmed through both theoretical derivations and numerical simulations. Combined with different criteria, an effective signal detection in S-transformation can be realized.展开更多
High-performance germanium photodiodes are crucial components in silicon photonic integrated circuits for large-capacity data communication.However,the bandwidths of most germanium photodiodes are limited by the intra...High-performance germanium photodiodes are crucial components in silicon photonic integrated circuits for large-capacity data communication.However,the bandwidths of most germanium photodiodes are limited by the intractable resistance–capacitance parasitic effect.Here,we introduce a unique U-shaped electrode to alleviate this issue,reducing the parasitic effect by 36%without compromising any other performance.Experimentally,a large bandwidth of 103 GHz,an optical responsivity of 0.95 A/W at 1550 nm,and a dark current as low as 1.3 nA are achieved,leading to a record high specific detectivity.This is the first breakthrough to 100 GHz bandwidth among all vertical germanium photodiodes,to the best of our knowledge.Open eye diagrams of 120 Gb/s on-off keying and 200 Gb/s four-level pulse amplitude signals are well received.This work provides a promising solution for chip-based ultra-fast photodetection.展开更多
Metasurface-based holograms,or metaholograms,offer unique advantages including enhanced imaging quality,expanded field of view,compact system size,and broad operational bandwidth.Multi-channel metaholograms,capable of...Metasurface-based holograms,or metaholograms,offer unique advantages including enhanced imaging quality,expanded field of view,compact system size,and broad operational bandwidth.Multi-channel metaholograms,capable of switching between multiple projected images based on the properties of illuminating light such as state of polarization and angle of incidence,have emerged as a promising solution for realizing switchable and dynamic holographic displays.Yet,existing designs typically grapple with challenges such as limited multiplexing channels and unwanted crosstalk,which severely constrain their practical use.Here,we present a new type of waveguidebased multi-channel metaholograms,which support six independent and fully crosstalk-free holographic display channels,simultaneously multiplexed by the spin and angle of guided incident light within the glass waveguide.We employ a k-space translation strategy that allows each of the six distinct target images to be selectively translated from evanescent-wave region to the center of propagation-wave region and projected into free space without crosstalk,when the metahologram is under illumination of a guided light with specific spin and azimuthal angle.In addition,by tailoring the encoded target images,we implement a three-channel polarization-independent metahologram and a two-channel full-color(RGB)metahologram.Moreover,the number of multiplexing channels can be further increased by expanding the k-space’s central-period region or combing the k-space translation strategy with other multiplexing techniques such as orbital angular momentum multiplexing.Our work provides a novel approach towards realization of high-performance and compact holographic optical elements with substantial information capacity,opening avenues for applications in AR/VR displays,image encryption,and information storage.展开更多
Nonlinear optical signal processing(NOSP)has the potential to significantly improve the throughput,flexibility,and cost-efficiency of optical communication networks by exploiting the intrinsically ultrafast optical no...Nonlinear optical signal processing(NOSP)has the potential to significantly improve the throughput,flexibility,and cost-efficiency of optical communication networks by exploiting the intrinsically ultrafast optical nonlinear wave mixing.It can support digital signal processing speeds of up to terabits per second,far exceeding the line rate of the electronic counterpart.In NOSP,high-intensity light fields are used to generate nonlinear optical responses,which can be used to process optical signals.Great efforts have been devoted to developing new materials and structures for NOSP.However,one of the challenges in implementing NOSP is the requirement of high-intensity light fields,which is difficult to generate and maintain.This has been a major roadblock to realize practical NOSP systems for high-speed,high-capacity optical communications.Here,we propose using a parity-time(PT)symmetric microresonator system to significantly enhance the light intensity and support high-speed operation by relieving the bandwidth-efficiency limit imposed on conventional single resonator systems.The design concept is the coexistence of a PT symmetry broken regime for a narrow-linewidth pump wave and near-exceptional point operation for broadband signal and idler waves.This enables us to achieve a new NOSP system with two orders of magnitude improvement in efficiency compared to a single resonator.With a highly nonlinear AlGaAs-on-Insulator platform,we demonstrate an NOSP at a data rate approaching 40 gigabits per second with a record low pump power of one milliwatt.These findings pave the way for the development of fully chip-scale NOSP devices with pump light sources integrated together,potentially leading to a wide range of applications in optical communication networks and classical or quantum computation.The combination of PT symmetry and NOSP may also open up opportunities for amplification,detection,and sensing,where response speed and efficiency are equally important.展开更多
Optical computing has shown immense application prospects in the post-Moore era.However,as a crucial component of logic computing,the digital multiplier can only be realized on a small scale in optics,restrained by th...Optical computing has shown immense application prospects in the post-Moore era.However,as a crucial component of logic computing,the digital multiplier can only be realized on a small scale in optics,restrained by the limited functionalities and inevitable loss of optical nonlinearity.In this paper,we propose a time-space multiplexed architecture to realize large-scale photonic-electronic digital multiplication.展开更多
Rapid and long-range distance measurements are essential in various industrial and scientific applications,and among them,the dual-comb ranging system attracts great attention due to its high precision.However,the tem...Rapid and long-range distance measurements are essential in various industrial and scientific applications,and among them,the dual-comb ranging system attracts great attention due to its high precision.However,the tem-poral asynchronous sampling results in the tradeoff between frame rate and ranging precision,and the non-ambiguity range(NAR)is also limited by the comb cycle,which hinders the further advancement of the dual-comb ranging system.Given this constraint,we introduce a Vernier spectral interferometry to improve the frame rate and NAR of the ranging system.First,leveraging the dispersive time-stretch technology,the dual-comb interferometry becomes spectral interferometry.Thus,the asynchronous time step is unlimited,and the frame rate is improved to 100 kHz.Second,dual-wavelength bands are introduced to implement a Vernier spectral interferometry,whose NAR is enlarged from 1.5 m to 1.5 km.Moreover,this fast and long-range system also demonstrated high precision,with a 22.91-nm Allan deviation over 10-ms averaging time.As a result,the proposed Vernier spectral interferometry ranging system is promising for diverse applications that necessitate rapid and extensive distance measurement.展开更多
基金the support from the National Key Research and Development Program of China(2022YFB2803900 and 2018YFA0704403)NSFC(62074064)。
文摘Full-Stokes polarimeters can detect the polarization states of light,which is critical for the next-generation optical and optoelectronic systems.Traditional full-Stokes polarimeters are either based on bulky optical systems or complex metasurface structures,which cause the system complexity with unessential energy loss.Recently,filterless on-chip full-Stokes polarimeters have been demonstrated by using optical anisotropic materials which are able to detect the circularly polarized light.Nevertheless,those on-chip full-Stokes polarimeters have either the limited detection wavelength range or relatively poor device performance that need to be further improved.Here,we report the high performance broadband full-Stokes polarimeters based on rhenium disulfide(ReS_(2)).While the anisotropic structure of the ReS_(2)introduces the in-plane optical anisotropy for linearly polarized light(LP)detection,Schottky contacts formed by the ReS_(2)-Au could break the symmetry,which can detect circularly polarized(CP)light.By building a proper model,all four Stokes parameters can be extracted by using the ReS_(2)nanobelt device.The device delivers a photoresponsivity of 181 A/W,a detectivity of 6.8×10^(10)Jones and can sense the four Stokes parameters of incident light within a wide range of wavelength from 565-800 nm with reasonable average errors.We believe our study provides an alternative strategy to develop high performance broadband on-chip full-Stokes polarimeters.
基金supported by the National Key Research and Development Program of China(Grant No.2022YFF0705904)the National Natural Science Foundation of China(Grant Nos.61927817 and 62075072).
文摘Dual-comb interferometric systems with high time accuracy have been realized for various applications.The flourishing ultralow noise dual-comb system promotes the measurement and characterization of relative timing jitter,thus improving time accuracy.With optical solutions,introducing an optical reference enables 105 harmonics measurements,thereby breaking the limit set by electrical methods;nonlinear processes or spectral interference schemes were also employed to track the relative timing jitter.However,such approaches operating in the time domain either require additional continuous references or impose stringent requirements on the amount of timing jitter.We propose a scheme to correct the relative timing jitter of a free-running dual-comb interferometry assisted by a Fabry-Pérot(F-P)cavity in the frequency domain.With high wavelength thermal stability provided by the F-P cavity,the absolute wavelength deviation in the operating bandwidth is compressed to<0.4 pm,corresponding to a subpicosecond sensitivity of pulse-to-pulse relative timing jitter.Also,Allan deviation of 10^(-10) is obtained under multiple coherent averaging,which lays the foundation for mode-resolved molecular spectroscopic applications.The spectral absorption features of hydrogen cyanide gas molecules at ambient temperature were measured and matched to the HITRAN database.Our scheme promises to provide new ideas on sensitive measurements of relative timing jitter.
基金supported by the National Key Research and Development Program of China(Grant No.2018YFA0704403)the National Natural Science Foundation of China(Grant No.61975249)+2 种基金the Program for HUST Academic Frontier Youth Team(Grant No.2018QYTD08)the Project of Key Laboratory of Radar Imaging and Microwave Photonics(Nanjing University of Aeronautics and Astronautics),Ministry of Education(Grant No.NJ20230001)the Independent Innovation Foundation of HUST(Grant No.5003187117).
文摘The microring resonator(MRR)plays an important role in signal processing because high-quality bandpass filtering can be obtained at its drop port.To promote the signal-to-noise ratio,a high rejection ratio is significantly demanded.However,it is still challenging to promote the rejection ratio of the MRR-based bandpass filter.To solve this problem,we propose to use an all-pass filter to enhance the rejection ratio of the MRR-based bandpass filter.Experimental results show that the improved rejection ratio is as high as 47.7 dB,which is improved by 23.6 dB compared with that of the MRR.Meanwhile,the bandwidth of the MRR-based bandpass filter is reduced from 2.61 to 1.14 GHz due to the constructive interference in the passband.In addition,the center frequency of this ultrahigh rejection MRR can be continuously tuned from 6.26 to 46.25 GHz.The quality factor(Q)of the MRR is improved from 7.4×10^(4) to 1.7×10^(5).During the adjustment,the rejection ratio of the bandpass filter exceeds 40 dB.The proposed approach can be used to achieve optical bandpass filters with high performance.
文摘Optical pulse processor meets the urgent demand for high-speed,ultra wideband devices,which can avoid electrical confinements in various fields,e.g.,alloptical communication,optical computing technology,cohcrcnt control and microwave fields.To date,great efforts have been madc particularly in on-chip programmable pulse proccessing.Here,we experimentally demonstrate a programmable pulse proceesor employing 16cascaded Mach-Zehnder interferometer coupled microring resonator(MZI-MRR)structure based on silicon-oninsulator wafer.With micro-heaters loaded to the device,both amplitude and frequency tunings can be realized in each MZI-MRR unit.Thanks to its reconfigurability and integration ability,First,it can serve as a fractional differentiator whose tuning range is 0.51-2.23 with deviation no more than 7%.Second,the device can be tuned into a programmable optical filter whose bandwidth varies from 0.15to 0.97nm.The optical filter is also shape tunable.Especially,15-channel wavelength selective switches are generated.
基金supported in part by the National Key Research and Development Project of China(No.2018YFB2201901)in part by the National Natural Science Foundation of China(Grant No.61805090).
文摘Applications of optical switches,such as signal routing and data-intensive computing,are critical in optical interconnects and optical computing.Integrated optical switches enabled by two-dimensional(2D)materials and beyond,such as graphene and black phosphorus,have demonstrated many advantages in terms of speed and energy consumption compared to their conventional silicon-based counterparts.Here we review the state-of-the-art of optical switches enabled by 2D materials and beyond and organize them into several tables.The performance tables and future projections show the frontiers of optical switches fabricated from 2D materials and beyond,providing researchers with an overview of this field and enabling them to identify existing challenges and predict promising research directions.
基金This work was supported by the National Natural Science Foundation of China(Nos.21773130,21871219 and 21971203)the Key Laboratory Construction Program of Xi'an Municipal Bu-reau of Science and Technology(No.201805056ZD7CG40)+1 种基金the Key Scientific and Technological Innovation Team of Shaanxi Province(No.2020TD-001)the Fundamental Research Funds for Central Universities。
文摘Molecules with long preserved magnetic moments are perceived as the smallest units for storing bytes,which could bring a new revolution for information technology.However,the rational design of such molecules remains challenging.Here two rigid adamantanol ligand based dysprosium(III)complexes([Dy(1-AdO)_(2)(py)_(5)]BPh_(4)-1 and[Dy(2-AdO)_(2)(py)_(5)]BPh_(4)-2)with pentagonal-bipyramidal coordination geometry and local D5h symmetry were successfully prepared,which display excellent single-molecule magnet(SMM)behavior(U_(eff)≈1835 K,T_(B)_(ZFC)≈24 K,T_(B)^(100s)≈17 K and T_(B)^(H)=23 K for 1;U_(eff)≈1756 K,T_(B)^(ZFC)≈20 K,T_(B)^(100s)≈16 K and T_(B)^(H)=23 K for 2)due to the much weakened vibration in low energy regimes.Remarkably,the large energy barriers and high blocking temperatures for these two complexes in solid states are well preserved in solution.This is never observed in previous studies of SMMs,indicating that the adamantanol is rigid and can be introduced to make the composed molecules stable enough to maintain the solid state magnetic property in solution.
基金the National Natural Science Foundation of China(Grant No.62075070 and 52172162)National Key Research and Development Program of China(Grant No.2021YFA1201500)+5 种基金Hubei Provincial Natural Science Foundation of China(Grant No.2022CFA053)the Innovation Fund of WNLOthe Natural Science Foundation of Guangdong Province(2022A1515012145)Shenzhen Science and Technology Program(JCYJ20220530162403007)Key Research and Development Plan of Hubei Provincethe Fundamental Research Funds for the Central Universities,HUST(Grant No.2022JYCXJJ009).
文摘Polaritons are quasi-particles that combine light with matter,enabling precise control of light at deep subwavelength scales.The excitation and propagation of polaritons are closely linked to the structural symmetries of the host materials,resulting in symmetrical polariton propagation in high-symmetry materials.However,in low-symmetry crystals,symmetry-broken polaritons exist,exhibiting enhanced directionality of polariton propagation for nanoscale light manipulation and steering.Here,we theoretically propose and experimentally demonstrate the existence of symmetry-broken polaritons,with hyperbolic dispersion,in a high-symmetry crystal.We show that an optical disk-antenna positioned on the crystal surface can act as an in-plane polarized excitation source,enabling dynamic tailoring of the asymmetry of hyperbolic polariton propagation in the high-symmetry crystal over a broad frequency range.Additionally,we provide an intuitive analysis model that predicts the condition under which the asymmetric polaritonic behavior is maximized,which is corroborated by our simulations and experiments.Our results demonstrate that the directionality of polariton propagation can be conveniently configured,independent of the structure symmetry of crystals,providing a tuning knob for the polaritonic response and in-plane anisotropy in nanophotonic applications.
基金National Science Foundation of China (No.60572055)Advanced Research Grant of Shanghai Normal University (No.DYL200809)Guangxi Science Foundation (No.0339068).
文摘The servo-motor possesses a strongly nonlinear property due to the effect of the stimulating input voltage, load-torque and environmental operating conditions. So it is rather difficult to derive a traditional mathematical model which is capable of expressing both its dynamics and steady-state characteristics. A neural network-based adaptive control strategy is proposed in this paper. In this method, two neural networks have been adopted for system identification （NNI） and control （NNC）, respectively. Then, the commonly-used specialized learning has been modified, by taking the NNI output as the approximation output of the servo-motor during the weights training to get sensitivity information. Moreover, the rule for choosing the learning rate is given on the basis of the analysis of Lyapunov stability. Finally, an example of applying the proposed control strategy on a servo-motor is presented to show its effectiveness.
基金National Natural Science Foundation of China(61805090, 62075075)National Key Research and Development Project of China (2018YFB2201901)。
文摘Encircling an exceptional point(EP) in a parity-time(PT) symmetric system has shown great potential for chiral optical devices,such as chiral mode switching for symmetric and antisymmetric modes.However,to our best knowledge,chiral switching for polarization states has never been reported,although chiral polarization manipulation has significant applications in imaging,sensing,communication,etc.Here,inspired by the anti-PT symmetry,we demonstrate,for the first time to our best knowledge,an on-chip chiral polarizer by constructing a polarization-coupled anti-PT symmetric system.The transmission axes of the chiral polarizer are different for forward and backward propagation.A polarization extinction ratio of over 10 dB is achieved for both propagating directions.Moreover,a telecommunication experiment is performed to demonstrate the potential applications in polarization encoding signals.It provides a novel functionality for encircling-an-EP parametric evolution and offers a new approach for on-chip chiral polarization manipulation.
基金National Key Research and Development Project of China(2018YFB2201901)National Natural Science Foundation of China(51702219,61435010,61805090,61905161,61961136001)。
文摘All-optical modulation based on the photothermal effect of two-dimensional(2 D)materials shows great promise for all-optical signal processing and communication.In this work,an all-optical modulator with a 2 D Pt Se2-onsilicon structure based on a microring resonator is proposed and demonstrated utilizing the photothermal effect of Pt Se2.A tuning efficiency of 0.0040 nm·m W-1 is achieved,and the 10%–90%rise and decay times are 304μs and 284μs,respectively.The fabricated device exhibits a long-term air stability of more than 3 months.The experimental results prove that 2 D Pt Se2 has great potential for optical modulation on a silicon photonic platform.
基金This work was supported by the National Key Research and Development Program of China(No.2018YFA0704400).
文摘Integrated photonics is widely regarded as an important post-Moore’s law research direction.However,it suffers from intrinsic limitations,such as lack of control and satisfactory photonic memory,that cannot be solved in the optical domain and must be combined with electronics for practical use.Inevitably,electronics and photonics will converge.The photonic fabrication and integration technology is gradually maturing and electronics-photonics convergence(EPC)is experiencing a transition from device integration to circuit design.We derive a conceptual framework consisting of regulator,oscillator,and memory for scalable integrated circuits based on the fundamental concepts of purposeful behavior in cybernetics,entropy in information theory,and symmetry breaking in physics.Leveraging this framework and emulating the successes experienced by electronic integrated circuits,we identify the key building blocks for the integrated circuits for EPC and review the recent advances.
基金supported by the National Key Research and Development Program of China(Grant No.2018YFA0704403)the National Natural Science Foundation of China(Grant No.61975249)the Program for HUST Academic Frontier Youth Team(Grant No.2018QYTD08).
文摘Parity‐time(PT)symmetry breaking offers mode selection capability for facilitating single‐mode oscillation in the optoelectronic oscillator(OEO)loop.However,most OEO implementations depend on discrete devices,which impedes proliferation due to size,weight,power consumption,and cost.In this work,we propose and experimentally demonstrate an on-chip tunable PT‐symmetric OEO.A tunable microwave photonic filter,a PT‐symmetric mode‐selective architecture,and two photodetectors are integrated on a silicon‐on‐insulator chip.By exploiting an on‐chip Mach–Zehnder interferometer to match the gain and loss of two mutually coupled optoelectronic loops,single‐mode oscillation can be obtained.In the experiment,the oscillation frequency of the on-chip tunable PT‐symmetric OEO can be tuned from 0 to 20 GHz.To emulate the integrated case,the OEO loop length is minimized,and no extra-long fiber is used in the experiment.When the oscillation frequency is 13.67 GHz,the single‐sideband phase noise at 10-kHz offset frequency is−80.96 dBc∕Hz and the side mode suppression ratio is 46 dB.The proposed on-chip tunable PT‐symmetric OEO significantly reduces the footprint of the system and enhances mode selection.
基金supported by the National Natural Science Foundation of China(Grant No.61975249)the National Key Research and Development Program of China(Grant No.2018YFA0704403)the Program for HUST Academic Frontier Youth Team(Grant No.2018QYTD08).
文摘Silicon nitride(Si3N4)waveguides with high confinement and low loss have been widely used in integrated nonlinear photonics.Indeed,state-of-the-art ultralow-loss Si3N4 waveguides are all fabricated using complex fabrication processes,and all of those reported that high Q microring resonators(MRRs)are fabricated in laboratories.We propose and demonstrate an ultralow-loss Si3N4 racetrack MRR by shaping the mode using a uniform multimode structure to reduce its overlap with the waveguide.The MRR is fabricated by the standard multi project wafer(MPW)foundry process.It consists of two multimode straight waveguides(MSWs)connected by two multimode waveguide bends(MWBs).In particular,the MWBs are based on modified Euler bends,and an MSW directional coupler is used to avoid higher-order mode excitation.In this way,although a multimode waveguide is used in the MRR,only the fundamental mode is excited and transmitted with ultralow loss.Meanwhile,thanks to the 180 deg Euler bend,a compact chip footprint of 2.226 mm perimeter with an effective radius as small as 195μm and a waveguide width of 3μm is achieved.Results show that based on the widely used MPW process,a propagation loss of only 3.3 dB∕m and a mean intrinsic Q of around 10.8 million are achieved for the first time.
基金National Natural Science Foundation of China(62275088,62075075,U21A20511)Innovation Project of Optics Valley Laboratory(Grant No.OVL2021BG001)+1 种基金Research Grants Council,University Grants Committee of Hong Kong SAR under Grant PolyU15301022Knowledge Innovation Program of Wuhan-Basic Research 2023010201010049.
文摘The increasing amount of data exchange requires higher-capacity optical communication links.Mode division multiplexing(MDM)is considered as a promising technology to support the higher data throughput.In an MDM system,the mode generator and sorter are the backbone.However,most of the current schemes lack the programmability and universality,which makes the MDM link susceptible to the mode crosstalk and environmental disturbances.In this paper,we propose an intelligent multimode optical communication link using universal mode processing(generation and sorting)chips.The mode processor consists of a programmable 4×4 Mach Zehnder interferometer(MZI)network and can be intelligently configured to generate or sort both quasi linearly polarized(LP)modes and orbital angular momentum(OAM)modes in any desired routing state.We experimentally establish a chip-to-chip MDM communication system.The mode basis can be freely switched between four LP modes and four OAM modes.We also demonstrate the multimode optical communication capability at a data rate of 25 Gbit/s.The proposed scheme shows significant advantages in terms of universality,intelligence,programmability and resistance to mode crosstalk,environmental disturbances,and fabrication errors,demonstrating that the MZI-based reconfigurable mode processor chip has great potential in longdistance chip-to-chip multimode optical communication systems.
文摘The characteristic property of white Gaussian noise (WGN) is derived in S-transformation domain. The results show that the distribution of normalized S-spectrum of WGN follows X2?distribution with two degrees of freedom. The conclusion has been confirmed through both theoretical derivations and numerical simulations. Combined with different criteria, an effective signal detection in S-transformation can be realized.
基金National Key Research and Development Program of China(2019YFB1803801)National Natural Science Foundation of China(61922034,62135004)+2 种基金Key Research and Development Program of Hubei Province(2021BAA005)Innovation Project of Optics Valley Laboratory(OVL2021BG005)Program for HUST Academic Frontier Youth Team(2018QYTD08)。
文摘High-performance germanium photodiodes are crucial components in silicon photonic integrated circuits for large-capacity data communication.However,the bandwidths of most germanium photodiodes are limited by the intractable resistance–capacitance parasitic effect.Here,we introduce a unique U-shaped electrode to alleviate this issue,reducing the parasitic effect by 36%without compromising any other performance.Experimentally,a large bandwidth of 103 GHz,an optical responsivity of 0.95 A/W at 1550 nm,and a dark current as low as 1.3 nA are achieved,leading to a record high specific detectivity.This is the first breakthrough to 100 GHz bandwidth among all vertical germanium photodiodes,to the best of our knowledge.Open eye diagrams of 120 Gb/s on-off keying and 200 Gb/s four-level pulse amplitude signals are well received.This work provides a promising solution for chip-based ultra-fast photodetection.
基金support by the National Natural Science Foundation of China(NSFC)under Grant Nos.62075078 and 62135004support from the Knowledge Innovation Program of Wuhan-Shuguang Project under Grant No.2022010801020095support by the NSFC under Grant No.62205113 and the support by China Post-doctoral Science Foundation under Grant No.2022M721244.
文摘Metasurface-based holograms,or metaholograms,offer unique advantages including enhanced imaging quality,expanded field of view,compact system size,and broad operational bandwidth.Multi-channel metaholograms,capable of switching between multiple projected images based on the properties of illuminating light such as state of polarization and angle of incidence,have emerged as a promising solution for realizing switchable and dynamic holographic displays.Yet,existing designs typically grapple with challenges such as limited multiplexing channels and unwanted crosstalk,which severely constrain their practical use.Here,we present a new type of waveguidebased multi-channel metaholograms,which support six independent and fully crosstalk-free holographic display channels,simultaneously multiplexed by the spin and angle of guided incident light within the glass waveguide.We employ a k-space translation strategy that allows each of the six distinct target images to be selectively translated from evanescent-wave region to the center of propagation-wave region and projected into free space without crosstalk,when the metahologram is under illumination of a guided light with specific spin and azimuthal angle.In addition,by tailoring the encoded target images,we implement a three-channel polarization-independent metahologram and a two-channel full-color(RGB)metahologram.Moreover,the number of multiplexing channels can be further increased by expanding the k-space’s central-period region or combing the k-space translation strategy with other multiplexing techniques such as orbital angular momentum multiplexing.Our work provides a novel approach towards realization of high-performance and compact holographic optical elements with substantial information capacity,opening avenues for applications in AR/VR displays,image encryption,and information storage.
基金supported in part by the National Key Research and Development Program of China(2019YFB2203100)the National Natural Science Foundation of China(NSFC)(No.62275087)+1 种基金the European Research Council(REFOCUS 853522),the Danish National Research Foundation,SPOC(ref.DNRF123)the Knowledge Innovation Program of Wuhan-Shuguang Project(No.2022010801010082).
文摘Nonlinear optical signal processing(NOSP)has the potential to significantly improve the throughput,flexibility,and cost-efficiency of optical communication networks by exploiting the intrinsically ultrafast optical nonlinear wave mixing.It can support digital signal processing speeds of up to terabits per second,far exceeding the line rate of the electronic counterpart.In NOSP,high-intensity light fields are used to generate nonlinear optical responses,which can be used to process optical signals.Great efforts have been devoted to developing new materials and structures for NOSP.However,one of the challenges in implementing NOSP is the requirement of high-intensity light fields,which is difficult to generate and maintain.This has been a major roadblock to realize practical NOSP systems for high-speed,high-capacity optical communications.Here,we propose using a parity-time(PT)symmetric microresonator system to significantly enhance the light intensity and support high-speed operation by relieving the bandwidth-efficiency limit imposed on conventional single resonator systems.The design concept is the coexistence of a PT symmetry broken regime for a narrow-linewidth pump wave and near-exceptional point operation for broadband signal and idler waves.This enables us to achieve a new NOSP system with two orders of magnitude improvement in efficiency compared to a single resonator.With a highly nonlinear AlGaAs-on-Insulator platform,we demonstrate an NOSP at a data rate approaching 40 gigabits per second with a record low pump power of one milliwatt.These findings pave the way for the development of fully chip-scale NOSP devices with pump light sources integrated together,potentially leading to a wide range of applications in optical communication networks and classical or quantum computation.The combination of PT symmetry and NOSP may also open up opportunities for amplification,detection,and sensing,where response speed and efficiency are equally important.
基金National Key Research and Development Program of China(2023YFB2806502)National Natural Science Foundation of China(62075075,62275088,U21A20511)Innovation Project of Optics Valley Laboratory(OVL2021BG001)。
文摘Optical computing has shown immense application prospects in the post-Moore era.However,as a crucial component of logic computing,the digital multiplier can only be realized on a small scale in optics,restrained by the limited functionalities and inevitable loss of optical nonlinearity.In this paper,we propose a time-space multiplexed architecture to realize large-scale photonic-electronic digital multiplication.
基金National Natural Science Foundation of China(61735006,61927817,62075072)National Key Research and Development Program of China(2022YFF0705904).
文摘Rapid and long-range distance measurements are essential in various industrial and scientific applications,and among them,the dual-comb ranging system attracts great attention due to its high precision.However,the tem-poral asynchronous sampling results in the tradeoff between frame rate and ranging precision,and the non-ambiguity range(NAR)is also limited by the comb cycle,which hinders the further advancement of the dual-comb ranging system.Given this constraint,we introduce a Vernier spectral interferometry to improve the frame rate and NAR of the ranging system.First,leveraging the dispersive time-stretch technology,the dual-comb interferometry becomes spectral interferometry.Thus,the asynchronous time step is unlimited,and the frame rate is improved to 100 kHz.Second,dual-wavelength bands are introduced to implement a Vernier spectral interferometry,whose NAR is enlarged from 1.5 m to 1.5 km.Moreover,this fast and long-range system also demonstrated high precision,with a 22.91-nm Allan deviation over 10-ms averaging time.As a result,the proposed Vernier spectral interferometry ranging system is promising for diverse applications that necessitate rapid and extensive distance measurement.
