In this study, SnNb_2O_6 and Sn_2Nb_2O_7 nanosheets are synthetized via microwave assisted hydrothermal method, and innovatively employed as anode materials for lithium-ion battery. The SnNb_2O_6 electrode exhibits hi...In this study, SnNb_2O_6 and Sn_2Nb_2O_7 nanosheets are synthetized via microwave assisted hydrothermal method, and innovatively employed as anode materials for lithium-ion battery. The SnNb_2O_6 electrode exhibits high reversible capacity and excellent cycling stability(498 mAh/g at 0.1 A/g after 100 cycles),which is superior to that of Sn_2Nb_2O_7 electrode(173 mAh/g at 0.1 A/g after 100 cycles). Even increasing the current density to 2.0 A/g, the SnNb_2O_6 electrode still delivers a reversible capacity up to 306 mAh/g.The rate performance of the SnNb_2O_6 electrode is also better than that of Sn_2 Nb_2O_7 electrode at different current densities from 0.1 A/g to 2.0 A/g. The enhanced electrochemical performance of SnNb_2O_6 nanosheets can be attributed to the unique layered structure, which is conducive to the diffusion of the lithium ions and the migration of electrons during discharge/charge.展开更多
Niobium-based oxides are considered promising anode materials for Li-ion batteries due to their high capacities,good cyclability,and excellent safety.Here,CuNb_(2)O_(6),ZnNb_(2)O_(6),and MnNb_(2)O_(6) niobate nanopart...Niobium-based oxides are considered promising anode materials for Li-ion batteries due to their high capacities,good cyclability,and excellent safety.Here,CuNb_(2)O_(6),ZnNb_(2)O_(6),and MnNb_(2)O_(6) niobate nanoparticles were prepared using a solvothermal method followed by heat treatment,and their electrochemical properties as anode materials for Li-ion batteries were explored.These CuNb_(2)O_(6),ZnNb_(2)O_(6),and MnNb_(2)O_(6) nanoparticles have BET surface areas of 3.17-11.53 m^(2) g^(-1).As anode materials,these nanoparticles display high reversible capacities of 256,309,and 352 mA h g^(-1),respectively,at C/10;in particular,the excellent capacity retention rates of the CuNb_(2)O_(6) nanoparticle sample at 5C and 10C are 158 and 131 mA h g-1,respectively.After the first cycle,the Li-ion diffusion coefficients lie between ~1.6×10^(-7) and ~2.1×10^(-10) cm^(2) s^(-1),which effectively promotes Li-ion uptake.Ex situ X-ray diffractometry provides insight into the insertion reaction by monitoring the changes in the crystal structures of the niobate samples during charge-discharge processes.We demonstrate that these niobate nanoparticle samples are possible alternative anode materials for use in rechargeable batteries.展开更多
One-dimensional(1D)nanostructures of perovskite piezoelectrics exhibit unique properties that distinct them from those of their bulk and thin-film counterparts.These 1D nanostructures feature cantilever-like flexibili...One-dimensional(1D)nanostructures of perovskite piezoelectrics exhibit unique properties that distinct them from those of their bulk and thin-film counterparts.These 1D nanostructures feature cantilever-like flexibility and elasticity,a relatively high piezoelectric constant,good stability and easiness of integration,making them highly promising for applications in energy harvesting,pressure sensing,piezo-catalysis,nano-actuators and smart human-machine interfaces.Among them,(K,Na)NbO_(3)(KNN)has been regarded as one of the most promising lead-free perovskite piezoelectrics owing to its excellent biocompatibility,good piezoelectric performance,and high Curie temperature.Recently,significant efforts have been made to develop high-performance 1D KNN nanostructures(1D KNNs).However,the controllable growth and enhancement in piezoelectric performance of 1D KNNs remain challenging.In this work,we systematically re-examine the effective approaches for the growth of 1D KNNs and explore their unique properties.Key strategies for structural designs and performance optimization are proposed based on the recent progress,along with perspectives in developing novel functionalities and micro/nano-devices such as energy harvesters,information storage,electronic skins,biomedical applications.展开更多
Rare-earth tantalates and niobates(REjTaO7 and REjNbO7)have been considered as promising candidate thermal barrier coating(TBC)materials in next generation gas-turbine engines due to their ultra-low thermal conductivi...Rare-earth tantalates and niobates(REjTaO7 and REjNbO7)have been considered as promising candidate thermal barrier coating(TBC)materials in next generation gas-turbine engines due to their ultra-low thermal conductivity and better thermal stability than yttria-stabilized zirconia(YSZ).However,the low Vickers hardness and toughness are the main shortcomings of RE;TaO-and REjNbOr that limit their applications as TBC materials.To increase the hardness,high entropy(Yu3Ybu3Er/3)sTaOr,(Y13YbnErns)NbO,and(Sm1/6Eu1/6Y 1/6Yb1/6Lu1/6Er1/6)3(Nb1/2Ta1/2)O7 are designed and synthesized in this study.These high entropy ceramics exhibit high Vickers hardness(10.912.0 GPa),close thermal expansion coefficients to that of single-principal-component RE3TaO,and RE;NbO,(7.9×10^-6-10.8×10-6 C-1 at room temperature),good phase stability,and good chemical compatibility with thermally grown Al2O3,which make them promising for applications as candidate TBC materials.展开更多
Highly matched and precisely locked to the absorption lines of rubidium(Rb)atoms,780 nm lasers play a crucial role in fields such as quantum computing,precision measurements,and high-sensitivity sensing,with clear req...Highly matched and precisely locked to the absorption lines of rubidium(Rb)atoms,780 nm lasers play a crucial role in fields such as quantum computing,precision measurements,and high-sensitivity sensing,with clear requirements for strong coherence and fast tunability.In this paper,based on the self-injection locking and ultra-high quality factor whispering gallery mode(WGM)cavity,a 780 nm narrow linewidth(23.8 kHz)tunable laser with a single longitudinal mode output is verified.More importantly,benefiting from the optimized combined coupling coefficient K and via the lithium niobate electro-optic effect,the laser frequency detuning is ef⁃fectively improved,with the experimental tuning range reaching 110 pm and the tuning efficiency of 6.4 pm/V.This work provides a high-performance design solution for fast-tunable narrow-linewidth lasers for applications in the near-infrared range,which is expected to play an essential role in the future.展开更多
This paper introduces an innovative Multifunction Integrated Optic Circuit(MIOC)design utilizing thin-film lithium niobate,surpassing traditional bulk waveguide-based MIOCs in terms of size,half-wave voltage requireme...This paper introduces an innovative Multifunction Integrated Optic Circuit(MIOC)design utilizing thin-film lithium niobate,surpassing traditional bulk waveguide-based MIOCs in terms of size,half-wave voltage requirements,and integration capabilities.By implementing a sub-wavelength grating structure,we achieve a Po⁃larization Extinction Ratio(PER)exceeding 29 dB.Furthermore,our electrode design facilitates a voltage-length product(V_(π)L)below 2 V·cm,while a double-tapered coupling structure significantly reduces insertion loss.This advancement provides a pivotal direction for the miniaturization and integration of optical gyroscopes,marking a substantial contribution to the field.展开更多
In the upcoming 6-generation(6G)revolution,the achievement of low power consumption has become a key objective in research concerning terahertz devices.As an important component of passive devices,there are very few l...In the upcoming 6-generation(6G)revolution,the achievement of low power consumption has become a key objective in research concerning terahertz devices.As an important component of passive devices,there are very few low-loss dielectric ceramics in the terahertz range.To elucidate the mechanism of loss and promote the application of microwave dielectric ceramics for future 6G technology(covering microwave and terahertz frequencies),the terahertz responses of ANb_(2)O_(6)(A=Zn,Co,Mn,and Ni)columbite niobates were studied.The influences of magnetic loss on the Qxf values in the microwave range with different transition metal ions in the A-site were reasonably analyzed.Moreover,due to the weakened magnetic relaxation properties in the terahertz range,the samples all exhibited low loss and approximate transparency,especially for MnNb_(2)O_(6) and NiNb_(2)O_(6)(tano<0.01 and absorption coefficient<10 cm^(-1) below 1.2 THz),which subverted the definition of traditional low-loss microwave dielectric ceramics.Ultimately,based on Mie theory,we designed a prototypical broadband metamaterial reflector to validate the applicability of the ANb_(2)O_(6) system in the terahertz band,which is highly important for the development of terahertz ceramic-based passive devices.展开更多
Photonic neural networks(PNNs)of sufficiently large physical dimensions and high operation accuracies are envisaged as ideal candidates for breaking the major bottlenecks in the current artificial intelligence archite...Photonic neural networks(PNNs)of sufficiently large physical dimensions and high operation accuracies are envisaged as ideal candidates for breaking the major bottlenecks in the current artificial intelligence architectures in terms of latency,energy efficiency,and computational power.To achieve this vision,it is of vital importance to scale up the PNNs while simultaneously reducing the high demand on the dimensions required by them.The underlying cause of this strategy is the enormous gap between the scales of photonic and electronic integrated circuits.Here,we demonstrate monolithically integrated optical convolutional processors on thin film lithium niobate(TFLN)that harness inherent parallelism in photonics to enable large-scale programmable convolution kernels and,in turn,greatly reduce the dimensions required by subsequent fully connected layers.Experimental validation achieves high classification accuracies of 96%(86%)on the MNIST(Fashion-MNIST)dataset and 84.6%on the AG News dataset while dramatically reducing the required subsequent fully connected layer dimensions to 196×10(from 784×10)and 175×4(from 800×4),respectively.Furthermore,our devices can be driven by commercial field-programmable gate array systems;a unique advantage in addition to their scalable channel number and kernel size.Our architecture provides a solution to build practical machine learning photonic devices.展开更多
3-dB couplers are key building blocks for on-chip optical switches,optical phased arrays,and photonic computing applications,for the ease of realizing balanced beam splitting and combining.Adiabatic3-dB couplers ensur...3-dB couplers are key building blocks for on-chip optical switches,optical phased arrays,and photonic computing applications,for the ease of realizing balanced beam splitting and combining.Adiabatic3-dB couplers ensure exclusive excitation and propagation of the fundamental eigenmode along the waveguide,characterized by low insertion loss,broad bandwidth,low power imbalance,and resilience to fabrication variations.However,conventional adiabatic designs need to extend the propagation length to achieve broadband performance.In this paper,we overcome such a length-bandwidth trade-off by employing fast quasi-adiabatic(FAQUAD)dynamics in the TFLN 3-dB couplers,thereby accelerating the mode evolution process.Theoretical analysis predicts that the proposed 2×2 FAQUAD 3-dB coupler exhibits an unprecedented operation bandwidth of 350 nm(1285 to 1635 nm)with a FAQUAD taper length of only 88.9μm.Experimental characterization of the fabricated device demonstrates broadband 3-dB power splitting over 165 nm(exceeding the range of the used tunable laser:1470 to 1635 nm),achieving the power imbalance of<0.5 dB and insertion loss of 0.14 dB.Those results establish the foundation for next-generation photonic integrated circuits featuring high efficiency,compact footprint,and ultra-wide bandwidth.展开更多
Lithium niobate(LN)has remained at the forefront of academic research and industrial applications due to its rich material properties,which include second-order nonlinear optic,electro-optic,and piezoelectric properti...Lithium niobate(LN)has remained at the forefront of academic research and industrial applications due to its rich material properties,which include second-order nonlinear optic,electro-optic,and piezoelectric properties.A further aspect of LN’s versatility stems from the ability to engineer ferroelectric domains with micro and even nano-scale precision in LN,which provides an additional degree of freedom to design acoustic and optical devices with improved performance and is only possible in a handful of other materials.In this review paper,we provide an overview of the domain engineering techniques developed for LN,their principles,and the typical domain size and pattern uniformity they provide,which is important for devices that require high-resolution domain patterns with good reproducibility.It also highlights each technique's benefits,limitations,and adaptability for an application,along with possible improvements and future advancement prospects.Further,the review provides a brief overview of domain visualization methods,which is crucial to gain insights into domain quality/shape and explores the adaptability of the proposed domain engineering methodologies for the emerging thin-film lithium niobate on an insulator platform,which creates opportunities for developing the next generation of compact and scalable photonic integrated circuits and high frequency acoustic devices.展开更多
Miniaturized erbium-doped waveguide amplifiers attracted great interests in recent decades due to their high gain-efficiency and function-scalability in the telecom C-band.In this work,an erbium-doped thin film lithiu...Miniaturized erbium-doped waveguide amplifiers attracted great interests in recent decades due to their high gain-efficiency and function-scalability in the telecom C-band.In this work,an erbium-doped thin film lithium niobate waveguide amplifier achieving>10 dB off-chip(fiber-to-fiber)net gain and>20 mW fiber-output amplified power is demonstrated,thanks to the low-propagation-loss waveguides and robust waveguide edge-couplers prepared by the photolithography assisted chemomechanical etching technique.Systematic investigation on the fabricated waveguide amplifiers reveals remarkable optical gain around the peak wavelength of 1532 nm as well as the low fiber-coupling loss of-1.2 dB/facet.A fiber Bragg-grating based waveguide laser is further demonstrated using the fabricated waveguide amplifier as the external gain chip,which generates>2 mW off-chip power continuous-wave lasing around the gain peak at 1532 nm.The unambiguous demonstration of fiber-to-fiber net gain of the erbium-doped thinfilm lithium niobate(TFLN)waveguide amplifier as well as its external gain chip application will benefit diverse fields demanding scalable gain elements with highspeed tunability.展开更多
The structural phase transitions and ferroelectric dynamics of lead-free AgNbO_(3)have attracted consid-erable attention owing to their potential in energy-storage device applications.Here,we examine the impact of Li+...The structural phase transitions and ferroelectric dynamics of lead-free AgNbO_(3)have attracted consid-erable attention owing to their potential in energy-storage device applications.Here,we examine the impact of Li+doping on the phase transitions and polarization behavior of(Ag_(1-x)Li_(x))NbO_(3)(x=0-7%)ceramics through comprehensive dielectric and ferroelectric analyses.Rietveld refinement reveals a Li+-induced phase transition from Pbcm to R3c,with x=5%and x=6%compositions near the morphotropic phase boundary(MPB).Dielectric anomalies identify key characteristic temperatures,supporting the con-struction of a low-field phase diagram.High-field studies uncover a direct relationship between phase structure and polarization behavior,culminating in a high-field phase diagram.Near-MPB compositions exhibit distinct structural states,elucidating the mechanisms of reversible and irreversible phase transi-tions.This work provides a comprehensive explanation of the evolution of hysteresis loop profiles,capturing their progression from double hysteresis loops to square loops and their subsequent reversion to double loops under varying electric field and temperature conditions.These temperature-composition(T-x)and temperature-electric field(T-E)phase diagrams provide a robust framework for understanding phase evolution,offering critical insights into optimizing AgNbO_(3)-based ceramics for advanced functional applications.展开更多
Thin-film lithium niobate(TFLN)has emerged as a powerful platform for integrated photonics,offering outstanding electro-optic,nonlinear optical,and ferroelectric properties.These unique material characteristics have o...Thin-film lithium niobate(TFLN)has emerged as a powerful platform for integrated photonics,offering outstanding electro-optic,nonlinear optical,and ferroelectric properties.These unique material characteristics have opened new opportunities for developing high-performance photodetectors with broad spectral response,high sensitivity,and compact integration.This review provides a comprehensive overview of recent progress in TFLN-based detectors,focusing on the underlying physical mechanisms and diverse device architectures.We first discuss the spontaneous polarization,bulk photovoltaic effect,and pyroelectric effect and frequency up-conversion in lithium niobate,which enable unconventional lightto-electricity conversion without external bias.Then,we introduce heterogeneously integrated photodetectors that combine TFLN with III-V semiconductors,silicon,and two-dimensional materials,under both free-space illumination and waveguide coupling configurations.We further highlight advances in integrating single-photon detectors on TFLN platforms,a key step toward scalable quantum photonic systems.In addition,we discuss the direct modification strategies such as ferroelectric domain engineering,doping,and ion implantation modification to enhance the photodetection performance of TFLN devices.Finally,we summarize the existing challenges and present perspectives on the future development of multifunctional,low-power,and quantum-compatible photodetectors based on the TFLN platform.展开更多
Thin-film lithium niobate(TFLN)possesses great potential because it enables high-speed modulation by voltage,which allows higher resolution and lower power consumption for laser beam scanning than direct laser modulat...Thin-film lithium niobate(TFLN)possesses great potential because it enables high-speed modulation by voltage,which allows higher resolution and lower power consumption for laser beam scanning than direct laser modulation.To achieve these functions,a red,green,and blue(RGB)multiplexer using TFLN is required as an important building block for photonic integrated circuits.We fabricated an RGB multiplexer using TFLN and experimentally confirmed its operation.Three different laser lights of red(λ=638 nm),green(λ=520 nm),and blue(λ=473 nm)were successfully coupled as a single laser beam by an RGB multiplexer composed of multimode interferometers.Furthermore,the TFLN was fabricated by sputter deposition,whereas conventionally,it is fabricated via bulk-lithium niobate adhesion to the substrate.The sputterdeposited TFLN is advantageous for large-volume mass production.展开更多
We report the fabrication of an 8-meter-long thin-flm lithium niobate optical true delay line using the photolithography-assisted chemomechanical etching technique,showing a low transmission loss of 0.036 dB/cm in the...We report the fabrication of an 8-meter-long thin-flm lithium niobate optical true delay line using the photolithography-assisted chemomechanical etching technique,showing a low transmission loss of 0.036 dB/cm in the conventional telecom band.展开更多
Due to its broken out-of-plane symmetry,z-cut periodically poled lithium niobate(PPLN)has exhibited ultrahigh second-order optical nonlinearity.Precise quantification of the domain structure of z-cut PPLN plays a crit...Due to its broken out-of-plane symmetry,z-cut periodically poled lithium niobate(PPLN)has exhibited ultrahigh second-order optical nonlinearity.Precise quantification of the domain structure of z-cut PPLN plays a critical role during poling fabrication.To enhance the imaging detection efficiency of the domain structure in z-cut PPLN,we have developed a second-harmonic generation microscope system specifically designed to produce a longitudinal electric field in foci for the imaging domain inversion.We demonstrated that imaging using a longitudinal electric field can achieve a contrast ratio enhancement by a factor of 1.77,showing high imaging efficiency and making the proposed method suitable for in situ monitoring of the z-cut PPLN poling process.展开更多
Novel thin films consisting of optical materials such as lithium niobate and barium titanate enable various high-performance integrated photonic devices.However,the nanofabrication of these devices requires high-quali...Novel thin films consisting of optical materials such as lithium niobate and barium titanate enable various high-performance integrated photonic devices.However,the nanofabrication of these devices requires high-quality etching of these thin films,necessitating the long-term development of the fabrication recipe and specialized equipment.Here we present a strong-confinement low-index-rib-loaded waveguide structure as the building block of various passive and active integrated photonic devices based on novel thin films.By optimizing this low-index-rib-loaded waveguide structure without etching the novel thin film,we can simultaneously realize strong optical power confinement in the thin film,low optical propagation loss,and strong electro-optic coupling for the fundamental transverse electric mode.Based on our low-index-rib-loaded waveguide structure,we designed and fabricated a thin film lithium niobate(TFLN)modulator,featuring a 3-dB modulation bandwidth over 110 GHz and a voltage-length product as low as 2.26 V·cm,which is comparable to those of the state-of-the-art etched TFLN modulators.By alleviating the etching of novel thin films,the proposed structure opens up new ways of fast proof-of-concept demonstration and even mass production of high-performance integrated electro-optic and nonlinear devices based on novel thin films.展开更多
Controlling the construction of physical colors on the surfaces of transparent dielectric crystals is crucial for surface coloration and anti-counterfeiting applications.In this study,we present a novel approach to cr...Controlling the construction of physical colors on the surfaces of transparent dielectric crystals is crucial for surface coloration and anti-counterfeiting applications.In this study,we present a novel approach to creating stable physical colors on the surface of lithium niobate crystals by combining gold ion implantation with laser direct writing technologies.The interaction between the laser,the implanted gold nanoparticles,and the crystal lattice induces permanent,localized modifications on the crystal surface.By fine-tuning the laser direct writing parameters,we reshaped the gold nanoparticles into spheres of varying sizes on the crystal surface,resulting in the display of red,green,blue,and pale-yellow colors.We investigated the influence of the implanted Au nanoparticles-particularly their localized surface plasmon resonances-on the modifications of the lithium niobate crystal lattice during the laser writing process using confocal Raman spectroscopy and high-resolution transmission electron microscopy.Our findings reveal that the embedded Au nanoparticles play a pivotal role in altering the conventional light-matter interaction between the crystal lattice and the laser,thereby facilitating the generation of surface colors.This work opens new avenues for the development of vibrant surface colors on transparent dielectric crystals.展开更多
Conventional approaches for obtaining the second and third harmonics typically employ several nonlinear crystals to generate them,which is restricted in application due to the complexity of the optical path and the bu...Conventional approaches for obtaining the second and third harmonics typically employ several nonlinear crystals to generate them,which is restricted in application due to the complexity of the optical path and the bulkiness of the device.In this work,we present a comprehensive theoretical and numerical investigation of the simultaneous generation and competition between the second harmonic waves(SHW)and the third harmonic waves(THW)in a single nonlinear crystal.Through analyzing both small-signal and large-signal regimes,we reveal the complex coupling mechanisms between SHW and THW generation processes.Using periodically poled lithium niobate as an example,we demonstrate that the relative conversion efficiencies between SHW and THW can be freely adjusted by controlling the input fundamental wave power.This work provides new insights for designing efficient frequency converters capable of generating both SHW and THW outputs with controllable intensity ratios.展开更多
Optical isolators,the photonic analogs of electronic diodes,are essential for ensuring the unidirectional flow of light in optical systems,thereby mitigating the destabilizing effects of back reflections.Thin-film lit...Optical isolators,the photonic analogs of electronic diodes,are essential for ensuring the unidirectional flow of light in optical systems,thereby mitigating the destabilizing effects of back reflections.Thin-film lithium niobate(TFLN),hailed as“the silicon of photonics,”has emerged as a pivotal material in the realm of chip-scale nonlinear optics,propelling the demand for compact optical isolators.We report a breakthrough in the development of a fully passive,integrated optical isolator on the TFLN platform,leveraging the Kerr effect to achieve an impressive 10.3 dB of isolation with a minimal insertion loss of 1.87 dB.Further theoretical simulations have demonstrated that our design,when applied to a microring resonator with a Q factor of 5×10^(6),can achieve 20 dB of isolation with an input power of merely 8 mW.This advancement underscores the immense potential of lithium niobate-based Kerr-effect isolators in propelling the integration and application of high-performance on-chip lasers,heralding a new era in integrated photonics.展开更多
基金support of Project Supported by the Natural Science Foundation of China(Nos.51502163 and 51502165)Keypoint Research and Invention in Shaanxi Province of China(No.2017GY-186)the Scientific Research Foundation for the Returned Overseas Chinese Scholars,State Education Ministry
文摘In this study, SnNb_2O_6 and Sn_2Nb_2O_7 nanosheets are synthetized via microwave assisted hydrothermal method, and innovatively employed as anode materials for lithium-ion battery. The SnNb_2O_6 electrode exhibits high reversible capacity and excellent cycling stability(498 mAh/g at 0.1 A/g after 100 cycles),which is superior to that of Sn_2Nb_2O_7 electrode(173 mAh/g at 0.1 A/g after 100 cycles). Even increasing the current density to 2.0 A/g, the SnNb_2O_6 electrode still delivers a reversible capacity up to 306 mAh/g.The rate performance of the SnNb_2O_6 electrode is also better than that of Sn_2 Nb_2O_7 electrode at different current densities from 0.1 A/g to 2.0 A/g. The enhanced electrochemical performance of SnNb_2O_6 nanosheets can be attributed to the unique layered structure, which is conducive to the diffusion of the lithium ions and the migration of electrons during discharge/charge.
基金supported by National Research Foundation of Korea(NRF)grant funded by the Korea government(MSIP)(No.2018R1C1B6004689)Basic Science Research Program through the National Research Foundation of Korea(NRF)funded by the Ministry of Education(No.2020R1I1A306182111).
文摘Niobium-based oxides are considered promising anode materials for Li-ion batteries due to their high capacities,good cyclability,and excellent safety.Here,CuNb_(2)O_(6),ZnNb_(2)O_(6),and MnNb_(2)O_(6) niobate nanoparticles were prepared using a solvothermal method followed by heat treatment,and their electrochemical properties as anode materials for Li-ion batteries were explored.These CuNb_(2)O_(6),ZnNb_(2)O_(6),and MnNb_(2)O_(6) nanoparticles have BET surface areas of 3.17-11.53 m^(2) g^(-1).As anode materials,these nanoparticles display high reversible capacities of 256,309,and 352 mA h g^(-1),respectively,at C/10;in particular,the excellent capacity retention rates of the CuNb_(2)O_(6) nanoparticle sample at 5C and 10C are 158 and 131 mA h g-1,respectively.After the first cycle,the Li-ion diffusion coefficients lie between ~1.6×10^(-7) and ~2.1×10^(-10) cm^(2) s^(-1),which effectively promotes Li-ion uptake.Ex situ X-ray diffractometry provides insight into the insertion reaction by monitoring the changes in the crystal structures of the niobate samples during charge-discharge processes.We demonstrate that these niobate nanoparticle samples are possible alternative anode materials for use in rechargeable batteries.
基金support by the Advanced Research and Technology Innovation Centre(ARTIC),through research project(ADT-RP2)supported by the National Natural Science Foundation of China(NSFC,Grant Nos.:U21A20500 and 52072115)+2 种基金the Natural Science Foundation of Hubei Province(Outstanding Youth Project,Grant No.2023AFA074)the Postdoctoral Fellowship Program of CPSF(Grant No.GZC20230744)the Postdoctoral Innovation Research Program in Hubei Provence(Grant No.352899).
文摘One-dimensional(1D)nanostructures of perovskite piezoelectrics exhibit unique properties that distinct them from those of their bulk and thin-film counterparts.These 1D nanostructures feature cantilever-like flexibility and elasticity,a relatively high piezoelectric constant,good stability and easiness of integration,making them highly promising for applications in energy harvesting,pressure sensing,piezo-catalysis,nano-actuators and smart human-machine interfaces.Among them,(K,Na)NbO_(3)(KNN)has been regarded as one of the most promising lead-free perovskite piezoelectrics owing to its excellent biocompatibility,good piezoelectric performance,and high Curie temperature.Recently,significant efforts have been made to develop high-performance 1D KNN nanostructures(1D KNNs).However,the controllable growth and enhancement in piezoelectric performance of 1D KNNs remain challenging.In this work,we systematically re-examine the effective approaches for the growth of 1D KNNs and explore their unique properties.Key strategies for structural designs and performance optimization are proposed based on the recent progress,along with perspectives in developing novel functionalities and micro/nano-devices such as energy harvesters,information storage,electronic skins,biomedical applications.
基金This study was financially supported by the National Natural Science Foundation of China(Nos.51672064 and 51972089).
文摘Rare-earth tantalates and niobates(REjTaO7 and REjNbO7)have been considered as promising candidate thermal barrier coating(TBC)materials in next generation gas-turbine engines due to their ultra-low thermal conductivity and better thermal stability than yttria-stabilized zirconia(YSZ).However,the low Vickers hardness and toughness are the main shortcomings of RE;TaO-and REjNbOr that limit their applications as TBC materials.To increase the hardness,high entropy(Yu3Ybu3Er/3)sTaOr,(Y13YbnErns)NbO,and(Sm1/6Eu1/6Y 1/6Yb1/6Lu1/6Er1/6)3(Nb1/2Ta1/2)O7 are designed and synthesized in this study.These high entropy ceramics exhibit high Vickers hardness(10.912.0 GPa),close thermal expansion coefficients to that of single-principal-component RE3TaO,and RE;NbO,(7.9×10^-6-10.8×10-6 C-1 at room temperature),good phase stability,and good chemical compatibility with thermally grown Al2O3,which make them promising for applications as candidate TBC materials.
基金Supported by the General Program of National Natural Science Foundation of China(62373331)the Joint Funds of the National Natural Science Foundation of China(U21A20141)+1 种基金the Innovative Research Group Project of the National Natural Science Foundation of China(51821003)the Natural Science Foundation of Shanxi Province(202403021211095).
文摘Highly matched and precisely locked to the absorption lines of rubidium(Rb)atoms,780 nm lasers play a crucial role in fields such as quantum computing,precision measurements,and high-sensitivity sensing,with clear requirements for strong coherence and fast tunability.In this paper,based on the self-injection locking and ultra-high quality factor whispering gallery mode(WGM)cavity,a 780 nm narrow linewidth(23.8 kHz)tunable laser with a single longitudinal mode output is verified.More importantly,benefiting from the optimized combined coupling coefficient K and via the lithium niobate electro-optic effect,the laser frequency detuning is ef⁃fectively improved,with the experimental tuning range reaching 110 pm and the tuning efficiency of 6.4 pm/V.This work provides a high-performance design solution for fast-tunable narrow-linewidth lasers for applications in the near-infrared range,which is expected to play an essential role in the future.
基金Supported by the Beijing Municipal Natural Science Foundation(424206)the Youth Innovation Promotion Association,CAS(2021108).
文摘This paper introduces an innovative Multifunction Integrated Optic Circuit(MIOC)design utilizing thin-film lithium niobate,surpassing traditional bulk waveguide-based MIOCs in terms of size,half-wave voltage requirements,and integration capabilities.By implementing a sub-wavelength grating structure,we achieve a Po⁃larization Extinction Ratio(PER)exceeding 29 dB.Furthermore,our electrode design facilitates a voltage-length product(V_(π)L)below 2 V·cm,while a double-tapered coupling structure significantly reduces insertion loss.This advancement provides a pivotal direction for the miniaturization and integration of optical gyroscopes,marking a substantial contribution to the field.
基金This work was supported by the National Key R&D Program of China(No.2022YFB3806000)the Basic Science Center Project of National Natural Science Foundation of China(No.52388201)+2 种基金the National Natural ScienceFoundationof China(Nos.52202370 and 52172122)the China Postdoctoral Science Foundation(No.2023T160359)the Natural Science Foundation of Shandong Province(No.ZR2023QF040)。
文摘In the upcoming 6-generation(6G)revolution,the achievement of low power consumption has become a key objective in research concerning terahertz devices.As an important component of passive devices,there are very few low-loss dielectric ceramics in the terahertz range.To elucidate the mechanism of loss and promote the application of microwave dielectric ceramics for future 6G technology(covering microwave and terahertz frequencies),the terahertz responses of ANb_(2)O_(6)(A=Zn,Co,Mn,and Ni)columbite niobates were studied.The influences of magnetic loss on the Qxf values in the microwave range with different transition metal ions in the A-site were reasonably analyzed.Moreover,due to the weakened magnetic relaxation properties in the terahertz range,the samples all exhibited low loss and approximate transparency,especially for MnNb_(2)O_(6) and NiNb_(2)O_(6)(tano<0.01 and absorption coefficient<10 cm^(-1) below 1.2 THz),which subverted the definition of traditional low-loss microwave dielectric ceramics.Ultimately,based on Mie theory,we designed a prototypical broadband metamaterial reflector to validate the applicability of the ANb_(2)O_(6) system in the terahertz band,which is highly important for the development of terahertz ceramic-based passive devices.
基金supported by the National Natural Science Foundation of China (Grant Nos.12192251,12334014,62335019,12134001,1230441812474378)+1 种基金the Quantum Science and Technology National Science and Technology Major Project(Grant No.2021ZD0301403)the Shanghai Municipal Science and Technology Major Project (Grant No.2019SHZDZX01)。
文摘Photonic neural networks(PNNs)of sufficiently large physical dimensions and high operation accuracies are envisaged as ideal candidates for breaking the major bottlenecks in the current artificial intelligence architectures in terms of latency,energy efficiency,and computational power.To achieve this vision,it is of vital importance to scale up the PNNs while simultaneously reducing the high demand on the dimensions required by them.The underlying cause of this strategy is the enormous gap between the scales of photonic and electronic integrated circuits.Here,we demonstrate monolithically integrated optical convolutional processors on thin film lithium niobate(TFLN)that harness inherent parallelism in photonics to enable large-scale programmable convolution kernels and,in turn,greatly reduce the dimensions required by subsequent fully connected layers.Experimental validation achieves high classification accuracies of 96%(86%)on the MNIST(Fashion-MNIST)dataset and 84.6%on the AG News dataset while dramatically reducing the required subsequent fully connected layer dimensions to 196×10(from 784×10)and 175×4(from 800×4),respectively.Furthermore,our devices can be driven by commercial field-programmable gate array systems;a unique advantage in addition to their scalable channel number and kernel size.Our architecture provides a solution to build practical machine learning photonic devices.
基金supported by the National Key Research and Development Program of China(Grant No.2024YFB2807903)the National Natural Science Foundation of China(Grant Nos.62025502 and 62475050)the Guangdong Introducing Innovative and Entrepreneurial Teams of“The Pearl River Talent Recruitment Program”(Grant No.2021ZT09X044)。
文摘3-dB couplers are key building blocks for on-chip optical switches,optical phased arrays,and photonic computing applications,for the ease of realizing balanced beam splitting and combining.Adiabatic3-dB couplers ensure exclusive excitation and propagation of the fundamental eigenmode along the waveguide,characterized by low insertion loss,broad bandwidth,low power imbalance,and resilience to fabrication variations.However,conventional adiabatic designs need to extend the propagation length to achieve broadband performance.In this paper,we overcome such a length-bandwidth trade-off by employing fast quasi-adiabatic(FAQUAD)dynamics in the TFLN 3-dB couplers,thereby accelerating the mode evolution process.Theoretical analysis predicts that the proposed 2×2 FAQUAD 3-dB coupler exhibits an unprecedented operation bandwidth of 350 nm(1285 to 1635 nm)with a FAQUAD taper length of only 88.9μm.Experimental characterization of the fabricated device demonstrates broadband 3-dB power splitting over 165 nm(exceeding the range of the used tunable laser:1470 to 1635 nm),achieving the power imbalance of<0.5 dB and insertion loss of 0.14 dB.Those results establish the foundation for next-generation photonic integrated circuits featuring high efficiency,compact footprint,and ultra-wide bandwidth.
基金supported by the Australian Research Council Centre of Excellence in Optical Microcombs for Breakthrough Science COMBS(CE230100006)the Australian Research Council grants DP220100488 and DE230100964funded by the Australian Government.
文摘Lithium niobate(LN)has remained at the forefront of academic research and industrial applications due to its rich material properties,which include second-order nonlinear optic,electro-optic,and piezoelectric properties.A further aspect of LN’s versatility stems from the ability to engineer ferroelectric domains with micro and even nano-scale precision in LN,which provides an additional degree of freedom to design acoustic and optical devices with improved performance and is only possible in a handful of other materials.In this review paper,we provide an overview of the domain engineering techniques developed for LN,their principles,and the typical domain size and pattern uniformity they provide,which is important for devices that require high-resolution domain patterns with good reproducibility.It also highlights each technique's benefits,limitations,and adaptability for an application,along with possible improvements and future advancement prospects.Further,the review provides a brief overview of domain visualization methods,which is crucial to gain insights into domain quality/shape and explores the adaptability of the proposed domain engineering methodologies for the emerging thin-film lithium niobate on an insulator platform,which creates opportunities for developing the next generation of compact and scalable photonic integrated circuits and high frequency acoustic devices.
基金financial supports from National Key R&D Program of China(Grant No.2022YFA1205100,2022YFA1404600)National Natural Science Foundation of China(Grant Nos.12192251,12334014,12474325,12134001,12304418,12474378,12274133,12174107,12174113,12274130)+2 种基金the Innovation Program for Quantum Science and Technology(Grant No.2021ZD0301403)Shanghai Municipal Science and Technology Major Project(Grant No.2019SHZDZX01)Fundamental Research Funds for the Central Universities,the Engineering Research Center for Nanophotonics&Advanced Instrument,Ministry of Education,East China Normal University(No.2023nmc005).
文摘Miniaturized erbium-doped waveguide amplifiers attracted great interests in recent decades due to their high gain-efficiency and function-scalability in the telecom C-band.In this work,an erbium-doped thin film lithium niobate waveguide amplifier achieving>10 dB off-chip(fiber-to-fiber)net gain and>20 mW fiber-output amplified power is demonstrated,thanks to the low-propagation-loss waveguides and robust waveguide edge-couplers prepared by the photolithography assisted chemomechanical etching technique.Systematic investigation on the fabricated waveguide amplifiers reveals remarkable optical gain around the peak wavelength of 1532 nm as well as the low fiber-coupling loss of-1.2 dB/facet.A fiber Bragg-grating based waveguide laser is further demonstrated using the fabricated waveguide amplifier as the external gain chip,which generates>2 mW off-chip power continuous-wave lasing around the gain peak at 1532 nm.The unambiguous demonstration of fiber-to-fiber net gain of the erbium-doped thinfilm lithium niobate(TFLN)waveguide amplifier as well as its external gain chip application will benefit diverse fields demanding scalable gain elements with highspeed tunability.
基金finically supported by the National Natural Science Foundation of China(Nos.52261135548,52302153,and 52402155)the China Postdoctoral Science Foundation(Nos.GZC20232075 and 2023M742767)+2 种基金The research was made possible by Russian Science Foundation(Project No 23-42-00116)The equipment of the Ural Center for Shared Use“Modern nanotech-nology”Ural Federal University(Reg.No2968)whichis supported by the Ministry of Science and Higher Education RF(Project No 075-15-2021-677)was usedThe SEM work was done at International Center for Dielectric Research(ICDR),Xi’an Jiaotong University,Xi’an,China.
文摘The structural phase transitions and ferroelectric dynamics of lead-free AgNbO_(3)have attracted consid-erable attention owing to their potential in energy-storage device applications.Here,we examine the impact of Li+doping on the phase transitions and polarization behavior of(Ag_(1-x)Li_(x))NbO_(3)(x=0-7%)ceramics through comprehensive dielectric and ferroelectric analyses.Rietveld refinement reveals a Li+-induced phase transition from Pbcm to R3c,with x=5%and x=6%compositions near the morphotropic phase boundary(MPB).Dielectric anomalies identify key characteristic temperatures,supporting the con-struction of a low-field phase diagram.High-field studies uncover a direct relationship between phase structure and polarization behavior,culminating in a high-field phase diagram.Near-MPB compositions exhibit distinct structural states,elucidating the mechanisms of reversible and irreversible phase transi-tions.This work provides a comprehensive explanation of the evolution of hysteresis loop profiles,capturing their progression from double hysteresis loops to square loops and their subsequent reversion to double loops under varying electric field and temperature conditions.These temperature-composition(T-x)and temperature-electric field(T-E)phase diagrams provide a robust framework for understanding phase evolution,offering critical insights into optimizing AgNbO_(3)-based ceramics for advanced functional applications.
基金supported by the National Natural Science Foundation of China(No.12235009,12134009)Open fund(SKLMRD-K202522)of the State Key Laboratory of Chemical Reaction Dynamics in DICP,CAS+1 种基金support from Taishan Scholars Program of Shandong Provincesupport from"Qilu Young Scholar Program"of Shandong University,China.
文摘Thin-film lithium niobate(TFLN)has emerged as a powerful platform for integrated photonics,offering outstanding electro-optic,nonlinear optical,and ferroelectric properties.These unique material characteristics have opened new opportunities for developing high-performance photodetectors with broad spectral response,high sensitivity,and compact integration.This review provides a comprehensive overview of recent progress in TFLN-based detectors,focusing on the underlying physical mechanisms and diverse device architectures.We first discuss the spontaneous polarization,bulk photovoltaic effect,and pyroelectric effect and frequency up-conversion in lithium niobate,which enable unconventional lightto-electricity conversion without external bias.Then,we introduce heterogeneously integrated photodetectors that combine TFLN with III-V semiconductors,silicon,and two-dimensional materials,under both free-space illumination and waveguide coupling configurations.We further highlight advances in integrating single-photon detectors on TFLN platforms,a key step toward scalable quantum photonic systems.In addition,we discuss the direct modification strategies such as ferroelectric domain engineering,doping,and ion implantation modification to enhance the photodetection performance of TFLN devices.Finally,we summarize the existing challenges and present perspectives on the future development of multifunctional,low-power,and quantum-compatible photodetectors based on the TFLN platform.
文摘Thin-film lithium niobate(TFLN)possesses great potential because it enables high-speed modulation by voltage,which allows higher resolution and lower power consumption for laser beam scanning than direct laser modulation.To achieve these functions,a red,green,and blue(RGB)multiplexer using TFLN is required as an important building block for photonic integrated circuits.We fabricated an RGB multiplexer using TFLN and experimentally confirmed its operation.Three different laser lights of red(λ=638 nm),green(λ=520 nm),and blue(λ=473 nm)were successfully coupled as a single laser beam by an RGB multiplexer composed of multimode interferometers.Furthermore,the TFLN was fabricated by sputter deposition,whereas conventionally,it is fabricated via bulk-lithium niobate adhesion to the substrate.The sputterdeposited TFLN is advantageous for large-volume mass production.
基金supported by the National Natural Science Foundation of China(Grant Nos.12192251,12334014,92480001,12134001,12304418,12274130,12274133,12474378,and 12404378)the National Key R&D Program of China(Grant Nos.2022YFA1404600 and 2022YFA1205100)+2 种基金Shanghai Municipal Science and Technology Major Project(Grant No.2019SHZDZX01)the Innovation Program for Quantum Science and Technology(Grant No.2021ZD0301403)the Engineering Research Center for Nanophotonics&Advanced Instrument,Ministry of Education,East China Normal University(Grant No.2023nmc005)。
文摘We report the fabrication of an 8-meter-long thin-flm lithium niobate optical true delay line using the photolithography-assisted chemomechanical etching technique,showing a low transmission loss of 0.036 dB/cm in the conventional telecom band.
基金supported by the National Key Research and Development Program of China(Grant Nos.2022YFC3401100 and 2022YFF0712500)the Guangdong Major Project of Basic and Applied Basic Research(Grant No.2020B0301030009)+2 种基金the National Natural Science Foundation of China(Grant Nos.12204017,12004012,12004013,12041602,91750203,91850111,and 92150301)the China Postdoctoral Science Foundation(Grant No.2020M680220 and 2020M680230)the Clinical Medicine Plus X-Young Scholars Project,Peking University,Fundamental Research Funds for the Central Universities.
文摘Due to its broken out-of-plane symmetry,z-cut periodically poled lithium niobate(PPLN)has exhibited ultrahigh second-order optical nonlinearity.Precise quantification of the domain structure of z-cut PPLN plays a critical role during poling fabrication.To enhance the imaging detection efficiency of the domain structure in z-cut PPLN,we have developed a second-harmonic generation microscope system specifically designed to produce a longitudinal electric field in foci for the imaging domain inversion.We demonstrated that imaging using a longitudinal electric field can achieve a contrast ratio enhancement by a factor of 1.77,showing high imaging efficiency and making the proposed method suitable for in situ monitoring of the z-cut PPLN poling process.
基金financial supports from National Key Research and Development Program of China (2021YFA1401000)National Natural Science Foundation of China (62435009)+2 种基金Beijing Municipal Natural Science Foundation (Z220008)Zhuhai Industry University Research Collaboration Project (ZH-2201700121010)supported by the Center of High Performance Computing,Tsinghua University
文摘Novel thin films consisting of optical materials such as lithium niobate and barium titanate enable various high-performance integrated photonic devices.However,the nanofabrication of these devices requires high-quality etching of these thin films,necessitating the long-term development of the fabrication recipe and specialized equipment.Here we present a strong-confinement low-index-rib-loaded waveguide structure as the building block of various passive and active integrated photonic devices based on novel thin films.By optimizing this low-index-rib-loaded waveguide structure without etching the novel thin film,we can simultaneously realize strong optical power confinement in the thin film,low optical propagation loss,and strong electro-optic coupling for the fundamental transverse electric mode.Based on our low-index-rib-loaded waveguide structure,we designed and fabricated a thin film lithium niobate(TFLN)modulator,featuring a 3-dB modulation bandwidth over 110 GHz and a voltage-length product as low as 2.26 V·cm,which is comparable to those of the state-of-the-art etched TFLN modulators.By alleviating the etching of novel thin films,the proposed structure opens up new ways of fast proof-of-concept demonstration and even mass production of high-performance integrated electro-optic and nonlinear devices based on novel thin films.
基金supported by the National Natural Science Foundation of China (NSFC) (Grants No. 12274236, 12134009, 12074223)Shandong Provincial Natural Science Foundation (Grants No. 2022HWYQ-047, ZR2024MA041)+3 种基金Taishan Scholars Program of Shandong Province (Grants No. tsqn201909041)“Qilu Young Scholar Program” of Shandong UniversityCore Facility Sharing Platform of Shandong UniversityOpen Foundation of the State Key Laboratory of Fluid Power and Mechatronic Systems
文摘Controlling the construction of physical colors on the surfaces of transparent dielectric crystals is crucial for surface coloration and anti-counterfeiting applications.In this study,we present a novel approach to creating stable physical colors on the surface of lithium niobate crystals by combining gold ion implantation with laser direct writing technologies.The interaction between the laser,the implanted gold nanoparticles,and the crystal lattice induces permanent,localized modifications on the crystal surface.By fine-tuning the laser direct writing parameters,we reshaped the gold nanoparticles into spheres of varying sizes on the crystal surface,resulting in the display of red,green,blue,and pale-yellow colors.We investigated the influence of the implanted Au nanoparticles-particularly their localized surface plasmon resonances-on the modifications of the lithium niobate crystal lattice during the laser writing process using confocal Raman spectroscopy and high-resolution transmission electron microscopy.Our findings reveal that the embedded Au nanoparticles play a pivotal role in altering the conventional light-matter interaction between the crystal lattice and the laser,thereby facilitating the generation of surface colors.This work opens new avenues for the development of vibrant surface colors on transparent dielectric crystals.
基金supported by the Science and Technology Project of Guangdong Province,China(Grant No.2020B010190001)the National Natural Science Foundation of China(Grant No.12434016)+1 种基金the National Key Research and Development Program of China(Grant No.2023YFA1406900)the Fund of the National Postdoctoral Researcher Program(Grant No.GZB20240785).
文摘Conventional approaches for obtaining the second and third harmonics typically employ several nonlinear crystals to generate them,which is restricted in application due to the complexity of the optical path and the bulkiness of the device.In this work,we present a comprehensive theoretical and numerical investigation of the simultaneous generation and competition between the second harmonic waves(SHW)and the third harmonic waves(THW)in a single nonlinear crystal.Through analyzing both small-signal and large-signal regimes,we reveal the complex coupling mechanisms between SHW and THW generation processes.Using periodically poled lithium niobate as an example,we demonstrate that the relative conversion efficiencies between SHW and THW can be freely adjusted by controlling the input fundamental wave power.This work provides new insights for designing efficient frequency converters capable of generating both SHW and THW outputs with controllable intensity ratios.
基金Project supported by the National Key Research and Development Program of China(Grant Nos.2022YFF0712800 and 2019YFA0308700)。
文摘Optical isolators,the photonic analogs of electronic diodes,are essential for ensuring the unidirectional flow of light in optical systems,thereby mitigating the destabilizing effects of back reflections.Thin-film lithium niobate(TFLN),hailed as“the silicon of photonics,”has emerged as a pivotal material in the realm of chip-scale nonlinear optics,propelling the demand for compact optical isolators.We report a breakthrough in the development of a fully passive,integrated optical isolator on the TFLN platform,leveraging the Kerr effect to achieve an impressive 10.3 dB of isolation with a minimal insertion loss of 1.87 dB.Further theoretical simulations have demonstrated that our design,when applied to a microring resonator with a Q factor of 5×10^(6),can achieve 20 dB of isolation with an input power of merely 8 mW.This advancement underscores the immense potential of lithium niobate-based Kerr-effect isolators in propelling the integration and application of high-performance on-chip lasers,heralding a new era in integrated photonics.
