Actin cytoskeleton plays crucial roles in various cellular functions.Extracellular matrix(ECM)can modulate cell morphology by remodeling the internal cytoskeleton.To define how geometry of ECM regulates the organizati...Actin cytoskeleton plays crucial roles in various cellular functions.Extracellular matrix(ECM)can modulate cell morphology by remodeling the internal cytoskeleton.To define how geometry of ECM regulates the organization of actin cytoskeleton,we plated individual NIH 3T3 cells on micropatterned substrates with distinct shapes and sizes.It was found that the stress fibers could form along the nonadhesive edges of T-shaped pattern,but were absent from the opening edge of V-shaped pattern,indicating that the organization of actin cytoskeleton was dependent on the mechanical environment.Furthermore,a secondary actin ring was observed on 50μm circular pattern while did not appear on 30μm and 40μm pattern,showing a size-dependent organization of actin cytoskeleton.Finally,osteoblasts,MDCK and A549 cells exhibited distinct organization of actin cytoskeleton on T-shaped pattern,suggesting a cell-type specificity in arrangement of actin cytoskeleton.Together,our findings brought novel insight into the organization of actin cytoskeleton on micropatterned environments.展开更多
Holographic display has attracted widespread interest because of its ability to show the complete information of the object and bring people an unprecedented sense of presence. The absence of ideal recording materials...Holographic display has attracted widespread interest because of its ability to show the complete information of the object and bring people an unprecedented sense of presence. The absence of ideal recording materials has hampered the realization of their commercial applications. Here we report that the response time of a bismuth and magnesium codoped lithium niobate(LN:Bi,Mg) crystal is shortened to 7.2 ms and a sensitivity as high as 646 cm/J. The crystal was used to demonstrate a real-time holographic display with a refresh rate of 60 Hz, as that of the popular high-definition television. Moreover, the first-principles calculations indicate that the electron mobility while Bi occupying Nb-site is significantly greater than that in Li-site, which directly induces the fast response of LN:Bi,Mg crystals when the concentration of Mg is above its doping threshold.展开更多
As the indispensable oxygen-transporting cells,erythrocytes exhibit extreme deformability and amazing stability as they are subject to huge reversible shear stress and extrusion force during massive circulation in the...As the indispensable oxygen-transporting cells,erythrocytes exhibit extreme deformability and amazing stability as they are subject to huge reversible shear stress and extrusion force during massive circulation in the body.The unique architecture of spectrin-actin-based membraneskeleton is considered to be responsible for such excellent mechanical properties of erythrocytes.Although erythrocytes have been recognized for more than 300 years,myriad questions about membrane-skeleton constantly attract people's attention.Here,we summarize the kinds of distinctive single-cell and single-molecule techniques that were used to investigate the structure and function of erythrocyte membrane-skeleton at macro and micro levels.展开更多
The oxidation behavior and kinetics of Ti_(2)AlC-20vol.%TiB_(2) composite at 600-900℃ in air were investigated.The results showed that the oxidation kinetics of the composite followed a logarithmic law within the giv...The oxidation behavior and kinetics of Ti_(2)AlC-20vol.%TiB_(2) composite at 600-900℃ in air were investigated.The results showed that the oxidation kinetics of the composite followed a logarithmic law within the given temperature range,which indicated that the composites had excellent oxidation resistance.The selective oxidation of Al in Ti_(2)AlC was greatly enhanced,which facilitated the formation of a continuous and dense protective layer of Al_(2)O_(3).Meanwhile,the existence of molten B_(2)O_(3) inhibited the outward diffusion of Ti and inward diffusion of oxygen,which prevented the growth of anatase TiO_(2) at 600℃ and rutile TiO_(2) at 700-900℃.Therefore,the incorporation of TiB_(2) completely inhibited the abnormally rapid oxidation of bulk Ti_(2)AlC at 600℃ and improved its oxidation resistance at 700-900℃.展开更多
Lithium niobate thin film frequency doubler has extensive applications in the preparation of classical and quantum sources.In this study,we successfully fabricated microdisk resonators with a quality factor of 2.2...Lithium niobate thin film frequency doubler has extensive applications in the preparation of classical and quantum sources.In this study,we successfully fabricated microdisk resonators with a quality factor of 2.2×10^(5) in reverse-polarization dual-layer x-cut lithium niobate for the first time.Based on the modal phase matching condition,efficient second harmonic generation with a record normalized conversion efficiency of~56000%W-1 and cascaded third harmonic generation with an efficiency of~6500%W-2 were obtained in the microdisk resonator.Compared with the periodically poled lithium niobate microcavity,the complex domain structure preparation processes are avoided.Our work provides a scheme for achieving highly efficient second-order nonlinear effects in non-periodically poled microcavities.展开更多
Lithium niobate(LN)thin film has received much attention as an integrated photonic platform,due to its rich and great photoelectric characteristics,based on which various functional photonic devices,such as electro-op...Lithium niobate(LN)thin film has received much attention as an integrated photonic platform,due to its rich and great photoelectric characteristics,based on which various functional photonic devices,such as electro-optic modulators and nonlinear wavelength converters,have been demonstrated with impressive performance.As an important part of the integrated photonic system,the long-awaited laser and amplifier on the LN thin-film platform have made a series of breakthroughs and important progress recently.In this review paper,the research progress of lasers and amplifiers realized on lithium niobate thin film platforms is reviewed comprehensively.Specifically,the research progress on optically pumped lasers and amplifiers based on rare-earth ions doping of LN thin films is introduced.Some important parameters and existing limitations of the current development are discussed.In addition,the implementation scheme and research progress of electrically pumped lasers and amplifiers on LN thin-film platforms are summarized.The advantages and disadvantages of optically and electrically pumped LN thin film light sources are analyzed.Finally,the applications of LN thin film lasers and amplifiers and other on-chip functional devices are envisaged.展开更多
Medium-or high-entropy materials have great potential for applications due to their diverse compo-sitions and unexpected physicochemical properties.Herein,a novel medium-entropy(TiVNb)_(2)AlC was synthesized via hot p...Medium-or high-entropy materials have great potential for applications due to their diverse compo-sitions and unexpected physicochemical properties.Herein,a novel medium-entropy(TiVNb)_(2)AlC was synthesized via hot pressing at 1400℃from three individual M_(2)AlC(M=Ti,V,Nb)MAX phases.The microstructure of(TiVNb)_(2)AlC was characterized from the microscale to the atomic scale by scanning electron microscope microscopy(SEM),scanning transmission electron microscopy(STEM),and energy dispersive spectroscopy(EDS).The results showed that Ti,V,and Nb atoms were fully solid-soluble in the M-sites of the M_(2)AlC MAX phase.Compared with three individual MAX phases,the thermal conduc-tivity of(TiVNb)_(2)AlC was reduced greatly in the temperature range of 293-1473 K,and its mechanical properties(including Young’s modulus,Vickers hardness,and bending strength)were all increased due to the solid solution strengthening and electronic mechanism.展开更多
The ability to amplify optical signals is of paramount importance in photonic integrated circuits(PICs). Recently,lithium niobate on insulator(LNOI) has attracted increasing interest as an emerging PIC platform. Howev...The ability to amplify optical signals is of paramount importance in photonic integrated circuits(PICs). Recently,lithium niobate on insulator(LNOI) has attracted increasing interest as an emerging PIC platform. However, the shortage of efficient active devices on the LNOI platform limits the development of optical amplification. Here,we report an efficient waveguide amplifier based on erbium and ytterbium co-doped LNOI by using electron beam lithography and an inductively coupled plasma reactive ion etching process. We have demonstrated that signal amplification emerges at a low pump power of 0.1 mW, and the net internal gain in the communication band is 16.52 dB/cm under pumping of a 974 nm continuous laser. Benefiting from the efficient pumping facilitated by energy transfer between ytterbium and erbium ions, an internal conversion efficiency of 10% has been achieved, which is currently the most efficient waveguide amplifier under unidirectional pumping reported on the LNOI platform, to our knowledge. This work proposes an efficient active device for LNOI integrated optical systems that may become an important fundamental component of future lithium niobate photonic integration platforms.展开更多
Thermal stability is a crucial index to assess application value of high-power LEDs,which is related to lattice defects.Herein,an effective structure-engineering strategy is proposed to achieve excellent properties.Un...Thermal stability is a crucial index to assess application value of high-power LEDs,which is related to lattice defects.Herein,an effective structure-engineering strategy is proposed to achieve excellent properties.Under the 394 nm excitation,Cs_3Zn_(5.94)B_9O_(21):0.06Eu^(3+)possesses two characteristic emissions peaked at 591 and 612 nm with limited thermal stability.By introducing Li^(+)ions into the lattice,the sample exhibits high color purity and excellent zero-thermal quenching because the defect contents of the phosphor can be effectively modulated via charge-compensation effect.Then,under the stimulus of high temperature,the corresponding trap levels with a suitable depth(E=1.27 eV)will release electrons to recombine with the luminescent centers,compensating for the energy loss.The study provides a meaningful guide for optimizing and designing novel functional photoluminescent materials.展开更多
The composition of materials in a micro-/nano-devices plays a key role in determining their mechanical,physical,and chemical properties.Especially,for devices with a compositional change on nanoscale which can often b...The composition of materials in a micro-/nano-devices plays a key role in determining their mechanical,physical,and chemical properties.Especially,for devices with a compositional change on nanoscale which can often be achieved by point-by-point direct writing technology using a focused ion beam(FIB),electron beam(EB),or laser beam(LB),but so far,nanoscale composition analysis of a large-area micro/nano structures with a variation composition remains a big challenge in cost,simpleness,and flexibility.Here we present a feasible route to realize large-area composition analysis with nanoscale spatial resolution by using Raman spectroscopy.We experimentally verified the capability of this method by analyzing a complex Sn-SnOx system of a microscale grayscale mask with nanoscale spatial resolution of composition.Further analyses using Auger electron spectroscopy,transmission electron microscopy,and atomic force microscopy indicated the effectiveness and practicality of our method.This work opens up a way to analyze the composition of a large-area complex system at a nanoscale spatial resolution,and the method can be extended to many other material systems.展开更多
Collective cell migration is a coordinated movement of multi-cell systems essential for various processes throughout life.The collective motions often occur under spatial restrictions,hallmarked by the collective rota...Collective cell migration is a coordinated movement of multi-cell systems essential for various processes throughout life.The collective motions often occur under spatial restrictions,hallmarked by the collective rotation of epithelial cells confined in circular substrates.Here,we aim to explore how geometric shapes of confinement regulate this collective cell movement.We develop quantitative methods for cell velocity orientation analysis,and find that boundary cells exhibit stronger tangential ordering migration than inner cells in circular pattern.Furthermore,decreased tangential ordering movement capability of collective cells in triangular and square patterns are observed,due to the disturbance of cell motion at unsmooth corners of these patterns.On the other hand,the collective cell rotation is slightly affected by a convex defect of the circular pattern,while almost hindered with a concave defect,also resulting from different smoothness features of their boundaries.Numerical simulations employing cell Potts model well reproduce and extend experimental observations.Together,our results highlight the importance of boundary smoothness in the regulation of collective cell tangential ordering migration.展开更多
Crystalline lithium niobate(LN)is an important optical material because of its broad transmission window that spans from ultraviolet to mid-infrared and its large nonlinear and electro-optic coefficients.Furthermore,t...Crystalline lithium niobate(LN)is an important optical material because of its broad transmission window that spans from ultraviolet to mid-infrared and its large nonlinear and electro-optic coefficients.Furthermore,the recent development and commercialization of LN-on-insulator(LNOI)technology has opened an avenue for the realization of integrated on-chip photonic devices with unprecedented performances in terms of propagation loss,optical nonlinearity,and electro-optic tunability.This review begins with a brief introduction of the history and current status of LNOI photonics.We then discuss the fabrication techniques of LNOI-based photonic structures and devices.The recent revolution in the LN photonic industry has been sparked and is still being powered by innovations of the nanofabrication technology of LNOI,which enables the production of building block structures,such as optical microresonators and waveguides of unprecedented optical qualities.The following sections present various on-chip LNOI devices categorized into nonlinear photonic and electro-optic tunable devices and photonic-integrated circuits.Some conclusions and future perspectives are provided.展开更多
In this study, we investigate the fabrication of periodically poled lithium niobate(PPLN) microdisk cavities on a chip. These resonators are fabricated from a PPLN film with a 16 μm poling period on insulator using c...In this study, we investigate the fabrication of periodically poled lithium niobate(PPLN) microdisk cavities on a chip. These resonators are fabricated from a PPLN film with a 16 μm poling period on insulator using conventional microfabrication techniques.The quality factor of the PPLN microdisk resonators with a 40-μm radius and a 700-nm thickness is 6.7×10~5. Second harmonic generation(SHG) with an efficiency of 2.2×10^(-6) mW(-1) is demonstrated in the fabricated PPLN microdisks. The nonlinear conversion efficiency could be considerably enhanced by optimizing the period and pattern of the poled structure and by improving the cavity quality factors.展开更多
Microcavity lasers based on erbium-doped lithium niobate on insulator(LNOI),which are key devices for LNOI integrated photonics,have attracted significant attention recently.In this study,we report the realization of ...Microcavity lasers based on erbium-doped lithium niobate on insulator(LNOI),which are key devices for LNOI integrated photonics,have attracted significant attention recently.In this study,we report the realization of a C-band single-mode laser using the Vernier effect in two coupled erbium-doped LNOI microrings with different radii under the pump of a 980-nm continuous laser.The laser,operating stably over a large range of pumping power,has a pump threshold of about 200μW and a side-mode suppression ratio exceeding 26 dB.The high-performance LNOI single-mode laser will promote the development of lithium niobate integrated photonics.展开更多
Lithium niobate on insulator(LNOI) provides a platform for the fundamental physics investigations and practical applications of integrated photonics. However, as an indispensable building block of integrated photonics...Lithium niobate on insulator(LNOI) provides a platform for the fundamental physics investigations and practical applications of integrated photonics. However, as an indispensable building block of integrated photonics, lasers are in short supply. In this paper, erbium-doped LNOI laser in the 1550-nm band was demonstrated in microdisk cavities with high quality factors fabricated in batches by UV exposure, inductively coupled plasma reactive ion etching, and chemomechanical polishing. The threshold and conversion efficiency of the erbium-doped LNOI microdisk laser were measured to be lower than 1 m W and 6.5×10^(-5)%, respectively. This work will benefit the development of integrated photonics based on LNOI.展开更多
A fabrication process allowing for the production of periodically poled lithium niobate(PPLN)photonic devices with any domain pattern and unit size down to 200 nm is developed by combining semiconductor fabrication te...A fabrication process allowing for the production of periodically poled lithium niobate(PPLN)photonic devices with any domain pattern and unit size down to 200 nm is developed by combining semiconductor fabrication techniques and piezo-force-microscopy tips polarization.Based on this fabrication process,PPLN microdisk resonators with quality factors of 8×10~4 were fabricated from a Z-cut lithium niobate film.Second-harmonic generation(SHG)utilizing d(33)in the whole cavity was demonstrated in a PPLN microdisk with a 2μm-spatialperiod radial domain pattern.The SHG conversion efficiency was measured to be 1.44×10^(-5)m W^(-1).This work paves the way to fabricate complex PPLN photonic devices and to obtain efficient nonlinear optical effects that have wide applications in both classical and quantum optics.展开更多
Many applications of metasurfaces require an ability to dynamically change their properties in the time domain. Electrical tuning techniques are of particular interest, since they pave a way to on-chip integration of ...Many applications of metasurfaces require an ability to dynamically change their properties in the time domain. Electrical tuning techniques are of particular interest, since they pave a way to on-chip integration of metasurfaces with optoelectronic devices.In this work, we propose and experimentally demonstrate an electro-optic lithium niobate(EO-LN) metasurface that shows dynamic modulations to phase retardation of transmitted light. Quasi-bound states in the continuum(QBIC) are observed from this metasurface. By applying external electric voltages, the refractive index of lithium niobate(LN) is changed by Pockels EO nonlinearity, leading to efficient phase modulations to the transmitted light around the QBIC wavelength. The EO-LN metasurface developed in this study opens up new routes for potential applications in the field of displaying, pulse shaping, and spatial light modulating.展开更多
Short-carbon-fibers(C_(sf))reinforced Ti_(3)SiC_(2) matrix composites(C_(sf)/Ti_(3)SiC_(2),the C_(sf) content was 0 vol%,2 vol%,5 vol%,and 10 vol%)were fabricated by spark plasma sintering(SPS)using Ti_(3)SiC_(2) powd...Short-carbon-fibers(C_(sf))reinforced Ti_(3)SiC_(2) matrix composites(C_(sf)/Ti_(3)SiC_(2),the C_(sf) content was 0 vol%,2 vol%,5 vol%,and 10 vol%)were fabricated by spark plasma sintering(SPS)using Ti_(3)SiC_(2) powders and C_(sf) as starting materials at 1300℃.The effects of C_(sf) addition on the phase compositions,microstructures,and mechanical properties(including hardness,flexural strength(σ_(f)),and KIC)of C_(sf)/Ti_(3)SiC_(2) composites were investigated.The C_(sf),with bi-layered transition layers,i.e.,T_(IC) and SiC layers,were homogeneously distributed in the as-prepared C_(sf)/Ti_(3)SiC_(2) composites.With the increase of C_(sf) content,the K_(IC) of C_(sf)/Ti_(3)SiC_(2) composites increased,but the σ_(f) decreased,and the Vickers hardness decreased initially and then increased steadily when the C_(sf) content was higher than 2 vol%.These changed performances(hardness,σ_(f),and K_(IC))could be attributed to the introduction of C_(sf) and the formation of stronger interfacial phases.展开更多
The flourishing of topological photonics in the last decade was achieved mainly due to developments in linear topological photonic structures.However,when nonlinearity is introduced,many intriguing questions arise.For...The flourishing of topological photonics in the last decade was achieved mainly due to developments in linear topological photonic structures.However,when nonlinearity is introduced,many intriguing questions arise.For example,are there universal fingerprints of the underlying topology when modes are coupled by nonlinearity,and what can happen to topological invariants during nonlinear propagation?To explore these questions,we experimentally demonstrate nonlinearity-induced coupling of light into topologically protected edge states using a photonic platform and develop a general theoretical framework for interpreting the mode-coupling dynamics in nonlinear topological systems.Performed on laser-written photonic Su-Schrieffer-Heeger lattices,our experiments show the nonlinear coupling of light into a nontrivial edge or interface defect channel that is otherwise not permissible due to topological protection.Our theory explains all the observations well.Furthermore,we introduce the concepts of inherited and emergent nonlinear topological phenomena as well as a protocol capable of revealing the interplay of nonlinearity and topology.These concepts are applicable to other nonlinear topological systems,both in higher dimensions and beyond our photonic platform.展开更多
We demonstrate both experimentally and theoretically the trapping and guiding of a weak signal pulse via a selfaccelerating Airy pulse. This is achieved by launching the Airy pulse in the anomalous dispersion regime o...We demonstrate both experimentally and theoretically the trapping and guiding of a weak signal pulse via a selfaccelerating Airy pulse. This is achieved by launching the Airy pulse in the anomalous dispersion regime of an optical fiber, thereby inducing a gravity-like potential that can compel the signal pulse in the normal dispersion regime to undergo co-acceleration. Such guiding pulse by pulse can be controlled at ease simply by altering the acceleration conditions of the Airy pulse. Furthermore, the guided signal can be featured with either single or double peaks, which is explained by using the theory of fundamental and second-order quasi-modes associated with the gravity-like potential. Our work represents, to our knowledge, the first demonstration of pulse guiding in the anomalous dispersion regime of any self-accelerating pulse.展开更多
基金This work was supported by the Guangdong Major Project of Basic and Applied Basic Research(2020B0301030009)the National Key Research and Development Program of China(2022YFC3400600)National Natural Science Foundation of China(12174208,32227802,11874231,31801134 and 31870843)+2 种基金Tianjin Natural Science Foundation(20JCYBJC01010)China Postdoctoral Science Foundation(2020M680032)Fundamental Research Funds for the Central Universities(2122021337 and 2122021405).
文摘Actin cytoskeleton plays crucial roles in various cellular functions.Extracellular matrix(ECM)can modulate cell morphology by remodeling the internal cytoskeleton.To define how geometry of ECM regulates the organization of actin cytoskeleton,we plated individual NIH 3T3 cells on micropatterned substrates with distinct shapes and sizes.It was found that the stress fibers could form along the nonadhesive edges of T-shaped pattern,but were absent from the opening edge of V-shaped pattern,indicating that the organization of actin cytoskeleton was dependent on the mechanical environment.Furthermore,a secondary actin ring was observed on 50μm circular pattern while did not appear on 30μm and 40μm pattern,showing a size-dependent organization of actin cytoskeleton.Finally,osteoblasts,MDCK and A549 cells exhibited distinct organization of actin cytoskeleton on T-shaped pattern,suggesting a cell-type specificity in arrangement of actin cytoskeleton.Together,our findings brought novel insight into the organization of actin cytoskeleton on micropatterned environments.
基金The National Key Research and Development Program of China(Grant No.2019YFA0705000)National Natural Science Foundation of China(No.12034010)Program for Changjiang Scholars and Innovative Research Team in University(No.IRT_13R29).
文摘Holographic display has attracted widespread interest because of its ability to show the complete information of the object and bring people an unprecedented sense of presence. The absence of ideal recording materials has hampered the realization of their commercial applications. Here we report that the response time of a bismuth and magnesium codoped lithium niobate(LN:Bi,Mg) crystal is shortened to 7.2 ms and a sensitivity as high as 646 cm/J. The crystal was used to demonstrate a real-time holographic display with a refresh rate of 60 Hz, as that of the popular high-definition television. Moreover, the first-principles calculations indicate that the electron mobility while Bi occupying Nb-site is significantly greater than that in Li-site, which directly induces the fast response of LN:Bi,Mg crystals when the concentration of Mg is above its doping threshold.
基金the National Natural Science Foundation of China(Nos.11874231,11574165 and 31801134)Tianjin Natural Science Foundation(No.18JCQNJC02000)+1 种基金the PCSIRT(No.IRT 13R29)the 111 Project(No.B07013).
文摘As the indispensable oxygen-transporting cells,erythrocytes exhibit extreme deformability and amazing stability as they are subject to huge reversible shear stress and extrusion force during massive circulation in the body.The unique architecture of spectrin-actin-based membraneskeleton is considered to be responsible for such excellent mechanical properties of erythrocytes.Although erythrocytes have been recognized for more than 300 years,myriad questions about membrane-skeleton constantly attract people's attention.Here,we summarize the kinds of distinctive single-cell and single-molecule techniques that were used to investigate the structure and function of erythrocyte membrane-skeleton at macro and micro levels.
基金supported by the National Natural Science Foundation of China(Grant No.52071318).
文摘The oxidation behavior and kinetics of Ti_(2)AlC-20vol.%TiB_(2) composite at 600-900℃ in air were investigated.The results showed that the oxidation kinetics of the composite followed a logarithmic law within the given temperature range,which indicated that the composites had excellent oxidation resistance.The selective oxidation of Al in Ti_(2)AlC was greatly enhanced,which facilitated the formation of a continuous and dense protective layer of Al_(2)O_(3).Meanwhile,the existence of molten B_(2)O_(3) inhibited the outward diffusion of Ti and inward diffusion of oxygen,which prevented the growth of anatase TiO_(2) at 600℃ and rutile TiO_(2) at 700-900℃.Therefore,the incorporation of TiB_(2) completely inhibited the abnormally rapid oxidation of bulk Ti_(2)AlC at 600℃ and improved its oxidation resistance at 700-900℃.
基金supported by the National Key Research and Development Program of China(Grant No.2019YFA0705000)the National Natural Science Foundation of China(Grant Nos.12034010,12134007,11734009,92050111,12074199,92050114,and 12004197)the 111 Project(Grant No.B23045)。
文摘Lithium niobate thin film frequency doubler has extensive applications in the preparation of classical and quantum sources.In this study,we successfully fabricated microdisk resonators with a quality factor of 2.2×10^(5) in reverse-polarization dual-layer x-cut lithium niobate for the first time.Based on the modal phase matching condition,efficient second harmonic generation with a record normalized conversion efficiency of~56000%W-1 and cascaded third harmonic generation with an efficiency of~6500%W-2 were obtained in the microdisk resonator.Compared with the periodically poled lithium niobate microcavity,the complex domain structure preparation processes are avoided.Our work provides a scheme for achieving highly efficient second-order nonlinear effects in non-periodically poled microcavities.
基金This work was financially supported by the National Key Research and Development Program of China(Grant No.2019YFA0705000)National Natural Science Foundation of China(Grant Nos.92250302,12034010,12134007,92050111,12074199,92050114,and 12004197)the 111 Project(Grant No.B23045).
文摘Lithium niobate(LN)thin film has received much attention as an integrated photonic platform,due to its rich and great photoelectric characteristics,based on which various functional photonic devices,such as electro-optic modulators and nonlinear wavelength converters,have been demonstrated with impressive performance.As an important part of the integrated photonic system,the long-awaited laser and amplifier on the LN thin-film platform have made a series of breakthroughs and important progress recently.In this review paper,the research progress of lasers and amplifiers realized on lithium niobate thin film platforms is reviewed comprehensively.Specifically,the research progress on optically pumped lasers and amplifiers based on rare-earth ions doping of LN thin films is introduced.Some important parameters and existing limitations of the current development are discussed.In addition,the implementation scheme and research progress of electrically pumped lasers and amplifiers on LN thin-film platforms are summarized.The advantages and disadvantages of optically and electrically pumped LN thin film light sources are analyzed.Finally,the applications of LN thin film lasers and amplifiers and other on-chip functional devices are envisaged.
基金This work was supported by the National Natural Science Foun-dation of China(Grant No.52071318)and the Fund of Science and Technology on Advanced Functional Composites Laboratory(Grant No.6142906210305).
文摘Medium-or high-entropy materials have great potential for applications due to their diverse compo-sitions and unexpected physicochemical properties.Herein,a novel medium-entropy(TiVNb)_(2)AlC was synthesized via hot pressing at 1400℃from three individual M_(2)AlC(M=Ti,V,Nb)MAX phases.The microstructure of(TiVNb)_(2)AlC was characterized from the microscale to the atomic scale by scanning electron microscope microscopy(SEM),scanning transmission electron microscopy(STEM),and energy dispersive spectroscopy(EDS).The results showed that Ti,V,and Nb atoms were fully solid-soluble in the M-sites of the M_(2)AlC MAX phase.Compared with three individual MAX phases,the thermal conduc-tivity of(TiVNb)_(2)AlC was reduced greatly in the temperature range of 293-1473 K,and its mechanical properties(including Young’s modulus,Vickers hardness,and bending strength)were all increased due to the solid solution strengthening and electronic mechanism.
基金National Key Research and Development Program of China (2019YFA0705000)National Natural Science Foundation of China (12034010, 12134007)+1 种基金Natural Science Foundation of Tianjin City (21JCQNJC00250,21JCZDJC00300)Program for Changjiang Scholars and Innovative Research Team in University (IRT_13R29)。
文摘The ability to amplify optical signals is of paramount importance in photonic integrated circuits(PICs). Recently,lithium niobate on insulator(LNOI) has attracted increasing interest as an emerging PIC platform. However, the shortage of efficient active devices on the LNOI platform limits the development of optical amplification. Here,we report an efficient waveguide amplifier based on erbium and ytterbium co-doped LNOI by using electron beam lithography and an inductively coupled plasma reactive ion etching process. We have demonstrated that signal amplification emerges at a low pump power of 0.1 mW, and the net internal gain in the communication band is 16.52 dB/cm under pumping of a 974 nm continuous laser. Benefiting from the efficient pumping facilitated by energy transfer between ytterbium and erbium ions, an internal conversion efficiency of 10% has been achieved, which is currently the most efficient waveguide amplifier under unidirectional pumping reported on the LNOI platform, to our knowledge. This work proposes an efficient active device for LNOI integrated optical systems that may become an important fundamental component of future lithium niobate photonic integration platforms.
基金the National Natural Science Foundation of China(11774187,U1902218)National Key R&D Program of China(2018YFE0203400)+1 种基金Natural Science Foundation of Tianjin city(19JCYBJC17600)111 Project(B07013)。
文摘Thermal stability is a crucial index to assess application value of high-power LEDs,which is related to lattice defects.Herein,an effective structure-engineering strategy is proposed to achieve excellent properties.Under the 394 nm excitation,Cs_3Zn_(5.94)B_9O_(21):0.06Eu^(3+)possesses two characteristic emissions peaked at 591 and 612 nm with limited thermal stability.By introducing Li^(+)ions into the lattice,the sample exhibits high color purity and excellent zero-thermal quenching because the defect contents of the phosphor can be effectively modulated via charge-compensation effect.Then,under the stimulus of high temperature,the corresponding trap levels with a suitable depth(E=1.27 eV)will release electrons to recombine with the luminescent centers,compensating for the energy loss.The study provides a meaningful guide for optimizing and designing novel functional photoluminescent materials.
基金This work was supported by the National Natural Science Foundation of China(Nos.51971070,and 10974037)the national Key Research and Development Program of China(No.2016YFA0200403)+4 种基金the CAS Strategy Pilot Program(No.XDA 09020300)Eu-FP7 Project(No 247644)Guangdong Provincial Key Laboratory Program(No.2021B1212040001)the Department of Science and Technology of Guangdong ProvinceThe work performed at SZTU was supported by NSFC(No.61805156)。
文摘The composition of materials in a micro-/nano-devices plays a key role in determining their mechanical,physical,and chemical properties.Especially,for devices with a compositional change on nanoscale which can often be achieved by point-by-point direct writing technology using a focused ion beam(FIB),electron beam(EB),or laser beam(LB),but so far,nanoscale composition analysis of a large-area micro/nano structures with a variation composition remains a big challenge in cost,simpleness,and flexibility.Here we present a feasible route to realize large-area composition analysis with nanoscale spatial resolution by using Raman spectroscopy.We experimentally verified the capability of this method by analyzing a complex Sn-SnOx system of a microscale grayscale mask with nanoscale spatial resolution of composition.Further analyses using Auger electron spectroscopy,transmission electron microscopy,and atomic force microscopy indicated the effectiveness and practicality of our method.This work opens up a way to analyze the composition of a large-area complex system at a nanoscale spatial resolution,and the method can be extended to many other material systems.
基金supported by the National Natural Science Foundation of China(Nos.12174208 and 32227802)National Key Research and Development Program of China(No.2022YFC3400600)+2 种基金Guangdong Major Project of Basic and Applied Basic Research(No.2020B0301030009)Fundamental Research Funds for the Central Universities(Nos.2122021337 and 2122021405)the 111 Project(No.B23045).
文摘Collective cell migration is a coordinated movement of multi-cell systems essential for various processes throughout life.The collective motions often occur under spatial restrictions,hallmarked by the collective rotation of epithelial cells confined in circular substrates.Here,we aim to explore how geometric shapes of confinement regulate this collective cell movement.We develop quantitative methods for cell velocity orientation analysis,and find that boundary cells exhibit stronger tangential ordering migration than inner cells in circular pattern.Furthermore,decreased tangential ordering movement capability of collective cells in triangular and square patterns are observed,due to the disturbance of cell motion at unsmooth corners of these patterns.On the other hand,the collective cell rotation is slightly affected by a convex defect of the circular pattern,while almost hindered with a concave defect,also resulting from different smoothness features of their boundaries.Numerical simulations employing cell Potts model well reproduce and extend experimental observations.Together,our results highlight the importance of boundary smoothness in the regulation of collective cell tangential ordering migration.
基金Natural Basic Research Program of China(2019YFA0705000)National Natural Science Foundation of China(11674181,11674340,11734009,11822410,11874154,11874375,61590934,61761136006)+5 种基金Key Research Program of Frontier Sciences(QYZDJ-SSWSLH010)Key Project of the Shanghai Science and Technology Committee(17JC1400400,18DZ1112700)Strategic Priority Research Program of Chinese Academy of Sciences(XDB16030300)Higher Education Discipline Innovation Project(B07013)Program for Changjiang Scholars and Innovative Research Team(IRT_13R29)State Key Laboratory of Advanced Optical Communication Systems and Networks(2019GZKF03006).
文摘Crystalline lithium niobate(LN)is an important optical material because of its broad transmission window that spans from ultraviolet to mid-infrared and its large nonlinear and electro-optic coefficients.Furthermore,the recent development and commercialization of LN-on-insulator(LNOI)technology has opened an avenue for the realization of integrated on-chip photonic devices with unprecedented performances in terms of propagation loss,optical nonlinearity,and electro-optic tunability.This review begins with a brief introduction of the history and current status of LNOI photonics.We then discuss the fabrication techniques of LNOI-based photonic structures and devices.The recent revolution in the LN photonic industry has been sparked and is still being powered by innovations of the nanofabrication technology of LNOI,which enables the production of building block structures,such as optical microresonators and waveguides of unprecedented optical qualities.The following sections present various on-chip LNOI devices categorized into nonlinear photonic and electro-optic tunable devices and photonic-integrated circuits.Some conclusions and future perspectives are provided.
基金supported by the National Natural Science Foundation of China(Grant Nos.11734009,11674181,11774182,and 11674184)the 111 Project(Grant No.B07013)+1 种基金PCSIRT(Grant No.IRT 13R29)CAS Interdisciplinary Innovation Team
文摘In this study, we investigate the fabrication of periodically poled lithium niobate(PPLN) microdisk cavities on a chip. These resonators are fabricated from a PPLN film with a 16 μm poling period on insulator using conventional microfabrication techniques.The quality factor of the PPLN microdisk resonators with a 40-μm radius and a 700-nm thickness is 6.7×10~5. Second harmonic generation(SHG) with an efficiency of 2.2×10^(-6) mW(-1) is demonstrated in the fabricated PPLN microdisks. The nonlinear conversion efficiency could be considerably enhanced by optimizing the period and pattern of the poled structure and by improving the cavity quality factors.
基金the National Key Research and Development Program of China(Grant No.2019YFA0705000)the National Natural Science Foundation of China(Grant Nos.12034010,11734009,92050111,12074199,92050114,12004197,and 1774182)the 111 Project(Grant No.B07013).
文摘Microcavity lasers based on erbium-doped lithium niobate on insulator(LNOI),which are key devices for LNOI integrated photonics,have attracted significant attention recently.In this study,we report the realization of a C-band single-mode laser using the Vernier effect in two coupled erbium-doped LNOI microrings with different radii under the pump of a 980-nm continuous laser.The laser,operating stably over a large range of pumping power,has a pump threshold of about 200μW and a side-mode suppression ratio exceeding 26 dB.The high-performance LNOI single-mode laser will promote the development of lithium niobate integrated photonics.
基金supported by the National Key Research and Development Program of China (Grant No. 2019YFA0705000)the National Natural Science Foundation of China (Grant Nos. 12034010, 11734009, 11674181,11674184, and 11774182)+2 种基金the Higher Education Discipline Innovation Project (Grant No. B07013)the National Science Fund for Talent Training in the Basic Sciences (Grant No. J1103208)the Program for Changjiang Scholars and Innovative Research Team in University (PCSIRT)(Grant No. IRT_13R29)。
文摘Lithium niobate on insulator(LNOI) provides a platform for the fundamental physics investigations and practical applications of integrated photonics. However, as an indispensable building block of integrated photonics, lasers are in short supply. In this paper, erbium-doped LNOI laser in the 1550-nm band was demonstrated in microdisk cavities with high quality factors fabricated in batches by UV exposure, inductively coupled plasma reactive ion etching, and chemomechanical polishing. The threshold and conversion efficiency of the erbium-doped LNOI microdisk laser were measured to be lower than 1 m W and 6.5×10^(-5)%, respectively. This work will benefit the development of integrated photonics based on LNOI.
基金National Key Research and Development Program of China(2019YFA0705000)National Natural Science Foundation of China(11674181,11674184,11734009,11774182)+2 种基金Higher Education Discipline Innovation Project(B07013)National Science Fund for Talent Training in the Basic Sciences(J1103208)PCSIRT(IRT13R29)。
文摘A fabrication process allowing for the production of periodically poled lithium niobate(PPLN)photonic devices with any domain pattern and unit size down to 200 nm is developed by combining semiconductor fabrication techniques and piezo-force-microscopy tips polarization.Based on this fabrication process,PPLN microdisk resonators with quality factors of 8×10~4 were fabricated from a Z-cut lithium niobate film.Second-harmonic generation(SHG)utilizing d(33)in the whole cavity was demonstrated in a PPLN microdisk with a 2μm-spatialperiod radial domain pattern.The SHG conversion efficiency was measured to be 1.44×10^(-5)m W^(-1).This work paves the way to fabricate complex PPLN photonic devices and to obtain efficient nonlinear optical effects that have wide applications in both classical and quantum optics.
基金supported by the Guangdong Major Project of Basic and Applied Basic Research (Grant No.2020B0301030009)the National Key R&D Program of China (Grant Nos.2017YFA0305100,2017YFA0303800,and 2019YFA0705000)+5 种基金the National Natural Science Foundation of China (Grant Nos.92050114,91750204,61775106,11904182,12074200,and 11774185)the 111 Project (Grant No.B07013)PCSIRT (Grant No.IRT0149)the Open Research Program of Key Laboratory of 3D Micro/Nano Fabrication and Characterization of Zhejiang ProvinceFundamental Research Funds for the Central Universities (Grant Nos.010-63201003,01063201008,and 010-63201009)Tianjin Youth Talent Support Program。
文摘Many applications of metasurfaces require an ability to dynamically change their properties in the time domain. Electrical tuning techniques are of particular interest, since they pave a way to on-chip integration of metasurfaces with optoelectronic devices.In this work, we propose and experimentally demonstrate an electro-optic lithium niobate(EO-LN) metasurface that shows dynamic modulations to phase retardation of transmitted light. Quasi-bound states in the continuum(QBIC) are observed from this metasurface. By applying external electric voltages, the refractive index of lithium niobate(LN) is changed by Pockels EO nonlinearity, leading to efficient phase modulations to the transmitted light around the QBIC wavelength. The EO-LN metasurface developed in this study opens up new routes for potential applications in the field of displaying, pulse shaping, and spatial light modulating.
基金supported by the Joint Fund of Liaoning-SYNL(Grant No.2019JH3/30100035)the Science and Technology Foundation of National Defense Key Laboratory(Grant No.HTKJ2019KL703006).
文摘Short-carbon-fibers(C_(sf))reinforced Ti_(3)SiC_(2) matrix composites(C_(sf)/Ti_(3)SiC_(2),the C_(sf) content was 0 vol%,2 vol%,5 vol%,and 10 vol%)were fabricated by spark plasma sintering(SPS)using Ti_(3)SiC_(2) powders and C_(sf) as starting materials at 1300℃.The effects of C_(sf) addition on the phase compositions,microstructures,and mechanical properties(including hardness,flexural strength(σ_(f)),and KIC)of C_(sf)/Ti_(3)SiC_(2) composites were investigated.The C_(sf),with bi-layered transition layers,i.e.,T_(IC) and SiC layers,were homogeneously distributed in the as-prepared C_(sf)/Ti_(3)SiC_(2) composites.With the increase of C_(sf) content,the K_(IC) of C_(sf)/Ti_(3)SiC_(2) composites increased,but the σ_(f) decreased,and the Vickers hardness decreased initially and then increased steadily when the C_(sf) content was higher than 2 vol%.These changed performances(hardness,σ_(f),and K_(IC))could be attributed to the introduction of C_(sf) and the formation of stronger interfacial phases.
基金supported by the National Key R&D Program of China under Grant No.2017YFA0303800the National Natural Science Foundation(11922408,91750204,11674180),PCSIRT+5 种基金the 111 Project(No.B07013)in Chinasupport in part by the Croatian Science Foundation Grant No.IP-2016-06-5885 SynthMagIAthe QuantiXLie Center of Excellence,a project co-financed by the Croatian Government and European Union through the European Regional Development Fund-the Competitiveness and Cohesion Operational Programme(Grant KK.01.1.1.01.0004)supported by the Australian Research Council(DE19010043)supported by the Institute for Basic Science in Korea(IBS-R024-Y1)support from the Russian Foundation for Basic Research(grant No.19-52-12053).
文摘The flourishing of topological photonics in the last decade was achieved mainly due to developments in linear topological photonic structures.However,when nonlinearity is introduced,many intriguing questions arise.For example,are there universal fingerprints of the underlying topology when modes are coupled by nonlinearity,and what can happen to topological invariants during nonlinear propagation?To explore these questions,we experimentally demonstrate nonlinearity-induced coupling of light into topologically protected edge states using a photonic platform and develop a general theoretical framework for interpreting the mode-coupling dynamics in nonlinear topological systems.Performed on laser-written photonic Su-Schrieffer-Heeger lattices,our experiments show the nonlinear coupling of light into a nontrivial edge or interface defect channel that is otherwise not permissible due to topological protection.Our theory explains all the observations well.Furthermore,we introduce the concepts of inherited and emergent nonlinear topological phenomena as well as a protocol capable of revealing the interplay of nonlinearity and topology.These concepts are applicable to other nonlinear topological systems,both in higher dimensions and beyond our photonic platform.
基金National Natural Science Foundation of China(11504186,61575098,91750204)National Key R&D Program of China(2017YFA0303800)Higher Education Discipline Innovation Project(B07013)
文摘We demonstrate both experimentally and theoretically the trapping and guiding of a weak signal pulse via a selfaccelerating Airy pulse. This is achieved by launching the Airy pulse in the anomalous dispersion regime of an optical fiber, thereby inducing a gravity-like potential that can compel the signal pulse in the normal dispersion regime to undergo co-acceleration. Such guiding pulse by pulse can be controlled at ease simply by altering the acceleration conditions of the Airy pulse. Furthermore, the guided signal can be featured with either single or double peaks, which is explained by using the theory of fundamental and second-order quasi-modes associated with the gravity-like potential. Our work represents, to our knowledge, the first demonstration of pulse guiding in the anomalous dispersion regime of any self-accelerating pulse.