The ability to overcome the negative effects,induced by obstacles and turbulent atmosphere,is a core challenge of long-distance information transmission,and it is of great significance in free-space optical communicat...The ability to overcome the negative effects,induced by obstacles and turbulent atmosphere,is a core challenge of long-distance information transmission,and it is of great significance in free-space optical communication.The spatial-coherence structure,that characterizes partially coherent fields,provides a new degree of freedom for carrying information.However,due to the influence of the complex transmission environment,the spatial-coherence structure is severely damaged during the propagation path,which undoubtedly limits its ability to transmit information.Here,we realize the robust far-field orbital angular momentum(OAM)transmission and detection by modulating the spatial-coherence structure of a partially coherent vortex beam with the help of the cross-phase.The cross-phase enables the OAM information,quantified by the topological charge,hidden in the spatial-coherence structure can be stably transmitted to the far field and can resist the influence of obstructions and turbulence within the communication link.This is due to the self-reconstruction property of the spatial-coherence structure embedded with the cross-phase.We demonstrate experimentally that the topological charge information can be recognized well by measuring the spatial-coherence structure in the far field,exhibiting a set of distinct and separated dark rings even under amplitude and phase perturbations.Our findings open a door for robust optical signal transmission through the complex environment and may find application in optical communication through a turbulent atmosphere.展开更多
To improve the processing efficiency and extend the tuning range of 3D isotropic fabrication,we apply the simultaneous spatiotemporal focusing(SSTF)technique to a high-repetition-rate femtosecond(fs)fiber laser system...To improve the processing efficiency and extend the tuning range of 3D isotropic fabrication,we apply the simultaneous spatiotemporal focusing(SSTF)technique to a high-repetition-rate femtosecond(fs)fiber laser system.In the SSTF scheme,we propose a pulse compensation scheme for the fiber laser with a narrow spectral bandwidth by building an extra-cavity pulse stretcher.We further demonstrate truly 3D isotropic microfabrication in photosensitive glass with a tunable resolution ranging from 8μm to 22μm using the SSTF of fs laser pulses.Moreover,we systematically investigate the influences of pulse energy,writing speed,processing depth,and spherical aberration on the fabrication resolution.As a proof-of-concept demonstration,the SSTF scheme was further employed for the fs laser-assisted etching of complicated glass microfluidic structures with 3D uniform sizes.The developed technique can be extended to many applications such as advanced photonics,3D biomimetic printing,micro-electromechanical systems,and lab-on-a-chips.展开更多
The optical coherence structures of random optical fields can determine beam propagation behavior,light–matter interactions,etc.Their performance makes a light beam robust against turbulence,scattering,and distortion...The optical coherence structures of random optical fields can determine beam propagation behavior,light–matter interactions,etc.Their performance makes a light beam robust against turbulence,scattering,and distortion.Recently,we proposed optical coherence encryption and robust far-field optical imaging techniques.All related applications place a high demand on precision in the experimental measurements of complex optical coherence structures,including their real and imaginary parts.Past studies on these measurements have mainly adopted theoretical mathematical approximations,limited to Gaussian statistic involving speckle statistic(time-consuming),or used complicated and delicate optical systems in the laboratory.In this study,we provide:a robust,convenient,and fast protocol to measure the optical coherence structures of random optical fields via generalized Arago(or Poisson)spot experiments with rigorous mathematical solutions.Our proposal only requires to capture the intensity thrice,and is applicable to any optical coherence structures,regardless of their type or optical statistics.The theoretical and experimental results demonstrated that the real and imaginary parts of the structures could be simultaneously recovered with high precision.We believe that such a protocol can be widely employed in phase measurement,optical imaging,and image transfer.展开更多
The degree of coherence(DOC)function that characterizes the second-order correlations at any two points in a light field is shown to provide a new degree of freedom for carrying information.As a rule,the DOC varies al...The degree of coherence(DOC)function that characterizes the second-order correlations at any two points in a light field is shown to provide a new degree of freedom for carrying information.As a rule,the DOC varies along the beam propagation path,preventing from the efficient information recovery.In this paper,we report that when a partially coher-ent beam carrying a cross phase propagates in free space,in a paraxial optical system or in a turbulent medium,the modulus of the far-field(focal plane)DOC acquires the same value as it has in the source plane.This unique propaga-tion feature is employed in a novel protocol for far-field imaging via the DOC,applicable to transmission in both free-space and turbulence.The advantages of the proposed approach are the confidentiality and resistance to turbulence,as well as the weaker requirement for the beam alignment accuracy.We demonstrate the feasibility and the robustness of the far-field imaging via the DOC in the turbulent media through both the experiment and the numerical simulations.Our findings have potential applications in optical imaging and remote sensing in natural environments,in the presence of op-tical turbulence.展开更多
We derive theoretically and verify experimentally a concise general expression for the normalized intensity correlations(IC)of partially coherent light in a weak atmospheric turbulence in the fast detector measurement...We derive theoretically and verify experimentally a concise general expression for the normalized intensity correlations(IC)of partially coherent light in a weak atmospheric turbulence in the fast detector measurement regime.The derived relation reveals that the medium turbulence acts,in general,as an additional noise source enhancing the IC of partially coherent beams.The maximum of the beam IC is,in general,enhanced,causing the fields to exhibit super-Gaussian statistics.On the other hand,the relation indicates that turbulence-induced noise is negligible for sufficiently low coherence light,which reveals the condition for the turbulence-free correlation imaging.展开更多
The advancement of terahertz technology in recent years and its applications in various fields lead to an urgent need for functional terahertz components,among which a terahertz switch is one example of the most impor...The advancement of terahertz technology in recent years and its applications in various fields lead to an urgent need for functional terahertz components,among which a terahertz switch is one example of the most importance because it provides an effective interface between terahertz signals and information in another physical quantity.To date many types of terahertz switches have been investigated mainly in the form of metamaterials made from metallic structures and optically-active medium.However,these reported terahertz switches usually suffer from an inferior performance,e.g.,requiring a high pump laser power density due to a low quality factor of the metallic metamaterial resonances.In this paper,we report and numerically investigate a symmetry-broken silicon disk based terahertz resonator array which exhibits one resonance with ultrahigh quality factor for normal incidence of the terahertz radiations.This resonance,which can never be excited for regular circular Si disks,can help to realize a superior terahertz switch with which only an ultra-low optical pump power density is required to modify the free carrier concentration in Si and its refractive index in the terahertz band.Our findings demonstrate that to realize a high terahertz transmittance change from 0 to above 50%,the required optical pump power density is more than 3 orders of magnitude smaller than that required for a split-ring resonator(SRR)based terahertz switch reported in the literature.展开更多
Vortex beams with orbital angular momentum play a crucial role in increasing the information capacity in optical communications.The magnitude of orbital angular momentum determines the ability of information encoding....Vortex beams with orbital angular momentum play a crucial role in increasing the information capacity in optical communications.The magnitude of orbital angular momentum determines the ability of information encoding.In practice,a vortex beam can encounter random objects or turbulence during free-space propagation,resulting in information damage.Therefore,accurately measuring the orbital angular momentum of a randomly fluctuated and obstructed vortex beam is a considerable challenge.Herein,we propose a single-shot method for the phase retrieval of a randomly fluctuated and obstructed vortex beam by combining the phase-shift theorem and self-reference holography.Experimental results reveal that the sign and magnitude of the initial orbital angular momentum can be simultaneously determined based on their quantitative relation with the number of coherence singularities on the observation plane,thus addressing the effects of random occlusion and atmospheric turbulence.The proposed method considerably improved the accurate decoding of orbital angular momentum information in nonideal freespace optical communications.展开更多
The deformation,flicker,and drift of a light field owing to complex media such as a turbulent atmosphere have limited its practical applications.Thus,research on invariants in randomly fluctuated light fields has garn...The deformation,flicker,and drift of a light field owing to complex media such as a turbulent atmosphere have limited its practical applications.Thus,research on invariants in randomly fluctuated light fields has garnered considerable attention in recent years.Coherence is a statistical property of light,while its full and quantitative characterization is challenging.Herein,we successfully realize the orthogonal modal decomposition of partially coherent beams and introduce the application of coherence entropy as a global coherence characteristic of such randomly fluctuated light fields.It is demonstrated that coherence entropy remains consistent during propagation in a unitary system by unraveling complex channels.As representative examples,we study the robustness of coherence entropy for partially coherent beams as they propagate through deformed optical systems and turbulent media.Coherence entropy is anticipated to serve as a key metric for evaluating the propagation of partially coherent beams in complex channels.This study paves the way for a broader application scope of a customized low-coherence light field through nonideal optical systems and complex media.展开更多
We investigated the Talbot effect in an anti-parity-time(PT)symmetric synthetic photonic lattice composed of two coupled fiber loops.We calculated the band structures and found that with an increase in the gain-loss p...We investigated the Talbot effect in an anti-parity-time(PT)symmetric synthetic photonic lattice composed of two coupled fiber loops.We calculated the band structures and found that with an increase in the gain-loss parameter,the band transitions from a real spectrum to a complex spectrum.We study the influence of phase in the Hermitian operator on the Talbot effect,and the Talbot effect disappears when the period of the input field is N>8.Further study shows that the variation of Talbot distance can also be modulated by non-Hermitian coefficients of gain and loss.This work may find significant applications in pulse repetition-rate multiplication,temporal invisibility,and tunable intensity amplifiers.展开更多
Optical information transmission is vital in modern optics and photonics due to its concurrent and multi-dimensional nature,leading to tremendous applications such as optical microscopy,holography,and optical sensing....Optical information transmission is vital in modern optics and photonics due to its concurrent and multi-dimensional nature,leading to tremendous applications such as optical microscopy,holography,and optical sensing.Conventional optical information transmission technologies suffer from bulky optical setup and information loss/crosstalk when meeting scatterers or obstacles in the light path.Here,we theoretically propose and experimentally realize the simultaneous manipulation of the coherence lengths and coherence structures of the light beams with the disordered metasurfaces.The ultra-robust optical information transmission and self-reconstruction can be realized by the generated partially coherent beam with modulated coherence structure even 93%of light is recklessly obstructed during light transmission,which brings new light to robust optical information transmission with a single metasurface.Our method provides a generic principle for the generalized coherence manipulation on the photonic platform and displays a variety of functionalities advancing capabilities in optical information transmission such as meta-holography and imaging in disordered and perturbative media.展开更多
Fractional vortex beams exhibit a higher degree of modulation dimensions than conventional vortices,thus inheriting superior anti-turbulent transmission properties through the incorporation of additional coherence mod...Fractional vortex beams exhibit a higher degree of modulation dimensions than conventional vortices,thus inheriting superior anti-turbulent transmission properties through the incorporation of additional coherence modulation.However,aliasing the mixed modes induced by coherence degradation makes the quantitative measurement of the topological charge in fractional vortex beams challenging.In this study,a coherence phase spectrum was introduced,and experimental demonstrations to quantitatively determine the fractional topological charge of partially coherent fractional vortex beams were performed.By leveraging the four-dimensional measurement of a partially coherent light field,the source coherence function was inversely reconstructed,and fractional topological charges were determined with high precision by extracting the phase spectrum of the coherence function.Laguerre–Gaussian,elliptical Gaussian,and plane-wave-fraction vortex beams with various degrees of coherence were used to demonstrate measurement precision.The proposed method is applicable to X-rays and electron vortices.It has potential applications in optical encryption,high-capacity optical communication,and quantum entanglement.展开更多
Structured light with more extended degrees of freedom(DoFs)and in higher dimensions is increasingly gaining traction and leading to breakthroughs such as super-resolution imaging,larger-capacity communication,and ult...Structured light with more extended degrees of freedom(DoFs)and in higher dimensions is increasingly gaining traction and leading to breakthroughs such as super-resolution imaging,larger-capacity communication,and ultraprecise optical trapping or tweezers.More DoFs for manipulating an object can access more maneuvers and radically increase maneuvering precision,which is of significance in biology and related microscopic detection.However,manipulating particles beyond three-dimensional(3D)spatial manipulation by using current all-optical tweezers technology remains difficult.To overcome this limitation,we theoretically and experimentally present six-dimensional(6D)structured optical tweezers based on tailoring structured light emulating rigid-body mechanics.Our method facilitates the evaluation of the methodology of rigid-body mechanics to synthesize six independent DoFs in a structured optical trapping system,akin to six-axis rigid-body manipulation,including surge,sway,heave,roll,pitch,and yaw.In contrast to previous 3D optical tweezers,our 6D structured optical tweezers significantly improved the flexibility of the path design of complex trajectories,thereby laying the foundation for next-generation functional optical manipulation,assembly,and micromechanics.展开更多
A general model for creating an optical vortex using a variable-width Fermat spiral slit(FSS)mask was developed.The generated optical vortex demonstrates much better quality than those produced by slits with a uniform...A general model for creating an optical vortex using a variable-width Fermat spiral slit(FSS)mask was developed.The generated optical vortex demonstrates much better quality than those produced by slits with a uniform width.The depth of focus was nearly doubled,which can be explained by discretizing the gradual-width FSS.To demonstrate the generation robustness,the slits were printed on a transparent slide,and an output vortex beam with greater than 98%intensity purity was obtained.With the high quality and simplicity of this vortex generation method,its analysis and generation scheme are expected to be extended to generation of plasmonic vortices and short-wavelength light sources such as X-rays and electron beams.Generation of highquality optical vortex beams at an almost negligible cost will make investigation much more accessible.展开更多
We introduce the Stokes scintillation indices and the corresponding overall Stokes scintillations for quantitatively studying the fluctuations of both the intensity and polarization of an optical vector beam transmitt...We introduce the Stokes scintillation indices and the corresponding overall Stokes scintillations for quantitatively studying the fluctuations of both the intensity and polarization of an optical vector beam transmitting through the atmospheric turbulence.With the aid of the multiple-phase-screen method,we examine the Stokes fluctuations of a radially polarized beam in Kolmogorov turbulence numerically.The results show that the overall scintillation for the intensity distribution is always larger than the overall scintillation for the polarization-dependent Stokes parameters,which indicates that the polarization state of a vector beam is stabler than its intensity distribution in the turbulence.We interpret the results with the depolarization effect of the vector beam in turbulence.The findings in this work may be useful in free-space optical communications utilizing vector beams.展开更多
Photonic moirésuperlattice as an emerging platform of flatbands can tightly confine the light inside the cavity and has important applications not only in linear optics but also in nonlinear optics.In this paper,...Photonic moirésuperlattice as an emerging platform of flatbands can tightly confine the light inside the cavity and has important applications not only in linear optics but also in nonlinear optics.In this paper,we numerically investigate the third-and fifth-order harmonic generation(THG and FHG)in photonic moirésuperlattices fabricated by the nonlinear material silicon.The high conversion efficiency of THG and FHG is obtained at a relatively low intensity of fundamental light,e.g.,the maximum conversion efficiency of THG and FHG arrives even up to be 10^(−2) and 10^(−9) at the fundamental intensity of 30 kW/m^(2),respectively,in the moirésuperlattice of near flat band formed by the twist angle 6.01°.The results indicate the photonic moirésuperlattice of a high-quality factor and flatbands is a promising platform for efficient nonlinear processes and advanced photonic devices.展开更多
Self-healing in optics generally refers to the ability to reconstruct itself and restore the original state after encountering obstacles in the propagation of the light field.In this research,we observe the processes ...Self-healing in optics generally refers to the ability to reconstruct itself and restore the original state after encountering obstacles in the propagation of the light field.In this research,we observe the processes of the wave fields from perfect to defect in front of the focal plane of the 4f system,finally returning to an intact situation after the plane.According to simulations and experimental results,there is a minimum self-healing distance for the moirélattice field that positively associates with the radius of the defect[obstacle]in the nondiffracting transmission range.Furthermore,it is observed that the defect self-healing is a process of“repairing the center and then repairing the edges.”These findings can be applied in areas such as optical imaging,capture,and information processing.展开更多
Ever since vortex beams were proposed, they are known for owning phase singularity and carrying orbital angular momentum (OAM). In the past decades, coherent optics developed rapidly. Vortex beams have been extended f...Ever since vortex beams were proposed, they are known for owning phase singularity and carrying orbital angular momentum (OAM). In the past decades, coherent optics developed rapidly. Vortex beams have been extended from fully coherent light to partially coherent light, from scalar light to vector light, from integral topological charge (TC) to fractional TC. Partially coherent vortex beams have attracted tremendous interest due to their hidden correlation singularity and unique propagation properties (e.g., beam shaping, beam rotation and self-reconstruction). Based on the sufficient condition for devising a genuine correlation function of partially coherent beam, partially coherent vortex beams with nonconventional correlation functions (i.e., non-Gaussian correlated Schell-model functions) were introduced recently. This timely review summarizes basic concepts, theoretical models, generation and propagation of partially coherent vortex beams.展开更多
It has been over 30 years since the concept of optical vortices was first proposed by Coullet et al.in 1989,and the field of structured beams has grown extremely.In the last two decades,partially coherent vortex beams...It has been over 30 years since the concept of optical vortices was first proposed by Coullet et al.in 1989,and the field of structured beams has grown extremely.In the last two decades,partially coherent vortex beams(PCVBs)have received increasing interest in the fields of optical manipulation,optical communication,optical imaging,etc.,and great progress has been made in the area of the coherence singularities,generation methods,topological charge measurements,and promising applications of PCVBs.In this review,we firstly outline the basic concepts of PCVBs.We explicate the relationship between the coherence vortices and optical vortices,and the evolution behavior of optical vortices to coherence vortices is summarized in detail.We discuss a special form of coherence singularity,ring dislocation,mathematically and physically.The ring dislocation in the correlation functions under low coherence is dependent on the mode indices,which provide a feasible approach to measure mode indices of PCVBs.Subsequently,we summarize the various methods for measuring the topological charge of PCVBs,highlight the measurement method based on the cross-correlation function,and a physical explanation on the relation between ring dislocation and topological charge is given.After that,we review the recent advances on experimental generation of several kinds of PCVBs.Lastly,we give an overview on the potential applications of PCVBs.展开更多
Optical channel waveguides with depressed cladding configurations have been produced in Nd,Gd∶CaF_(2)laser crystals by using ultrafast laser inscription.Waveguide properties are investigated in terms of guiding behav...Optical channel waveguides with depressed cladding configurations have been produced in Nd,Gd∶CaF_(2)laser crystals by using ultrafast laser inscription.Waveguide properties are investigated in terms of guiding behaviors and localized laserinduced lattice damages.Under an optical pump of 808 nm light,continuous-wave waveguide lasing at 1.06μm is achieved,with a single-mode operation and a minimum lasing threshold of 98.8 m W.Furthermore,the visible emissions of Nd^(3+)with short wavelengths ranging from 415 nm to 550 nm and long wavelengths from 550 nm to 625 nm are observed upon 808 nm laser excitation via the up-converted process.The intensity ratios of two wavelength ranges are proved to be tunable through changing the pumping polarizations.展开更多
Lommel beams have been potential candidates for optical communication and optical manipulation,due to their adjustable symmetry of transverse intensity distribution and continuously variable orbital angular momentum.H...Lommel beams have been potential candidates for optical communication and optical manipulation,due to their adjustable symmetry of transverse intensity distribution and continuously variable orbital angular momentum.However,the wavefront of the Lommel beam is scrambled when it transmits through highly scattering media.Here,we explore the construction of Lommel beams through highly scattering media with a transmission matrix-based point spread function engineering method.Experimentally,various Lommel beams with different parameters were generated through a ZnO scattering layer by use of a digital micromirror device.The construction of Lommel beams under high scattering is expected to benefit the optical applications behind highly scattering media.展开更多
基金National Key Research and Development Program of China (2022YFA1404800,2019YFA0705000)National Natural Science Foundation of China (12104264,12192254,92250304,and 12374311)+2 种基金China Postdoctoral Science Foundation (2022T150392)Natural Science Foundation of Shandong Province (ZR2021QA014 and ZR2023YQ006)Qingchuang Science and Technology Plan of Shandong Province (2022KJ246).
文摘The ability to overcome the negative effects,induced by obstacles and turbulent atmosphere,is a core challenge of long-distance information transmission,and it is of great significance in free-space optical communication.The spatial-coherence structure,that characterizes partially coherent fields,provides a new degree of freedom for carrying information.However,due to the influence of the complex transmission environment,the spatial-coherence structure is severely damaged during the propagation path,which undoubtedly limits its ability to transmit information.Here,we realize the robust far-field orbital angular momentum(OAM)transmission and detection by modulating the spatial-coherence structure of a partially coherent vortex beam with the help of the cross-phase.The cross-phase enables the OAM information,quantified by the topological charge,hidden in the spatial-coherence structure can be stably transmitted to the far field and can resist the influence of obstructions and turbulence within the communication link.This is due to the self-reconstruction property of the spatial-coherence structure embedded with the cross-phase.We demonstrate experimentally that the topological charge information can be recognized well by measuring the spatial-coherence structure in the far field,exhibiting a set of distinct and separated dark rings even under amplitude and phase perturbations.Our findings open a door for robust optical signal transmission through the complex environment and may find application in optical communication through a turbulent atmosphere.
基金supported by the National Key Research and Development Program of China(2019YFA0705000,2022YFA1404800)National Natural Science Foundation of China(12004221,12174107,12192254,11734009,12192251,92250304,11974218)+4 种基金Postdoctoral Innovation Talents Support Program of Shandong Province(No.SDBX2019005)Science and Technology Commission of Shanghai Municipality(21DZ1101500)Local science and technology development project of the central government(YDZX20203700001766)Shanghai Municipal Science and Technology Major ProjectNatural Science Foundation of Shandong Province(ZR2021ZD02).
文摘To improve the processing efficiency and extend the tuning range of 3D isotropic fabrication,we apply the simultaneous spatiotemporal focusing(SSTF)technique to a high-repetition-rate femtosecond(fs)fiber laser system.In the SSTF scheme,we propose a pulse compensation scheme for the fiber laser with a narrow spectral bandwidth by building an extra-cavity pulse stretcher.We further demonstrate truly 3D isotropic microfabrication in photosensitive glass with a tunable resolution ranging from 8μm to 22μm using the SSTF of fs laser pulses.Moreover,we systematically investigate the influences of pulse energy,writing speed,processing depth,and spherical aberration on the fabrication resolution.As a proof-of-concept demonstration,the SSTF scheme was further employed for the fs laser-assisted etching of complicated glass microfluidic structures with 3D uniform sizes.The developed technique can be extended to many applications such as advanced photonics,3D biomimetic printing,micro-electromechanical systems,and lab-on-a-chips.
基金This work was supported by the National Key Research and Development Program of China(2022YFA1404800,2019YFA0705000)National Natural Science Foundation of China(11974218,12004220,12104264,12192254,92250304)+2 种基金Regional Science and Technology Development Project of the Central Government(YDZX20203700001766)China Postdoctoral Science Foundation(2022T150392)the Natural Science Foundation of Shandong Province(ZR2021QA014,ZR2021ZD02).
文摘The optical coherence structures of random optical fields can determine beam propagation behavior,light–matter interactions,etc.Their performance makes a light beam robust against turbulence,scattering,and distortion.Recently,we proposed optical coherence encryption and robust far-field optical imaging techniques.All related applications place a high demand on precision in the experimental measurements of complex optical coherence structures,including their real and imaginary parts.Past studies on these measurements have mainly adopted theoretical mathematical approximations,limited to Gaussian statistic involving speckle statistic(time-consuming),or used complicated and delicate optical systems in the laboratory.In this study,we provide:a robust,convenient,and fast protocol to measure the optical coherence structures of random optical fields via generalized Arago(or Poisson)spot experiments with rigorous mathematical solutions.Our proposal only requires to capture the intensity thrice,and is applicable to any optical coherence structures,regardless of their type or optical statistics.The theoretical and experimental results demonstrated that the real and imaginary parts of the structures could be simultaneously recovered with high precision.We believe that such a protocol can be widely employed in phase measurement,optical imaging,and image transfer.
文摘The degree of coherence(DOC)function that characterizes the second-order correlations at any two points in a light field is shown to provide a new degree of freedom for carrying information.As a rule,the DOC varies along the beam propagation path,preventing from the efficient information recovery.In this paper,we report that when a partially coher-ent beam carrying a cross phase propagates in free space,in a paraxial optical system or in a turbulent medium,the modulus of the far-field(focal plane)DOC acquires the same value as it has in the source plane.This unique propaga-tion feature is employed in a novel protocol for far-field imaging via the DOC,applicable to transmission in both free-space and turbulence.The advantages of the proposed approach are the confidentiality and resistance to turbulence,as well as the weaker requirement for the beam alignment accuracy.We demonstrate the feasibility and the robustness of the far-field imaging via the DOC in the turbulent media through both the experiment and the numerical simulations.Our findings have potential applications in optical imaging and remote sensing in natural environments,in the presence of op-tical turbulence.
基金National Natural Science Foundation of China(Grant Nos.11525418,91750201,11874046,11974218,11904247,and 11947239)the National Key Research and Development Project of China(Grant No.2019YFA0705000),Innovation Group of Jinan,China(Grant No.2018GXRC010)+3 种基金Natural Science Foundation of the Jiangsu Higher Education Institutions of China(Grant No.19KJB140017)China Postdoctoral Science Foundation(Grant No.2019M661915)Natural Science Foundation of Shandong Province,China(Grant No.ZR2019QA004)Priority Academic Program Development of Jiangsu Higher Education Institutions,China,Qing Lan Project of Jiangsu Province,China,and Natural Sciences and Engineering Research Council of Canada(Grant No.RGPIN-2018-05497).
文摘We derive theoretically and verify experimentally a concise general expression for the normalized intensity correlations(IC)of partially coherent light in a weak atmospheric turbulence in the fast detector measurement regime.The derived relation reveals that the medium turbulence acts,in general,as an additional noise source enhancing the IC of partially coherent beams.The maximum of the beam IC is,in general,enhanced,causing the fields to exhibit super-Gaussian statistics.On the other hand,the relation indicates that turbulence-induced noise is negligible for sufficiently low coherence light,which reveals the condition for the turbulence-free correlation imaging.
基金the National Key R&D Program of China(Grant No.2017YFA0701005)the National Natural Science Foundation of China(Grant Nos.11974221,91750201,61927813,and 61775229)+1 种基金Z.Han also acknowledges the support from the Taishan Scholar Program of Shandong Province,China(Grant No.tsqn201909079)Zhejiang Provincial Natural Science Foundation of China(Grant No.LY15F050008).
文摘The advancement of terahertz technology in recent years and its applications in various fields lead to an urgent need for functional terahertz components,among which a terahertz switch is one example of the most importance because it provides an effective interface between terahertz signals and information in another physical quantity.To date many types of terahertz switches have been investigated mainly in the form of metamaterials made from metallic structures and optically-active medium.However,these reported terahertz switches usually suffer from an inferior performance,e.g.,requiring a high pump laser power density due to a low quality factor of the metallic metamaterial resonances.In this paper,we report and numerically investigate a symmetry-broken silicon disk based terahertz resonator array which exhibits one resonance with ultrahigh quality factor for normal incidence of the terahertz radiations.This resonance,which can never be excited for regular circular Si disks,can help to realize a superior terahertz switch with which only an ultra-low optical pump power density is required to modify the free carrier concentration in Si and its refractive index in the terahertz band.Our findings demonstrate that to realize a high terahertz transmittance change from 0 to above 50%,the required optical pump power density is more than 3 orders of magnitude smaller than that required for a split-ring resonator(SRR)based terahertz switch reported in the literature.
基金supported by the National Key Research and Development Program of China(Grant Nos.2022YFA1404800,and 2019YFA0705000)the National Natural Science Foundation of China(Grant Nos.12174280,12204340,12192254,11974218,92250304,and 92050202)+1 种基金the China Postdoctoral Science Foundation(Grant No.2022M722325)the Priority Academic Program Development of Jiangsu Higher Education Institutions,Key Lab of Modern Optical Technologies of Jiangsu Province(Grant No.KJS2138)。
文摘Vortex beams with orbital angular momentum play a crucial role in increasing the information capacity in optical communications.The magnitude of orbital angular momentum determines the ability of information encoding.In practice,a vortex beam can encounter random objects or turbulence during free-space propagation,resulting in information damage.Therefore,accurately measuring the orbital angular momentum of a randomly fluctuated and obstructed vortex beam is a considerable challenge.Herein,we propose a single-shot method for the phase retrieval of a randomly fluctuated and obstructed vortex beam by combining the phase-shift theorem and self-reference holography.Experimental results reveal that the sign and magnitude of the initial orbital angular momentum can be simultaneously determined based on their quantitative relation with the number of coherence singularities on the observation plane,thus addressing the effects of random occlusion and atmospheric turbulence.The proposed method considerably improved the accurate decoding of orbital angular momentum information in nonideal freespace optical communications.
基金supported by the National Key Research and Development Program of China(Grant Nos.2022YFA1404800 and 2019YFA0705000)the National Natural Science Foundation of China(Grant Nos.12174280,12204340,12192254,92250304,and 92050202)+2 种基金the China Postdoctoral Science Foundation(Grant No.2022M722325)the Priority Academic Program Development of Jiangsu Higher Education Institutionsthe Key Lab of Modern Optical Technologies of Jiangsu Province(Grant No.KJS2138)
文摘The deformation,flicker,and drift of a light field owing to complex media such as a turbulent atmosphere have limited its practical applications.Thus,research on invariants in randomly fluctuated light fields has garnered considerable attention in recent years.Coherence is a statistical property of light,while its full and quantitative characterization is challenging.Herein,we successfully realize the orthogonal modal decomposition of partially coherent beams and introduce the application of coherence entropy as a global coherence characteristic of such randomly fluctuated light fields.It is demonstrated that coherence entropy remains consistent during propagation in a unitary system by unraveling complex channels.As representative examples,we study the robustness of coherence entropy for partially coherent beams as they propagate through deformed optical systems and turbulent media.Coherence entropy is anticipated to serve as a key metric for evaluating the propagation of partially coherent beams in complex channels.This study paves the way for a broader application scope of a customized low-coherence light field through nonideal optical systems and complex media.
基金supported by the National Key Research and Development Program of China(Nos.2022YFA1404800 and 2019YFA0705000)the National Natural Science Foundation of China(Nos.12104272,12274270,91950104,12192254,92250304,and 11974218)the Local Science and Technology Development Project of the Central Government(No.YDZX20203700001766)。
文摘We investigated the Talbot effect in an anti-parity-time(PT)symmetric synthetic photonic lattice composed of two coupled fiber loops.We calculated the band structures and found that with an increase in the gain-loss parameter,the band transitions from a real spectrum to a complex spectrum.We study the influence of phase in the Hermitian operator on the Talbot effect,and the Talbot effect disappears when the period of the input field is N>8.Further study shows that the variation of Talbot distance can also be modulated by non-Hermitian coefficients of gain and loss.This work may find significant applications in pulse repetition-rate multiplication,temporal invisibility,and tunable intensity amplifiers.
基金the National Key Research and Development Program of China(2022YFA1404800,2021YFA1400601)the National Natural Science Fund for Distinguished Young Scholar(11925403)+3 种基金the National Natural Science Foundation of China(12122406,12192253,12192254,92250304,12304365)Natural Science Foundation of Tianjin City(22JCYBJC00800,22JCZDJC00400)the China Postdoctoral Science Foundation(2022M721993)the 111 Project(B23045).
文摘Optical information transmission is vital in modern optics and photonics due to its concurrent and multi-dimensional nature,leading to tremendous applications such as optical microscopy,holography,and optical sensing.Conventional optical information transmission technologies suffer from bulky optical setup and information loss/crosstalk when meeting scatterers or obstacles in the light path.Here,we theoretically propose and experimentally realize the simultaneous manipulation of the coherence lengths and coherence structures of the light beams with the disordered metasurfaces.The ultra-robust optical information transmission and self-reconstruction can be realized by the generated partially coherent beam with modulated coherence structure even 93%of light is recklessly obstructed during light transmission,which brings new light to robust optical information transmission with a single metasurface.Our method provides a generic principle for the generalized coherence manipulation on the photonic platform and displays a variety of functionalities advancing capabilities in optical information transmission such as meta-holography and imaging in disordered and perturbative media.
基金National Key Research and Development Program of China(2019YFA0705000,2022YFA1404800)National Natural Science Foundation of China(11974218,12174280,12192254,12204340,92050202,92250304)+2 种基金China Postdoctoral Science Foundation(2022M722325)Priority Academic Program Development of Jiangsu Higher Education InstitutionsKey Laboratory of Modern Optical Technologies of Jiangsu Province(KJS2138)。
文摘Fractional vortex beams exhibit a higher degree of modulation dimensions than conventional vortices,thus inheriting superior anti-turbulent transmission properties through the incorporation of additional coherence modulation.However,aliasing the mixed modes induced by coherence degradation makes the quantitative measurement of the topological charge in fractional vortex beams challenging.In this study,a coherence phase spectrum was introduced,and experimental demonstrations to quantitatively determine the fractional topological charge of partially coherent fractional vortex beams were performed.By leveraging the four-dimensional measurement of a partially coherent light field,the source coherence function was inversely reconstructed,and fractional topological charges were determined with high precision by extracting the phase spectrum of the coherence function.Laguerre–Gaussian,elliptical Gaussian,and plane-wave-fraction vortex beams with various degrees of coherence were used to demonstrate measurement precision.The proposed method is applicable to X-rays and electron vortices.It has potential applications in optical encryption,high-capacity optical communication,and quantum entanglement.
基金National Key Research and Development Program of China(2022YFA1404800,2019YFA0705000)National Natural Science Foundation of China(12274116,11974102,12192254,92250304,11974218)+2 种基金Key Scientific Research Projects of Institutions of Higher Learning of Henan Province Education Department(21zx002)Natural Science Foundation of Henan Province(232300421019)State Key Laboratory of Transient Optics and Photonics(SKLST202216)。
文摘Structured light with more extended degrees of freedom(DoFs)and in higher dimensions is increasingly gaining traction and leading to breakthroughs such as super-resolution imaging,larger-capacity communication,and ultraprecise optical trapping or tweezers.More DoFs for manipulating an object can access more maneuvers and radically increase maneuvering precision,which is of significance in biology and related microscopic detection.However,manipulating particles beyond three-dimensional(3D)spatial manipulation by using current all-optical tweezers technology remains difficult.To overcome this limitation,we theoretically and experimentally present six-dimensional(6D)structured optical tweezers based on tailoring structured light emulating rigid-body mechanics.Our method facilitates the evaluation of the methodology of rigid-body mechanics to synthesize six independent DoFs in a structured optical trapping system,akin to six-axis rigid-body manipulation,including surge,sway,heave,roll,pitch,and yaw.In contrast to previous 3D optical tweezers,our 6D structured optical tweezers significantly improved the flexibility of the path design of complex trajectories,thereby laying the foundation for next-generation functional optical manipulation,assembly,and micromechanics.
基金supported by the National Key Research and Development Program of China(Grant Nos.2022YFA1404800,and 2019YFA0705000)the National Natural Science Foundation of China(Grant Nos.12204340,12174280,12192254,11974218,92250304,and 92050202)+4 种基金the China Postdoctoral Science Foundation(Grant No.2022M722325)the Priority Academic Program Development of Jiangsu Higher Education Institutions,Tang ScholarLocal Science and Technology Development Project of the Central Government(Grant No.YDZX20203700001766)the Key Lab of Modern Optical Technologies of Jiangsu Province(Grant No.KJS2138)the Postgraduate Research&Practice Innovation Program of Jiangsu Province(Grant No.KYCX22_3183)。
文摘A general model for creating an optical vortex using a variable-width Fermat spiral slit(FSS)mask was developed.The generated optical vortex demonstrates much better quality than those produced by slits with a uniform width.The depth of focus was nearly doubled,which can be explained by discretizing the gradual-width FSS.To demonstrate the generation robustness,the slits were printed on a transparent slide,and an output vortex beam with greater than 98%intensity purity was obtained.With the high quality and simplicity of this vortex generation method,its analysis and generation scheme are expected to be extended to generation of plasmonic vortices and short-wavelength light sources such as X-rays and electron beams.Generation of highquality optical vortex beams at an almost negligible cost will make investigation much more accessible.
基金supported by the National Key Research and Development Program of China(Nos.2022YFA1404800 and 2019YFA0705000)the National Natural Science Foundation of China(Nos.11874046,12192254,92250304,11974218,11904247,12174279,12274310,and 12274311)the Local Science and Technology Development Project of the Central Government(No.YDZX20203700001766).
文摘We introduce the Stokes scintillation indices and the corresponding overall Stokes scintillations for quantitatively studying the fluctuations of both the intensity and polarization of an optical vector beam transmitting through the atmospheric turbulence.With the aid of the multiple-phase-screen method,we examine the Stokes fluctuations of a radially polarized beam in Kolmogorov turbulence numerically.The results show that the overall scintillation for the intensity distribution is always larger than the overall scintillation for the polarization-dependent Stokes parameters,which indicates that the polarization state of a vector beam is stabler than its intensity distribution in the turbulence.We interpret the results with the depolarization effect of the vector beam in turbulence.The findings in this work may be useful in free-space optical communications utilizing vector beams.
基金support from the National Natural Science Foundation of China(Grant Nos.12174228,12274271,and 11874243).
文摘Photonic moirésuperlattice as an emerging platform of flatbands can tightly confine the light inside the cavity and has important applications not only in linear optics but also in nonlinear optics.In this paper,we numerically investigate the third-and fifth-order harmonic generation(THG and FHG)in photonic moirésuperlattices fabricated by the nonlinear material silicon.The high conversion efficiency of THG and FHG is obtained at a relatively low intensity of fundamental light,e.g.,the maximum conversion efficiency of THG and FHG arrives even up to be 10^(−2) and 10^(−9) at the fundamental intensity of 30 kW/m^(2),respectively,in the moirésuperlattice of near flat band formed by the twist angle 6.01°.The results indicate the photonic moirésuperlattice of a high-quality factor and flatbands is a promising platform for efficient nonlinear processes and advanced photonic devices.
基金supported by the National Key Research and Development Program of China(No.2019YFA0705000)the National Natural Science Foundation of China(NSFC)(Nos.12104272,12192254,91750201,and 11974218)+1 种基金the Innovation Group of Jinan(No.2018GXRC010)the Local Science and Technology Development Project of the Central Government(No.YDZX20203700001766)。
文摘Self-healing in optics generally refers to the ability to reconstruct itself and restore the original state after encountering obstacles in the propagation of the light field.In this research,we observe the processes of the wave fields from perfect to defect in front of the focal plane of the 4f system,finally returning to an intact situation after the plane.According to simulations and experimental results,there is a minimum self-healing distance for the moirélattice field that positively associates with the radius of the defect[obstacle]in the nondiffracting transmission range.Furthermore,it is observed that the defect self-healing is a process of“repairing the center and then repairing the edges.”These findings can be applied in areas such as optical imaging,capture,and information processing.
基金Authors are thankful for the support of the National Natural Science Foundation of China (Grant Nos. 91750201,1152541 & 11774250 and 11804198),Project of the Priority Academic Program Development of Jiangsu Higher Education Institutions.
文摘Ever since vortex beams were proposed, they are known for owning phase singularity and carrying orbital angular momentum (OAM). In the past decades, coherent optics developed rapidly. Vortex beams have been extended from fully coherent light to partially coherent light, from scalar light to vector light, from integral topological charge (TC) to fractional TC. Partially coherent vortex beams have attracted tremendous interest due to their hidden correlation singularity and unique propagation properties (e.g., beam shaping, beam rotation and self-reconstruction). Based on the sufficient condition for devising a genuine correlation function of partially coherent beam, partially coherent vortex beams with nonconventional correlation functions (i.e., non-Gaussian correlated Schell-model functions) were introduced recently. This timely review summarizes basic concepts, theoretical models, generation and propagation of partially coherent vortex beams.
基金supported by the National Natural Science Foundation of China(Grant Nos.11874102,11525418,91750201,and 11974218)the Sichuan Province Science and Technology Support Program(Grant No.20CXRC0086)+1 种基金the Innovation Group of Jinan(Grant No.2018GXRC010)the Fundamental Research Funds for the Central Universities(Grant No.ZYGX2019J102)。
文摘It has been over 30 years since the concept of optical vortices was first proposed by Coullet et al.in 1989,and the field of structured beams has grown extremely.In the last two decades,partially coherent vortex beams(PCVBs)have received increasing interest in the fields of optical manipulation,optical communication,optical imaging,etc.,and great progress has been made in the area of the coherence singularities,generation methods,topological charge measurements,and promising applications of PCVBs.In this review,we firstly outline the basic concepts of PCVBs.We explicate the relationship between the coherence vortices and optical vortices,and the evolution behavior of optical vortices to coherence vortices is summarized in detail.We discuss a special form of coherence singularity,ring dislocation,mathematically and physically.The ring dislocation in the correlation functions under low coherence is dependent on the mode indices,which provide a feasible approach to measure mode indices of PCVBs.Subsequently,we summarize the various methods for measuring the topological charge of PCVBs,highlight the measurement method based on the cross-correlation function,and a physical explanation on the relation between ring dislocation and topological charge is given.After that,we review the recent advances on experimental generation of several kinds of PCVBs.Lastly,we give an overview on the potential applications of PCVBs.
基金supported by the National Key Research and Development Project of China(No.2019YFA0705000)the National Natural Science Foundation of China(NSFC)(Nos.11874243,11525418,91750201,and 11974218)+1 种基金the Innovation Group of Jinan(No.2018GXRC010)the Local Science and Technology Development Project of the Central Government(No.YDZX20203700001766)。
文摘Optical channel waveguides with depressed cladding configurations have been produced in Nd,Gd∶CaF_(2)laser crystals by using ultrafast laser inscription.Waveguide properties are investigated in terms of guiding behaviors and localized laserinduced lattice damages.Under an optical pump of 808 nm light,continuous-wave waveguide lasing at 1.06μm is achieved,with a single-mode operation and a minimum lasing threshold of 98.8 m W.Furthermore,the visible emissions of Nd^(3+)with short wavelengths ranging from 415 nm to 550 nm and long wavelengths from 550 nm to 625 nm are observed upon 808 nm laser excitation via the up-converted process.The intensity ratios of two wavelength ranges are proved to be tunable through changing the pumping polarizations.
基金supported by the National Key Research and Development Program of China(No.2019YFA0705000)the National Natural Science Foundation of China(NSFC)(Nos.12004219,12192254,91750201,and 11974218)+1 种基金the Innovation Group of Jinan(No.2018GXRC010)the Local Science and Technology Development Project of the Central Government(No.YDZX20203700001766)。
文摘Lommel beams have been potential candidates for optical communication and optical manipulation,due to their adjustable symmetry of transverse intensity distribution and continuously variable orbital angular momentum.However,the wavefront of the Lommel beam is scrambled when it transmits through highly scattering media.Here,we explore the construction of Lommel beams through highly scattering media with a transmission matrix-based point spread function engineering method.Experimentally,various Lommel beams with different parameters were generated through a ZnO scattering layer by use of a digital micromirror device.The construction of Lommel beams under high scattering is expected to benefit the optical applications behind highly scattering media.