As the combination of surface plasmon polariton and femtosecond laser pulse,femtosecond surface plasmon polariton has both nanoscale spatial resolution and femtosecond temporal resolution,and thus provides promising m...As the combination of surface plasmon polariton and femtosecond laser pulse,femtosecond surface plasmon polariton has both nanoscale spatial resolution and femtosecond temporal resolution,and thus provides promising methods for light field manipulation and light-matter interaction in extreme small spatiotemporal scales.Nowadays,the research on femtosecond surface plasmon polariton is mainly concentrated on two aspects:one is investigation and characterization of excitation,propagation,and dispersion properties of femtosecond surface plasmon polariton in different structures or materials;the other one is developing new applications based on its unique properties in the fields of nonlinear enhancement,pulse shaping,spatiotemporal super-resolved imaging,and others.Here,we introduce the research progress of properties and applications of femtosecond surface plasmon polariton,and prospect its future research trends.With the further development of femtosecond surface plasmon polariton research,it will have a profound impact on nano-optoelectronics,molecular dynamics,biomedicine and other fields.展开更多
On-chip manipulation of the spatiotemporal characteristics of optical signals is important in the transmission and processing of information.However,the simultaneous modulation of on-chip optical pulses,both spatially...On-chip manipulation of the spatiotemporal characteristics of optical signals is important in the transmission and processing of information.However,the simultaneous modulation of on-chip optical pulses,both spatially at the nano-scale and temporally over ultra-fast intervals,is challenging.Here,we propose a spatiotemporal Fourier transform method for on-chip control of the propagation of femtosecond optical pulses and verify this method employing surface plasmon polariton(SPP)pulses on metal surface.An analytical model is built for the method and proved by numerical simulations.By varying space-and frequency-dependent parameters,we demonstrate that the traditional SPP focal spot may be bent into a ring shape,and that the direction of propagation of a curved SPP-Airy beam may be reversed at certain moments to create an S-shaped path.Compared with conventional spatial modulation of SPPs,this method offers potentially a variety of extraordinary effects in SPP modulation especially associated with the temporal domain,thereby providing a new platform for on-chip spatiotemporal manipulation of optical pulses with applications including ultrafast on-chip photonic information processing,ultrafast pulse/beam shaping,and optical computing.展开更多
Backflow is a counterintuitive phenomenon that is widely predicted in the fields of quantum physics and optics.In contrast to quantum backflow,which is challenging to be observed,optical backflow is prevailing in stru...Backflow is a counterintuitive phenomenon that is widely predicted in the fields of quantum physics and optics.In contrast to quantum backflow,which is challenging to be observed,optical backflow is prevailing in structured lights.For instance,the azimuthal backflow has been recently observed experimentally in optics via the superposition of two beams carrying different orbital angular momentum topological charges.In this paper,we investigate the spin-momentum characteristics of the superimposed orbital angular momentum beams to confirm the optical azimuthal backflow,which is closely related to off-axis vortex flow and super-oscillations.Furthermore,we extend our study to axial backflow,characterized by a reversed axial energy flow in tightly focused cylindrical vector vortex beams.Then,we explore the application of optical backflow in the manipulation of dipolar nanoparticles.By optimizing material parameters,we achieve on-demand control of optical forces in both azimuthal and axial backflow scenarios.Our findings provide in-depth insights into the optical backflow phenomena with potential applications in optical manipulations.展开更多
The interactions between ultrafast lasers and materials reveal a range of nonlinear transient phenomena that are crucial in advanced manufacturing.Understanding these interactions during ultrafast laser ablation requi...The interactions between ultrafast lasers and materials reveal a range of nonlinear transient phenomena that are crucial in advanced manufacturing.Understanding these interactions during ultrafast laser ablation requires detailed measurements of material properties and structural changes with high temporal and spatial resolutions.Traditional spatiotemporal imaging techniques relying on reflective imaging often fail to capture comprehensive information,resulting in predominantly qualitative theoretical models of these interactions.To overcome this limitation,we propose a dual-modal ultrafast microscopy system that combines two-dimensional reflectivity and three-dimensional topography imaging.By integrating pump-probe techniques with an interferometric imaging system,impressive spatiotemporal resolutions of 236 nm and 256 fs were achieved.Furthermore,using this system,we successfully examined the dynamics of laser-induced periodic surface structure formation,strengthening,and erasure on Si surfaces.The results demonstrate that the dual-modal spatiotemporal imaging technique can serve as a robust tool for the comprehensive analysis of ablation dynamics,facilitating a deeper understanding of the fundamental physics involved and enabling more accurate optimisation of ultrafast laser fabrication processes.展开更多
Optical tweezers have proved to be a powerful tool with a wide range of applications.The gradient force plays a vital role in the stable optical trapping of nano-objects.The scalar method is convenient and effective f...Optical tweezers have proved to be a powerful tool with a wide range of applications.The gradient force plays a vital role in the stable optical trapping of nano-objects.The scalar method is convenient and effective for analyzing the gradient force in traditional optical trapping.However,when the third-order nonlinear effect of the nano-object is stimulated,the scalar method cannot adequately present the optical response of the metal nanoparticle to the external optical field.Here,we propose a theoretical model to interpret the nonlinear gradient force using the vector method.By combining the optical Kerr effect,the polarizability vector of the metallic nanoparticle is derived.A quantitative analysis is obtained for the gradient force as well as for the optical potential well.The vector method yields better agreement with reported experimental observations.We suggest that this method could lead to a deeper understanding of the physics relevant to nonlinear optical trapping and binding phenomena.展开更多
The topic of optical precise displacement measurement has garnered significant attention and generated widespread interest recently. The use of optical singularity offers a potential solution for this purpose, althoug...The topic of optical precise displacement measurement has garnered significant attention and generated widespread interest recently. The use of optical singularity offers a potential solution for this purpose, although effectively manipulating the singularity in an ideal manner remains challenging. In this work, we propose a theoretical approach to achieve controllable position modulation of the C-point in the focal plane, whose spatial position can be easily modulated by adjusting the relative offset factor β and the offset angle α of an azimuthal polarization beam(APB), while the interval and orientation of the C-points can be flexibly regulated. Notably, the chiral polarization state undergoes a distinct reversal along the link-line connecting the two C-points, thereby providing a promising approach for accurate displacement sensing. To evaluate its sensing characteristics, the varying pattern of the scattered field intensity is monitored when sweeping a gold helix and nanoparticle along the link-line. The results of simulation quality index Q verify that the equilibrium factor of the scattering field possesses an obvious linear relationship with the displacement, signifying a precise sub-nanometric sensitivity.This research introduces new methods for the flexible control of polarization singularities in tightly focused fields,thereby enhancing the utilization of circular polarization properties near C-points for displacement sensing.These findings not only enrich the field of nanometer measurement technology but also pave the way for new avenues of research in this domain.展开更多
Optical trapping has revolutionized various scientific disciplines with its non-invasive,high-resolution manipulation capabilities.However,conventional optical tweezers face limitations in effectively manipulating met...Optical trapping has revolutionized various scientific disciplines with its non-invasive,high-resolution manipulation capabilities.However,conventional optical tweezers face limitations in effectively manipulating metallic particles due to their high reflectivity and associated scattering forces.Plasmonic tweezers,harnessing surface plasmons in metallic nanostructures,offer a promising solution by confining light to deep subwavelength scales and enhancing optical forces.However,dynamically manipulating metallic particles with plasmonic tweezers without mechanical adjustments remains a significant challenge.In this paper,we propose a novel approach utilizing dynamic optical tweezers with tunable plasmonic fields for metallic particle manipulation.By dynamically tailoring plasmonic fields with holograms,metallic particles can be manipulated without mechanical adjustments.Finite-difference timedomain simulations and Maxwell stress tensor calculations demonstrate the effectiveness of this technique,which offers simplicity,precision,and motionlessness in metallic particle manipulation.This advancement holds promise for applications in surface-enhanced Raman scattering,biosensing,super-resolved detection,and nanoparticle assembly,opening new avenues in plasmonic tweezers technology.展开更多
Data transmission rates in optical communication systems are approaching the limits of conventional multiplexing methods.Orbital angular momentum(OAM)in optical vortex beams offers a new degree of freedom and the pote...Data transmission rates in optical communication systems are approaching the limits of conventional multiplexing methods.Orbital angular momentum(OAM)in optical vortex beams offers a new degree of freedom and the potential to increase the capacity of free-space optical communication systems,with OAM beams acting as information carriers for OAM division multiplexing(OAM-DM).We demonstrate independent collinear OAM channel generation,transmission and simultaneous detection using Dammann optical vortex gratings(DOVGs).We achieve 80/160 Tbit s^(-1) capacity with uniform power distributions along all channels,with 1600 individually modulated quadrature phase-shift keying(QPSK)/16-QAM data channels multiplexed by 10 OAM states,80 wavelengths and two polarizations.DOVG-enabled OAM multiplexing technology removes the bottleneck of massive OAM state parallel detection and offers an opportunity to raise optical communication systems capacity to Pbit s^(-1) level.展开更多
Thirty years ago,Coullet et al.proposed that a special optical field exists in laser cavities bearing some analogy with the superfluid vortex.Since then,optical vortices have been widely studied,inspired by the hydrod...Thirty years ago,Coullet et al.proposed that a special optical field exists in laser cavities bearing some analogy with the superfluid vortex.Since then,optical vortices have been widely studied,inspired by the hydrodynamics sharing similar mathematics.Akin to a fluid vortex with a central flow singularity,an optical vortex beam has a phase singularity with a certain topological charge,giving rise to a hollow intensity distribution.Such a beam with helical phase fronts and orbital angular momentum reveals a subtle connection between macroscopic physical optics and microscopic quantum optics.These amazing properties provide a new understanding of a wide range of optical and physical phenomena,including twisting photons,spin–orbital interactions,Bose-Einstein condensates,etc.,while the associated technologies for manipulating optical vortices have become increasingly tunable and flexible.Hitherto,owing to these salient properties and optical manipulation technologies,tunable vortex beams have engendered tremendous advanced applications such as optical tweezers,high-order quantum entanglement,and nonlinear optics.This article reviews the recent progress in tunable vortex technologies along with their advanced applications.展开更多
On-chip twisted light emitters are essential components of orbital angular momentum(OAM)communication devices1,2.These devices address the growing demand for high-capacity communication systems by providing an additio...On-chip twisted light emitters are essential components of orbital angular momentum(OAM)communication devices1,2.These devices address the growing demand for high-capacity communication systems by providing an additional degree of freedom for wavelength/frequency division multiplexing(WDM/FDM).Although whispering-gallery-mode-enabled OAM emitters have been shown to possess some advantages3–5,such as compactness and phase accuracy,their inherent narrow bandwidths prevent them from being compatible with WDM/FDM techniques.Here,we demonstrate an ultra-broadband multiplexed OAM emitter that utilizes a novel joint path-resonance phase control concept.The emitter has a micron-sized radius and nanometer-sized features.Coaxial OAM beams are emitted across the entire telecommunication band from 1,450 to 1,650 nm.We applied the emitter to an OAM communication with a data rate of 1.2 Tbit/s assisted by 30-channel optical frequency combs(OFCs).The emitter provides a new solution to further increase capacity in the OFC communication scenario.展开更多
Phase and polarization singularities are important degrees of freedom for electromagnetic field manipulation.Detecting these singularities is essential for modern optics,but it is still a challenge,especially in integ...Phase and polarization singularities are important degrees of freedom for electromagnetic field manipulation.Detecting these singularities is essential for modern optics,but it is still a challenge,especially in integrated optical systems.In this paper,we propose an on-chip plasmonic spin-Hall nanograting structure that simultaneously detects both the polarization and phase singularities of the incident cylindrical vortex vector beam(CVVB).The nanograting is symmetry-breaking with different periods for the upper and lower parts,which enables the unidirectional excitation of the surface plasmon polariton depending on the topological charge of the incident optical vortex beam.Additionally,spin-Hall meta-slits are integrated onto the grating so that the structure has a chiral response for polarization detection.We demonstrate theoretically and experimentally that the designed structure fully discriminates both the topological charges and polarization states of the incident beam simultaneously.The proposed structure has great potential in compact integrated photonic circuits.展开更多
Optical tweezers and associated manipulation tools in the far field have had a major impact on scientific and engineering research by offering precise manipulation of small objects.More recently,the possibility of per...Optical tweezers and associated manipulation tools in the far field have had a major impact on scientific and engineering research by offering precise manipulation of small objects.More recently,the possibility of performing manipulation with surface plasmons has opened opportunities not feasible with conventional far-field optical methods.The use of surface plasmon techniques enables excitation of hotspots much smaller than the free-space wavelength;with this confinement,the plasmonic field facilitates trapping of various nanostructures and materials with higher precision.The successful manipulation of small particles has fostered numerous and expanding applications.In this paper,we review the principles of and developments in plasmonic tweezers techniques,including both nanostructure-assisted platforms and structureless systems.Construction methods and evaluation criteria of the techniques are presented,aiming to provide a guide for the design and optimization of the systems.The most common novel applications of plasmonic tweezers,namely,sorting and transport,sensing and imaging,and especially those in a biological context,are critically discussed.Finally,we consider the future of the development and new potential applications of this technique and discuss prospects for its impact on science.展开更多
Strong plasmonic focal spots, excited by radially polarized light on a smooth thin metallic film, have been widely applied to trap various micro-and nano-sized objects. However, the direct transmission part of the inc...Strong plasmonic focal spots, excited by radially polarized light on a smooth thin metallic film, have been widely applied to trap various micro-and nano-sized objects. However, the direct transmission part of the incident light leads to the scattering force exerted on trapped particles, which seriously affects the stability of the plasmonic trap.Here we employ a novel perfect radially polarized beam to solve this problem. Both theoretical and experimental results verify that such a beam could strongly suppress the directly transmitted light to reduce the piconewton scattering force, and an enhanced plasmonic trapping stiffness that is 2.6 times higher is achieved in experiments.The present work opens up new opportunities for a variety of research requiring the stable manipulations of particles.展开更多
Polarization imaging finds applications in many areas, such as photoelasticity, ellipsometry, and biomedical imaging. A compact, snapshot, and high-efficiency imaging polarimeter is highly desirable for many applicati...Polarization imaging finds applications in many areas, such as photoelasticity, ellipsometry, and biomedical imaging. A compact, snapshot, and high-efficiency imaging polarimeter is highly desirable for many applications.Here, based on a single multifunctional geometric phase optical element(GPOE), a new method is proposed for high-efficiency snapshot imaging polarimetry. With tailored spatially varying orientation of each anisotropic unit cell, the GPOE works highly efficiently as both a spin sorter and a half-wave plate, enabling snapshot retrieving of a full Stokes vector of incident light. The designed GPOE is implemented in the form of liquid crystal fabricated with a photo-alignment technology, and its application in imaging polarimetry is experimentally demonstrated by retrieving full Stokes parameters of a cylinder vector beam. This method can also work in the form of plasmonic or dielectric metasurfaces, enabling ultra-compact polarization detection systems by monolithic integration with other devices such as metalenses.展开更多
Nonlinear responses of nanoparticles induce enlightening phenomena in optical tweezers. With thegradual increase in optical intensity, effects from saturable absorption (SA) and reverse SA (RSA) arise insequence and t...Nonlinear responses of nanoparticles induce enlightening phenomena in optical tweezers. With thegradual increase in optical intensity, effects from saturable absorption (SA) and reverse SA (RSA) arise insequence and thereby modulate the nonlinear properties of materials. In current nonlinear optical traps,however, the underlying physical mechanism is mainly confined within the SA regime because thresholdvalues required to excite the RSA regime are extremely high. Herein, we demonstrate, both in theory andexperiment, nonlinear optical tweezing within the RSA regime, proving that a fascinating composite trappingstate is achievable at ultrahigh intensities through an optical force reversal induced through nonlinearabsorption. Integrated results help in perfecting the nonlinear optical trapping system, thereby providingbeneficial guidance for wider applications of nonlinear optics.展开更多
Optical surface waves have widely been used in optical tweezers systems for trapping particles sized from the nanoto microscale,with specific importance and needs in applications of super-resolved detection and imagin...Optical surface waves have widely been used in optical tweezers systems for trapping particles sized from the nanoto microscale,with specific importance and needs in applications of super-resolved detection and imaging if a single particle can be trapped and manipulated accurately.However,it is difficult to achieve such trapping with high precision in conventional optical surface-wave tweezers.Here,we propose and experimentally demonstrate a new method to accurately trap and dynamically manipulate a single particle or a desired number of particles in holographic optical surface-wave tweezers.By tailoring the optical potential wells formed by surface waves,we achieved trapping of the targeted single particle while pushing away all surrounding particles and further dynamically controlling the particle by a holographic tweezers beam.We also prove that different particle samples,including gold particles and biological cells,can be applied in our system.This method can be used for different-type optical surface-wave tweezers,with significant potential applications in single-particle spectroscopy,particle sorting,nano-assembly,and others.展开更多
Optical traps use focused laser beams to generate forces on targeted objects ranging in size from nanometers to micrometers. However, for their high coefficients of scattering and absorption, micrometer-sized metallic...Optical traps use focused laser beams to generate forces on targeted objects ranging in size from nanometers to micrometers. However, for their high coefficients of scattering and absorption, micrometer-sized metallic particles were deemed non-trappable in three dimensions using a single beam. This barrier is now removed. We demon- strate, both in theory and experiment, three-dimensional （3D） dynamic all-optical manipulations of micrometer- sized gold particles under high focusing conditions. The force of gravity is found to balance the positive axial optical force exerted on particles in an inverted optical tweezers system to form two trapping positions along the vertical direction. Both theoretical and experimental results confirm that stable 3D manipulations are achievable for these particles regardl for a variety of in-depth ess of beam polarization and wavelength. research requiting metallic particles. The present work opens up new opportunities .展开更多
Imaging ultrafast processes in femtosecond(fs) laser–material interactions such as fs laser ablation is very important to understand the physical mechanisms involved. To achieve this goal with high resolutions in bot...Imaging ultrafast processes in femtosecond(fs) laser–material interactions such as fs laser ablation is very important to understand the physical mechanisms involved. To achieve this goal with high resolutions in both spatial and temporal domains, a combination of optical pump–probe microscopy and structured illumination microscopy can be a promising approach, but suffers from the multiple-frame method with a phase shift that is inapplicable to irreversible ultrafast processes such as ablation. Here, we propose and build a wide-field singleprobe structured light microscopy(SPSLM) to image the ultrafast three-dimensional topography evolution induced by fs lasers, where only a single imaging frame with a single structured probe pulse is required for topography reconstruction, benefiting from Fourier transform profilometry. The second harmonic of the fs laser is used as the structured probe light to improve spatial lateral resolution into the subwavelength region of ~478 nm, and the spatial axial and temporal resolutions are estimated to be ~22 nm and ~256 fs, respectively. With SPSLM, we successfully image the ultrafast topography evolution of a silicon wafer surface impacted by single and multiple fs pulses. The variable formation and evolution of the laser induced periodic surface structures during an ultrashort time are visualized and analyzed. We believe that SPSLM will be a significant approach for revealing and understanding various ultrafast dynamics, especially in fs laser ablation and material science.展开更多
Because of the fingerprint-like specificity of its characteristic spectrogram, Raman spectral imaging has been applied widely in various research areas. Using a combination of structured illumination with the surface-...Because of the fingerprint-like specificity of its characteristic spectrogram, Raman spectral imaging has been applied widely in various research areas. Using a combination of structured illumination with the surface- enhanced Raman scattering （SERS） technique, wide-field Raman imaging is developed with a significant improve- ment in spatial resolution. As a result of the relatively narrow Raman characteristic peaks, optically encoded SERS nanoparticles can be used to perform multiplexed imaging. The results show excellent superresolution wide-fidd multiplexed imaging performance. The developed technique has extraordinary potential for applications in biological imaging and other related fields.展开更多
Cell identification and sorting have been hot topics recently.However,most conventional approaches can only predict the category of a single target,and lack the ability to perform multitarget tasks to provide coordina...Cell identification and sorting have been hot topics recently.However,most conventional approaches can only predict the category of a single target,and lack the ability to perform multitarget tasks to provide coordinate information of the targets.This limits the development of high-throughput cell screening technologies.Fortunately,artificial intelligence(AI)systems based on deep-learning algorithms provide the possibility to extract hidden features of cells from original image information.Here,we demonstrate an AI-assisted multitarget processing system for cell identification and sorting.With this system,each target cell can be swiftly and accurately identified in a mixture by extracting cell morphological features,whereafter accurate cell sorting is achieved through noninvasive manipulation by optical tweezers.The AI-assisted model shows promise in guiding the precise manipulation and intelligent detection of high-flux cells,thereby realizing semiautomatic cell research.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.91750205,61427819,U1701661,11674178,and 61975128)the Leading Talents of Guangdong Province Program,China(Grant No.00201505)+2 种基金the Natural Science Foundation of Guangdong Province,China(Grant Nos.2016A030312010 and 2017A030313351)the Science and Technology Innovation Commission of Shenzhen City(Grant Nos.JCYJ20180507182035270,KQTD2017033011044403,KQJSCX20170727100838364,ZDSYS201703031605029,and JCYJ2017818144338999)the K.C.Wong Education Foundation(Grant No.GJTD-2018-08)。
文摘As the combination of surface plasmon polariton and femtosecond laser pulse,femtosecond surface plasmon polariton has both nanoscale spatial resolution and femtosecond temporal resolution,and thus provides promising methods for light field manipulation and light-matter interaction in extreme small spatiotemporal scales.Nowadays,the research on femtosecond surface plasmon polariton is mainly concentrated on two aspects:one is investigation and characterization of excitation,propagation,and dispersion properties of femtosecond surface plasmon polariton in different structures or materials;the other one is developing new applications based on its unique properties in the fields of nonlinear enhancement,pulse shaping,spatiotemporal super-resolved imaging,and others.Here,we introduce the research progress of properties and applications of femtosecond surface plasmon polariton,and prospect its future research trends.With the further development of femtosecond surface plasmon polariton research,it will have a profound impact on nano-optoelectronics,molecular dynamics,biomedicine and other fields.
基金the Guangdong Major Project of Basic and Applied Basic Research (2020B0301030009)National Natural Science Foundation of China (91750205,62175157,61935013,61975128)+2 种基金Leading Talents of Guangdong Province Program (00201505)Natural Science Foundation of Guangdong Province (2019TQ05X750)Shenzhen ScienceandTechnologyProgram(JCYJ20210324120403011,KQTD20170330110444030,RCJC20210609103232046)
文摘On-chip manipulation of the spatiotemporal characteristics of optical signals is important in the transmission and processing of information.However,the simultaneous modulation of on-chip optical pulses,both spatially at the nano-scale and temporally over ultra-fast intervals,is challenging.Here,we propose a spatiotemporal Fourier transform method for on-chip control of the propagation of femtosecond optical pulses and verify this method employing surface plasmon polariton(SPP)pulses on metal surface.An analytical model is built for the method and proved by numerical simulations.By varying space-and frequency-dependent parameters,we demonstrate that the traditional SPP focal spot may be bent into a ring shape,and that the direction of propagation of a curved SPP-Airy beam may be reversed at certain moments to create an S-shaped path.Compared with conventional spatial modulation of SPPs,this method offers potentially a variety of extraordinary effects in SPP modulation especially associated with the temporal domain,thereby providing a new platform for on-chip spatiotemporal manipulation of optical pulses with applications including ultrafast on-chip photonic information processing,ultrafast pulse/beam shaping,and optical computing.
基金National Natural Science Foundation of China(12174266,92250304,61935013)Basic and Applied Basic Research Foundation of Guangdong Province(2020B0301030009)Research Team Cultivation Program of Shenzhen University(2023QNT014)。
文摘Backflow is a counterintuitive phenomenon that is widely predicted in the fields of quantum physics and optics.In contrast to quantum backflow,which is challenging to be observed,optical backflow is prevailing in structured lights.For instance,the azimuthal backflow has been recently observed experimentally in optics via the superposition of two beams carrying different orbital angular momentum topological charges.In this paper,we investigate the spin-momentum characteristics of the superimposed orbital angular momentum beams to confirm the optical azimuthal backflow,which is closely related to off-axis vortex flow and super-oscillations.Furthermore,we extend our study to axial backflow,characterized by a reversed axial energy flow in tightly focused cylindrical vector vortex beams.Then,we explore the application of optical backflow in the manipulation of dipolar nanoparticles.By optimizing material parameters,we achieve on-demand control of optical forces in both azimuthal and axial backflow scenarios.Our findings provide in-depth insights into the optical backflow phenomena with potential applications in optical manipulations.
基金supported by the Guangdong Major Project of Basic and Applied Basic Research(2020B0301030009)National Natural Science Foundation of China(62175157,62375177,and 92150301)+2 种基金Shenzhen Science and Technology Program(JCYJ20210324120403011,RCJC20210609103232046)Research Team Cultivation Program of Shen Zhen University(2023QNT014)Shenzhen University 2035 Initiative(2023B004).
文摘The interactions between ultrafast lasers and materials reveal a range of nonlinear transient phenomena that are crucial in advanced manufacturing.Understanding these interactions during ultrafast laser ablation requires detailed measurements of material properties and structural changes with high temporal and spatial resolutions.Traditional spatiotemporal imaging techniques relying on reflective imaging often fail to capture comprehensive information,resulting in predominantly qualitative theoretical models of these interactions.To overcome this limitation,we propose a dual-modal ultrafast microscopy system that combines two-dimensional reflectivity and three-dimensional topography imaging.By integrating pump-probe techniques with an interferometric imaging system,impressive spatiotemporal resolutions of 236 nm and 256 fs were achieved.Furthermore,using this system,we successfully examined the dynamics of laser-induced periodic surface structure formation,strengthening,and erasure on Si surfaces.The results demonstrate that the dual-modal spatiotemporal imaging technique can serve as a robust tool for the comprehensive analysis of ablation dynamics,facilitating a deeper understanding of the fundamental physics involved and enabling more accurate optimisation of ultrafast laser fabrication processes.
基金supported by the Key Research Project of Zhejiang Lab(No.2022MG0AC05)the Guangdong Major Project of Basic and Applied Basic Research(No.2020B0301030009)+3 种基金the National Natural Science Foundation of China(Nos.61975128,61935013,and 62175157)the Shenzhen Science and Technology Program(Nos.JCYJ20210324120403011 and RCJC20210609103232046)the Natural Science Foundation of Guangdong Province(No.2019TQ05X750)the Shenzhen Peacock Plan(No.KQTD20170330110444030)。
文摘Optical tweezers have proved to be a powerful tool with a wide range of applications.The gradient force plays a vital role in the stable optical trapping of nano-objects.The scalar method is convenient and effective for analyzing the gradient force in traditional optical trapping.However,when the third-order nonlinear effect of the nano-object is stimulated,the scalar method cannot adequately present the optical response of the metal nanoparticle to the external optical field.Here,we propose a theoretical model to interpret the nonlinear gradient force using the vector method.By combining the optical Kerr effect,the polarizability vector of the metallic nanoparticle is derived.A quantitative analysis is obtained for the gradient force as well as for the optical potential well.The vector method yields better agreement with reported experimental observations.We suggest that this method could lead to a deeper understanding of the physics relevant to nonlinear optical trapping and binding phenomena.
基金Guangdong Major Project of Basic and Applied Basic Research (2020B0301030009)National Natural Science Foundation of China (62375177,62175157, 12304330, 92250304, 92150301)+3 种基金Shenzhen Science and Technology Program (JCYJ20210324120403011,RCJC20210609103232046)Shenzhen Peacock Plan(KQTD20170330110444030)China Postdoctoral Science Foundation (2022M722906)Natural Science Foundation of Zhejiang Province (LQ24F050014)。
文摘The topic of optical precise displacement measurement has garnered significant attention and generated widespread interest recently. The use of optical singularity offers a potential solution for this purpose, although effectively manipulating the singularity in an ideal manner remains challenging. In this work, we propose a theoretical approach to achieve controllable position modulation of the C-point in the focal plane, whose spatial position can be easily modulated by adjusting the relative offset factor β and the offset angle α of an azimuthal polarization beam(APB), while the interval and orientation of the C-points can be flexibly regulated. Notably, the chiral polarization state undergoes a distinct reversal along the link-line connecting the two C-points, thereby providing a promising approach for accurate displacement sensing. To evaluate its sensing characteristics, the varying pattern of the scattered field intensity is monitored when sweeping a gold helix and nanoparticle along the link-line. The results of simulation quality index Q verify that the equilibrium factor of the scattering field possesses an obvious linear relationship with the displacement, signifying a precise sub-nanometric sensitivity.This research introduces new methods for the flexible control of polarization singularities in tightly focused fields,thereby enhancing the utilization of circular polarization properties near C-points for displacement sensing.These findings not only enrich the field of nanometer measurement technology but also pave the way for new avenues of research in this domain.
基金National Natural Science Foundation of China(62175162)Scientific Instrument Developing Project of Shenzhen University(2023YQ001)+1 种基金Shenzhen University 2035 Program for Excellent Research(2022C013)Research Team Cultivation Program of Shenzhen University(2023QNT012).
文摘Optical trapping has revolutionized various scientific disciplines with its non-invasive,high-resolution manipulation capabilities.However,conventional optical tweezers face limitations in effectively manipulating metallic particles due to their high reflectivity and associated scattering forces.Plasmonic tweezers,harnessing surface plasmons in metallic nanostructures,offer a promising solution by confining light to deep subwavelength scales and enhancing optical forces.However,dynamically manipulating metallic particles with plasmonic tweezers without mechanical adjustments remains a significant challenge.In this paper,we propose a novel approach utilizing dynamic optical tweezers with tunable plasmonic fields for metallic particle manipulation.By dynamically tailoring plasmonic fields with holograms,metallic particles can be manipulated without mechanical adjustments.Finite-difference timedomain simulations and Maxwell stress tensor calculations demonstrate the effectiveness of this technique,which offers simplicity,precision,and motionlessness in metallic particle manipulation.This advancement holds promise for applications in surface-enhanced Raman scattering,biosensing,super-resolved detection,and nanoparticle assembly,opening new avenues in plasmonic tweezers technology.
基金This work was partially supported by the National Natural Science Foundation of China under Grant numbers 61036013,61138003,61427819,61001101 and 61435006XY acknowledges support from the Ministry of Science and Technology of China under National Basic Research Program of China(973)grant no.2015CB352004.
文摘Data transmission rates in optical communication systems are approaching the limits of conventional multiplexing methods.Orbital angular momentum(OAM)in optical vortex beams offers a new degree of freedom and the potential to increase the capacity of free-space optical communication systems,with OAM beams acting as information carriers for OAM division multiplexing(OAM-DM).We demonstrate independent collinear OAM channel generation,transmission and simultaneous detection using Dammann optical vortex gratings(DOVGs).We achieve 80/160 Tbit s^(-1) capacity with uniform power distributions along all channels,with 1600 individually modulated quadrature phase-shift keying(QPSK)/16-QAM data channels multiplexed by 10 OAM states,80 wavelengths and two polarizations.DOVG-enabled OAM multiplexing technology removes the bottleneck of massive OAM state parallel detection and offers an opportunity to raise optical communication systems capacity to Pbit s^(-1) level.
基金funded by The National Key Research and Development Program of China(Grant No.2017YFB1104500)Natural Science Foundation of Beijing Municipality(4172030)+3 种基金Beijing Young Talents Support Project(2017000020124G044)Leading talents of Guangdong province program(00201505)National Natural Science Foundation of China(U1701661,91750205,61975133,11604218,61975087)Natural Science Foundation of Guangdong Province(2016A030312010,2017A030313351).
文摘Thirty years ago,Coullet et al.proposed that a special optical field exists in laser cavities bearing some analogy with the superfluid vortex.Since then,optical vortices have been widely studied,inspired by the hydrodynamics sharing similar mathematics.Akin to a fluid vortex with a central flow singularity,an optical vortex beam has a phase singularity with a certain topological charge,giving rise to a hollow intensity distribution.Such a beam with helical phase fronts and orbital angular momentum reveals a subtle connection between macroscopic physical optics and microscopic quantum optics.These amazing properties provide a new understanding of a wide range of optical and physical phenomena,including twisting photons,spin–orbital interactions,Bose-Einstein condensates,etc.,while the associated technologies for manipulating optical vortices have become increasingly tunable and flexible.Hitherto,owing to these salient properties and optical manipulation technologies,tunable vortex beams have engendered tremendous advanced applications such as optical tweezers,high-order quantum entanglement,and nonlinear optics.This article reviews the recent progress in tunable vortex technologies along with their advanced applications.
基金supported by the National Natural Science Foundation of China(Grant Nos.U1701661,61490712,61525502,61435006,61490715,91750205,11774240,11604218,61601199)the National Key Research and Development Program of China(Grant No.2016YFC0102401)+6 种基金the National Basic Research Program of China(973)(Grant No.2015CB352004)the support given by the leading talents of Guangdong province program no.00201505the Natural Science Foundation of Guangdong Province,China(No.2016A030312010)the Science and Technology Innovation Commission of Shenzhen under grant Nos.KQTD2015071016560101,KQJSCX20170727100838364,KQJSCX20160226193555889 and ZDSYS201703031605029the support of the Guangdong Natural Science Foundation No.2017A030313351Excellent Young Teacher Program No.YQ2014151the support of the National Research Foundation of Singapore(NRF-CRP12-2013-04)。
文摘On-chip twisted light emitters are essential components of orbital angular momentum(OAM)communication devices1,2.These devices address the growing demand for high-capacity communication systems by providing an additional degree of freedom for wavelength/frequency division multiplexing(WDM/FDM).Although whispering-gallery-mode-enabled OAM emitters have been shown to possess some advantages3–5,such as compactness and phase accuracy,their inherent narrow bandwidths prevent them from being compatible with WDM/FDM techniques.Here,we demonstrate an ultra-broadband multiplexed OAM emitter that utilizes a novel joint path-resonance phase control concept.The emitter has a micron-sized radius and nanometer-sized features.Coaxial OAM beams are emitted across the entire telecommunication band from 1,450 to 1,650 nm.We applied the emitter to an OAM communication with a data rate of 1.2 Tbit/s assisted by 30-channel optical frequency combs(OFCs).The emitter provides a new solution to further increase capacity in the OFC communication scenario.
基金partially supported by the National Natural Science Foundation of China(91750205,U1701661,61935013,61905147)Leading Talents Program of Guangdong Province(00201505,2019JC01Y178)+2 种基金Natural Science Foundation of Guangdong Province(2016A030312010,2020A1515010598)Shenzhen Science and Technology Innovation Commission(JCYJ20180507182035270,KQTD2017033011044403,KQTD20180412181324255)Shenzhen university starting funding(2019073).
文摘Phase and polarization singularities are important degrees of freedom for electromagnetic field manipulation.Detecting these singularities is essential for modern optics,but it is still a challenge,especially in integrated optical systems.In this paper,we propose an on-chip plasmonic spin-Hall nanograting structure that simultaneously detects both the polarization and phase singularities of the incident cylindrical vortex vector beam(CVVB).The nanograting is symmetry-breaking with different periods for the upper and lower parts,which enables the unidirectional excitation of the surface plasmon polariton depending on the topological charge of the incident optical vortex beam.Additionally,spin-Hall meta-slits are integrated onto the grating so that the structure has a chiral response for polarization detection.We demonstrate theoretically and experimentally that the designed structure fully discriminates both the topological charges and polarization states of the incident beam simultaneously.The proposed structure has great potential in compact integrated photonic circuits.
基金the National Natural Science Foundation of China(91750205,61975128,61975129 and 61427819)Leading Talents of Guangdong Province Programme(00201505)+1 种基金Natural Science Foundation of Guangdong Province(2016A030312010 and 2019TQ05X750)and Science and Technology Innovation Commission of Shenzhen(KQTD2017033011044403,ZDSYS201703031605029,KQTD20180412181324255,JCYJ20180305125418079,andJCYJ2017818144338999).
文摘Optical tweezers and associated manipulation tools in the far field have had a major impact on scientific and engineering research by offering precise manipulation of small objects.More recently,the possibility of performing manipulation with surface plasmons has opened opportunities not feasible with conventional far-field optical methods.The use of surface plasmon techniques enables excitation of hotspots much smaller than the free-space wavelength;with this confinement,the plasmonic field facilitates trapping of various nanostructures and materials with higher precision.The successful manipulation of small particles has fostered numerous and expanding applications.In this paper,we review the principles of and developments in plasmonic tweezers techniques,including both nanostructure-assisted platforms and structureless systems.Construction methods and evaluation criteria of the techniques are presented,aiming to provide a guide for the design and optimization of the systems.The most common novel applications of plasmonic tweezers,namely,sorting and transport,sensing and imaging,and especially those in a biological context,are critically discussed.Finally,we consider the future of the development and new potential applications of this technique and discuss prospects for its impact on science.
基金National Natural Science Foundation of China(NSFC)(61427819,61490712,91750205,U1701661,61605117,11604219)National Key Basic Research Program of China(973)(2015CB352004)+5 种基金National Key Research and Development Program of China(2016YFC0102401)Leading Talents Program of Guangdong Province(00201505)Natural Science Foundation of Guangdong Province(2016A030312010,2016A030310063,2017A030313351)Science and Technology Innovation Commission of Shenzhen(KQTD2015071016560101,KQTD2017033011044403,ZDSYS201703031605029,JCYJ2017818144338999)Excellent Young Teacher Program of Guangdong Province(YQ2014151)China Post-doctoral Science Foundation(2017M612722)
文摘Strong plasmonic focal spots, excited by radially polarized light on a smooth thin metallic film, have been widely applied to trap various micro-and nano-sized objects. However, the direct transmission part of the incident light leads to the scattering force exerted on trapped particles, which seriously affects the stability of the plasmonic trap.Here we employ a novel perfect radially polarized beam to solve this problem. Both theoretical and experimental results verify that such a beam could strongly suppress the directly transmitted light to reduce the piconewton scattering force, and an enhanced plasmonic trapping stiffness that is 2.6 times higher is achieved in experiments.The present work opens up new opportunities for a variety of research requiring the stable manipulations of particles.
基金National Natural Science Foundation of China(NSFC)(11604219,61427819,61490712,61605117,91750205,U1701661)Natural Science Foundation of Guangdong Province(2016A030310063,2016A030312010,2017A030313351)+2 种基金Shenzhen Science and Technology Innovation Commission(JCYJ20180507182035270,JCYJ2017818144338999,KQTD2017033011044403,ZDSYS201703031605029)Ministry of Science and Technology of the People’s Republic of China(MOST)(2015CB352004)Guangdong Science and Technology Department(GDSTC)(00201505)
文摘Polarization imaging finds applications in many areas, such as photoelasticity, ellipsometry, and biomedical imaging. A compact, snapshot, and high-efficiency imaging polarimeter is highly desirable for many applications.Here, based on a single multifunctional geometric phase optical element(GPOE), a new method is proposed for high-efficiency snapshot imaging polarimetry. With tailored spatially varying orientation of each anisotropic unit cell, the GPOE works highly efficiently as both a spin sorter and a half-wave plate, enabling snapshot retrieving of a full Stokes vector of incident light. The designed GPOE is implemented in the form of liquid crystal fabricated with a photo-alignment technology, and its application in imaging polarimetry is experimentally demonstrated by retrieving full Stokes parameters of a cylinder vector beam. This method can also work in the form of plasmonic or dielectric metasurfaces, enabling ultra-compact polarization detection systems by monolithic integration with other devices such as metalenses.
基金This work was supported by the Guangdong Major Project of Basic and Applied Basic Research(Grant No.2020B0301030009)the National Natural Science Foundation of China(Grant Nos.61975128,61935013,and 62175157)+3 种基金the Shenzhen Science and Technology Program(Grant Nos.JCYJ20210324120403011 and RCJC20210609103232046)the Natural Science Foundation of Guangdong Province(Grant No.2019TQ05X750)the Key Research Project of Zhejiang Lab(Grant No.2022MG0AC05)thre Shenzhen Peacock Plan(Grant No.KQTD20170330110444030)。
文摘Nonlinear responses of nanoparticles induce enlightening phenomena in optical tweezers. With thegradual increase in optical intensity, effects from saturable absorption (SA) and reverse SA (RSA) arise insequence and thereby modulate the nonlinear properties of materials. In current nonlinear optical traps,however, the underlying physical mechanism is mainly confined within the SA regime because thresholdvalues required to excite the RSA regime are extremely high. Herein, we demonstrate, both in theory andexperiment, nonlinear optical tweezing within the RSA regime, proving that a fascinating composite trappingstate is achievable at ultrahigh intensities through an optical force reversal induced through nonlinearabsorption. Integrated results help in perfecting the nonlinear optical trapping system, thereby providingbeneficial guidance for wider applications of nonlinear optics.
基金Guangdong Major Project of Basic and Applied Basic Research(2020B0301030009)National Natural Science Foundation of China(91750205,61935013,62175157,61975128,61975129)+3 种基金Leading Talents of Guangdong Province Program(00201505)Natural Science Foundation of Guangdong Province(2016A030312010,2019TQ05X750)Shenzhen Peacock Plan(KQTD20170330110444030)Science and Technology Innovation Commission of Shenzhen(JCYJ20180305125418079,JCYJ20180507182035270,JCYJ20210324120403011,ZDSYS201703031605029)。
文摘Optical surface waves have widely been used in optical tweezers systems for trapping particles sized from the nanoto microscale,with specific importance and needs in applications of super-resolved detection and imaging if a single particle can be trapped and manipulated accurately.However,it is difficult to achieve such trapping with high precision in conventional optical surface-wave tweezers.Here,we propose and experimentally demonstrate a new method to accurately trap and dynamically manipulate a single particle or a desired number of particles in holographic optical surface-wave tweezers.By tailoring the optical potential wells formed by surface waves,we achieved trapping of the targeted single particle while pushing away all surrounding particles and further dynamically controlling the particle by a holographic tweezers beam.We also prove that different particle samples,including gold particles and biological cells,can be applied in our system.This method can be used for different-type optical surface-wave tweezers,with significant potential applications in single-particle spectroscopy,particle sorting,nano-assembly,and others.
基金National Natural Science Foundation of China(NSFC)(91750205,61377052,61422506,61427819,61605117)National Key Basic Research Program of China(973)(2015CB352004)+3 种基金National Key Research and Development Program of China(2016YFC0102401)Leading Talents of Guangdong Province Program(00201505)Natural Science Foundation of Guangdong Province(2016A030312010,2016A030310063)Excellent Young Teacher Program of Guangdong Province(YQ2014151)
文摘Optical traps use focused laser beams to generate forces on targeted objects ranging in size from nanometers to micrometers. However, for their high coefficients of scattering and absorption, micrometer-sized metallic particles were deemed non-trappable in three dimensions using a single beam. This barrier is now removed. We demon- strate, both in theory and experiment, three-dimensional （3D） dynamic all-optical manipulations of micrometer- sized gold particles under high focusing conditions. The force of gravity is found to balance the positive axial optical force exerted on particles in an inverted optical tweezers system to form two trapping positions along the vertical direction. Both theoretical and experimental results confirm that stable 3D manipulations are achievable for these particles regardl for a variety of in-depth ess of beam polarization and wavelength. research requiting metallic particles. The present work opens up new opportunities .
基金Guangdong Major Project of Basic and Applied Basic Research(2020B0301030009)National Natural Science Foundation of China(62175157,61935013,61975128,62005175)+3 种基金Leading Talents of Guangdong Province(00201505)Natural Science Foundation of Guangdong Province(2019TQ05X750)Shenzhen Science and Technology Program(JCYJ20210324120403011,KQTD20170330110444030,RCJC20210609103232046)Jilin Provincial Science&Technology Development Project(20200201086JC)。
文摘Imaging ultrafast processes in femtosecond(fs) laser–material interactions such as fs laser ablation is very important to understand the physical mechanisms involved. To achieve this goal with high resolutions in both spatial and temporal domains, a combination of optical pump–probe microscopy and structured illumination microscopy can be a promising approach, but suffers from the multiple-frame method with a phase shift that is inapplicable to irreversible ultrafast processes such as ablation. Here, we propose and build a wide-field singleprobe structured light microscopy(SPSLM) to image the ultrafast three-dimensional topography evolution induced by fs lasers, where only a single imaging frame with a single structured probe pulse is required for topography reconstruction, benefiting from Fourier transform profilometry. The second harmonic of the fs laser is used as the structured probe light to improve spatial lateral resolution into the subwavelength region of ~478 nm, and the spatial axial and temporal resolutions are estimated to be ~22 nm and ~256 fs, respectively. With SPSLM, we successfully image the ultrafast topography evolution of a silicon wafer surface impacted by single and multiple fs pulses. The variable formation and evolution of the laser induced periodic surface structures during an ultrashort time are visualized and analyzed. We believe that SPSLM will be a significant approach for revealing and understanding various ultrafast dynamics, especially in fs laser ablation and material science.
基金National Natural Science Foundation of China(NSFC)(61490712,61427819,91750205,61605117)National Key Basic Research Program of China(973)(2015CB352004)+4 种基金Leading Talents of Guangdong Province Program(00201505)Natural Science Foundation of Guangdong Province(2016A030312010,2016A030310063,2017A030313351)National Key Research and Development Program of China(2016YFC0102401)Science and Technology Innovation Commission of Shenzhen(KQTD2017033011044403,KQTD2015071016560101,ZDSYS201703031605029)Excellent Young Teacher Program of Guangdong Province(YQ2014151)
文摘Because of the fingerprint-like specificity of its characteristic spectrogram, Raman spectral imaging has been applied widely in various research areas. Using a combination of structured illumination with the surface- enhanced Raman scattering （SERS） technique, wide-field Raman imaging is developed with a significant improve- ment in spatial resolution. As a result of the relatively narrow Raman characteristic peaks, optically encoded SERS nanoparticles can be used to perform multiplexed imaging. The results show excellent superresolution wide-fidd multiplexed imaging performance. The developed technique has extraordinary potential for applications in biological imaging and other related fields.
基金supported by the National Natural Science Foundation of China(Nos.61975128,62175157,92150301,and 62375177)the Shenzhen Science and Technology Program(Nos.JCYJ20210324120403011 and RCJC20210609103232046)the Guangdong Major Project of Basic and Applied Basic Research(No.2020B0301030009)。
文摘Cell identification and sorting have been hot topics recently.However,most conventional approaches can only predict the category of a single target,and lack the ability to perform multitarget tasks to provide coordinate information of the targets.This limits the development of high-throughput cell screening technologies.Fortunately,artificial intelligence(AI)systems based on deep-learning algorithms provide the possibility to extract hidden features of cells from original image information.Here,we demonstrate an AI-assisted multitarget processing system for cell identification and sorting.With this system,each target cell can be swiftly and accurately identified in a mixture by extracting cell morphological features,whereafter accurate cell sorting is achieved through noninvasive manipulation by optical tweezers.The AI-assisted model shows promise in guiding the precise manipulation and intelligent detection of high-flux cells,thereby realizing semiautomatic cell research.
