Surface-enhanced Raman scattering(SERS)platform,which enables trace analyte detection,has important application prospects.By structuring/modifying the surface of the SERSsubstrate,analyte in highly diluted solutions c...Surface-enhanced Raman scattering(SERS)platform,which enables trace analyte detection,has important application prospects.By structuring/modifying the surface of the SERSsubstrate,analyte in highly diluted solutions can be concentrated into localized active areas for highly sensitive detection.However,subject to the difficulty of the fabrication process,itremains challenging to balance hot-spot construction and the concentration capacity of analyte simultaneously.Therefore,preparing SERS substrates with densely ordered hot spots andefficient concentration capacity is of great significance for highly sensitive detection.Herein,we propose an Ag and fluoroalkyl-modified hierarchical armour substrate(Ag/F-HA),which has a double-layer stacking design to combine analyte concentration with hotspot construction.The microarmour structure is fabricated by femtosecond-laser processing to serve as asuperhydrophobic and low-adhesive surface to concentrate analyte,while the anodic aluminium oxide(AAO)template creates a nanopillar array serving as dense and ordered hot spots.Under the synergistic action of hot spots and analyte concentration,Ag/F-HA achieves a detectionlimit down to 10^(-7)M doxorubicin(DOX)molecules with a RSD of 7.69%.Additionally,Ag/F-HA exhibits excellent robustness to resist external disturbances such as liquid splash or abrasion.Based on our strategy,SERS substrates with directional analyte concentrations are further explored by patterning microcone arrays with defects.This work opens a way to the realistic implementation of SERS in diverse scenarios.展开更多
Last decade has witnessed a rapid development of the generation of terahertz(THz)vortex beams as well as their wide applications,mainly due to their unique combination characteristics of regular THz radiation and orbi...Last decade has witnessed a rapid development of the generation of terahertz(THz)vortex beams as well as their wide applications,mainly due to their unique combination characteristics of regular THz radiation and orbital angular momentum(OAM).Here we have reviewed the ways to generate THz vortex beams by two representative scenarios,i.e.,THz wavefront modulation via specific devices,and direct excitation of the helicity of THz vortex beams.The former is similar to those wavefront engineering devices in the optical and infrared(IR)domain,but just with suitable THz materials,while the latter is newly-developed in THz regime and some of the physical mechanisms still have not been explained explicitly enough though,which would provide both challenges and opportunities for THz vortex beam generation.As for their applications,thanks to the recent development of THz optics and singular optics,THz vortex beams have potentials to open doors towards a myriad of practice applications in many fields.Besides,some representative potential applications are evaluated such as THz wireless communication,THz super-resolution imaging,manipulating chiral matters,accelerating electron bunches,and detecting astrophysical sources.展开更多
We propose a kind of spectral polarization-encoding(SPE)for broadband light pulses,which is realized by inducing optical rotatory dispersion(ORD),and decoded by compensating ORD.Combining with polarization-sensitive d...We propose a kind of spectral polarization-encoding(SPE)for broadband light pulses,which is realized by inducing optical rotatory dispersion(ORD),and decoded by compensating ORD.Combining with polarization-sensitive devices,SPE can not only work to control polarization-dependent transmission for central wavelength or bandwidth-tunable filtering,but also can be used for broadband regenerative or multi-pass amplification with a polarization-dependent gain medium to improve output bandwidth.SPE is entirely passive thus very simple to be designed and aligned.By using an ORD crystal with a good transmission beyond 3-μm mid-infrared region,e.g.,Ag Ga S_(2),SPE promises to be applied for the wavelength tuning lasers in mid-infrared region,where the tunning devices are rather under developed compared with those in visible and near-infrared region.展开更多
In the recent decade,single-shot ultrafast optical imaging by active detection,called single-shot active ultrafast optical imaging(SS-AUOI)here,has made great progress,e.g.,with a temporal resolution of 50 fs and a fr...In the recent decade,single-shot ultrafast optical imaging by active detection,called single-shot active ultrafast optical imaging(SS-AUOI)here,has made great progress,e.g.,with a temporal resolution of 50 fs and a frame rate beyond 10 trillion frames per second.Now,it has become indispensable for charactering the nonrepeatable and difficult-to-reproduce events and revealing the underlying physical,chemical,and biological mechanisms.On the basis of this delightful status,we would like to make a review of SS-AUOI.On the basis of a brief introduction of SS-AUOI,our review starts with discussing its characteristics and then focuses on the survey and prospect of SS-AUOI technology.展开更多
In recent years,multi-wavelength fiber lasers play a significant role in plenty of fields,ranging from optical communications to mechanical processing and laser biomedicine,owing to their high beam quality,low cost,an...In recent years,multi-wavelength fiber lasers play a significant role in plenty of fields,ranging from optical communications to mechanical processing and laser biomedicine,owing to their high beam quality,low cost,and excellent heat dissipation properties.Benefitting from increasing maturity of optical elements,the multi-wavelength fiber laser has made rapid developments.In this review,we summarize and analyze diverse implementation methods covering continuous wave and pulsed fiber lasers at room temperature conditions:inserting an optical filter device and intensity-dependent loss structure in the resonant cavity,and applying ultrafast nonlinear optical response of materials and a dual-cavity structure.Finally,future challenges and perspectives of the multi-wavelength fiber laser are discussed and addressed.展开更多
Black phosphorus(BP), with thickness-dependent direct energy bandgaps(0.3–2 eV), shows an enhanced nonlinear optical response at near-and mid-infrared wavelengths. In this paper, we present experimentally multilayer ...Black phosphorus(BP), with thickness-dependent direct energy bandgaps(0.3–2 eV), shows an enhanced nonlinear optical response at near-and mid-infrared wavelengths. In this paper, we present experimentally multilayer BP flakes coated on microfiber(BCM) as a saturable absorber with a modulation depth of 16% and a saturable intensity of 6.8 MW∕cm^2. After inserting BCM into an Er-doped fiber ring laser, a stable dual-wavelength Q-switched state with central wavelengths of 1542.4 nm and 1543.2 nm(with wavelength spacing as small as 0.8 nm) is obtained with the aid of two cascaded fiber Bragg gratings as a coarse wavelength selector.Moreover, single-wavelength Q-switched operation at 1542.4 nm or 1543.2 nm is also realized, which can be switched between the two wavelengths flexibly just by adjusting the intracavity birefringence. These results suggest that BP combined with the cascaded fiber gratings can provide a simple and feasible candidate for a multiwavelength fiber laser. Our fiber laser may have potential applications in terahertz generation, laser radar,and so on.展开更多
We report a framing imaging based on noncollinear optical parametric amplification(NCOPA),named FINCOPA,which applies NCOPA for the first time to single-shot ultrafast optical imaging.In an experiment targeting a lase...We report a framing imaging based on noncollinear optical parametric amplification(NCOPA),named FINCOPA,which applies NCOPA for the first time to single-shot ultrafast optical imaging.In an experiment targeting a laser-induced air plasma grating,FINCOPA achieved 50 fs-resolved optical imaging with a spatial resolution of^83 lp∕mm and an effective frame rate of 10 trillion frames per second(Tfps).It has also successfully visualized an ultrafast rotating optical field with an effective frame rate of 15 Tfps.FINCOPA has simultaneously a femtosecond-level temporal resolution and frame interval and a micrometer-level spatial resolution.Combining outstanding spatial and temporal resolutions with an ultrahigh frame rate,FINCOPA will contribute to high-spatiotemporal resolution observations of ultrafast transient events,such as atomic or molecular dynamics in photonic materials,plasma physics,and laser inertial-confinement fusion.展开更多
A tunable ultrafast intensity-rotating optical field is generated by overlapping a pair of 20Hz,800 nm chirped pulses with a Michelson interferometer(MI).Its rotating rate can be up to 10 trillion radians per second(T...A tunable ultrafast intensity-rotating optical field is generated by overlapping a pair of 20Hz,800 nm chirped pulses with a Michelson interferometer(MI).Its rotating rate can be up to 10 trillion radians per second(Trad/s),which can be flexibly tuned with a mirror in the MI.Besides,its fold rotational symmetry structure is also changeable by controlling the difference from the topological charges of the pulse pair.Experimentally,we have successfully developed a twopetal lattice with a tunable rotating speed from 3.9 Trad/s up to 11.9 Trad/s,which is confirmed by our single-shot ultrafast frame imager based on noncollinear optical-parametric amplification with its highest frame rate of 15 trillion frames per second(Tfps).This work is carried out at a low repetition rate.Therefore,it can be applied at relativistic,even ultrarelativistic,intensities,which usually operate in low repetition rate ultrashort and ultraintense laser systems.We believe that it may have application in laser-plasma-based accelerators,strong terahertz radiations and celestial phenomena.展开更多
To seek high signal-to-noise ratio(SNR) is critical but challenging for single-shot intense terahertz(THz)coherent detection. This paper presents an improved common-path spectral interferometer for single-shot THz det...To seek high signal-to-noise ratio(SNR) is critical but challenging for single-shot intense terahertz(THz)coherent detection. This paper presents an improved common-path spectral interferometer for single-shot THz detection with a single chirped pulse as the probe for THz electro-optic(EO) sampling. Here, the spectral interference occurs between the two orthogonal polarization components with a required relative time delay generated with only a birefringent plate after the EO sensor. Our experiments show that this interferometer can effectively suppress the noise usually suffered in a non-common-path interferometer. The measured single-shot SNR is up to 88.85, and the measured THz waveforms are independent of the orientation of the used Zn Te EO sensor, so it is easy to operate and the results are more reliable. These features mean that the interferometer is quite qualified for applications where strong THz pulses, usually with single-shot or low repetition rate, are indispensable.展开更多
We report on a vortex laser chirped-pulse amplification(CPA)system that delivers pulses with a peak power of 45 TW.A focused intensity exceeding 1019 W/cm2 has been demonstrated for the first time by the vortex amplif...We report on a vortex laser chirped-pulse amplification(CPA)system that delivers pulses with a peak power of 45 TW.A focused intensity exceeding 1019 W/cm2 has been demonstrated for the first time by the vortex amplification scheme.Compared with other schemes of strong-field vortex generation with high energy flux but narrowband vortex-converting elements at the end of the laser,an important advantage of our scheme is that we can use a broadband but size-limited q-plate to realize broadband mode-converting in the front end of the CPA system,and achieve high-power amplification with a series of amplifiers.This method is low cost and can be easily implemented in an existing laser system.The results have verified the feasibility to obtain terawatt and even petawatt vortex laser amplification by a CPA system,which has important potential applications in strong-field laser physics,for example,generation of vortex particle beams with orbital angular momentum,fast ignition for inertial confinement fusion and simulation of the extreme astrophysical environment.展开更多
Light springs(LSs) have played essential roles in particle rotation and manipulation, optical super-resolution imaging, and optical information coding. In related research areas, it is important to accurately measure ...Light springs(LSs) have played essential roles in particle rotation and manipulation, optical super-resolution imaging, and optical information coding. In related research areas, it is important to accurately measure spatiotemporal information on LSs to understand and analyze their applications. However, there is no experimental method that can accurately detect the drastic spatial evolution of ultrafast LSs to date. Therefore, in this study, we propose a compressed ultrafast photography(CUP) technique to observe LSs in spatial and temporal dimensions with a snapshot. Using our home-built CUP system, we successfully capture spatiotemporal information on picosecond LSs with two and four petals, involving spatial structure and rotation velocity;furthermore, the experimental measurements are in good agreement with theoretical simulations. This study provides a novel visualization method for specifically measuring the spatial structure and temporal evolution of LSs, thus establishing a new idea for accurately characterizing spatiotemporal information on complex ultrafast laser fields.展开更多
This paper reports the experimental realization of efficiently sorting vector beams by polarization topological charge （PTC）. The PTC of a vector beam can be defined as the repetition number of polarization state ch...This paper reports the experimental realization of efficiently sorting vector beams by polarization topological charge （PTC）. The PTC of a vector beam can be defined as the repetition number of polarization state change along the azimuthal axis, while its sign stands for the rotating direction of the polarization. Here, a couple of liquid crystal Pancharatnam-Berry optical dements （PBOEs） have been used to introduce conjugated spatial phase modulations for two orthogonal circular polarization states. Applying these PBOEs in a 4-foptical system, our experiments show the setup can work for PTC sorting with a separation efficiency of more than 58%. This work provides an effective way to decode information from different PTCs, which may be interesting in many fields, especially in optical communication.展开更多
Applying an ultrafast vortex laser as the pump,optical parametric amplification can be used for spiral phase-contrast imaging with high gain,wide spatial bandwidth,and high imaging contrast.Our experiments show that t...Applying an ultrafast vortex laser as the pump,optical parametric amplification can be used for spiral phase-contrast imaging with high gain,wide spatial bandwidth,and high imaging contrast.Our experiments show that this design has realized the 1064 nm spiral phase-contrast idler imaging of biological tissues(frog egg cells and onion epidermis)with a spatial resolution at several microns level and a superior imaging contrast to both the traditional bright-or dark-field imaging under a weak illumination of 7 nW/cm^(2).This work provides a powerful way for biological tissue imaging in the second near-infrared region.展开更多
This paper presents a complete two-step phase-shifting(TSPS) spectral phase interferometry for direct electric-field reconstruction(SPIDER) to improve the reconstruction of ultrafast optical fields. Here, complete TSP...This paper presents a complete two-step phase-shifting(TSPS) spectral phase interferometry for direct electric-field reconstruction(SPIDER) to improve the reconstruction of ultrafast optical fields. Here, complete TSPS acts as a balanced detection that can not only remove the effect of the dc term of the interferogram, but also reduce measurement noises,and thereby improve the capability of SPIDER to measure the pulses with narrow spectra or complex spectral structures.Some prisms are chosen to replace some environment-sensitive optical components, especially reflective optics to improve operating stability and improve signal-to-noise ratio further. Our experiments show that the available shear can be decreased to 1.5% of the spectral width, which is only about 1/3 compared with traditional SPIDER.展开更多
Radially polarized beams characterized by an axially symmetric polarization distribution can be sharply focused to produce strong longitudinal fields in the vicinity.Future applications of these beams will be facilita...Radially polarized beams characterized by an axially symmetric polarization distribution can be sharply focused to produce strong longitudinal fields in the vicinity.Future applications of these beams will be facilitated by the availability of higher powers and shorter durations.Currently,the ultrafast radially polarized pulse is typically generated via wavefront reconstruction from conventional linearly polarized states.Achievable pulse duration and intensity limits are strictly dependent on extra-cavity optics.Herein,a chirp-assisted near-degenerate type-II parametric process is presented as a pulse-energy-scalable method of accessing ultrafast radially polarized pulses.In a proof-of-principle experiment,the broadband gain balance between the orthogonally polarized signal components was realized via controlling the chirp of the pump pulse.Through an analogous pulseduration transfer effect,the radially polarized signal inherited the temporal and spectral characteristics of the pump pulse and maintained the radial polarization state of each frequency component of the signal.With a shorter pump pulse,the generation of few-cycle radially polarized pulses should be achievable,which may facilitate a wide range of ultrafast applications such as vacuum electron acceleration and high-harmonic generation.展开更多
This paper presents a novel design for single-shot terahertz polarization detection based on terahertz time-domain spectroscopy(THz-TDS).Its validity has been confirmed by comparing its detection results with those of...This paper presents a novel design for single-shot terahertz polarization detection based on terahertz time-domain spectroscopy(THz-TDS).Its validity has been confirmed by comparing its detection results with those of the THz common-path spectral interferometer through two separate measurements for the orthogonal components.Our results also show that its detection signal-to-noise ratios(SNRs)are obviously superior to those of the 45°optical bias THz-TDS by electro-optical sampling due to its operation on common-path spectral interference rather than the polarization-sensitive intensity modulation.The setup works without need of any optical scan,which does not only save time,but also efficiently avoids the disturbances from the fluctuations of the system and environment.Its single-shot mode allows it to work well for the applications with poor or no repeatability.展开更多
Ultra-intense femtosecond vortex pulses can provide an opportunity to investigate the new phenomena with orbital angular momentum(OAM)involved in extreme cases.This paper reports a high gain optical vortex amplifier f...Ultra-intense femtosecond vortex pulses can provide an opportunity to investigate the new phenomena with orbital angular momentum(OAM)involved in extreme cases.This paper reports a high gain optical vortex amplifier for intense femtosecond vortex pulses generation.Traditional regeneration amplifiers can offer high gain for Gaussian mode pulses but cannot amplify optical vortex pulses while maintaining the phase singularity because of mode competition.Here,we present a regeneration amplifier with a ring-shaped pump.By controlling the radius of the pump,the system can realize the motivation of the Laguerre–Gaussian[LG0,1(−1)]mode and the suppression of the Gaussian mode.Without seeds,the amplifier has a donut-shaped output containing two opposite OAM states simultaneously,as our prediction by simulation.If seeded by a pulse of a topologic charge of 1 or−1,the system will output an amplified LG0,1(−1)mode pulse with the same topologic charge as the seed.To our knowledge,this amplifier can offer the highest gain as 1.45×106 for optical vortex amplification.Finally,we obtain a 1.8 mJ,51 fs compressed optical vortex seeded from a 2 nJ optical vortex.展开更多
基金National Natural Science Foundation of China(Nos.92050203,52122511,52305319,52375582)Shenzhen Fundamental Research Program(Nos.JCYJ20200109105606426,JCYJ20190808164007485)。
文摘Surface-enhanced Raman scattering(SERS)platform,which enables trace analyte detection,has important application prospects.By structuring/modifying the surface of the SERSsubstrate,analyte in highly diluted solutions can be concentrated into localized active areas for highly sensitive detection.However,subject to the difficulty of the fabrication process,itremains challenging to balance hot-spot construction and the concentration capacity of analyte simultaneously.Therefore,preparing SERS substrates with densely ordered hot spots andefficient concentration capacity is of great significance for highly sensitive detection.Herein,we propose an Ag and fluoroalkyl-modified hierarchical armour substrate(Ag/F-HA),which has a double-layer stacking design to combine analyte concentration with hotspot construction.The microarmour structure is fabricated by femtosecond-laser processing to serve as asuperhydrophobic and low-adhesive surface to concentrate analyte,while the anodic aluminium oxide(AAO)template creates a nanopillar array serving as dense and ordered hot spots.Under the synergistic action of hot spots and analyte concentration,Ag/F-HA achieves a detectionlimit down to 10^(-7)M doxorubicin(DOX)molecules with a RSD of 7.69%.Additionally,Ag/F-HA exhibits excellent robustness to resist external disturbances such as liquid splash or abrasion.Based on our strategy,SERS substrates with directional analyte concentrations are further explored by patterning microcone arrays with defects.This work opens a way to the realistic implementation of SERS in diverse scenarios.
基金Project supported partly by the National Natural Science Foundation of China(Grant Nos.61775142 and 61705132)Shenzhen Fundamental Research and Discipline Layout Project,China(Grant Nos.JCYJ20170412105812811,JCYJ20190808164007485,JCYJ20190808121817100,and JCYJ20190808115601653).
文摘Last decade has witnessed a rapid development of the generation of terahertz(THz)vortex beams as well as their wide applications,mainly due to their unique combination characteristics of regular THz radiation and orbital angular momentum(OAM).Here we have reviewed the ways to generate THz vortex beams by two representative scenarios,i.e.,THz wavefront modulation via specific devices,and direct excitation of the helicity of THz vortex beams.The former is similar to those wavefront engineering devices in the optical and infrared(IR)domain,but just with suitable THz materials,while the latter is newly-developed in THz regime and some of the physical mechanisms still have not been explained explicitly enough though,which would provide both challenges and opportunities for THz vortex beam generation.As for their applications,thanks to the recent development of THz optics and singular optics,THz vortex beams have potentials to open doors towards a myriad of practice applications in many fields.Besides,some representative potential applications are evaluated such as THz wireless communication,THz super-resolution imaging,manipulating chiral matters,accelerating electron bunches,and detecting astrophysical sources.
基金the National Natural Science Foundation of China(Grant Nos.92050203,62075138,61827815,and 61775142)Shenzhen Fundamental Research Project(Grant Nos.JCYJ20190808164007485,JCYJ20190808121817100,JSGG20191231144201722,and JCYJ20190808115601653)。
文摘We propose a kind of spectral polarization-encoding(SPE)for broadband light pulses,which is realized by inducing optical rotatory dispersion(ORD),and decoded by compensating ORD.Combining with polarization-sensitive devices,SPE can not only work to control polarization-dependent transmission for central wavelength or bandwidth-tunable filtering,but also can be used for broadband regenerative or multi-pass amplification with a polarization-dependent gain medium to improve output bandwidth.SPE is entirely passive thus very simple to be designed and aligned.By using an ORD crystal with a good transmission beyond 3-μm mid-infrared region,e.g.,Ag Ga S_(2),SPE promises to be applied for the wavelength tuning lasers in mid-infrared region,where the tunning devices are rather under developed compared with those in visible and near-infrared region.
基金National Natural Science Foundation of China(92050203,62075138,62275163,and 12174264)Natural Science Foundation of Guangdong Province(2021A1515011909 and 2022A1515011457)Shenzhen Fundamental Research Program(JCYJ20200109105606426,JCYJ20190808164007485,JCYJ20210324095213037,JCYJ20190808121817100,JCYJ20190808143419622,JSGG20191231144201722,and JCYJ20190808115601653).
文摘In the recent decade,single-shot ultrafast optical imaging by active detection,called single-shot active ultrafast optical imaging(SS-AUOI)here,has made great progress,e.g.,with a temporal resolution of 50 fs and a frame rate beyond 10 trillion frames per second.Now,it has become indispensable for charactering the nonrepeatable and difficult-to-reproduce events and revealing the underlying physical,chemical,and biological mechanisms.On the basis of this delightful status,we would like to make a review of SS-AUOI.On the basis of a brief introduction of SS-AUOI,our review starts with discussing its characteristics and then focuses on the survey and prospect of SS-AUOI technology.
基金partially supported by the Science and Technology Development Fund,Macao Special Administration Region(SAR)(Nos.007/2017/A1 and 132/2017/A3)National Natural Science Foundation of China(NSFC)(Nos.61875138,61435010,61775142,and 6181101252)+1 种基金Science and Technology Innovation Commission of Shenzhen(Nos.KQTD2015032416270385,JCYJ20150625103619275,and JCYJ20170811093453105)Shenzhen Basic Research Project on Subject Layout(No.JCYJ20170412105812811)。
文摘In recent years,multi-wavelength fiber lasers play a significant role in plenty of fields,ranging from optical communications to mechanical processing and laser biomedicine,owing to their high beam quality,low cost,and excellent heat dissipation properties.Benefitting from increasing maturity of optical elements,the multi-wavelength fiber laser has made rapid developments.In this review,we summarize and analyze diverse implementation methods covering continuous wave and pulsed fiber lasers at room temperature conditions:inserting an optical filter device and intensity-dependent loss structure in the resonant cavity,and applying ultrafast nonlinear optical response of materials and a dual-cavity structure.Finally,future challenges and perspectives of the multi-wavelength fiber laser are discussed and addressed.
基金National Natural Science Foundation of China(NSFC)(61490710,61505122,61775142)Science and Technology Planning Project of Guangdong Province(2016B050501005)+1 种基金Specialized Research Fund for the Shenzhen Strategic Emerging Industries Development(JCYJ20170412105812811)Natural Science Foundation of SZU(2017018)
文摘Black phosphorus(BP), with thickness-dependent direct energy bandgaps(0.3–2 eV), shows an enhanced nonlinear optical response at near-and mid-infrared wavelengths. In this paper, we present experimentally multilayer BP flakes coated on microfiber(BCM) as a saturable absorber with a modulation depth of 16% and a saturable intensity of 6.8 MW∕cm^2. After inserting BCM into an Er-doped fiber ring laser, a stable dual-wavelength Q-switched state with central wavelengths of 1542.4 nm and 1543.2 nm(with wavelength spacing as small as 0.8 nm) is obtained with the aid of two cascaded fiber Bragg gratings as a coarse wavelength selector.Moreover, single-wavelength Q-switched operation at 1542.4 nm or 1543.2 nm is also realized, which can be switched between the two wavelengths flexibly just by adjusting the intracavity birefringence. These results suggest that BP combined with the cascaded fiber gratings can provide a simple and feasible candidate for a multiwavelength fiber laser. Our fiber laser may have potential applications in terahertz generation, laser radar,and so on.
基金supported partly by the National Natural Science Foundation of China(Nos.61775142 and 61705132)the Shenzhen Basic Research Project on the subject layout(No.JCYJ20170412105812811)+1 种基金the Shenzhen Basic Research Projects(Nos.JCYJ20170412105812811,JCYJ20190808164007485,and JCYJ20190808115601653)the Natural Sciences and Engineering Research Council of Canada(Nos.RGPIN-2017-05959 and RGPAS-507845-2017)
文摘We report a framing imaging based on noncollinear optical parametric amplification(NCOPA),named FINCOPA,which applies NCOPA for the first time to single-shot ultrafast optical imaging.In an experiment targeting a laser-induced air plasma grating,FINCOPA achieved 50 fs-resolved optical imaging with a spatial resolution of^83 lp∕mm and an effective frame rate of 10 trillion frames per second(Tfps).It has also successfully visualized an ultrafast rotating optical field with an effective frame rate of 15 Tfps.FINCOPA has simultaneously a femtosecond-level temporal resolution and frame interval and a micrometer-level spatial resolution.Combining outstanding spatial and temporal resolutions with an ultrahigh frame rate,FINCOPA will contribute to high-spatiotemporal resolution observations of ultrafast transient events,such as atomic or molecular dynamics in photonic materials,plasma physics,and laser inertial-confinement fusion.
基金supported by the National Natural Science Foundation of China(Nos.61775142,61705132,61490710 and 61827815)China Postdoctoral Science Foundation(No.2017M612726)+1 种基金Shenzhen Basic Research Project on Subject Layout(No.JCYJ20170412105812811)Fund of the International Collaborative Laboratory of 2D Materials for Optoelectronics Science and Technology,Shenzhen University(No.2DMOST2018019)。
文摘A tunable ultrafast intensity-rotating optical field is generated by overlapping a pair of 20Hz,800 nm chirped pulses with a Michelson interferometer(MI).Its rotating rate can be up to 10 trillion radians per second(Trad/s),which can be flexibly tuned with a mirror in the MI.Besides,its fold rotational symmetry structure is also changeable by controlling the difference from the topological charges of the pulse pair.Experimentally,we have successfully developed a twopetal lattice with a tunable rotating speed from 3.9 Trad/s up to 11.9 Trad/s,which is confirmed by our single-shot ultrafast frame imager based on noncollinear optical-parametric amplification with its highest frame rate of 15 trillion frames per second(Tfps).This work is carried out at a low repetition rate.Therefore,it can be applied at relativistic,even ultrarelativistic,intensities,which usually operate in low repetition rate ultrashort and ultraintense laser systems.We believe that it may have application in laser-plasma-based accelerators,strong terahertz radiations and celestial phenomena.
基金National Natural Science Foundation of China(NSFC)(61490710,61775142,61705132)Science and Technology Planning Project of Guangdong Province(2016B050501005)Specialized Research Fund for the Shenzhen Strategic Emerging Industries Development(JCYJ20150324141711651,JCYJ20150525092941064,JCYJ20170412105812811)
文摘To seek high signal-to-noise ratio(SNR) is critical but challenging for single-shot intense terahertz(THz)coherent detection. This paper presents an improved common-path spectral interferometer for single-shot THz detection with a single chirped pulse as the probe for THz electro-optic(EO) sampling. Here, the spectral interference occurs between the two orthogonal polarization components with a required relative time delay generated with only a birefringent plate after the EO sensor. Our experiments show that this interferometer can effectively suppress the noise usually suffered in a non-common-path interferometer. The measured single-shot SNR is up to 88.85, and the measured THz waveforms are independent of the orientation of the used Zn Te EO sensor, so it is easy to operate and the results are more reliable. These features mean that the interferometer is quite qualified for applications where strong THz pulses, usually with single-shot or low repetition rate, are indispensable.
基金supported by the National Natural Science Foundation of China(Nos.92050203,61925507,12174264,12004261,62075138,and 61827815)the Natural Science Foundation of Guangdong Province(Nos.2021A1515011909 and 2022A1515011457)the Shenzhen Fundamental Research Projects(Nos.JCYJ20200109105606426,JCYJ20190808164007485,JCYJ20190808121817100,JCYJ20190808143419622,and JCYJ20190808115601653).
文摘We report on a vortex laser chirped-pulse amplification(CPA)system that delivers pulses with a peak power of 45 TW.A focused intensity exceeding 1019 W/cm2 has been demonstrated for the first time by the vortex amplification scheme.Compared with other schemes of strong-field vortex generation with high energy flux but narrowband vortex-converting elements at the end of the laser,an important advantage of our scheme is that we can use a broadband but size-limited q-plate to realize broadband mode-converting in the front end of the CPA system,and achieve high-power amplification with a series of amplifiers.This method is low cost and can be easily implemented in an existing laser system.The results have verified the feasibility to obtain terawatt and even petawatt vortex laser amplification by a CPA system,which has important potential applications in strong-field laser physics,for example,generation of vortex particle beams with orbital angular momentum,fast ignition for inertial confinement fusion and simulation of the extreme astrophysical environment.
基金supported by the National Natural Science Foundation of China(Grant Nos.91850202,12074121,11774094,11804097,62105101,62175066,92050203,11727810,and 12034008)Science and Technology Commission of Shanghai Municipality(Grant Nos.19560710300,20ZR1417100,and 21XD1400900)。
文摘Light springs(LSs) have played essential roles in particle rotation and manipulation, optical super-resolution imaging, and optical information coding. In related research areas, it is important to accurately measure spatiotemporal information on LSs to understand and analyze their applications. However, there is no experimental method that can accurately detect the drastic spatial evolution of ultrafast LSs to date. Therefore, in this study, we propose a compressed ultrafast photography(CUP) technique to observe LSs in spatial and temporal dimensions with a snapshot. Using our home-built CUP system, we successfully capture spatiotemporal information on picosecond LSs with two and four petals, involving spatial structure and rotation velocity;furthermore, the experimental measurements are in good agreement with theoretical simulations. This study provides a novel visualization method for specifically measuring the spatial structure and temporal evolution of LSs, thus establishing a new idea for accurately characterizing spatiotemporal information on complex ultrafast laser fields.
基金National Natural Science Foundation of China(NSFC)(61490710,61705132,61775142)Science and Technology Planning Project of Guangdong Province(2016B050501005)Specialized Research Fund for the Shenzhen Strategic Emerging Industries Development(JCYJ20170412105812811)
文摘This paper reports the experimental realization of efficiently sorting vector beams by polarization topological charge （PTC）. The PTC of a vector beam can be defined as the repetition number of polarization state change along the azimuthal axis, while its sign stands for the rotating direction of the polarization. Here, a couple of liquid crystal Pancharatnam-Berry optical dements （PBOEs） have been used to introduce conjugated spatial phase modulations for two orthogonal circular polarization states. Applying these PBOEs in a 4-foptical system, our experiments show the setup can work for PTC sorting with a separation efficiency of more than 58%. This work provides an effective way to decode information from different PTCs, which may be interesting in many fields, especially in optical communication.
基金partially supported by the National Natural Science Foundation of China(Nos.92050203,62075138,12174264,61827815,12004261,and 61775142)Natural Science Foundation of Guangdong Province(Nos.2021A1515011909 and 2022A1515011457)+1 种基金Shenzhen Fundamental Research Program(Nos.JCYJ20200109105606426,JCYJ20190808164007485,JCYJ20210324095213037,JCYJ20190808121817100,JCYJ20190808143419622,and JCYJ20190808115601653)Shenzhen Key Technology Projects(Nos.JSGG20191231144201722 and JSGG20211108092800001).
文摘Applying an ultrafast vortex laser as the pump,optical parametric amplification can be used for spiral phase-contrast imaging with high gain,wide spatial bandwidth,and high imaging contrast.Our experiments show that this design has realized the 1064 nm spiral phase-contrast idler imaging of biological tissues(frog egg cells and onion epidermis)with a spatial resolution at several microns level and a superior imaging contrast to both the traditional bright-or dark-field imaging under a weak illumination of 7 nW/cm^(2).This work provides a powerful way for biological tissue imaging in the second near-infrared region.
基金supported by the National Natural Science Foundation of China(Nos.61775142,61490710and 61705132)China Postdoctoral Science Foundation(No.2017M612726)Shenzhen Basic Research Project on Subject Layout(No.JCYJ20170412105812811)
文摘This paper presents a complete two-step phase-shifting(TSPS) spectral phase interferometry for direct electric-field reconstruction(SPIDER) to improve the reconstruction of ultrafast optical fields. Here, complete TSPS acts as a balanced detection that can not only remove the effect of the dc term of the interferogram, but also reduce measurement noises,and thereby improve the capability of SPIDER to measure the pulses with narrow spectra or complex spectral structures.Some prisms are chosen to replace some environment-sensitive optical components, especially reflective optics to improve operating stability and improve signal-to-noise ratio further. Our experiments show that the available shear can be decreased to 1.5% of the spectral width, which is only about 1/3 compared with traditional SPIDER.
基金supported by the National Natural Science Foundation of China(Grant No.92050203)the Natural Science Foundation of Guangdong Province(Grant No.2020A1515010541)the Science and Technology Project of Shenzhen(Grant Nos.JCYJ20200109105606426,JCYJ20190808143419622,and JCYJ20190808145016980)。
文摘Radially polarized beams characterized by an axially symmetric polarization distribution can be sharply focused to produce strong longitudinal fields in the vicinity.Future applications of these beams will be facilitated by the availability of higher powers and shorter durations.Currently,the ultrafast radially polarized pulse is typically generated via wavefront reconstruction from conventional linearly polarized states.Achievable pulse duration and intensity limits are strictly dependent on extra-cavity optics.Herein,a chirp-assisted near-degenerate type-II parametric process is presented as a pulse-energy-scalable method of accessing ultrafast radially polarized pulses.In a proof-of-principle experiment,the broadband gain balance between the orthogonally polarized signal components was realized via controlling the chirp of the pump pulse.Through an analogous pulseduration transfer effect,the radially polarized signal inherited the temporal and spectral characteristics of the pump pulse and maintained the radial polarization state of each frequency component of the signal.With a shorter pump pulse,the generation of few-cycle radially polarized pulses should be achievable,which may facilitate a wide range of ultrafast applications such as vacuum electron acceleration and high-harmonic generation.
基金National Natural Science Foundation of China(12004261,12174264,61775142,62075138,92050203)Natural Science Foundation of Guangdong Province(2021A1515011909)Shenzhen Fundamental Research Program(JCYJ20190808164007485,JCYJ20190808115601653,JCYJ20190808121817100,JCYJ20190808143419622,JCYJ20200109105606426)。
文摘This paper presents a novel design for single-shot terahertz polarization detection based on terahertz time-domain spectroscopy(THz-TDS).Its validity has been confirmed by comparing its detection results with those of the THz common-path spectral interferometer through two separate measurements for the orthogonal components.Our results also show that its detection signal-to-noise ratios(SNRs)are obviously superior to those of the 45°optical bias THz-TDS by electro-optical sampling due to its operation on common-path spectral interference rather than the polarization-sensitive intensity modulation.The setup works without need of any optical scan,which does not only save time,but also efficiently avoids the disturbances from the fluctuations of the system and environment.Its single-shot mode allows it to work well for the applications with poor or no repeatability.
基金National Natural Science Foundation of China(61490710,61705132,61775142)Shenzhen Basic Research Project on Subject Layout(JCYJ20170412105812811)Shenzhen Basic Research Projects(JCYJ20190808115601653,JCYJ20190808164007485).
文摘Ultra-intense femtosecond vortex pulses can provide an opportunity to investigate the new phenomena with orbital angular momentum(OAM)involved in extreme cases.This paper reports a high gain optical vortex amplifier for intense femtosecond vortex pulses generation.Traditional regeneration amplifiers can offer high gain for Gaussian mode pulses but cannot amplify optical vortex pulses while maintaining the phase singularity because of mode competition.Here,we present a regeneration amplifier with a ring-shaped pump.By controlling the radius of the pump,the system can realize the motivation of the Laguerre–Gaussian[LG0,1(−1)]mode and the suppression of the Gaussian mode.Without seeds,the amplifier has a donut-shaped output containing two opposite OAM states simultaneously,as our prediction by simulation.If seeded by a pulse of a topologic charge of 1 or−1,the system will output an amplified LG0,1(−1)mode pulse with the same topologic charge as the seed.To our knowledge,this amplifier can offer the highest gain as 1.45×106 for optical vortex amplification.Finally,we obtain a 1.8 mJ,51 fs compressed optical vortex seeded from a 2 nJ optical vortex.
