Tunable mid-infrared lasers are essential for optical sensing and imaging.Existing technologies,however,face challenges in simultaneously achieving broadband spectral tunability and ultra-rapid scan rates,limiting the...Tunable mid-infrared lasers are essential for optical sensing and imaging.Existing technologies,however,face challenges in simultaneously achieving broadband spectral tunability and ultra-rapid scan rates,limiting their utility in dynamic scenarios such as real-time characterization of multiple molecular absorption bands.We present a high-speed approach for broadband wavelength sweeping in the mid-infrared region,leveraging spectral focusing via difference-frequency generation between a chirped fiber laser and an asynchronous,frequency-modulated electro-optic comb.This method enables pulse-to-pulse spectral tuning at a speed of 5.6 THz∕μs with 380 elements.Applied to spectroscopic sensing,our technique achieves broad spectral coverage(2600 to 3780 cm−1)with moderate spectral resolution(8 cm−1)and rapid acquisition time(-6.3μs).Notably,the controllable electro-optic comb facilitates high scan rates of up to 2 Mscans∕s across the full spectral range(corresponding to a speed of 60 THz∕μs),with trade-offs in number of elements(-30)and spectral point spacing or resolution(33 cm−1).Nevertheless,these capabilities make our platform highly promising for applications such as flow cytometry,chemical reaction monitoring,and mid-infrared ranging and imaging.展开更多
Synchronized dual-wavelength mode-locked laser is investigated numerically and experimentally in the normal dispersion regime.A programmable optical processor is introduced to shape the spectral profile and adjust the...Synchronized dual-wavelength mode-locked laser is investigated numerically and experimentally in the normal dispersion regime.A programmable optical processor is introduced to shape the spectral profile and adjust the net dispersion,which is demonstrated be a convenient and reliable approach to generate dual-color solitons.The time-stretch dispersive Fourier transform and frequency-resolved optical grating techniques are utilized to measure the spectral and temporal characteristics of dual-color solitons,respectively.The numerical results are consistent with experimental results.This work may facilitate the development of filter-based mode-locked laser and the understanding of multi-wavelength soliton dynamics.展开更多
Soliton molecules(SMs),bounded and self-assembled of particle-like dissipative solitons,exist with versatile mutual interactions and manifest substantial potential in soliton communication and optical data storage.How...Soliton molecules(SMs),bounded and self-assembled of particle-like dissipative solitons,exist with versatile mutual interactions and manifest substantial potential in soliton communication and optical data storage.However,controllable manipulation of the bounded molecular patterns remains challenging,as reaching a specific operation regime in lasers generally involves adjusting multiple control parameters in connection with a wide range of accessible pulse dynamics.An evolutionary algorithm is implemented for intelligent control of SMs in a 2μm ultrafast fiber laser mode locked through nonlinear polarization rotation.Depending on the specifications of the merit function used for the optimization procedure,various SM operations are obtained,including spectra shape programming and controllable deterministic switching of doublet and triplet SMs operating in stationary or pulsation states with reconfigurable temporal separations,frequency locking of pulsation SMs,doublet and SM complexes with controllable pulsation ratio,etc.Digital encoding is further demonstrated in this platform by employing the self-assembled characteristics of SMs.Our work opens up an avenue for active SM control beyond conventional telecom bands and brings useful insights into nonlinear science and applications.展开更多
Sensitive mid-infrared(MIR)detection is in high demand in various applications,ranging from remote sensing,infrared surveillance,and environmental monitoring to industrial inspection.Among others,upconversion infrared...Sensitive mid-infrared(MIR)detection is in high demand in various applications,ranging from remote sensing,infrared surveillance,and environmental monitoring to industrial inspection.Among others,upconversion infrared detectors have recently attracted increasing attention due to their advantageous features of high sensitivity,fast response,and room-temperature operation.However,it remains challenging to realize high-performance passive MIR sensing due to the stringent requirement of high-power continuouswave pumping.Here,we propose and implement a high-efficiency and low-noise MIR upconversion detection system based on pumping enhancement via a low-loss optical cavity.Specifically,a singlelongitudinal-mode pump at 1064 nm is significantly enhanced by a factor of 36,thus allowing for a peak conversion efficiency of up to 22%at an intracavity average power of 55 W.The corresponding noise equivalent power is achieved as low as 0.3 fW∕Hz^(1∕2),which indicates at least a 10-fold improvement over previous results.Notably,the involved single-frequency pumping would facilitate high-fidelity spectral mapping,which is particularly attractive for high-precision MIR upconversion spectroscopy in photonstarved scenarios.展开更多
Filament-and plasma-grating-induced breakdown spectroscopy(F-GIBS)was demonstrated as an efficient technique for sensitive detection of metals in water,where plasma gratings were established through synchronized nonli...Filament-and plasma-grating-induced breakdown spectroscopy(F-GIBS)was demonstrated as an efficient technique for sensitive detection of metals in water,where plasma gratings were established through synchronized nonlinear interaction of two noncollinear filaments and an additional filament was generated with another fs laser beam propagating along their bisector.A water jet was constructed vertically to the three coplanar filaments,overcoming side effects from violent plasma explosion and bubble generation.Three distinct regimes of different mechanisms were validated for nonlinear couplings of the third filament with plasma gratings.As the third filament was temporally overlapped with the two noncollinear filaments in the interaction zone,all the three filaments participated in synchronous nonlinear interaction and plasma grating structures were altered by the addition of the third filament.As the third filament was positively or negatively delayed,the as-formed plasma gratings were elongated by the delayed third filament,or plasma gratings were formed in the presence of plasma expansion of the ahead third filament,respectively.Using F-GIBS for trace metal detection in water,significant spectral line enhancements were observed.展开更多
When this article was originally published in High Power Laser Science and Engineering it contained an error in the name of the author Jiandong Liu.This has now been fixed.The publisher apologises for this error.
Dual-comb spectroscopy(DCS)is a powerful technique for spectroscopic sensing,offering exceptional spectral bandwidth,resolution,precision,and speed.However,its performance is fundamentally limited by quantum noise inh...Dual-comb spectroscopy(DCS)is a powerful technique for spectroscopic sensing,offering exceptional spectral bandwidth,resolution,precision,and speed.However,its performance is fundamentally limited by quantum noise inherent to coherent-state optical combs.Here,we overcome this barrier by introducing quantum correlation-enhanced DCS using correlated twin combs generated via seeded four-wave mixing.One comb acts as a local oscillator to decode molecular signals,while the twin suppresses shot noise through intensity-difference squeezing,achieving a 2 dB signal-to-noise ratio improvement beyond the shot-noise limit-equivalent to a 2.6×measurement speed enhancement.Notably,when coupled with up-conversion spectroscopy,our technique records comb-line-resolved,high-resolution(7.5 pm)spectra in the critical 3μm region for molecular fingerprinting.These results bridge quantum optics and frequency comb spectroscopy,offering great potential for trace gas detection,precision metrology,and chemical analysis.Future developments in detector efficiency and nanophotonic integration could further enhance its scalability and impact.展开更多
Frequency combs show various applications in molecular fingerprinting,imaging,communications,and so on.In the terahertz frequency range,semiconductor-based quantum cascade lasers(QCLs)are ideal platforms for realizing...Frequency combs show various applications in molecular fingerprinting,imaging,communications,and so on.In the terahertz frequency range,semiconductor-based quantum cascade lasers(QCLs)are ideal platforms for realizing the frequency comb operation.Although self-started frequency comb operation can be obtained in free-running terahertz QCLs due to the four-wave mixing locking effects,resonant/off-resonant microwave injection,phase locking,and femtosecond laser based locking techniques have been widely used to broaden and stabilize terahertz QCL combs.These active locking methods indeed show significant effects on the frequency stabilization of terahertz QCL combs,but they simultaneously have drawbacks,such as introducing large phase noise and requiring complex optical coupling and/or electrical circuits.Here,we demonstrate Farey tree locking of terahertz QCL frequency combs under microwave injection.The frequency competition between the Farey fraction frequency and the cavity round-trip frequency results in the frequency locking of terahertz QCL combs,and the Farey fraction frequencies can be accurately anticipated based on the downward trend of the Farey tree hierarchy.Furthermore,dual-comb experimental results show that the phase noise of the dual-comb spectral lines is significantly reduced by employing the Farey tree locking method.These results pave the way to deploying compact and low phase noise terahertz frequency comb sources.展开更多
We demonstrated a high-power,high-energy regenerative amplifier(RA)based on Yb-doped CaGdAlO_(4)(Yb:CALGO)crystal,which achieves a maximum average power exceeding 50 W at a repetition rate greater than 50 kHz,and a ma...We demonstrated a high-power,high-energy regenerative amplifier(RA)based on Yb-doped CaGdAlO_(4)(Yb:CALGO)crystal,which achieves a maximum average power exceeding 50 W at a repetition rate greater than 50 kHz,and a maximum pulse energy of approximately 7 mJ at a repetition rate of up to 5 kHz.After compression,130 fs pulses with a peak power of nearly 45 GW are achieved.To the best of our knowledge,this represents the highest average power and pulse energy reported for a Yb:CALGO RA.The RA cavity is specifically designed to maintain excellent stability and output beam quality under a pumping power of 380 W,resulting in a continuous-wave output power exceeding 70 W.For the seeder,a fiber laser utilizing a nonlinear amplification process,which yields a broadband spectrum to support approximately 80 fs pulses,is employed for the high-peak-power pulse generation.展开更多
Single-mode lasing in whispering-gallery mode(WGM)microresonators is challenging to achieve.In bottle microresonators,the highly non-degenerated WGMs are spatially well-separated along the long-axis direction and prov...Single-mode lasing in whispering-gallery mode(WGM)microresonators is challenging to achieve.In bottle microresonators,the highly non-degenerated WGMs are spatially well-separated along the long-axis direction and provide mode-selection capability.In this work,by engineering the pump intensity to modify the spatial gain profiles of bottle microresonators,we demonstrate a simple and general approach to realizing single-mode WGM lasing in polymer bottle microresonators.The pump intensity is engineered into an interference distribution on the bottle microresonator surface.By tuning the spacing between axial positions of the interference pump patterns,the mode intensity profiles of single-bottle WGMs can be spatially overlapped with the interference stripes,intrinsically enabling single-mode lasing and selection.Attractive advantages of the system,including high sidemode suppression factors 420 dB,large spectral tunability 48 nm,low-lasing threshold and reversible control,are presented.Our demonstrated approach may have a variety of promising applications,ranging from tunable single-mode lasing and sensing to nonlinear optics.展开更多
Optical detectors with single-photon sensitivity and large dynamic range would facilitate a variety of applications.Specifically,the capability of extending operation wavelengths into the mid-infrared region is highly...Optical detectors with single-photon sensitivity and large dynamic range would facilitate a variety of applications.Specifically,the capability of extending operation wavelengths into the mid-infrared region is highly attractive.Here we implement a mid-infrared frequency upconversion detector for counting and resolving photons at 3μm.Thanks to the spectrotemporal engineering of the involved optical fields,the mid-infrared photons could be spectrally translated into the visible band with a conversion efficiency of 80%.In combination with a silicon avalanche photodiode,we obtained unprecedented performance with a high overall detection efficiency of 37%and a low noise equivalent power of 1.8×10^(-17) W∕Hz1∕2.Furthermore,photon-number-resolving detection at mid-infrared wavelengths was demonstrated,for the first time to our knowledge,with a multipixel photon counter.The implemented upconversion detector exhibited a maximal resolving photon number up to 9 with a noise probability per pulse of 0.14%at the peak detection efficiency.The achieved photon counting and resolving performance might open up new possibilities in trace molecule spectroscopy,sensitive biochemical sensing,and free-space communications,among others.展开更多
InGaAs/InP avalanche photodiodes typically work in the gated Geiger mode to achieve near-infrared singlephoton detection. By using ultrashort gates and combining with the robust spike-canceling technique that consists...InGaAs/InP avalanche photodiodes typically work in the gated Geiger mode to achieve near-infrared singlephoton detection. By using ultrashort gates and combining with the robust spike-canceling technique that consists of the capacitance-balancing and low-pass filtering technique, we demonstrate an InGaAs/InP single-photon detector(SPD) with widely tunable repetition rates in this paper. The operation frequency could be tuned conveniently from 100 MHz to 1.25 GHz with the SPD's performance measured to maintain good performance, making it quite suitable for quantum key distribution, laser ranging, and optical time domain reflectometry. Furthermore,the SPD exhibited extremely low-noise characteristics. The detection efficiency of this SPD could reach 20% with the dark count rate of 2.5 × 10^(-6)∕gate and after-pulse probability of 4.1% at 1 GHz.展开更多
We have proposed and experimentally demonstrated a novel scheme for efficient mid-infrared difference-frequency generation based on passively synchronized fiber lasers. The adoption of coincident seeding pulses in the...We have proposed and experimentally demonstrated a novel scheme for efficient mid-infrared difference-frequency generation based on passively synchronized fiber lasers. The adoption of coincident seeding pulses in the nonlinear conversion process could substantially lower the pumping threshold for mid-infrared parametric emission. Consequently,a picosecond mid-infrared source at 3.1 μm was prepared with watt-level average power, and a maximum power conversion efficiency of 77% was realized from pump to down-converted light. Additionally, the long-term stability of generated power was manifested with a relative fluctuation as low as 0.17% over one hour. Thanks to the all-optical passive synchronization and all-polarization-maintaining fiber architecture, the implemented laser system was also featured with simplicity, compactness and robustness, which would favor subsequent applications beyond laboratory operation.展开更多
We report on environmentally stable long-cavity ultrashort erbium-doped fiber lasers,which self-start mode-locking at quite low thresholds by using spectrally filtered and phase-biased nonlinear amplifying long-loop m...We report on environmentally stable long-cavity ultrashort erbium-doped fiber lasers,which self-start mode-locking at quite low thresholds by using spectrally filtered and phase-biased nonlinear amplifying long-loop mirrors.By employing 100-m polarization-maintaining fiber(PMF)in the nonlinear loop,the fundamental repetition rate reaches 1.84 MHz and no practical limitation is found to further decrease the repetition rate.The filter used in the long loop not only suppresses Kelly sidebands of the solitons,but also eliminates the amplified spontaneous emission which exists widely in lowrepetition-rate ultrafast fiber lasers.The bandwidth of the filter is optimized by using a numerical model.The laser emits approximately 3-ps pulses with an energy of 17.4 p J,which is further boosted to 1.5μJ by using a fiber amplifier.展开更多
.Laser-induced breakdown spectroscopy(LIBS)is a useful tool for determination of elements in solids,liquids,and gases.For nanosecond LIBS(ns-LIBS),the plasma shielding effect limits its reproducibility,repeatability,a....Laser-induced breakdown spectroscopy(LIBS)is a useful tool for determination of elements in solids,liquids,and gases.For nanosecond LIBS(ns-LIBS),the plasma shielding effect limits its reproducibility,repeatability,and signal-to-noise ratios.Although femtosecond laser filament induced breakdown spectroscopy(FIBS)has no plasma shielding effects,the power density clamping inside the filaments limits the measurement sensitivity.We propose and demonstrate plasma-grating-induced breakdown spectroscopy(GIBS).The technique relies on a plasma excitation source-a plasma grating generated by the interference of two noncollinear femtosecond filaments.We demonstrate that GIBS can overcome the limitations of standard techniques such as ns-LIBS and FIBS.Signal intensity enhancement with GIBS is observed to be greater than 3 times that of FIBS.The matrix effect is also significantly reduced with GIBS,by virtue of the high power and electron density of the plasma grating,demonstrating great potential for analyzing samples with complex matrix.展开更多
Terahertz(THz) waves could be generated through exciting a gravity-guided, free-flowing water wedge by a dual-color pulse. It is not required to rotate the optimal angle considering the water film as an ionization med...Terahertz(THz) waves could be generated through exciting a gravity-guided, free-flowing water wedge by a dual-color pulse. It is not required to rotate the optimal angle considering the water film as an ionization medium.It is demonstrated to be more effective to generate stronger THz radiation when the ionization position is on the front surface of the air water interface of the water wedge by moving its position. The effect of pulse energy on THz generation is also investigated, and it is observed that with the increase of pulse energy the THz electric field shows a quadratic rising trend. These observations are consistent with air plasma induced THz emission.展开更多
Active mid-infrared(MIR)imagers capable of retrieving three-dimensional(3D)structure and reflectivity information are highly attractive in a wide range of biomedical and industrial applications.However,infrared 3D ima...Active mid-infrared(MIR)imagers capable of retrieving three-dimensional(3D)structure and reflectivity information are highly attractive in a wide range of biomedical and industrial applications.However,infrared 3D imaging at lowlight levels is still challenging due to the deficiency of sensitive and fast MiR sensors.Here we propose and implement a MiR time-of-flight imaging system that operates at single-photon sensitivity and femtosecond timing resolution.Specifically,back-scattered infrared photons from a scene are optically gated by delay-controlled ultrashort pump pulses through nonlinear frequency upconversion.The upconverted images with time stamps are then recorded by a silicon camera to facilitate the 3D reconstruction with high lateral and depth resolutions.Moreover,an effective numerical denoiser based on spatiotemporal correlation allows us to reveal the object profle and reflectivity under photon-starving conditions with a detected flux below 0.05 photons/pixel/second.The presented MIR 3D imager features high detection sensitivity,precise timing resolution,and wide-field operation,which may open new possibilities in life and material sciences.展开更多
We demonstrate absorption spectroscopy of water vapor for the determination of gas temperature. An adaptive dual-comb detection system is utilized to obtain precise spectroscopic data in a broadband range from 7143 to...We demonstrate absorption spectroscopy of water vapor for the determination of gas temperature. An adaptive dual-comb detection system is utilized to obtain precise spectroscopic data in a broadband range from 7143 to7240 cm^-1 with a spectral resolution of 0.049 cm^-1. The measured spectra are in accordance with the simulated results from the HITRAN(high-resolution transmission molecular absorption) database. Several measurements are investigated in the temperature range of 500–1000 K, revealing relative deviations of less than 5% compared to the thermocouple. This broadband and accurate adaptive dual-comb spectral detection method could be a powerful tool for non-invasive combustion diagnosis.展开更多
We demonstrate here an environmentally stable and extremely compactable Er-doped fiber laser system capable of delivering sub-100-fs temporal duration and tens of nanojoules at a repetition rate of 10 MHz.This laser s...We demonstrate here an environmentally stable and extremely compactable Er-doped fiber laser system capable of delivering sub-100-fs temporal duration and tens of nanojoules at a repetition rate of 10 MHz.This laser source employs a semiconductor saturable absorber mirror mode-locked soliton laser to generate seed pulses.A singlemode-fiber amplifier and a double-cladding-fiber amplifier(both with double-pass configuration)are bridged by a divider and used to manage the dispersion map and boost the soliton pulses.By using 64 replicas,pulses with as high as 60 n J energy within 95 fs duration are obtained at 10 MHz,corresponding to 600 kW peak power.展开更多
In this paper, we demonstrated a series of short-living mode-locking(ML) states(each lasting a few to a hundred microseconds) that happened before a fiber laser reached a steady ML state.With time-stretched dispersion...In this paper, we demonstrated a series of short-living mode-locking(ML) states(each lasting a few to a hundred microseconds) that happened before a fiber laser reached a steady ML state.With time-stretched dispersion Fourier transform spectroscopy, a rich diversity of transient multi-pulse dynamics were revealed spectrally and temporally.As a result, we found that the formation of the short-living ML states was related to abundant pump power, and their decaying evolution dynamics were possibly governed by gain depletion and recovery.Our results revealed unexpected transient lasing behaviors of a soliton laser and thus might be useful to understand the complex dynamics of mode-locked lasers.展开更多
基金supported by the Innovation Program for Quantum Science and Technology(Grant No.2023ZD0301000)the Chongqing Technology Innovation and Application Develop-ment Project(Grant No.CSTB2022TIAD-DEX0031).
文摘Tunable mid-infrared lasers are essential for optical sensing and imaging.Existing technologies,however,face challenges in simultaneously achieving broadband spectral tunability and ultra-rapid scan rates,limiting their utility in dynamic scenarios such as real-time characterization of multiple molecular absorption bands.We present a high-speed approach for broadband wavelength sweeping in the mid-infrared region,leveraging spectral focusing via difference-frequency generation between a chirped fiber laser and an asynchronous,frequency-modulated electro-optic comb.This method enables pulse-to-pulse spectral tuning at a speed of 5.6 THz∕μs with 380 elements.Applied to spectroscopic sensing,our technique achieves broad spectral coverage(2600 to 3780 cm−1)with moderate spectral resolution(8 cm−1)and rapid acquisition time(-6.3μs).Notably,the controllable electro-optic comb facilitates high scan rates of up to 2 Mscans∕s across the full spectral range(corresponding to a speed of 60 THz∕μs),with trade-offs in number of elements(-30)and spectral point spacing or resolution(33 cm−1).Nevertheless,these capabilities make our platform highly promising for applications such as flow cytometry,chemical reaction monitoring,and mid-infrared ranging and imaging.
基金Project supported by the Innovation Program for Quantum Science and Technology(Grant No.2023ZD0301000)the National Natural Science Foundation of China(Grant Nos.12434018,62475073,1243000542,11621404,11561121003,11727812,61775059,12074122,62405090,62035005,and 11704123)+1 种基金the Natural Science Foundation of Shanghai(Grant No.23ZR1419000)China Postdoctoral Science Foundation(Grant Nos.2023M741188 and 2024T170275)。
文摘Synchronized dual-wavelength mode-locked laser is investigated numerically and experimentally in the normal dispersion regime.A programmable optical processor is introduced to shape the spectral profile and adjust the net dispersion,which is demonstrated be a convenient and reliable approach to generate dual-color solitons.The time-stretch dispersive Fourier transform and frequency-resolved optical grating techniques are utilized to measure the spectral and temporal characteristics of dual-color solitons,respectively.The numerical results are consistent with experimental results.This work may facilitate the development of filter-based mode-locked laser and the understanding of multi-wavelength soliton dynamics.
基金supported by the Research Grants Council of the Hong Kong Special Administrative Region of China(Grant Nos.HKU 17212824,HKU 17210522,HKU C7074-21G,HKU R7003-21,and HKU 17205321)the Innovation and Technology Commission of the Hong Kong SAR Government(Grant Nos.MHP/073/20 and MHP/057/21),and the Health@InnoHK program.
文摘Soliton molecules(SMs),bounded and self-assembled of particle-like dissipative solitons,exist with versatile mutual interactions and manifest substantial potential in soliton communication and optical data storage.However,controllable manipulation of the bounded molecular patterns remains challenging,as reaching a specific operation regime in lasers generally involves adjusting multiple control parameters in connection with a wide range of accessible pulse dynamics.An evolutionary algorithm is implemented for intelligent control of SMs in a 2μm ultrafast fiber laser mode locked through nonlinear polarization rotation.Depending on the specifications of the merit function used for the optimization procedure,various SM operations are obtained,including spectra shape programming and controllable deterministic switching of doublet and triplet SMs operating in stationary or pulsation states with reconfigurable temporal separations,frequency locking of pulsation SMs,doublet and SM complexes with controllable pulsation ratio,etc.Digital encoding is further demonstrated in this platform by employing the self-assembled characteristics of SMs.Our work opens up an avenue for active SM control beyond conventional telecom bands and brings useful insights into nonlinear science and applications.
基金supported by the National Key Research and Development Program(Grant No.2021YFB2801100)the National Natural Science Foundation of China(Grant Nos.62175064,62235019,62035005,and 12022411)+3 种基金the Shanghai Pilot Program for Basic Research(Grant No.TQ20220104)the Natural Science Foundation of Chongqing(Grant Nos.CSTB2023NSCQ-JQX0011,CSTB2022NSCQ-MSX0451,and CSTB2022NSCQ-JQX0016)the Shanghai Municipal Science and Technology Major Project(Grant No.2019SHZDZX01)the Fundamental Research Funds for the Central Universities.
文摘Sensitive mid-infrared(MIR)detection is in high demand in various applications,ranging from remote sensing,infrared surveillance,and environmental monitoring to industrial inspection.Among others,upconversion infrared detectors have recently attracted increasing attention due to their advantageous features of high sensitivity,fast response,and room-temperature operation.However,it remains challenging to realize high-performance passive MIR sensing due to the stringent requirement of high-power continuouswave pumping.Here,we propose and implement a high-efficiency and low-noise MIR upconversion detection system based on pumping enhancement via a low-loss optical cavity.Specifically,a singlelongitudinal-mode pump at 1064 nm is significantly enhanced by a factor of 36,thus allowing for a peak conversion efficiency of up to 22%at an intracavity average power of 55 W.The corresponding noise equivalent power is achieved as low as 0.3 fW∕Hz^(1∕2),which indicates at least a 10-fold improvement over previous results.Notably,the involved single-frequency pumping would facilitate high-fidelity spectral mapping,which is particularly attractive for high-precision MIR upconversion spectroscopy in photonstarved scenarios.
基金sponsored by Shanghai Rising-Star Program(Grant No.22QC1401000)the National Defense Administration of Science,Technology and Industry(Grant No.HTKJ2021KL504014)+2 种基金the National Key Research and Development Program(Grant No.2018YFB0504400)the National Natural Science Foundation of China(Grant Nos.11621404,11727812,and 62035005)Shanghai Municipal Science and Technology Major Project(Grant No.2019SHZDZX01-ZX05).
文摘Filament-and plasma-grating-induced breakdown spectroscopy(F-GIBS)was demonstrated as an efficient technique for sensitive detection of metals in water,where plasma gratings were established through synchronized nonlinear interaction of two noncollinear filaments and an additional filament was generated with another fs laser beam propagating along their bisector.A water jet was constructed vertically to the three coplanar filaments,overcoming side effects from violent plasma explosion and bubble generation.Three distinct regimes of different mechanisms were validated for nonlinear couplings of the third filament with plasma gratings.As the third filament was temporally overlapped with the two noncollinear filaments in the interaction zone,all the three filaments participated in synchronous nonlinear interaction and plasma grating structures were altered by the addition of the third filament.As the third filament was positively or negatively delayed,the as-formed plasma gratings were elongated by the delayed third filament,or plasma gratings were formed in the presence of plasma expansion of the ahead third filament,respectively.Using F-GIBS for trace metal detection in water,significant spectral line enhancements were observed.
文摘When this article was originally published in High Power Laser Science and Engineering it contained an error in the name of the author Jiandong Liu.This has now been fixed.The publisher apologises for this error.
基金supported by Innovation Program for Quantum Science and Technology(2023ZD0301000)National Natural Science Foundation of China(62035005)。
文摘Dual-comb spectroscopy(DCS)is a powerful technique for spectroscopic sensing,offering exceptional spectral bandwidth,resolution,precision,and speed.However,its performance is fundamentally limited by quantum noise inherent to coherent-state optical combs.Here,we overcome this barrier by introducing quantum correlation-enhanced DCS using correlated twin combs generated via seeded four-wave mixing.One comb acts as a local oscillator to decode molecular signals,while the twin suppresses shot noise through intensity-difference squeezing,achieving a 2 dB signal-to-noise ratio improvement beyond the shot-noise limit-equivalent to a 2.6×measurement speed enhancement.Notably,when coupled with up-conversion spectroscopy,our technique records comb-line-resolved,high-resolution(7.5 pm)spectra in the critical 3μm region for molecular fingerprinting.These results bridge quantum optics and frequency comb spectroscopy,offering great potential for trace gas detection,precision metrology,and chemical analysis.Future developments in detector efficiency and nanophotonic integration could further enhance its scalability and impact.
基金supported by the Innovation Program for Quantum Science and Technology(2023ZD0301000)the National Science Fund for Distinguished Young Scholars(62325509)+2 种基金the National Natural Science Foundation of China(62235019,61875220,61927813,61991430,62035005,62105351,and 62305364)the“From 0 to 1”Innovation Program of the Chinese Academy of Sciences(ZDBS-LY-JSC009)the CAS Project for Young Scientists in Basic Research(YSBR-069).
文摘Frequency combs show various applications in molecular fingerprinting,imaging,communications,and so on.In the terahertz frequency range,semiconductor-based quantum cascade lasers(QCLs)are ideal platforms for realizing the frequency comb operation.Although self-started frequency comb operation can be obtained in free-running terahertz QCLs due to the four-wave mixing locking effects,resonant/off-resonant microwave injection,phase locking,and femtosecond laser based locking techniques have been widely used to broaden and stabilize terahertz QCL combs.These active locking methods indeed show significant effects on the frequency stabilization of terahertz QCL combs,but they simultaneously have drawbacks,such as introducing large phase noise and requiring complex optical coupling and/or electrical circuits.Here,we demonstrate Farey tree locking of terahertz QCL frequency combs under microwave injection.The frequency competition between the Farey fraction frequency and the cavity round-trip frequency results in the frequency locking of terahertz QCL combs,and the Farey fraction frequencies can be accurately anticipated based on the downward trend of the Farey tree hierarchy.Furthermore,dual-comb experimental results show that the phase noise of the dual-comb spectral lines is significantly reduced by employing the Farey tree locking method.These results pave the way to deploying compact and low phase noise terahertz frequency comb sources.
基金supported by the National Key R&D Program of China(2022YFF0706001)the Innovation Program for Quantum Science and Technology(2023ZD0301000)+1 种基金the National Natural Science Foundation of China(62205206,62375173)the China Postdoctoral Science Foundation(2023M732320).
文摘We demonstrated a high-power,high-energy regenerative amplifier(RA)based on Yb-doped CaGdAlO_(4)(Yb:CALGO)crystal,which achieves a maximum average power exceeding 50 W at a repetition rate greater than 50 kHz,and a maximum pulse energy of approximately 7 mJ at a repetition rate of up to 5 kHz.After compression,130 fs pulses with a peak power of nearly 45 GW are achieved.To the best of our knowledge,this represents the highest average power and pulse energy reported for a Yb:CALGO RA.The RA cavity is specifically designed to maintain excellent stability and output beam quality under a pumping power of 380 W,resulting in a continuous-wave output power exceeding 70 W.For the seeder,a fiber laser utilizing a nonlinear amplification process,which yields a broadband spectrum to support approximately 80 fs pulses,is employed for the high-peak-power pulse generation.
基金supported by the National Natural Science Foundation of China(11674230)973 Program(2015CB352001)National Natural Science Foundation of China(11434005).
文摘Single-mode lasing in whispering-gallery mode(WGM)microresonators is challenging to achieve.In bottle microresonators,the highly non-degenerated WGMs are spatially well-separated along the long-axis direction and provide mode-selection capability.In this work,by engineering the pump intensity to modify the spatial gain profiles of bottle microresonators,we demonstrate a simple and general approach to realizing single-mode WGM lasing in polymer bottle microresonators.The pump intensity is engineered into an interference distribution on the bottle microresonator surface.By tuning the spacing between axial positions of the interference pump patterns,the mode intensity profiles of single-bottle WGMs can be spatially overlapped with the interference stripes,intrinsically enabling single-mode lasing and selection.Attractive advantages of the system,including high sidemode suppression factors 420 dB,large spectral tunability 48 nm,low-lasing threshold and reversible control,are presented.Our demonstrated approach may have a variety of promising applications,ranging from tunable single-mode lasing and sensing to nonlinear optics.
基金National Key Research and Development Program of China(2018YFB0407100)Science and Technology Innovation Program of Basic Science Foundation of Shanghai(18JC1412000)+2 种基金Program for Professor of Special Appointment(Eastern Scholar)at Shanghai Institutions of Higher LearningNational Natural Science Foundation of China(11621404,11727812)Shanghai Municipal Science and Technology Major Project(2019SHZDZX01)。
文摘Optical detectors with single-photon sensitivity and large dynamic range would facilitate a variety of applications.Specifically,the capability of extending operation wavelengths into the mid-infrared region is highly attractive.Here we implement a mid-infrared frequency upconversion detector for counting and resolving photons at 3μm.Thanks to the spectrotemporal engineering of the involved optical fields,the mid-infrared photons could be spectrally translated into the visible band with a conversion efficiency of 80%.In combination with a silicon avalanche photodiode,we obtained unprecedented performance with a high overall detection efficiency of 37%and a low noise equivalent power of 1.8×10^(-17) W∕Hz1∕2.Furthermore,photon-number-resolving detection at mid-infrared wavelengths was demonstrated,for the first time to our knowledge,with a multipixel photon counter.The implemented upconversion detector exhibited a maximal resolving photon number up to 9 with a noise probability per pulse of 0.14%at the peak detection efficiency.The achieved photon counting and resolving performance might open up new possibilities in trace molecule spectroscopy,sensitive biochemical sensing,and free-space communications,among others.
基金National Natural Science Foundation of China(NSFC)(11404212,11604209,61127014)National Key Scientific Instrument Project(2012YQ150092)+1 种基金Shanghai Science and Technology Foundation(16JC1400404)Hujiang Foundation of China(D15014)
文摘InGaAs/InP avalanche photodiodes typically work in the gated Geiger mode to achieve near-infrared singlephoton detection. By using ultrashort gates and combining with the robust spike-canceling technique that consists of the capacitance-balancing and low-pass filtering technique, we demonstrate an InGaAs/InP single-photon detector(SPD) with widely tunable repetition rates in this paper. The operation frequency could be tuned conveniently from 100 MHz to 1.25 GHz with the SPD's performance measured to maintain good performance, making it quite suitable for quantum key distribution, laser ranging, and optical time domain reflectometry. Furthermore,the SPD exhibited extremely low-noise characteristics. The detection efficiency of this SPD could reach 20% with the dark count rate of 2.5 × 10^(-6)∕gate and after-pulse probability of 4.1% at 1 GHz.
基金supported in part by the National Key Research and Development Program(No.2018YFB0407100)Science and Technology Innovation Program of Basic Science Foundation of Shanghai(No.18JC1412000)+1 种基金Program for Professor of Special Appointment(Eastern Scholar)at Shanghai Institutions of Higher Learning,National Natural Science Foundation of China(Nos.11621404 and 11727812)Shanghai Municipal Science and Technology Major Project(No.2019SHZDZX01)。
文摘We have proposed and experimentally demonstrated a novel scheme for efficient mid-infrared difference-frequency generation based on passively synchronized fiber lasers. The adoption of coincident seeding pulses in the nonlinear conversion process could substantially lower the pumping threshold for mid-infrared parametric emission. Consequently,a picosecond mid-infrared source at 3.1 μm was prepared with watt-level average power, and a maximum power conversion efficiency of 77% was realized from pump to down-converted light. Additionally, the long-term stability of generated power was manifested with a relative fluctuation as low as 0.17% over one hour. Thanks to the all-optical passive synchronization and all-polarization-maintaining fiber architecture, the implemented laser system was also featured with simplicity, compactness and robustness, which would favor subsequent applications beyond laboratory operation.
基金supported by the National Key Research and Development Program (No. 2018YFB0407100)National Natural Science Foundation of China (Nos. 11434005 and 11621404)Key Project of Shanghai Education Commission (No. 2017-01-07-00-05-E00021)
文摘We report on environmentally stable long-cavity ultrashort erbium-doped fiber lasers,which self-start mode-locking at quite low thresholds by using spectrally filtered and phase-biased nonlinear amplifying long-loop mirrors.By employing 100-m polarization-maintaining fiber(PMF)in the nonlinear loop,the fundamental repetition rate reaches 1.84 MHz and no practical limitation is found to further decrease the repetition rate.The filter used in the long loop not only suppresses Kelly sidebands of the solitons,but also eliminates the amplified spontaneous emission which exists widely in lowrepetition-rate ultrafast fiber lasers.The bandwidth of the filter is optimized by using a numerical model.The laser emits approximately 3-ps pulses with an energy of 17.4 p J,which is further boosted to 1.5μJ by using a fiber amplifier.
基金We acknowledge the support fromthe National Key Research and Development Program(No.2018YFB0407100)the National Natural Science Foundation of China(No.11621404)the Key Project of Shanghai Education Commission(No.2017-01-07-00-05-E00021).
文摘.Laser-induced breakdown spectroscopy(LIBS)is a useful tool for determination of elements in solids,liquids,and gases.For nanosecond LIBS(ns-LIBS),the plasma shielding effect limits its reproducibility,repeatability,and signal-to-noise ratios.Although femtosecond laser filament induced breakdown spectroscopy(FIBS)has no plasma shielding effects,the power density clamping inside the filaments limits the measurement sensitivity.We propose and demonstrate plasma-grating-induced breakdown spectroscopy(GIBS).The technique relies on a plasma excitation source-a plasma grating generated by the interference of two noncollinear femtosecond filaments.We demonstrate that GIBS can overcome the limitations of standard techniques such as ns-LIBS and FIBS.Signal intensity enhancement with GIBS is observed to be greater than 3 times that of FIBS.The matrix effect is also significantly reduced with GIBS,by virtue of the high power and electron density of the plasma grating,demonstrating great potential for analyzing samples with complex matrix.
基金supported by the National Natural Science Foundation of China(Nos.11727812 and 61927813)the National Key Research and Development Program of China(No.2018YFB0504400)
文摘Terahertz(THz) waves could be generated through exciting a gravity-guided, free-flowing water wedge by a dual-color pulse. It is not required to rotate the optimal angle considering the water film as an ionization medium.It is demonstrated to be more effective to generate stronger THz radiation when the ionization position is on the front surface of the air water interface of the water wedge by moving its position. The effect of pulse energy on THz generation is also investigated, and it is observed that with the increase of pulse energy the THz electric field shows a quadratic rising trend. These observations are consistent with air plasma induced THz emission.
基金supported by the National Natural Science Foundation of China(Nos.62175064,62235019,62035005)Shanghai Pilot Program for Basic Research(TQ20220104)+1 种基金Shanghai Municipal Science and Technology Major Project(2019SHZDZX01)Fundamental Research Funds for the Central Universities.
文摘Active mid-infrared(MIR)imagers capable of retrieving three-dimensional(3D)structure and reflectivity information are highly attractive in a wide range of biomedical and industrial applications.However,infrared 3D imaging at lowlight levels is still challenging due to the deficiency of sensitive and fast MiR sensors.Here we propose and implement a MiR time-of-flight imaging system that operates at single-photon sensitivity and femtosecond timing resolution.Specifically,back-scattered infrared photons from a scene are optically gated by delay-controlled ultrashort pump pulses through nonlinear frequency upconversion.The upconverted images with time stamps are then recorded by a silicon camera to facilitate the 3D reconstruction with high lateral and depth resolutions.Moreover,an effective numerical denoiser based on spatiotemporal correlation allows us to reveal the object profle and reflectivity under photon-starving conditions with a detected flux below 0.05 photons/pixel/second.The presented MIR 3D imager features high detection sensitivity,precise timing resolution,and wide-field operation,which may open new possibilities in life and material sciences.
基金the National Natural Science Foundation of China(Nos.11727812 and 11704253)the National Key R&D Program of China(No.2018YFB0407100)+1 种基金the Science and Technology Innovation Program of Basic Science Foundation of Shanghai(No.18JC1412000)the Shanghai Youth Science and Technology Talent Sailing Program(No.17YF1413100)。
文摘We demonstrate absorption spectroscopy of water vapor for the determination of gas temperature. An adaptive dual-comb detection system is utilized to obtain precise spectroscopic data in a broadband range from 7143 to7240 cm^-1 with a spectral resolution of 0.049 cm^-1. The measured spectra are in accordance with the simulated results from the HITRAN(high-resolution transmission molecular absorption) database. Several measurements are investigated in the temperature range of 500–1000 K, revealing relative deviations of less than 5% compared to the thermocouple. This broadband and accurate adaptive dual-comb spectral detection method could be a powerful tool for non-invasive combustion diagnosis.
基金supported by the National Key R&D Program of China(No.2018YFB0407100)
文摘We demonstrate here an environmentally stable and extremely compactable Er-doped fiber laser system capable of delivering sub-100-fs temporal duration and tens of nanojoules at a repetition rate of 10 MHz.This laser source employs a semiconductor saturable absorber mirror mode-locked soliton laser to generate seed pulses.A singlemode-fiber amplifier and a double-cladding-fiber amplifier(both with double-pass configuration)are bridged by a divider and used to manage the dispersion map and boost the soliton pulses.By using 64 replicas,pulses with as high as 60 n J energy within 95 fs duration are obtained at 10 MHz,corresponding to 600 kW peak power.
基金supported by the National Key Research and Development Program (No.2018YFB0504400)National Natural Science Foundation of China (NSFC)(Nos.61875243and 11804100)+1 种基金Shanghai Municipal Science and Technology Major Project (No.2019SHZDZX01)Science and Technology Innovation Program of Basic Science Foundation of Shanghai (No.18JC1412000)。
文摘In this paper, we demonstrated a series of short-living mode-locking(ML) states(each lasting a few to a hundred microseconds) that happened before a fiber laser reached a steady ML state.With time-stretched dispersion Fourier transform spectroscopy, a rich diversity of transient multi-pulse dynamics were revealed spectrally and temporally.As a result, we found that the formation of the short-living ML states was related to abundant pump power, and their decaying evolution dynamics were possibly governed by gain depletion and recovery.Our results revealed unexpected transient lasing behaviors of a soliton laser and thus might be useful to understand the complex dynamics of mode-locked lasers.
