The cavity-enhanced spontaneous parametric down-conversion far below threshold can be used to generate a narrow-band photon pair efficiently. Previous experiments on the cavity-enhanced spontaneous parametric down- co...The cavity-enhanced spontaneous parametric down-conversion far below threshold can be used to generate a narrow-band photon pair efficiently. Previous experiments on the cavity-enhanced spontaneous parametric down- conversion almost always utilize continuous wave pump light, but the pulse pumped case is rarely reported. One disadvantage of the continuous wave case is that the photon pair is produced randomly within the coherence time of the pump, which limits its application in the quantum information realm. However, a pulse pump can help to solve this problem. In this paper, we theoretically analyze pulse pumped cavity-enhanced spontaneous parametric down- conversion in detail and show how the pump pulse affects the multi-photon interference visibility, two-photon waveform, joint spectrum and spectral brightness.展开更多
A diode pumped Kerr-lens mode-locked femtosecond Yb：LSO laser is experimentally demonstrated for the first time. The 54fs laser pulses at central wavelength of 1052nm with a bandwidth of 22.5nm are obtained at the re...A diode pumped Kerr-lens mode-locked femtosecond Yb：LSO laser is experimentally demonstrated for the first time. The 54fs laser pulses at central wavelength of 1052nm with a bandwidth of 22.5nm are obtained at the repetition rate of 113 MHz. To the best of our knowledge, this is the shortest pulse duration ever produced from the Yb-doped orthosilicates lasers family.展开更多
The influence of pumping laser pulse on the property of quasi-continuous-wave(QCW)diode-side-pumped Nd:YAG laser is investigated theoretically and experimentally.Under remaining a fixed duty cycle,the average output p...The influence of pumping laser pulse on the property of quasi-continuous-wave(QCW)diode-side-pumped Nd:YAG laser is investigated theoretically and experimentally.Under remaining a fixed duty cycle,the average output power increases,and the corresponding thermal focal length shorten with the increase of the pump pulse duration,which attributes to the decrease of the ratio of pulse buildup time to the pulse duration.At a pump power of 146 W,the laser output power changes from 65.1 W to 81.2 W when the pulse duration is adjusted from 150μs to 1000μs,confirming a significant enhancement of 24.7%.A laser rate equation model incorporating the amplified spontaneous emission is also utilized and numerically solved,and the simulated results agree well with the experimental data.展开更多
To assess the effectiveness of the flashlamp- pumped pulsed dye laser (Photogeneca V, Synosure Corp, Boston, United States) in the treatment of port- wine stains. Methods. One hundred and ninety- four consecutive pati...To assess the effectiveness of the flashlamp- pumped pulsed dye laser (Photogeneca V, Synosure Corp, Boston, United States) in the treatment of port- wine stains. Methods. One hundred and ninety- four consecutive patients with port- wine stains were treated with a flashlamp- pumped pulsed dye laser in Peking Union Medical College Hospital from January 1998 to August 1999. Results. Of 194 patients who completed treatment, 56.2％ had more than 60％ fading of the lesion and only 6.7％ had less than 20％ fading. An average of 3.6 treatments were needed to achieve more than 60％ fading. The response was better in children than in adults, although the difference was not significant. Pigmentary change (usually transient) occurred in 3.1％ of patients. Conclusions. This study confirms the efficacy of the flashlamp- pumped pulsed dye laser in the treatment of port- wine stains in children and adults.展开更多
Resonance enhancement has been increasingly employed in the emergent felntosecond stimu- lated Raman spectroscopy （FSRS） to selectively monitor molecular structure and dynamics with improved spectral and temporal re...Resonance enhancement has been increasingly employed in the emergent felntosecond stimu- lated Raman spectroscopy （FSRS） to selectively monitor molecular structure and dynamics with improved spectral and temporal resolutions and signal-to-noise ratios. Such joint eflforts by the technique- and application-oriented scientists and engineers have laid the foundation for exploiting the tunable FSRS methodology to investigate a great variety of photosensitive systems and elucidate the underlying functional mechanisms on molecular time scales. Dur- ing spectral analysis, peak line shapes remain a major concern with an intricate dependence on resonance conditions. Here, we present a comprehensive study of line shapes by tuning the Rarnan pump wavelength from red to blue side of the ground-state absorption band of the fluorescent dye rhodarnine 6G in solution. Distinct line shape patterns in Stokes and anti-Stokes FSRS as well as from the low to high-frequency modes highlight the competition between multiple third-order and higher-order nonlinear pathways, governed by difl^rent res- onance conditions achieved by Raman pump and probe pulses. In particular, the resonance condition of probe wavelength is revealed to play an important role in generating circular line shape changes through oppositely phased dispersion via hot luminescence （HL） pathways. Meanwhile, on-resonance conditions of the Rarnan pump could promote excited-state vibrational modes which are broadened and red-shifted from the coincident ground-state vibrational modes, posing challenges for spectral analysis. Certain strategies in tuning the Raman pump and probe to characteristic regions across an electronic transition band are discussed to improve the FSRS usability and versatility as a powerful structural dynamics toolset to advance chemical, physical, materials, and biological sciences.展开更多
Concrete pump pipe pulse force fixed device is one of the important equipment in engineering construction. Its role is to transport mixed concrete. Concrete pump pipe pulse force fixed device is particularly important...Concrete pump pipe pulse force fixed device is one of the important equipment in engineering construction. Its role is to transport mixed concrete. Concrete pump pipe pulse force fixed device is particularly important in high-rise buildings, because it can save labors, and improve the production efficiency of engineering construction. However, when pumping concrete, the pump pipe will produce strong impulse impact force, which may lead to pump pipe rupture and support system instability collapse accident, resulting in casualties, and it is easy to destroy the cross-section size of the formwork and cause the deviation of the position of the structural reinforcement, affecting the quality of concrete, thereby endangering the safety of the structure. For this purpose, the pump pipe needs to be fixed. The existing fixing method is to reinforce the pump pipe through the well-shaped scaffold, which is mostly rigid structure, and the impact force produced by the pump pipe in the pumping process is easy to damage the pump pipe. Based on the above research, this paper explores the invention of a reusable pulse force fixing device for concrete pump pipe, hoping to be helpful to other workers in the concrete industry.展开更多
The influence of the ultra-short pulse wavelength on the populations in the three electronic states of CsI molecule is investigated using the time-dependent wave packet method. The calculated results show that the pop...The influence of the ultra-short pulse wavelength on the populations in the three electronic states of CsI molecule is investigated using the time-dependent wave packet method. The calculated results show that the populations in the two excited states approach to the maxima at the wavelengths of 369 nm and 297 nm, respectively. The photodissociation reaction channels of the CsI molecule can be chosen by controlling the pump pulse wavelength.展开更多
We demonstrate the generation of supercontinuum (SC) of over 1350 nm by injecting 790-nm, 15-fs, 74-MHz optical pulses into a 183-mm-long microstructured fiber with combination core and random cladding. The maximum to...We demonstrate the generation of supercontinuum (SC) of over 1350 nm by injecting 790-nm, 15-fs, 74-MHz optical pulses into a 183-mm-long microstructured fiber with combination core and random cladding. The maximum total power of SC is 73 mW with 290-mW pump power from 40x microscope objective. The wavelength and power ranging in SC as well as the polarization states and waveguide modes of the visible light can be tuned by adjusting the input end of MF.In particular, white light has been observed. To our knowledge, this is the first report of tunable properties in SC generation process using microstructured fiber with combination core and random cladding.展开更多
We demonstrate a high-pulse-energy, short-pulse-width passively Q-switched（PQS） Nd：YAG∕V3t：YAG laser at 1.3 μm, which is end-pumped by a pulsed laser diode. During the PQS regime, a maximum total output pulse en...We demonstrate a high-pulse-energy, short-pulse-width passively Q-switched（PQS） Nd：YAG∕V3t：YAG laser at 1.3 μm, which is end-pumped by a pulsed laser diode. During the PQS regime, a maximum total output pulse energy of 3.3 m J is obtained under an absorbed pump pulse energy of 21.9 m J. Up to 400 μJ single-pulse energy is realized with the shortest pulse width of 6.16 ns and a pulse repetition frequency of 34.1 k Hz,corresponding to a peak power of 64.9 k W. The high-energy laser pulse is operated in the dual wavelengths of 1319 and 1338 nm, which is a potential laser source for THz generation.展开更多
We report the recent progress of our pulsed optically pumped（POP） vapor cell rubidium clock with dispersive detection.A new compact physics package is made.A rubidium cell with a high precision buffer gases mixing r...We report the recent progress of our pulsed optically pumped（POP） vapor cell rubidium clock with dispersive detection.A new compact physics package is made.A rubidium cell with a high precision buffer gases mixing ratio is obtained,and the temperature controlling system is renovated to reduce fractional frequency sensitivity to temperature variation.The resolution of the servo control voltage is also optimized.With these improvements,a clock frequency stability of 3.53×10-13 at 1s is obtained,and a fractional frequency stability of 4.91×10-15 is achieved at an average time of τ=2000 s.展开更多
Supercontinuum generation（SC） of more than one octave spectrum spanning covering from 400 nm to 820 nm was achieved by pumping a piece of aluminum nitride（AIN） single crystal using a nanosecond 355 nm ultraviolet ...Supercontinuum generation（SC） of more than one octave spectrum spanning covering from 400 nm to 820 nm was achieved by pumping a piece of aluminum nitride（AIN） single crystal using a nanosecond 355 nm ultraviolet laser. The AlN with a thickness of ~0.8 mm was grown by an optimized physical vapor transport technique and polished with solidification technology. Compared to previously reported ones, the achieved visible SC exhibited the broadest spectrum spanning from bulk materials pumped by a nanosecond pulse laser. The visible supercontinuum in Al N presents new opportunities for bulk material-based white light SC and may find more potential applications beyond typical applications in integrated semiconductive photoelectronic devices.展开更多
Free-space strong-field terahertz(THz)pulses,generated via optical rectification of femtosecond lasers in nonlinear crystals,are pivotal in various applications.However,conventional Ti:sapphire lasers struggle to prod...Free-space strong-field terahertz(THz)pulses,generated via optical rectification of femtosecond lasers in nonlinear crystals,are pivotal in various applications.However,conventional Ti:sapphire lasers struggle to produce high-average-power THz sources due to their limited output power.While kilowatt ytterbium lasers are increasingly adopted,their application in THz generation faces challenges:low optical-to-THz conversion efficiency(attributed to long pulse duration and low energy)and crystal damage under high pumping power.Here,we report a high-average-power strong-field THz source using a lithium niobate crystal pumped by a 1030 nm,570 fs,1 mJ,50 kHz ytterbium femtosecond laser with tilted pulse front pumping(TPFP).By systematically optimizing TPFP implementations and comparing grating-and echelon-type configurations,we achieve a THz source with 64.5 mW average power at 42 W,50 kHz pumping,and focused peak electric field of 525 kV/cm at 0.83 mJ,1 kHz operation.Additionally,we observe Zeeman torque signals in cobalt-iron ferromagnetic nanofilms.This high-repetition-rate,high-average-power THz system,combined with its potential capabilities in high signal-to-noise ratio spectroscopy and imaging,promises transformative impacts in quantum matter manipulation,non-destructive testing,and biomedicine.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.10874171)the National Basic Research Program of China(Grant No.2009CB929601)+1 种基金the Innovation Fund from Chinese Academy of Sciencesthe Program for New Century Excellent Talents in University of China(Grant No.NCET-07-0791)
文摘The cavity-enhanced spontaneous parametric down-conversion far below threshold can be used to generate a narrow-band photon pair efficiently. Previous experiments on the cavity-enhanced spontaneous parametric down- conversion almost always utilize continuous wave pump light, but the pulse pumped case is rarely reported. One disadvantage of the continuous wave case is that the photon pair is produced randomly within the coherence time of the pump, which limits its application in the quantum information realm. However, a pulse pump can help to solve this problem. In this paper, we theoretically analyze pulse pumped cavity-enhanced spontaneous parametric down- conversion in detail and show how the pump pulse affects the multi-photon interference visibility, two-photon waveform, joint spectrum and spectral brightness.
基金Supported by the National Basic Research Program of China under Grant No 2013CB922402the National Key Scientific Instrument and Equipment Development Project under Grant No 2012YQ120047+1 种基金the Fundamental Research Funds for the Central Universities under Grant No JB140502the National Natural Science Foundation of China under Grant Nos 11174361 and61205130
文摘A diode pumped Kerr-lens mode-locked femtosecond Yb：LSO laser is experimentally demonstrated for the first time. The 54fs laser pulses at central wavelength of 1052nm with a bandwidth of 22.5nm are obtained at the repetition rate of 113 MHz. To the best of our knowledge, this is the shortest pulse duration ever produced from the Yb-doped orthosilicates lasers family.
基金Project supported by the National Key Research and Development Program of China(Grant No.2016YFB0402103)the Knowledge Innovation Program of the Chinese Academy of Sciences(Grant No.GJJSTD20180004)the Fund of Technical Institute of Physics and Chemistry,Chinese Academy of Sciences(Grant No.Y8A9021H11)。
文摘The influence of pumping laser pulse on the property of quasi-continuous-wave(QCW)diode-side-pumped Nd:YAG laser is investigated theoretically and experimentally.Under remaining a fixed duty cycle,the average output power increases,and the corresponding thermal focal length shorten with the increase of the pump pulse duration,which attributes to the decrease of the ratio of pulse buildup time to the pulse duration.At a pump power of 146 W,the laser output power changes from 65.1 W to 81.2 W when the pulse duration is adjusted from 150μs to 1000μs,confirming a significant enhancement of 24.7%.A laser rate equation model incorporating the amplified spontaneous emission is also utilized and numerically solved,and the simulated results agree well with the experimental data.
文摘To assess the effectiveness of the flashlamp- pumped pulsed dye laser (Photogeneca V, Synosure Corp, Boston, United States) in the treatment of port- wine stains. Methods. One hundred and ninety- four consecutive patients with port- wine stains were treated with a flashlamp- pumped pulsed dye laser in Peking Union Medical College Hospital from January 1998 to August 1999. Results. Of 194 patients who completed treatment, 56.2％ had more than 60％ fading of the lesion and only 6.7％ had less than 20％ fading. An average of 3.6 treatments were needed to achieve more than 60％ fading. The response was better in children than in adults, although the difference was not significant. Pigmentary change (usually transient) occurred in 3.1％ of patients. Conclusions. This study confirms the efficacy of the flashlamp- pumped pulsed dye laser in the treatment of port- wine stains in children and adults.
基金supported by the U.S.National Science Foundation CAREER grant(CHE-1455353)the Oregon State University(OSU) Research Equipment Reserve Fund(Spring 2014)to C.Fang(USTC9603)the Wei Family Private Foundation in supporting C.Chen(USTC 0903) during his graduate studies at OSU Chemistry
文摘Resonance enhancement has been increasingly employed in the emergent felntosecond stimu- lated Raman spectroscopy （FSRS） to selectively monitor molecular structure and dynamics with improved spectral and temporal resolutions and signal-to-noise ratios. Such joint eflforts by the technique- and application-oriented scientists and engineers have laid the foundation for exploiting the tunable FSRS methodology to investigate a great variety of photosensitive systems and elucidate the underlying functional mechanisms on molecular time scales. Dur- ing spectral analysis, peak line shapes remain a major concern with an intricate dependence on resonance conditions. Here, we present a comprehensive study of line shapes by tuning the Rarnan pump wavelength from red to blue side of the ground-state absorption band of the fluorescent dye rhodarnine 6G in solution. Distinct line shape patterns in Stokes and anti-Stokes FSRS as well as from the low to high-frequency modes highlight the competition between multiple third-order and higher-order nonlinear pathways, governed by difl^rent res- onance conditions achieved by Raman pump and probe pulses. In particular, the resonance condition of probe wavelength is revealed to play an important role in generating circular line shape changes through oppositely phased dispersion via hot luminescence （HL） pathways. Meanwhile, on-resonance conditions of the Rarnan pump could promote excited-state vibrational modes which are broadened and red-shifted from the coincident ground-state vibrational modes, posing challenges for spectral analysis. Certain strategies in tuning the Raman pump and probe to characteristic regions across an electronic transition band are discussed to improve the FSRS usability and versatility as a powerful structural dynamics toolset to advance chemical, physical, materials, and biological sciences.
文摘Concrete pump pipe pulse force fixed device is one of the important equipment in engineering construction. Its role is to transport mixed concrete. Concrete pump pipe pulse force fixed device is particularly important in high-rise buildings, because it can save labors, and improve the production efficiency of engineering construction. However, when pumping concrete, the pump pipe will produce strong impulse impact force, which may lead to pump pipe rupture and support system instability collapse accident, resulting in casualties, and it is easy to destroy the cross-section size of the formwork and cause the deviation of the position of the structural reinforcement, affecting the quality of concrete, thereby endangering the safety of the structure. For this purpose, the pump pipe needs to be fixed. The existing fixing method is to reinforce the pump pipe through the well-shaped scaffold, which is mostly rigid structure, and the impact force produced by the pump pipe in the pumping process is easy to damage the pump pipe. Based on the above research, this paper explores the invention of a reusable pulse force fixing device for concrete pump pipe, hoping to be helpful to other workers in the concrete industry.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 10674114 and 10604045)
文摘The influence of the ultra-short pulse wavelength on the populations in the three electronic states of CsI molecule is investigated using the time-dependent wave packet method. The calculated results show that the populations in the two excited states approach to the maxima at the wavelengths of 369 nm and 297 nm, respectively. The photodissociation reaction channels of the CsI molecule can be chosen by controlling the pump pulse wavelength.
基金This work was supPorted by the Henan Cultivatlon Project for University Innovatlon Thlents.
文摘We demonstrate the generation of supercontinuum (SC) of over 1350 nm by injecting 790-nm, 15-fs, 74-MHz optical pulses into a 183-mm-long microstructured fiber with combination core and random cladding. The maximum total power of SC is 73 mW with 290-mW pump power from 40x microscope objective. The wavelength and power ranging in SC as well as the polarization states and waveguide modes of the visible light can be tuned by adjusting the input end of MF.In particular, white light has been observed. To our knowledge, this is the first report of tunable properties in SC generation process using microstructured fiber with combination core and random cladding.
基金supported by the National Natural Science Foundation of China(Grant Nos.61275142 12751426,1308042,31608042,and 51321091)the China Postdoctoral Science Foundation(Grant No.2014T70633)the Foundation for Outstanding Young Scientists in Shandong Province(Grant No.BS2012ZZ001)
文摘We demonstrate a high-pulse-energy, short-pulse-width passively Q-switched（PQS） Nd：YAG∕V3t：YAG laser at 1.3 μm, which is end-pumped by a pulsed laser diode. During the PQS regime, a maximum total output pulse energy of 3.3 m J is obtained under an absorbed pump pulse energy of 21.9 m J. Up to 400 μJ single-pulse energy is realized with the shortest pulse width of 6.16 ns and a pulse repetition frequency of 34.1 k Hz,corresponding to a peak power of 64.9 k W. The high-energy laser pulse is operated in the dual wavelengths of 1319 and 1338 nm, which is a potential laser source for THz generation.
基金supported by the National Natural Science Foundation of China under Grant Nos.91536220 and 11504393
文摘We report the recent progress of our pulsed optically pumped（POP） vapor cell rubidium clock with dispersive detection.A new compact physics package is made.A rubidium cell with a high precision buffer gases mixing ratio is obtained,and the temperature controlling system is renovated to reduce fractional frequency sensitivity to temperature variation.The resolution of the servo control voltage is also optimized.With these improvements,a clock frequency stability of 3.53×10-13 at 1s is obtained,and a fractional frequency stability of 4.91×10-15 is achieved at an average time of τ=2000 s.
基金supported by the National Natural Science Foundation of China(NSFC)(Nos.61575129 and 11447029)the Science&Technology Innovation Committee Foundation of Shenzhen(No.JCYJ20160328144942069)
文摘Supercontinuum generation（SC） of more than one octave spectrum spanning covering from 400 nm to 820 nm was achieved by pumping a piece of aluminum nitride（AIN） single crystal using a nanosecond 355 nm ultraviolet laser. The AlN with a thickness of ~0.8 mm was grown by an optimized physical vapor transport technique and polished with solidification technology. Compared to previously reported ones, the achieved visible SC exhibited the broadest spectrum spanning from bulk materials pumped by a nanosecond pulse laser. The visible supercontinuum in Al N presents new opportunities for bulk material-based white light SC and may find more potential applications beyond typical applications in integrated semiconductive photoelectronic devices.
基金Scientific Research Innovation Capability Support Project for Young(ZYGXQNJSKYCXNLZCXMI3)National Key Research and Development Program of China(2022YFA1604402)+1 种基金National Natural Science Foundation of China(U23A6002,92250307)Open Project Program of Wuhan National Laboratory for Optoelectronics(2022WNLOKF006)。
文摘Free-space strong-field terahertz(THz)pulses,generated via optical rectification of femtosecond lasers in nonlinear crystals,are pivotal in various applications.However,conventional Ti:sapphire lasers struggle to produce high-average-power THz sources due to their limited output power.While kilowatt ytterbium lasers are increasingly adopted,their application in THz generation faces challenges:low optical-to-THz conversion efficiency(attributed to long pulse duration and low energy)and crystal damage under high pumping power.Here,we report a high-average-power strong-field THz source using a lithium niobate crystal pumped by a 1030 nm,570 fs,1 mJ,50 kHz ytterbium femtosecond laser with tilted pulse front pumping(TPFP).By systematically optimizing TPFP implementations and comparing grating-and echelon-type configurations,we achieve a THz source with 64.5 mW average power at 42 W,50 kHz pumping,and focused peak electric field of 525 kV/cm at 0.83 mJ,1 kHz operation.Additionally,we observe Zeeman torque signals in cobalt-iron ferromagnetic nanofilms.This high-repetition-rate,high-average-power THz system,combined with its potential capabilities in high signal-to-noise ratio spectroscopy and imaging,promises transformative impacts in quantum matter manipulation,non-destructive testing,and biomedicine.
