We report a high-average-power noise-like pulse(NLP) and dissipative soliton(DS) pulse fiber laser. Average power as high as 4.8 W could be obtained at the fundamental mode-locked repetition rate. The NLP can also be ...We report a high-average-power noise-like pulse(NLP) and dissipative soliton(DS) pulse fiber laser. Average power as high as 4.8 W could be obtained at the fundamental mode-locked repetition rate. The NLP can also be transformed into a more powerful DS mode-locking state by optimizing the polarization and losses of intra-cavity pulses in the nonlinear polarization evolution regime. The operation mode between the NLP and DS can be switched, and the laser output performance in both modes has been studied. The main advantage of this work is switchable high-power operation between the NLP and DS. In comparison with conventional single-mode NLP fiber lasers, the multi-function high-power optical source will greatly push its application in supercontinuum generation, coherence tomography, and industrial processing.展开更多
The high harmonic generation(HHG)by few-cycle laser pulses is essential for research in strong-field solid-state physics.Through comparison of high harmonic spectra of solids generated by laser pulses with varying dur...The high harmonic generation(HHG)by few-cycle laser pulses is essential for research in strong-field solid-state physics.Through comparison of high harmonic spectra of solids generated by laser pulses with varying durations,we discovered that lasers with good dispersion compensation are capable of producing a broad spectrum of high harmonics.As the pulse duration is further compressed,several interference peaks appear in the broad spectrum.Moreover,we conducted simulations using the semiconductor Bloch equation,considering the effect of Berry curvature,to better understand this process.Our work provides a valuable approach for studying HHG by few-cycle laser pulses in solid materials,expanding the application of HHG in attosecond physics.展开更多
The attosecond laser station （ALS） at the Synergetic Extreme Condition User Facility （SECUF） is a sophisticated and user-friendly platform for the investigation of the electron dynamics in atoms, molecules, and co...The attosecond laser station （ALS） at the Synergetic Extreme Condition User Facility （SECUF） is a sophisticated and user-friendly platform for the investigation of the electron dynamics in atoms, molecules, and condensed matter on timescales ranging from tens of femtoseconds to tens of attoseconds. Short and tunable coherent extreme-ultraviolet （XUV） light sources based on high-order harmonic generation in atomic gases are being developed to drive a variety of endstations for inspecting and controlling ultrafast electron dynamics in real time. The combination of such light sources and end-stations offers a route to investigate fundamental physical processes in atoms, molecules, and condensed matter. The ALS consists of four beamlines, each containing a light source designed specifically for application experiments that will be performed in its own end-station. The first beamline will produce broadband XUV light for attosecond photoelectron spectroscopy and attosecond transient absorption spectroscopy. It is also capable of performing attosecond streaking to characterize isolated attosecond pulses and will allow studies on the electron dynamics in atoms, moleculars, and condensed matter. The second XUV beamline will produce narrowband femtoseeond XUV pulses for time-resolved and angle-resolved photoelectron spectroscopy, to study the electronic dynamics on the timescale of fundamental correlations and interactions in solids, especially in superconductors and topological insulators. The third beamline will produce broadband XUV pulses for attosecond coincidence spectroscopy in a cold-target recoil-ion momentum spectrometer, to study the ultrafast dynamics and reactions in atomic and molecular systems. The last beamline produces broadband attosecond XUV pulses designed for time-resolved photoemission electron microscopy, to study the ultrafast dynamics of plasmons in nanostructures and the surfaces of solid materials with high temporal and spatial resolutions simultaneously. The main object of the ALS is to provide domestic and international scientists with unique tools to study fundamental processes in physics, chemistry, biology, and material sciences with ultrafast temporal resolutions on the atomic scale.展开更多
A femtosecond LBO optical parametric oscillator(OPO)with widely adjustable repetition rate by fractionally decrement of the cavity length is demonstrated.The repetition rate of 755 MHz to 1.43 GHz at an interval of 75...A femtosecond LBO optical parametric oscillator(OPO)with widely adjustable repetition rate by fractionally decrement of the cavity length is demonstrated.The repetition rate of 755 MHz to 1.43 GHz at an interval of 75.5 MHz is realized,which is 10 to 19 times that of the pump laser.The properties of output signal at 750 nm at different repetition rates are studied.The power of signal decreases with increasing the repetition rate.The maximum power of 194 mW at the repetition rate of 755 MHz and the minimum power of 22 mW at repetition rate of 1.43 GHz for the signal at 750 nm are obtained for the pump power of 3 W.展开更多
γ-LiAlO2 single crystal is a promising substrate for GaN heteroepitaxy. In this paper, we present the growth of large-sized LiAlO2 crystal by modified Czochralski method. The crystal quality was characterized by high...γ-LiAlO2 single crystal is a promising substrate for GaN heteroepitaxy. In this paper, we present the growth of large-sized LiAlO2 crystal by modified Czochralski method. The crystal quality was characterized by high-resolution X-ray diffraction and chemical etching. The results show that the as-grown crystal has perfect quality with the full width at half maximum （FWHM） of 17.7-22.6 arcsec and etch pits density of （0.3- 2.2）×10^4 cm^-2 throughout the crystal boule. The bottom of the crystal boule shows the best quality. The optical transmission spectra from UV to IR exhibits that the crystal is transparent from 0.2 to 5.5μm and becomes completely absorbing around 6.7μm wavelength, The optical absorption edge in near UV region is about 191 nm.展开更多
We report on the generation of optical pulses with a nearly one octave-spanning spectrum ranging from 1300 nm to2500 nm at 1 kHz repetition rate, which are based on intra-pulse difference frequency generation(DFG) in ...We report on the generation of optical pulses with a nearly one octave-spanning spectrum ranging from 1300 nm to2500 nm at 1 kHz repetition rate, which are based on intra-pulse difference frequency generation(DFG) in β-barium borate crystal(β-BBO) and passively carrier-envelope-phase(CEP) stabilized. The DFG is induced by few-cycle pulses initiated from spectral broadening in multiple thin plates driven by a Ti: sapphire chirped-pulse amplifier. Furthermore, a numerical simulation is developed to estimate the conversion efficiency and output spectrum of the DFG. Our results show that the pulses from the DFG have the potential for seeding intense mid-infrared(MIR) laser generation and amplification to study strong-field physics and attosecond science.展开更多
The advent of chirped-pulse amplification （CPA） has greatly advanced the field of ultrafast and ultra-intense laser technology. CPA has become an indispensable platform for multidisciplinary research, such as physic...The advent of chirped-pulse amplification （CPA） has greatly advanced the field of ultrafast and ultra-intense laser technology. CPA has become an indispensable platform for multidisciplinary research, such as physics, chemistry, life sciences, and precision metrology. The femtosecond laser facility at the Synergic Extreme Condition User Facility （SECUF） is a comprehensive experimental platform with an advanced femtosecond laser source for ultrafast scientific research. It will provide an ultrafast scientific research system having a few-cycle pulse duration, wide spectral range, high energy, and high repetition rate for multipurpose applications.展开更多
We implement an experimental study for the generation of wideband tunable femtosecond laser with a home-made power-scaled mode-locked fiber oscillator as the pump source.By coupling the sub-100 fs mode-locked pulses i...We implement an experimental study for the generation of wideband tunable femtosecond laser with a home-made power-scaled mode-locked fiber oscillator as the pump source.By coupling the sub-100 fs mode-locked pulses into a nonlinear photonic crystal fiber(NL-PCF),the exited spectra have significant nonlinear broadening and cover a spectra range of hundreds of nm.In experiment,by reasonably optimizing the structure parameters of NL-PCF and regulating the power of the incident pulses,femtosecond laser with tuning range of 900-1290 nm is realized.The research approach promotes the development of femtosecond lasers with center wavelengths out of the traditional laser gain media toward the direction of simplicity and ease of implementation.展开更多
A high efficiency compact Yb:KGW regenerative amplifier using an all-fiber laser seed source was comprehensively studied.With thermal lensing effect compensated by the cavity design,the compressed pulses with energy o...A high efficiency compact Yb:KGW regenerative amplifier using an all-fiber laser seed source was comprehensively studied.With thermal lensing effect compensated by the cavity design,the compressed pulses with energy of 1 mJ at 1 kHz and 0.4 mJ at 10 kHz in sub-400-fs pulse duration using chirped fiber Bragg grating(CFBG)stretcher were demonstrated.A modified Frantz-Nodvik equation was developed to emulate the dynamic behavior of the regenerative amplifier.The simulation results were in good agreement with the experiment.Numerical simulations and experimental results show that the scheme can be scalable to higher energy of multi-mJ,sub-300 fs pulses.展开更多
The recent years have witnessed the rapid economic growth of our country.The medical industry has also come to a new era.The number of hospital staff continues to increase,while some problems of managing human resourc...The recent years have witnessed the rapid economic growth of our country.The medical industry has also come to a new era.The number of hospital staff continues to increase,while some problems of managing human resource have gradually emerged.These problems have a bad impact on the functions of the hospital.We must attach great importance to solve them.In the process of managing the human resources of hospital,we must insist to put people first.That is how we can better boost the working initiative of medical staff,setting the foundation for the development of hospital in a long run.This article has conducted deepening research on this issue.First of all,it briefly introduced the theory of putting people first.And then it stated the connotation of the theory of putting people first applied in managing human resources of hospital.At last,it explored the strategies on applying the theory of putting people first in managing human resources of hospital in accordance to the concrete conditions.展开更多
We utilized a set of fused silica thin plates to broaden the spectrum of 1kHz,30 fs Ti:sapphire amplified laser pulses to an octave.Following the compression by chirped mirror pairs,the generated few-cycle pulses were...We utilized a set of fused silica thin plates to broaden the spectrum of 1kHz,30 fs Ti:sapphire amplified laser pulses to an octave.Following the compression by chirped mirror pairs,the generated few-cycle pulses were focused onto an argon filled gas cell.We detected high order harmonics corresponding to a train of 209 as pulses,characterized by the reconstruction of attosecond beating by interference of two-photon transition(RABITT)technique.Compared with the conventional attosecond pulse trains,the broad harmonics in such pulse trains cover more energy range,so it is more efficient in studying some typical cases,such as resonances,with frequency resolved RABITT.As the solid thin plates can support high power supercontinuum generation,it is feasible to tailor the spectrum to have different central wavelength and spectral width,which will make the RABITT source work in different applications.展开更多
The multiple filamentation of terawatt femtosecond （fs） laser pulses is experimentally studied in a natural environment. A more than 30-m long plasma filament with a millimeter diameter is formed by the collimated f...The multiple filamentation of terawatt femtosecond （fs） laser pulses is experimentally studied in a natural environment. A more than 30-m long plasma filament with a millimeter diameter is formed by the collimated fs laser pulse freely propagating in an open atmosphere. This study provides the first quantitative experimental data about the electron density of a long range light filament in the atmosphere. The electron density of such a filament is quantitatively detected by using an electric method, showing that it is at the 1011-cm -3 level.展开更多
Isolated attosecond pulse generation in argon is theoretically investigated for different gas pressures and medium lengths.The output of attosecond pulse is effectively enhanced by using a longer gas medium with optim...Isolated attosecond pulse generation in argon is theoretically investigated for different gas pressures and medium lengths.The output of attosecond pulse is effectively enhanced by using a longer gas medium with optimized pressure.The peak intensity of the attosecond pulse by using 6 mm gas medium is doubled compared with that of 1-3 mm gas cell,which is usually used in the experiment.Our simulation shows that the distortion of the driving laser waveform and the absorption are the main factors that limit the output of the attosecond pulse for the long gas medium.Optimized generation condition could be found by balancing the medium length and pressure.展开更多
基金supported by the National Natural Science Foundation of China (Grant No. 12164030)the Major Program of the National Natural Science Foundation of China (Grant No. 12034020)+1 种基金Young Science and Technology Talents of Inner Mongolia, China (Grant No. NJYT22101)the Talent Development Fund of Inner Mongolia, China。
文摘We report a high-average-power noise-like pulse(NLP) and dissipative soliton(DS) pulse fiber laser. Average power as high as 4.8 W could be obtained at the fundamental mode-locked repetition rate. The NLP can also be transformed into a more powerful DS mode-locking state by optimizing the polarization and losses of intra-cavity pulses in the nonlinear polarization evolution regime. The operation mode between the NLP and DS can be switched, and the laser output performance in both modes has been studied. The main advantage of this work is switchable high-power operation between the NLP and DS. In comparison with conventional single-mode NLP fiber lasers, the multi-function high-power optical source will greatly push its application in supercontinuum generation, coherence tomography, and industrial processing.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.91850209 and 11974416)。
文摘The high harmonic generation(HHG)by few-cycle laser pulses is essential for research in strong-field solid-state physics.Through comparison of high harmonic spectra of solids generated by laser pulses with varying durations,we discovered that lasers with good dispersion compensation are capable of producing a broad spectrum of high harmonics.As the pulse duration is further compressed,several interference peaks appear in the broad spectrum.Moreover,we conducted simulations using the semiconductor Bloch equation,considering the effect of Berry curvature,to better understand this process.Our work provides a valuable approach for studying HHG by few-cycle laser pulses in solid materials,expanding the application of HHG in attosecond physics.
基金Project supported by the National Key R&D Program of China(Grant Nos.2018YFB1107200,2017YFC0110301,and 2017YFB0405202)Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB0703030)the National Natural Science Foundation of China(Grant Nos.11474002,11674386,61575219,and 61690221)
文摘The attosecond laser station （ALS） at the Synergetic Extreme Condition User Facility （SECUF） is a sophisticated and user-friendly platform for the investigation of the electron dynamics in atoms, molecules, and condensed matter on timescales ranging from tens of femtoseconds to tens of attoseconds. Short and tunable coherent extreme-ultraviolet （XUV） light sources based on high-order harmonic generation in atomic gases are being developed to drive a variety of endstations for inspecting and controlling ultrafast electron dynamics in real time. The combination of such light sources and end-stations offers a route to investigate fundamental physical processes in atoms, molecules, and condensed matter. The ALS consists of four beamlines, each containing a light source designed specifically for application experiments that will be performed in its own end-station. The first beamline will produce broadband XUV light for attosecond photoelectron spectroscopy and attosecond transient absorption spectroscopy. It is also capable of performing attosecond streaking to characterize isolated attosecond pulses and will allow studies on the electron dynamics in atoms, moleculars, and condensed matter. The second XUV beamline will produce narrowband femtoseeond XUV pulses for time-resolved and angle-resolved photoelectron spectroscopy, to study the electronic dynamics on the timescale of fundamental correlations and interactions in solids, especially in superconductors and topological insulators. The third beamline will produce broadband XUV pulses for attosecond coincidence spectroscopy in a cold-target recoil-ion momentum spectrometer, to study the ultrafast dynamics and reactions in atomic and molecular systems. The last beamline produces broadband attosecond XUV pulses designed for time-resolved photoemission electron microscopy, to study the ultrafast dynamics of plasmons in nanostructures and the surfaces of solid materials with high temporal and spatial resolutions simultaneously. The main object of the ALS is to provide domestic and international scientists with unique tools to study fundamental processes in physics, chemistry, biology, and material sciences with ultrafast temporal resolutions on the atomic scale.
基金Supported by the National Key R&D Program of China under Grant Nos 2017YFC0110301 and 2017YFB0405202the National Natural Science Foundation of China under Grant Nos 91850209,11774410 and 61575217+2 种基金the Youth Innovation Promotion Association,Chinese Academy of Sciences(No 2018007)the Strategic Priority Research Program of CAS(XDB16030200)the Key Research Program of Frontier Sciences of CAS(KJZD-EW-L11-03)
文摘A femtosecond LBO optical parametric oscillator(OPO)with widely adjustable repetition rate by fractionally decrement of the cavity length is demonstrated.The repetition rate of 755 MHz to 1.43 GHz at an interval of 75.5 MHz is realized,which is 10 to 19 times that of the pump laser.The properties of output signal at 750 nm at different repetition rates are studied.The power of signal decreases with increasing the repetition rate.The maximum power of 194 mW at the repetition rate of 755 MHz and the minimum power of 22 mW at repetition rate of 1.43 GHz for the signal at 750 nm are obtained for the pump power of 3 W.
基金supported by the Project of High Technology Research and Development of China(2006AA03A101 and 2006AA03A103)the National Natural Science Foundation of China(60676004)the Science Research Program of Shanghai(05PJ14100 and 06dz11402).
文摘γ-LiAlO2 single crystal is a promising substrate for GaN heteroepitaxy. In this paper, we present the growth of large-sized LiAlO2 crystal by modified Czochralski method. The crystal quality was characterized by high-resolution X-ray diffraction and chemical etching. The results show that the as-grown crystal has perfect quality with the full width at half maximum （FWHM） of 17.7-22.6 arcsec and etch pits density of （0.3- 2.2）×10^4 cm^-2 throughout the crystal boule. The bottom of the crystal boule shows the best quality. The optical transmission spectra from UV to IR exhibits that the crystal is transparent from 0.2 to 5.5μm and becomes completely absorbing around 6.7μm wavelength, The optical absorption edge in near UV region is about 191 nm.
基金Project supported by the National Key R&D Program of China(Grant No.2017YFB0405202)the Major Program of the National Natural Science Foundation of China(Grant No.61690221)+1 种基金the Key Program of the National Natural Science Foundation of China(Grant No.11434016)the National Natural Science Foundation of China(Grant Nos.11574384 and 11674386)
文摘We report on the generation of optical pulses with a nearly one octave-spanning spectrum ranging from 1300 nm to2500 nm at 1 kHz repetition rate, which are based on intra-pulse difference frequency generation(DFG) in β-barium borate crystal(β-BBO) and passively carrier-envelope-phase(CEP) stabilized. The DFG is induced by few-cycle pulses initiated from spectral broadening in multiple thin plates driven by a Ti: sapphire chirped-pulse amplifier. Furthermore, a numerical simulation is developed to estimate the conversion efficiency and output spectrum of the DFG. Our results show that the pulses from the DFG have the potential for seeding intense mid-infrared(MIR) laser generation and amplification to study strong-field physics and attosecond science.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61575217 and 11774410)the Strategic Priority Research Program of Chinese Academy of Sciences(Grant No.XDB16030200)
文摘The advent of chirped-pulse amplification （CPA） has greatly advanced the field of ultrafast and ultra-intense laser technology. CPA has become an indispensable platform for multidisciplinary research, such as physics, chemistry, life sciences, and precision metrology. The femtosecond laser facility at the Synergic Extreme Condition User Facility （SECUF） is a comprehensive experimental platform with an advanced femtosecond laser source for ultrafast scientific research. It will provide an ultrafast scientific research system having a few-cycle pulse duration, wide spectral range, high energy, and high repetition rate for multipurpose applications.
基金Project supported by the National Natural Science Foundation of China(Grant No.61805274)the Major Program of the National Natural Science Foundation of China(Grant No.12034020)Research Foundation of Inner Mongolia University of China(Grant No.21200-5215108)。
文摘We implement an experimental study for the generation of wideband tunable femtosecond laser with a home-made power-scaled mode-locked fiber oscillator as the pump source.By coupling the sub-100 fs mode-locked pulses into a nonlinear photonic crystal fiber(NL-PCF),the exited spectra have significant nonlinear broadening and cover a spectra range of hundreds of nm.In experiment,by reasonably optimizing the structure parameters of NL-PCF and regulating the power of the incident pulses,femtosecond laser with tuning range of 900-1290 nm is realized.The research approach promotes the development of femtosecond lasers with center wavelengths out of the traditional laser gain media toward the direction of simplicity and ease of implementation.
基金Project supported by Major Program of the National Natural Science Foundation of China (Grant No. 12034020)the National Natural Science Foundation of China (Grant No. 61805274)+1 种基金the National Key R&D Program of China (Grant No. 2018YFB1107201)the Synergic Extreme Condition User Facility
文摘A high efficiency compact Yb:KGW regenerative amplifier using an all-fiber laser seed source was comprehensively studied.With thermal lensing effect compensated by the cavity design,the compressed pulses with energy of 1 mJ at 1 kHz and 0.4 mJ at 10 kHz in sub-400-fs pulse duration using chirped fiber Bragg grating(CFBG)stretcher were demonstrated.A modified Frantz-Nodvik equation was developed to emulate the dynamic behavior of the regenerative amplifier.The simulation results were in good agreement with the experiment.Numerical simulations and experimental results show that the scheme can be scalable to higher energy of multi-mJ,sub-300 fs pulses.
文摘The recent years have witnessed the rapid economic growth of our country.The medical industry has also come to a new era.The number of hospital staff continues to increase,while some problems of managing human resource have gradually emerged.These problems have a bad impact on the functions of the hospital.We must attach great importance to solve them.In the process of managing the human resources of hospital,we must insist to put people first.That is how we can better boost the working initiative of medical staff,setting the foundation for the development of hospital in a long run.This article has conducted deepening research on this issue.First of all,it briefly introduced the theory of putting people first.And then it stated the connotation of the theory of putting people first applied in managing human resources of hospital.At last,it explored the strategies on applying the theory of putting people first in managing human resources of hospital in accordance to the concrete conditions.
基金Project supported by the National Key R&D Program of China(Grant No.2017YFB0405202)the Major Program of the National Natural Science Foundation of China(Grant No.61690221)+1 种基金the Key Program of the National Natural Science Foundation of China(Grant No.11434016)the National Natural Science Foundation of China(Grant Nos.11574384,11674386,and 11774277)
文摘We utilized a set of fused silica thin plates to broaden the spectrum of 1kHz,30 fs Ti:sapphire amplified laser pulses to an octave.Following the compression by chirped mirror pairs,the generated few-cycle pulses were focused onto an argon filled gas cell.We detected high order harmonics corresponding to a train of 209 as pulses,characterized by the reconstruction of attosecond beating by interference of two-photon transition(RABITT)technique.Compared with the conventional attosecond pulse trains,the broad harmonics in such pulse trains cover more energy range,so it is more efficient in studying some typical cases,such as resonances,with frequency resolved RABITT.As the solid thin plates can support high power supercontinuum generation,it is feasible to tailor the spectrum to have different central wavelength and spectral width,which will make the RABITT source work in different applications.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11574387,11404335,11474002,and 11535001)the National Basic Research Program of China(Grant Nos.2013CBA01501 and 2013CB922401)+1 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(Grants Nos.XDB16010200 and XDB07030300)the Science Challenge Project,China(Grant No.TZ2016005)
文摘The multiple filamentation of terawatt femtosecond （fs） laser pulses is experimentally studied in a natural environment. A more than 30-m long plasma filament with a millimeter diameter is formed by the collimated fs laser pulse freely propagating in an open atmosphere. This study provides the first quantitative experimental data about the electron density of a long range light filament in the atmosphere. The electron density of such a filament is quantitatively detected by using an electric method, showing that it is at the 1011-cm -3 level.
基金Project supported by the National Key R&D Program of China(Grant No.2018YFB1107200)the National Natural Science Foundation of China(Grant Nos.11974416 and 91850209)。
文摘Isolated attosecond pulse generation in argon is theoretically investigated for different gas pressures and medium lengths.The output of attosecond pulse is effectively enhanced by using a longer gas medium with optimized pressure.The peak intensity of the attosecond pulse by using 6 mm gas medium is doubled compared with that of 1-3 mm gas cell,which is usually used in the experiment.Our simulation shows that the distortion of the driving laser waveform and the absorption are the main factors that limit the output of the attosecond pulse for the long gas medium.Optimized generation condition could be found by balancing the medium length and pressure.
