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 compact high power diode-pumped passively mode-locked Nd:YVO_4 laser with high repetition rate is realized.Using an Nd:YVO_4 crystal and a semiconductor saturable absorber mirror(SESAM) in the oscillator, the picose...A compact high power diode-pumped passively mode-locked Nd:YVO_4 laser with high repetition rate is realized.Using an Nd:YVO_4 crystal and a semiconductor saturable absorber mirror(SESAM) in the oscillator, the picosecond pulse output with an average power of 1.38 W, a repetition rate of 3.24 GHz, and a pulse duration of 11.4 ps is achieved. After one stage of amplification, the final output power reaches 11.34 W, corresponding to a total optical-to-optical efficiency of about 32%. The root mean square(RMS) value of power fluctuation is demonstrated to be less than 0.6% in 24 hours,showing a superior stability with the compact configuration.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
Due to the remarkable carrier mobility and nonlinear characteristic, MoS2 is considered to be a powerful competitor as an effective optical modulated material in fiber lasers. In this paper, the MoS2 films are prepare...Due to the remarkable carrier mobility and nonlinear characteristic, MoS2 is considered to be a powerful competitor as an effective optical modulated material in fiber lasers. In this paper, the MoS2 films are prepared by the chemical vapor deposition method to guarantee the high quality of the crystal lattice and uniform thickness. The transfer of the films to microfiber and the operation of gold plated films ensure there is no heat-resistant damage and anti-oxidation. The modulation depth of the prepared integrated microfiber-MoS2 saturable absorber is 11.07%. When the microfiber-MoS2 saturable absorber is used as a light modulator in the Q-switching fiber laser, the stable pulse train with a pulse duration of 888 ns at 1530.9 nm is obtained. The ultimate output power and pulse energy of output pulses are 18.8 mW and 88 nJ, respectively. The signal-to-noise ratio up to 60 dB indicates the good stability of the laser. This work demonstrates that the MoS2 saturable absorber prepared by the chemical vapor deposition method can serve as an effective nonlinear control device for the Q-switching fiber laser.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
We present a fully stabilized Yb-fiber frequency comb locked to a microwave standard and an optical reference separately. The carrier-envelope offset frequency is generated by a standard f–2f interferometer with 40 d...We present a fully stabilized Yb-fiber frequency comb locked to a microwave standard and an optical reference separately. The carrier-envelope offset frequency is generated by a standard f–2f interferometer with 40 dB signal-tonoise ratio. The offset frequency and the repetition rate are stabilized simultaneously to the radio frequency reference for more than 30 hours, and the fractional Allan deviation of the comb is the same as the microwave standard of 10^(-12) at 1 s.Alternatively, the comb is locked to an ultra-stable optical reference at 972 nm using an intracavity electro-optic modulator,exhibiting a residual integrated phase noise of 458 mrad(1 Hz–10 MHz) and an in-loop tracking stability of 1.77× 10^(-18) at 1 s, which is significantly raised by six orders comparing to the case locked to the microwave frequency standard.展开更多
A monolithic O-f scheme-based femtosecond optical frequency comb directly driven by a high-power Ti:sapphire laser oscillator is demonstrated.The spectrum covering from 650 nm to 950 nm is generated from the Ti:sapphi...A monolithic O-f scheme-based femtosecond optical frequency comb directly driven by a high-power Ti:sapphire laser oscillator is demonstrated.The spectrum covering from 650 nm to 950 nm is generated from the Ti:sapphire oscillator with a repetition rate of 170 MHz.The average output power up to 630 mW is delivered under the pump power of 4.5 W.A 44-dB signal-to-noise ratio(SNR)of the carrier-envelope phase offset(CEO)beat note is achieved under the resolution of 100 kHz and is long-term stabilized to a reference source at 20 MHz.The integrated phase noise(IPN)in the range from 1 Hz to 1 MHz is calculated to be 138 mrad,corresponding to the timing jitter of 63 as at the central wavelength of 790 nm.展开更多
We propose a novel kind of wide-range refractive index optical sensor based on photonic crystal fiber(PCF) covered with nano-ring gold film.The refractive index sensing performance of the PCF sensor is analyzed and si...We propose a novel kind of wide-range refractive index optical sensor based on photonic crystal fiber(PCF) covered with nano-ring gold film.The refractive index sensing performance of the PCF sensor is analyzed and simulated by the finite element method(FEM).The refractive index liquid is infiltrated into the cladding air hole of the PCF.By comparing the sensing performance of two kinds of photonic crystal fiber structures, a wide range and high sensitivity structure is optimized.The surface plasmon resonance(SPR) excitation material is chose as gold, and large gold nanorings are embedded around the first cladding air hole of the PCF.The higher order surface plasmon modes are generated in this designed optical fiber structure.The resonance coupling between the fundamental mode and the 5 th order surface plasmon polariton(SPP)modes is excited when the phase matching condition is matched.Therefore, the 3 rd loss peaks appear obvious red-shift with the increase of the analyte refractive index, which shows a remarkable polynomial fitting law.The fitnesses of two structures are 0.99 and 0.98, respectively.When the range of refractive indices is from 1.40 to 1.43, the two kinds of sensors have high linear sensitivities of 1604 nm/RIU and 3978 nm/RIU, respectively.展开更多
We have demonstrated a high power diode-pumped mode-locked femtosecond Yb:KGW laser with semiconductor saturable absorber mirror(SESAM). By using an output coupler with 10% transmittance, the laser delivered 160-fs pu...We have demonstrated a high power diode-pumped mode-locked femtosecond Yb:KGW laser with semiconductor saturable absorber mirror(SESAM). By using an output coupler with 10% transmittance, the laser delivered 160-fs pulses with average output power of 7.6 W at a repetition rate of 78 MHz, corresponding to pulse energy of 97 nJ and peak power of 606 kW.展开更多
The generation of continuous spectrum centered at 400 nm from solid thin plates is demonstrated in this work.A continuum covering 365 nm to 445 nm is obtained when 125-µJ frequency-doubled Ti:sapphire laser pulse...The generation of continuous spectrum centered at 400 nm from solid thin plates is demonstrated in this work.A continuum covering 365 nm to 445 nm is obtained when 125-µJ frequency-doubled Ti:sapphire laser pulses are applied to six thin fused silica plates at 1-kHz repetition rate.The generalized nonlinear Schrodinger equation simplified for forward propagation is solved numerically,the spectral broadening with the experimental parameters is simulated,and good agreement between simulated result and experimental measurement is achieved.The variation of electron density in the thin plate and the advantage of a low electron density in the spectral broadening process are discussed.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
We demonstrated a nonlinear temporal filter based on the self-diffraction(SD)process.Temporal contrast enhancement,angular dispersion and spectrum broadening properties of the SD process are investigated in experiment...We demonstrated a nonlinear temporal filter based on the self-diffraction(SD)process.Temporal contrast enhancement,angular dispersion and spectrum broadening properties of the SD process are investigated in experiment and simulation.Driven by spectral phase well compensated laser pulses with bandwidth of 28 nm,the filter produced clean pulses with a temporal contrast higher than 10^(10) and excellent spatial profile,the spectrum of which was smoothed and broadened to 64 nm.After implementing this filter into a home-made 30 TW Ti:sapphire amplifier,temporal contrast of the amplified pulses was enhanced to 10^(10) within the time scale of−400 ps.展开更多
Universality of the dynamic characteristic relationship between the characteristic time tc and the two-electron Coulomb interaction energy V12 of the ground state in the two-photon double ionization process is investi...Universality of the dynamic characteristic relationship between the characteristic time tc and the two-electron Coulomb interaction energy V12 of the ground state in the two-photon double ionization process is investigated via changing the parameters of the two-electron atomic system and the corresponding laser conditions.The numerical results show that the product tcV12 keeps constant around 4.1 in the cases of changing the nucleus charge,the electron charge,the electron mass,and changing simultaneously the nucleus charge and the electron charge.These results demonstrate that the dynamic characteristic relationship in the two-photon double ionization process is universal.This work sheds more light on the dynamic characteristic relationship in ultrafast processes and may find its application in measurements of attosecond pulses.展开更多
We demonstrate a high-quality cross-polarized-wave filter based on spectral phase modulation. Driven by Well- eompressed spectral-phase fully-compensated fundamental laser lmlses, the filter stretches the pulse bandwi...We demonstrate a high-quality cross-polarized-wave filter based on spectral phase modulation. Driven by Well- eompressed spectral-phase fully-compensated fundamental laser lmlses, the filter stretches the pulse bandwidth from 35 nm to 7Ohm with a conversion efficeiency of 20%.展开更多
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Project supported by the Strategic Priority Research Program of Chinese Academy of Sciences(Grant No.XDB16030200)the National Natural Science Foundation of China(Grant Nos.11774410 and 61575217)+1 种基金the National Key Scientific Instruments Development Program of China(Grant No.2012YQ120047)the Key Research Program of Frontier Sciences of Chinese Academy of Sciences(Grant No.KJZD-EW-L11-03)
文摘A compact high power diode-pumped passively mode-locked Nd:YVO_4 laser with high repetition rate is realized.Using an Nd:YVO_4 crystal and a semiconductor saturable absorber mirror(SESAM) in the oscillator, the picosecond pulse output with an average power of 1.38 W, a repetition rate of 3.24 GHz, and a pulse duration of 11.4 ps is achieved. After one stage of amplification, the final output power reaches 11.34 W, corresponding to a total optical-to-optical efficiency of about 32%. The root mean square(RMS) value of power fluctuation is demonstrated to be less than 0.6% in 24 hours,showing a superior stability with the compact configuration.
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Project supported by the National Natural Science Foundation of China(Grant No.11674036)the Beijing Youth Top-notch Talent Support Program,China(Grant No.2017000026833ZK08)the Fund of State Key Laboratory of Information Photonics and Optical Communications,Beijing University of Posts and Telecommunications,China(Grant Nos.IPOC2016ZT04 and IPOC2017ZZ05)
文摘Due to the remarkable carrier mobility and nonlinear characteristic, MoS2 is considered to be a powerful competitor as an effective optical modulated material in fiber lasers. In this paper, the MoS2 films are prepared by the chemical vapor deposition method to guarantee the high quality of the crystal lattice and uniform thickness. The transfer of the films to microfiber and the operation of gold plated films ensure there is no heat-resistant damage and anti-oxidation. The modulation depth of the prepared integrated microfiber-MoS2 saturable absorber is 11.07%. When the microfiber-MoS2 saturable absorber is used as a light modulator in the Q-switching fiber laser, the stable pulse train with a pulse duration of 888 ns at 1530.9 nm is obtained. The ultimate output power and pulse energy of output pulses are 18.8 mW and 88 nJ, respectively. The signal-to-noise ratio up to 60 dB indicates the good stability of the laser. This work demonstrates that the MoS2 saturable absorber prepared by the chemical vapor deposition method can serve as an effective nonlinear control device for the Q-switching fiber laser.
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 Strategic Priority Research Program of the Chinese Academy of Sciences(Grant Nos.XDA1502040404 and XDB21010400)the National Natural Science Foundation of China(Grant Nos.91850209 and 11774234)。
文摘We present a fully stabilized Yb-fiber frequency comb locked to a microwave standard and an optical reference separately. The carrier-envelope offset frequency is generated by a standard f–2f interferometer with 40 dB signal-tonoise ratio. The offset frequency and the repetition rate are stabilized simultaneously to the radio frequency reference for more than 30 hours, and the fractional Allan deviation of the comb is the same as the microwave standard of 10^(-12) at 1 s.Alternatively, the comb is locked to an ultra-stable optical reference at 972 nm using an intracavity electro-optic modulator,exhibiting a residual integrated phase noise of 458 mrad(1 Hz–10 MHz) and an in-loop tracking stability of 1.77× 10^(-18) at 1 s, which is significantly raised by six orders comparing to the case locked to the microwave frequency standard.
基金National Key R&D Program of China(Grant No.2017YFC0110301)National Natural Science Foundation of China(Grant Nos.91950113,61575219,61210017,11774234,11674386,11434016,and 91850209)+1 种基金Strategic Priority Research Program of the CAS(Grant No.XDB23030203)Youth Innovation Promotion Association of the CAS(Grant No.2018007)。
文摘A monolithic O-f scheme-based femtosecond optical frequency comb directly driven by a high-power Ti:sapphire laser oscillator is demonstrated.The spectrum covering from 650 nm to 950 nm is generated from the Ti:sapphire oscillator with a repetition rate of 170 MHz.The average output power up to 630 mW is delivered under the pump power of 4.5 W.A 44-dB signal-to-noise ratio(SNR)of the carrier-envelope phase offset(CEO)beat note is achieved under the resolution of 100 kHz and is long-term stabilized to a reference source at 20 MHz.The integrated phase noise(IPN)in the range from 1 Hz to 1 MHz is calculated to be 138 mrad,corresponding to the timing jitter of 63 as at the central wavelength of 790 nm.
基金Project supported by the National Key Research and Development Program of China(Grant No.2017YFC0110301)the National Natural Science Foundation of China(Grant Nos.61575219,91850209,and 11434016)+2 种基金the College Young Talents Program of Hebei Province,China(Grant No.BJ2018040)the Hebei University of Science and Technology Talent Introduction Project,China(Grant No.1181324)the Youth Innovation Promotion Association,Chinese Academy of Sciences(Grant No.2018007)
文摘We propose a novel kind of wide-range refractive index optical sensor based on photonic crystal fiber(PCF) covered with nano-ring gold film.The refractive index sensing performance of the PCF sensor is analyzed and simulated by the finite element method(FEM).The refractive index liquid is infiltrated into the cladding air hole of the PCF.By comparing the sensing performance of two kinds of photonic crystal fiber structures, a wide range and high sensitivity structure is optimized.The surface plasmon resonance(SPR) excitation material is chose as gold, and large gold nanorings are embedded around the first cladding air hole of the PCF.The higher order surface plasmon modes are generated in this designed optical fiber structure.The resonance coupling between the fundamental mode and the 5 th order surface plasmon polariton(SPP)modes is excited when the phase matching condition is matched.Therefore, the 3 rd loss peaks appear obvious red-shift with the increase of the analyte refractive index, which shows a remarkable polynomial fitting law.The fitnesses of two structures are 0.99 and 0.98, respectively.When the range of refractive indices is from 1.40 to 1.43, the two kinds of sensors have high linear sensitivities of 1604 nm/RIU and 3978 nm/RIU, respectively.
基金Project supported by the Strategic Priority Research Program of Chinese Academy of Sciences(Grant No.XDB16030200)the National Natural Science Foundation of China(Grant Nos.11774410,61575217,and 61675158)+1 种基金the National Key Scientific Instruments Development Program of China(Grant No.2012YQ120047)the Key Research Program of Frontier Sciences of Chinese Academy of Sciences(Grant No.KJZD-EW-L11-03)
文摘We have demonstrated a high power diode-pumped mode-locked femtosecond Yb:KGW laser with semiconductor saturable absorber mirror(SESAM). By using an output coupler with 10% transmittance, the laser delivered 160-fs pulses with average output power of 7.6 W at a repetition rate of 78 MHz, corresponding to pulse energy of 97 nJ and peak power of 606 kW.
基金supported by the National Key Research and Development Program of China(Grant No.2017YFB0405202),the Major Program of the National Natural Science Foundation of China(Grant No.61690221)the General Program of the National Natural Science Foundation of China(Grant No.11774277).
文摘The generation of continuous spectrum centered at 400 nm from solid thin plates is demonstrated in this work.A continuum covering 365 nm to 445 nm is obtained when 125-µJ frequency-doubled Ti:sapphire laser pulses are applied to six thin fused silica plates at 1-kHz repetition rate.The generalized nonlinear Schrodinger equation simplified for forward propagation is solved numerically,the spectral broadening with the experimental parameters is simulated,and good agreement between simulated result and experimental measurement is achieved.The variation of electron density in the thin plate and the advantage of a low electron density in the spectral broadening process are discussed.
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Supported by the National Natural Science Foundation of China(Grant Nos.11774410 and 91850209)the Strategic Priority Research Program of CAS(Grant No.XDB16030200).
文摘We demonstrated a nonlinear temporal filter based on the self-diffraction(SD)process.Temporal contrast enhancement,angular dispersion and spectrum broadening properties of the SD process are investigated in experiment and simulation.Driven by spectral phase well compensated laser pulses with bandwidth of 28 nm,the filter produced clean pulses with a temporal contrast higher than 10^(10) and excellent spatial profile,the spectrum of which was smoothed and broadened to 64 nm.After implementing this filter into a home-made 30 TW Ti:sapphire amplifier,temporal contrast of the amplified pulses was enhanced to 10^(10) within the time scale of−400 ps.
基金Supported by the National Natural Science Foundation of China(Grant Nos.91850209,11774129,and 11774411)the National Key Research and Development Program of China(Grant Nos.2019YFA0307700 and 2016YFA0401100)。
文摘Universality of the dynamic characteristic relationship between the characteristic time tc and the two-electron Coulomb interaction energy V12 of the ground state in the two-photon double ionization process is investigated via changing the parameters of the two-electron atomic system and the corresponding laser conditions.The numerical results show that the product tcV12 keeps constant around 4.1 in the cases of changing the nucleus charge,the electron charge,the electron mass,and changing simultaneously the nucleus charge and the electron charge.These results demonstrate that the dynamic characteristic relationship in the two-photon double ionization process is universal.This work sheds more light on the dynamic characteristic relationship in ultrafast processes and may find its application in measurements of attosecond pulses.
基金Supported by the National Key Basic Research Program of China under Grant No 2013CB922402the National Natural Science Foundation of China under Grant Nos 61575217 and 11434016+1 种基金the Key Research Program of Frontier Sciences of Chinese Academy of Sciences under Grant Nos KJZD-EW-L11-03 and QYZDJ-SSW-JSC006the Strategic Priority Research Program of Chinese Academy of Sciences under Grant No XDB16030200
文摘We demonstrate a high-quality cross-polarized-wave filter based on spectral phase modulation. Driven by Well- eompressed spectral-phase fully-compensated fundamental laser lmlses, the filter stretches the pulse bandwidth from 35 nm to 7Ohm with a conversion efficeiency of 20%.