A numerical model based on measured fictive temperature distributions is explored to evaluate the residual stress fields of CO_(2)laser-annealed mitigated fused silica damage sites.The proposed model extracts the resi...A numerical model based on measured fictive temperature distributions is explored to evaluate the residual stress fields of CO_(2)laser-annealed mitigated fused silica damage sites.The proposed model extracts the residual strain from the differences in thermoelastic contraction of fused silica with different fictive temperatures from the initial frozen-in temperatures to ambient temperature.The residual stress fields of mitigated damage sites for the CO_(2)laser-annealed case are obtained by a finite element analysis of equilibrium equations and constitutive equations.The simulated results indicate that the proposed model can accurately evaluate the residual stress fields of laser-annealed mitigated damage sites with a complex thermal history.The calculated maximum hoop stress is in good agreement with the reported experimental result.The estimated optical retardance profiles from the calculated radial and hoop stress fields are consistent with the photoelastic measurements.These results provide sufficient evidence to demonstrate the suitability of the proposed model for describing the residual stresses of mitigated fused silica damage sites after CO_(2)laser annealing.展开更多
The third paragraph in Sec.IV REGENERATIVE AMPLIFICATION erroneously states“In other words,the distribution of spectral components is time-dependent,and the spectral distortion in the amplification process will not c...The third paragraph in Sec.IV REGENERATIVE AMPLIFICATION erroneously states“In other words,the distribution of spectral components is time-dependent,and the spectral distortion in the amplification process will not change the time-domain shape.”展开更多
A direct Kerr-lens mode-locked Tm:LuYO_(3)ceramic laser without the aid of any mode-locked starting element is reported for the first time. A pulse duration as short as 259 fs and a maximum average output power of 326...A direct Kerr-lens mode-locked Tm:LuYO_(3)ceramic laser without the aid of any mode-locked starting element is reported for the first time. A pulse duration as short as 259 fs and a maximum average output power of 326 m W are obtained at a repetition rate of 97.1 MHz. The corresponding optical spectrum centered at 2053 nm exhibits a bandwidth of 19.8 nm,which indicates the presence of nearly Fourier transform-limited pulses. Such a Kerr-lens mode-locked Tm:LuYO_(3)ceramic laser is a promising ultrashort pulse source, with both the excellent laser characteristics of Tm:LuYO3and the high-power 790 nm laser diode pumping scheme.展开更多
The dielectric laser accelerator(DLA) is a promising technology for achieving high-gradient acceleration in a compact design. Its advantages include ease of cascading and an energy gain per unit distance which can exc...The dielectric laser accelerator(DLA) is a promising technology for achieving high-gradient acceleration in a compact design. Its advantages include ease of cascading and an energy gain per unit distance which can exceed that of conventional accelerators by two orders of magnitude. This paper establishes rules for efficient particle acceleration using dielectric structures based on basic equations, proposes a design principle for DLA structures with clear physical images and verifies the accuracy of the corresponding formula for energy gain. DLA structures with different specifications, materials and geometric shapes are constructed, and the achievable acceleration gradient is calculated. Our results demonstrate that effective acceleration can be achieved when the electric field sensed by particles in the acceleration cavity has zero frequency,which provides a powerful method for designing such devices. Furthermore, we demonstrate that the simplified formula for calculating energy gain presented in this paper can accurately determine the energy gain of particles during the design of acceleration structures using a dielectric accelerator.展开更多
A study of a nanosecond laser irradiation on the titanium-layer-buried gold planar target is presented. The timeresolved x-ray emission spectra of titanium tracer are measured by a streaked crystal spectrometer. By co...A study of a nanosecond laser irradiation on the titanium-layer-buried gold planar target is presented. The timeresolved x-ray emission spectra of titanium tracer are measured by a streaked crystal spectrometer. By comparing the simulated spectra obtained by using the FLYCHK code with the measured titanium spectra, the temporal plasma states, i.e.,the electron temperatures and densities, are deduced. To evaluate the feasibility of using the method for the characterization of Au plasma states, the deduced plasma states from the measured titanium spectra are compared with the Multi-1D hydrodynamic simulations of laser-produced Au plasmas. By comparing the measured and simulated results, an overall agreement for the electron temperatures is found, whereas there are deviations in the electron densities. The experiment–theory discrepancy may suggest that the plasma state could not be well reproduced by the Multi-1D hydrodynamic simulation, in which the radial gradient is not taken into account. Further investigations on the spectral characterization and hydrodynamic simulations of the plasma states are needed. All the measured and FLYCHK simulated spectra are given in this paper as datasets. The datasets are openly available at http://www.doi.org/10.57760/sciencedb.j00113.00032.展开更多
We demonstrate a high-energy and high-power pulse laser on a xenon lamp-pumped Er:YAP crystal. The laser performance and thermal focal lengths under different working frequencies are discussed. The results show that t...We demonstrate a high-energy and high-power pulse laser on a xenon lamp-pumped Er:YAP crystal. The laser performance and thermal focal lengths under different working frequencies are discussed. The results show that the thermal lens effect is gradually aggravated with the increase of working frequencies, and even working at 100 Hz, a single pulse energy of 234 m J can be achieved. A maximum average power of 41.5 W is achieved with a working frequency of 20 Hz and slope efficiency of 2.82%. This output power is much higher than other xenon lamp-pumped erbium laser devices.A Q-switched laser is demonstrated by using the TeO2crystal, the maximum output energies of 11.5 m J and 3.5 m J are obtained at 50 and 100 Hz, the corresponding peak powers are 93.4 k W and 17.2 kW, respectively.The laser wavelengths and beam quality factors are also characterized in the free-running and Q-switched modes. A higher pulse energy and peak power laser could be achieved further by improving the damage threshold of TeO2acousto-optical Q-switching. All the experimental results illustrate that the xenon lamp-pumped Er:YAP laser is a promising candidate for high-power and high-frequency mid-infrared laser devices.展开更多
Low-noise terahertz(THz)radiation over 100 MV/cm generation by a linearly-polarized relativistic laser pulse interacting with a near-critical-density(NCD)plasma slab is studied by theory and particle-in-cell(PIC)simul...Low-noise terahertz(THz)radiation over 100 MV/cm generation by a linearly-polarized relativistic laser pulse interacting with a near-critical-density(NCD)plasma slab is studied by theory and particle-in-cell(PIC)simulations.A theoretical model is established to examine the dipole-like radiation emission.The THz radiation is attributed to the singlecycle low-frequency surface current,which is longitudinally constrained by the quasi-equilibrium established by the laser ponderomotive force and the ponderomotively induced electrostatic force.Through theoretical analysis,the spatiotemporal characteristics,polarization property of the THz radiation,and the relation between the radiation strength with the initial parameters of driving laser and plasma are obtained,which are in good consistence with the PIC simulation results.Furthermore,it is found by PIC simulations that the generation of thermal electrons can be suppressed within the appropriate parameter regime,resulting in a clear THz radiation waveform.The appropriate parameter region is given for generating a low-noise intense THz radiation with peak strength reaching 100 MV/cm,which could find potential applications in nonlinear THz physics.展开更多
Ultraintense short-period infrared laser pulses play an important role in frontier scientific research,but their power is quite low when generated using current technology.This paper demonstrates a scheme for generati...Ultraintense short-period infrared laser pulses play an important role in frontier scientific research,but their power is quite low when generated using current technology.This paper demonstrates a scheme for generating an ultraintense few-cycle infrared pulse by directly compressing a long infrared pulse.In this scheme,an infrared picosecond-to-nanosecond laser pulse counterpropagates with a rapidly extending plasma grating that is created by ionizing an undulated gas by a short laser pulse,and the infrared laser pulse is reflected by the rapidly extending plasma grating.Because of the high expansion velocity of the latter,the infrared laser pulse is compressed in the reflection process.One-and two-dimensional particle-in-cell simulations show that by this method,a pulse with a duration of tens of picoseconds in the mid-to far-infrared range can be compressed to a few cycles with an efficiency exceeding 60%,thereby making ultraintense few-cycle infrared pulses possible.展开更多
Broadband low-coherence light is considered to be an effective way to suppress laser plasma instability.Recent studies have demonstrated the ability of low-coherence laser facilities to reduce back-scattering during b...Broadband low-coherence light is considered to be an effective way to suppress laser plasma instability.Recent studies have demonstrated the ability of low-coherence laser facilities to reduce back-scattering during beam–target coupling.However,to ensure simultaneous low coherence and high energy,complex spectral modulation methods and amplification routes have to be adopted.In this work,we propose the use of a random fiber laser(RFL)as the seed source.The spectral features of this RFL can be carefully tailored to provide a good match with the gain characteristics of the laser amplification medium,thus enabling efficient amplification while maintaining low coherence.First,a theoretical model is constructed to give a comprehensive description of the output characteristics of the spectrum-tailored RFL,after which the designed RFL is experimentally realized as a seed source.Through precise pulse shaping and efficient regenerative amplification,a shaped random laser pulse output of 28 mJ is obtained,which is the first random laser system with megawatt-class peak power that is able to achieve low coherence and efficient spectrum-conformal regenerative amplification.展开更多
Dielectric laser accelerators(DLAs)are considered promising candidates for on-chip particle accelerators that can achieve high acceleration gradients.This study explores various combinations of dielectric materials an...Dielectric laser accelerators(DLAs)are considered promising candidates for on-chip particle accelerators that can achieve high acceleration gradients.This study explores various combinations of dielectric materials and accelerated structures based on the inverse Cherenkov effect.The designs utilize conventional processing methods and laser parameters currently in use.We optimize the structural model to enhance the gradient of acceleration and the electron energy gain.To achieve higher acceleration gradients and energy gains,the selection of materials and structures should be based on the initial electron energy.Furthermore,we observed that the variation of the acceleration gradient of the material is different at different initial electron energies.These findings suggest that on-chip accelerators are feasible with the help of these structures and materials.展开更多
In this paper,we propose a novel stacked laser dielectric acceleration structure.This structure is based on the inverse Cherenkov effect and represented by a parametric design formulation.Compared to existing dielectr...In this paper,we propose a novel stacked laser dielectric acceleration structure.This structure is based on the inverse Cherenkov effect and represented by a parametric design formulation.Compared to existing dielectric laser accelerators relying on the inverse Smith–Purcell effect,the proposed structure provides an extended-duration synchronous acceleration field without requiring the pulse front tilting technique.This advantage significantly reduces the required pulse duration.In addition,the easy to integrate layered structure facilitates cascade acceleration,and simulations have shown that low-energy electron beams can be cascaded through high gradients over extended distances.These practical advantages demonstrate the potential of this new structure for future chip accelerators.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant No.62275235).
文摘A numerical model based on measured fictive temperature distributions is explored to evaluate the residual stress fields of CO_(2)laser-annealed mitigated fused silica damage sites.The proposed model extracts the residual strain from the differences in thermoelastic contraction of fused silica with different fictive temperatures from the initial frozen-in temperatures to ambient temperature.The residual stress fields of mitigated damage sites for the CO_(2)laser-annealed case are obtained by a finite element analysis of equilibrium equations and constitutive equations.The simulated results indicate that the proposed model can accurately evaluate the residual stress fields of laser-annealed mitigated damage sites with a complex thermal history.The calculated maximum hoop stress is in good agreement with the reported experimental result.The estimated optical retardance profiles from the calculated radial and hoop stress fields are consistent with the photoelastic measurements.These results provide sufficient evidence to demonstrate the suitability of the proposed model for describing the residual stresses of mitigated fused silica damage sites after CO_(2)laser annealing.
文摘The third paragraph in Sec.IV REGENERATIVE AMPLIFICATION erroneously states“In other words,the distribution of spectral components is time-dependent,and the spectral distortion in the amplification process will not change the time-domain shape.”
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 62165012 and 61665010)Key research and development projects in Gansu Province (Grant No. 21YFIGE300)+5 种基金Gansu Province College Industry Support Plan Project (Grant Nos. 2020C-23 and 2022CYZC-59)Department of Education of Gansu Province: The Education Project of Open Competition for the Best Candidates (Grant No. 2021jyjbgs-06)Gansu Provincial University Innovation Fund Project (Grant No. 2021B-190)Qinzhou District Science and Technology Plan Project (Grant No. 2021-SHFZG1442)Gansu Province College Young Doctor Support Project (Grant No. 2023QB-013)Gansu Province Excellent Graduate Innovation Star Project (Grant No. 2022CXZX796)。
文摘A direct Kerr-lens mode-locked Tm:LuYO_(3)ceramic laser without the aid of any mode-locked starting element is reported for the first time. A pulse duration as short as 259 fs and a maximum average output power of 326 m W are obtained at a repetition rate of 97.1 MHz. The corresponding optical spectrum centered at 2053 nm exhibits a bandwidth of 19.8 nm,which indicates the presence of nearly Fourier transform-limited pulses. Such a Kerr-lens mode-locked Tm:LuYO_(3)ceramic laser is a promising ultrashort pulse source, with both the excellent laser characteristics of Tm:LuYO3and the high-power 790 nm laser diode pumping scheme.
基金Project supported by the National Natural Science Foundation of China (Grant No. 11975214)。
文摘The dielectric laser accelerator(DLA) is a promising technology for achieving high-gradient acceleration in a compact design. Its advantages include ease of cascading and an energy gain per unit distance which can exceed that of conventional accelerators by two orders of magnitude. This paper establishes rules for efficient particle acceleration using dielectric structures based on basic equations, proposes a design principle for DLA structures with clear physical images and verifies the accuracy of the corresponding formula for energy gain. DLA structures with different specifications, materials and geometric shapes are constructed, and the achievable acceleration gradient is calculated. Our results demonstrate that effective acceleration can be achieved when the electric field sensed by particles in the acceleration cavity has zero frequency,which provides a powerful method for designing such devices. Furthermore, we demonstrate that the simplified formula for calculating energy gain presented in this paper can accurately determine the energy gain of particles during the design of acceleration structures using a dielectric accelerator.
基金Project supported by the National Key Research and Development Program of China (Grant No.2017YFA0403300)the National Natural Science Foundation of China (Grant Nos.12074352 and 11675158)Fundamental Research Funds for the Central Universities in China (Grant No.YJ202144)。
文摘A study of a nanosecond laser irradiation on the titanium-layer-buried gold planar target is presented. The timeresolved x-ray emission spectra of titanium tracer are measured by a streaked crystal spectrometer. By comparing the simulated spectra obtained by using the FLYCHK code with the measured titanium spectra, the temporal plasma states, i.e.,the electron temperatures and densities, are deduced. To evaluate the feasibility of using the method for the characterization of Au plasma states, the deduced plasma states from the measured titanium spectra are compared with the Multi-1D hydrodynamic simulations of laser-produced Au plasmas. By comparing the measured and simulated results, an overall agreement for the electron temperatures is found, whereas there are deviations in the electron densities. The experiment–theory discrepancy may suggest that the plasma state could not be well reproduced by the Multi-1D hydrodynamic simulation, in which the radial gradient is not taken into account. Further investigations on the spectral characterization and hydrodynamic simulations of the plasma states are needed. All the measured and FLYCHK simulated spectra are given in this paper as datasets. The datasets are openly available at http://www.doi.org/10.57760/sciencedb.j00113.00032.
基金supported by the Natural Science Foundation of Anhui Province (Grant No. 2208085QF217)the National Natural Science Foundation of China (Grant No. 52102012)the Hefei Institutes of Physical Science (HFIPS) Director’s Fund (Grant No. YZJJ2022QN08)。
文摘We demonstrate a high-energy and high-power pulse laser on a xenon lamp-pumped Er:YAP crystal. The laser performance and thermal focal lengths under different working frequencies are discussed. The results show that the thermal lens effect is gradually aggravated with the increase of working frequencies, and even working at 100 Hz, a single pulse energy of 234 m J can be achieved. A maximum average power of 41.5 W is achieved with a working frequency of 20 Hz and slope efficiency of 2.82%. This output power is much higher than other xenon lamp-pumped erbium laser devices.A Q-switched laser is demonstrated by using the TeO2crystal, the maximum output energies of 11.5 m J and 3.5 m J are obtained at 50 and 100 Hz, the corresponding peak powers are 93.4 k W and 17.2 kW, respectively.The laser wavelengths and beam quality factors are also characterized in the free-running and Q-switched modes. A higher pulse energy and peak power laser could be achieved further by improving the damage threshold of TeO2acousto-optical Q-switching. All the experimental results illustrate that the xenon lamp-pumped Er:YAP laser is a promising candidate for high-power and high-frequency mid-infrared laser devices.
基金the National Natural Science Foundation of China(Grant Nos.11774430,12075157,11775202,and 12175310)the Scientific Research Foundation of Hunan Provincial Education Department(Grant No.20A042).
文摘Low-noise terahertz(THz)radiation over 100 MV/cm generation by a linearly-polarized relativistic laser pulse interacting with a near-critical-density(NCD)plasma slab is studied by theory and particle-in-cell(PIC)simulations.A theoretical model is established to examine the dipole-like radiation emission.The THz radiation is attributed to the singlecycle low-frequency surface current,which is longitudinally constrained by the quasi-equilibrium established by the laser ponderomotive force and the ponderomotively induced electrostatic force.Through theoretical analysis,the spatiotemporal characteristics,polarization property of the THz radiation,and the relation between the radiation strength with the initial parameters of driving laser and plasma are obtained,which are in good consistence with the PIC simulation results.Furthermore,it is found by PIC simulations that the generation of thermal electrons can be suppressed within the appropriate parameter regime,resulting in a clear THz radiation waveform.The appropriate parameter region is given for generating a low-noise intense THz radiation with peak strength reaching 100 MV/cm,which could find potential applications in nonlinear THz physics.
基金China Academy of Engineering Physics(Grant No.CX20200022)the National Key Program for S&T Research and Development(Grant No.2018YFA0404804)the National Natural Science Foundation of China(Grant No.11875240).
文摘Ultraintense short-period infrared laser pulses play an important role in frontier scientific research,but their power is quite low when generated using current technology.This paper demonstrates a scheme for generating an ultraintense few-cycle infrared pulse by directly compressing a long infrared pulse.In this scheme,an infrared picosecond-to-nanosecond laser pulse counterpropagates with a rapidly extending plasma grating that is created by ionizing an undulated gas by a short laser pulse,and the infrared laser pulse is reflected by the rapidly extending plasma grating.Because of the high expansion velocity of the latter,the infrared laser pulse is compressed in the reflection process.One-and two-dimensional particle-in-cell simulations show that by this method,a pulse with a duration of tens of picoseconds in the mid-to far-infrared range can be compressed to a few cycles with an efficiency exceeding 60%,thereby making ultraintense few-cycle infrared pulses possible.
基金support of the National Natural Science Foundation of China(Grant Nos.62075030,62075201,and 11904339)the Sichuan Provincial Project for Outstanding Young Scholars in Science and Technology(Grant No.2020JDJQ0024)。
文摘Broadband low-coherence light is considered to be an effective way to suppress laser plasma instability.Recent studies have demonstrated the ability of low-coherence laser facilities to reduce back-scattering during beam–target coupling.However,to ensure simultaneous low coherence and high energy,complex spectral modulation methods and amplification routes have to be adopted.In this work,we propose the use of a random fiber laser(RFL)as the seed source.The spectral features of this RFL can be carefully tailored to provide a good match with the gain characteristics of the laser amplification medium,thus enabling efficient amplification while maintaining low coherence.First,a theoretical model is constructed to give a comprehensive description of the output characteristics of the spectrum-tailored RFL,after which the designed RFL is experimentally realized as a seed source.Through precise pulse shaping and efficient regenerative amplification,a shaped random laser pulse output of 28 mJ is obtained,which is the first random laser system with megawatt-class peak power that is able to achieve low coherence and efficient spectrum-conformal regenerative amplification.
基金the National Natural Science Foundation of China(Grant No.11975214)。
文摘Dielectric laser accelerators(DLAs)are considered promising candidates for on-chip particle accelerators that can achieve high acceleration gradients.This study explores various combinations of dielectric materials and accelerated structures based on the inverse Cherenkov effect.The designs utilize conventional processing methods and laser parameters currently in use.We optimize the structural model to enhance the gradient of acceleration and the electron energy gain.To achieve higher acceleration gradients and energy gains,the selection of materials and structures should be based on the initial electron energy.Furthermore,we observed that the variation of the acceleration gradient of the material is different at different initial electron energies.These findings suggest that on-chip accelerators are feasible with the help of these structures and materials.
基金the National Natural Science Foundation of China(Nos.12004353,11975214,11991071,11905202,and 12174350)Key Laboratory Foundation of the Sciences and Technology on Plasma Physics Laboratory(No.6142A04200103)Independent Scientific Research(No.JCKYS2021212011).
文摘In this paper,we propose a novel stacked laser dielectric acceleration structure.This structure is based on the inverse Cherenkov effect and represented by a parametric design formulation.Compared to existing dielectric laser accelerators relying on the inverse Smith–Purcell effect,the proposed structure provides an extended-duration synchronous acceleration field without requiring the pulse front tilting technique.This advantage significantly reduces the required pulse duration.In addition,the easy to integrate layered structure facilitates cascade acceleration,and simulations have shown that low-energy electron beams can be cascaded through high gradients over extended distances.These practical advantages demonstrate the potential of this new structure for future chip accelerators.