With the rapid development of ultrafast intense laser technologies, the interaction of intense laser radiation with mat- ter has been a frontier for few decades. The International Conference on Multiphoton Processes ...With the rapid development of ultrafast intense laser technologies, the interaction of intense laser radiation with mat- ter has been a frontier for few decades. The International Conference on Multiphoton Processes （ICOMP）, initiated in 1977, covers the latest advances in the field every three years. The special issue is based on the spirit of the 13th International Conference on Multi-Photon Processes, ICOMP13, which was held in Shanghai, organized by Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, on Dec. 7-10, 2014展开更多
The .Er<sup>3+</sup>-Yb<sup>3+</sup>-doped fiber has a broadened absorption spectrum, which means the pumping sources can work efficiently from 810 to 1100nm. Among them 980nm is the maximum.ab...The .Er<sup>3+</sup>-Yb<sup>3+</sup>-doped fiber has a broadened absorption spectrum, which means the pumping sources can work efficiently from 810 to 1100nm. Among them 980nm is the maximum.absorption （10 dB/km） wavelength. By energy transferring and multiphoton process, the visible and ultraviolet radiation occurs when the Er<sup>3+</sup>-Yb<sup>3+</sup>-doped fiber is pumped by the laser at 980-nm band. Further researches on the mechanism of the fluorescence of Er<sup>3+</sup>-Yb<sup>3+</sup>-doped silica fiber pumped by Ti: A1<sub>2</sub>O<sub>3</sub> tunable laser at 980-nm band are helpful展开更多
Multiply charged ions of Ar and NO were observed in MPI experiment Of NO/Ar with TOF-MS. A delayable pulsed acceleration field wn applied tO investigate the effect of the photoelectrons on the formation of the multi...Multiply charged ions of Ar and NO were observed in MPI experiment Of NO/Ar with TOF-MS. A delayable pulsed acceleration field wn applied tO investigate the effect of the photoelectrons on the formation of the multiply charged ions. The multiply charged ions were suggested to be produced by photoelectron impact ionization, in the region bentween the extractor grid and the repeller plate, step by step, from neutral species and lower charged ions. The 50-60ns of FWHM of the ion peaks implies that the pulse width of the photoelectrons should be shorter considering the broadening effect during the ionization process.展开更多
We present a cooling scheme with a tripod configuration atomic ensemble trapped in an optomechanical cavity.With the employment of two different quantum interference processes,our scheme illustrates that it is possibl...We present a cooling scheme with a tripod configuration atomic ensemble trapped in an optomechanical cavity.With the employment of two different quantum interference processes,our scheme illustrates that it is possible to cool a resonator to its ground state in the strong cavity-atom coupling regime.Moreover,with the assistance of one additional energy level,our scheme takes a larger cooling rate to realize the ground state cooling.In addition,this scheme is a feasible candidate for experimental applications.展开更多
Near-infrared to visible upconversion luminescence was observed in a multicomponent silicate （BK7） glass containing Ce^3 ＋ ions under focused infrared femtosecond laser irradiation. The emission spectra show that t...Near-infrared to visible upconversion luminescence was observed in a multicomponent silicate （BK7） glass containing Ce^3 ＋ ions under focused infrared femtosecond laser irradiation. The emission spectra show that the upconversion luminescence comes from the 4f-5d transition of the Ce^3 ＋ ions. The relationship between the intensity of the Ce^3 ＋ emission and the pump power reveals that a three-photon absorption predominates in the conversion process from the near-infrared into the blue luminescence. The analysis of the upconversion mechanism suggests that the upconversion luminescence may come from a three-photon simultaneous absorption that leads to a population of the 5d level in which the characteristic luminescence occurs.展开更多
The analytic formula of the ionization efficiency in the process of double resonance enhanced multi-photon ionization （DREMPI） is derived from the dynamic rate equation about the interaction of photon and material. ...The analytic formula of the ionization efficiency in the process of double resonance enhanced multi-photon ionization （DREMPI） is derived from the dynamic rate equation about the interaction of photon and material. Based on this formula, the ionization efficiency and the laser power index versus laser intensity in the DREMPI process of NO molecule, via A2E and S2E intermediate resonant states, is numerically simulated. It is shown that the ionization efficiency of NO molecule increases with the laser intensity until getting saturation, while the laser power index decreases with the enhancement of the laser intensity and changes to zero at last. The variation of the laser power index with the laser intensity indicates that the ionization efficiency reaches saturation in the one, two, and three excitation steps respectively. It is also found that the narrower the laser pulse duration is, the higher becomes the laser intensity for saturation.展开更多
Infrared to visible upconversion luminescence was demonstrated in trivalent Europium doped Ca2Al2SiO7 crystal （Eu^3＋：Ca2Al2SiO7） irradiated by focused infrared femtosecond laser. The upconversion luminescence orig...Infrared to visible upconversion luminescence was demonstrated in trivalent Europium doped Ca2Al2SiO7 crystal （Eu^3＋：Ca2Al2SiO7） irradiated by focused infrared femtosecond laser. The upconversion luminescence originated from 5D0 to 7Ej （j= 1, 2） transitions of Eu^3＋ The relationship between the upconversion luminescence intensity and the pump power indicated that the upconversion from near-infrared to red is dominated by a two-photon absorption process of Eu^3＋ Analysis suggested that two-photon simultaneous absorption induced population inversion should be the predominant frequency upconversion mechanism.展开更多
It is demonstrated that the production mechanism of a pair which is produced from vacuum under an external field can be characterized by its conversion energy, a quantity defined as total mass-energy of this pair. The...It is demonstrated that the production mechanism of a pair which is produced from vacuum under an external field can be characterized by its conversion energy, a quantity defined as total mass-energy of this pair. The value of this quantity is checked with quantum field theoretical simulations for several field configurations and it is found that conversion energy can show all the production channels and give the yields of each channel specifically. We detect signatures of effective mass, combination of different photons as well as dynamically assisted Schwinger mechanism and represented more features of these processes in the view of conversion energy.展开更多
A new type of solid-conversion gas detector is investigated for high energy X-ray industrial computed tomography (HECT). The conversion efficiency is calculated by using the EGSnrc Monte Carlo code on the Linux platfo...A new type of solid-conversion gas detector is investigated for high energy X-ray industrial computed tomography (HECT). The conversion efficiency is calculated by using the EGSnrc Monte Carlo code on the Linux platform to simulate the transport process of photons and electrons in the detector. The simulation results show that the conversion efficiency could be more than 65%, if the X-ray beam width is less than about 0.2 mm, and a tungsten slab with 0.2 mm thickness and 30 mm length is employed as a radiation conversion medium. Meanwhile the results indicate that this new detector has higher conversion efficiency as well as less volume. Theoretically this new kind of detector could take place of the traditional scintillation detector for HECT.展开更多
Optical microscopy of biological tissues at the 1700 nm window has enabled deeper penetration,due to the combined advantage of relatively small water absorption and tissue scattering at this wavelength.Compared with e...Optical microscopy of biological tissues at the 1700 nm window has enabled deeper penetration,due to the combined advantage of relatively small water absorption and tissue scattering at this wavelength.Compared with excitation at other wavelengths,such as the commonly used 800 nm window for two-photon microscopy,water absorption at the 1700nm window is more than one order of magnitude higher.As a result,more temperature rise can be expected and can be potentially detrimental to biological tissues.Here,we present theoretical estimation of temper-ature rise at the focus of objective lens at the 1700nm window,purely due to water absorption.Our calculated result shows that under realistic experimental conditions,temperature rise due to water absorption is still below 1 K and may not cause tissue damage during imaging.展开更多
文摘With the rapid development of ultrafast intense laser technologies, the interaction of intense laser radiation with mat- ter has been a frontier for few decades. The International Conference on Multiphoton Processes （ICOMP）, initiated in 1977, covers the latest advances in the field every three years. The special issue is based on the spirit of the 13th International Conference on Multi-Photon Processes, ICOMP13, which was held in Shanghai, organized by Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, on Dec. 7-10, 2014
文摘The .Er<sup>3+</sup>-Yb<sup>3+</sup>-doped fiber has a broadened absorption spectrum, which means the pumping sources can work efficiently from 810 to 1100nm. Among them 980nm is the maximum.absorption （10 dB/km） wavelength. By energy transferring and multiphoton process, the visible and ultraviolet radiation occurs when the Er<sup>3+</sup>-Yb<sup>3+</sup>-doped fiber is pumped by the laser at 980-nm band. Further researches on the mechanism of the fluorescence of Er<sup>3+</sup>-Yb<sup>3+</sup>-doped silica fiber pumped by Ti: A1<sub>2</sub>O<sub>3</sub> tunable laser at 980-nm band are helpful
文摘Multiply charged ions of Ar and NO were observed in MPI experiment Of NO/Ar with TOF-MS. A delayable pulsed acceleration field wn applied tO investigate the effect of the photoelectrons on the formation of the multiply charged ions. The multiply charged ions were suggested to be produced by photoelectron impact ionization, in the region bentween the extractor grid and the repeller plate, step by step, from neutral species and lower charged ions. The 50-60ns of FWHM of the ion peaks implies that the pulse width of the photoelectrons should be shorter considering the broadening effect during the ionization process.
基金Project supported by the National Key Research and Development Program of China(Grant No.2017YFA0304503)Key Research and Development Project of Guangdong Province,China(Grant No.2020B030300001)the National Natural Science Foundation of China(Grant Nos.828330256,11636220,11805279,1173401,and 11504430)。
文摘We present a cooling scheme with a tripod configuration atomic ensemble trapped in an optomechanical cavity.With the employment of two different quantum interference processes,our scheme illustrates that it is possible to cool a resonator to its ground state in the strong cavity-atom coupling regime.Moreover,with the assistance of one additional energy level,our scheme takes a larger cooling rate to realize the ground state cooling.In addition,this scheme is a feasible candidate for experimental applications.
基金Project supported bythe National Natural Science Foundation of China (50125258 and 60377040)
文摘Near-infrared to visible upconversion luminescence was observed in a multicomponent silicate （BK7） glass containing Ce^3 ＋ ions under focused infrared femtosecond laser irradiation. The emission spectra show that the upconversion luminescence comes from the 4f-5d transition of the Ce^3 ＋ ions. The relationship between the intensity of the Ce^3 ＋ emission and the pump power reveals that a three-photon absorption predominates in the conversion process from the near-infrared into the blue luminescence. The analysis of the upconversion mechanism suggests that the upconversion luminescence may come from a three-photon simultaneous absorption that leads to a population of the 5d level in which the characteristic luminescence occurs.
基金supported by the National Natural Science Foundation of China (No.10647130)the Doctoral Foundation of North China Electric Power University (No.200612003).
文摘The analytic formula of the ionization efficiency in the process of double resonance enhanced multi-photon ionization （DREMPI） is derived from the dynamic rate equation about the interaction of photon and material. Based on this formula, the ionization efficiency and the laser power index versus laser intensity in the DREMPI process of NO molecule, via A2E and S2E intermediate resonant states, is numerically simulated. It is shown that the ionization efficiency of NO molecule increases with the laser intensity until getting saturation, while the laser power index decreases with the enhancement of the laser intensity and changes to zero at last. The variation of the laser power index with the laser intensity indicates that the ionization efficiency reaches saturation in the one, two, and three excitation steps respectively. It is also found that the narrower the laser pulse duration is, the higher becomes the laser intensity for saturation.
基金Funded by the National Natural Science Foundation of China (No.50672087 and No.60778039)National Basic Research Program of China (No.2006CB806000)National High Technology Program of China (No.2006AA03Z304)
文摘Infrared to visible upconversion luminescence was demonstrated in trivalent Europium doped Ca2Al2SiO7 crystal （Eu^3＋：Ca2Al2SiO7） irradiated by focused infrared femtosecond laser. The upconversion luminescence originated from 5D0 to 7Ej （j= 1, 2） transitions of Eu^3＋ The relationship between the upconversion luminescence intensity and the pump power indicated that the upconversion from near-infrared to red is dominated by a two-photon absorption process of Eu^3＋ Analysis suggested that two-photon simultaneous absorption induced population inversion should be the predominant frequency upconversion mechanism.
基金Supported by the National Natural Science Foundation of China under Grant No.11475026
文摘It is demonstrated that the production mechanism of a pair which is produced from vacuum under an external field can be characterized by its conversion energy, a quantity defined as total mass-energy of this pair. The value of this quantity is checked with quantum field theoretical simulations for several field configurations and it is found that conversion energy can show all the production channels and give the yields of each channel specifically. We detect signatures of effective mass, combination of different photons as well as dynamically assisted Schwinger mechanism and represented more features of these processes in the view of conversion energy.
基金supported by the National Natural Science Foundation of China (No.60672098)the Tackling Key Problems of Science and Technology of ChongQing (No.CSTC2009AC3047)
文摘A new type of solid-conversion gas detector is investigated for high energy X-ray industrial computed tomography (HECT). The conversion efficiency is calculated by using the EGSnrc Monte Carlo code on the Linux platform to simulate the transport process of photons and electrons in the detector. The simulation results show that the conversion efficiency could be more than 65%, if the X-ray beam width is less than about 0.2 mm, and a tungsten slab with 0.2 mm thickness and 30 mm length is employed as a radiation conversion medium. Meanwhile the results indicate that this new detector has higher conversion efficiency as well as less volume. Theoretically this new kind of detector could take place of the traditional scintillation detector for HECT.
基金the National Natural Science Foundation of China(Grants Nos.61475103 and 11404218)the National Hi-Tech Research and Development Program of China(Grant No.2015A A020515)+3 种基金the Natural Science Founda-tion of SZU(Grant No.00002701)the Project of Department of Education of Guangdong Province(No.2014KTSCX114)the Science and Technology Innovation Commission of Shenzhen(Grants No.KQJSCX20160226194151 and KQTD20150710165601017)the Scient ific Research Founda-tion for the Returned Overseas Chinese Scholars,State Education Ministry.
文摘Optical microscopy of biological tissues at the 1700 nm window has enabled deeper penetration,due to the combined advantage of relatively small water absorption and tissue scattering at this wavelength.Compared with excitation at other wavelengths,such as the commonly used 800 nm window for two-photon microscopy,water absorption at the 1700nm window is more than one order of magnitude higher.As a result,more temperature rise can be expected and can be potentially detrimental to biological tissues.Here,we present theoretical estimation of temper-ature rise at the focus of objective lens at the 1700nm window,purely due to water absorption.Our calculated result shows that under realistic experimental conditions,temperature rise due to water absorption is still below 1 K and may not cause tissue damage during imaging.
