1 IntroductionLiNbO3 optical modulators have become essential transmission devices for current and future wideband fibre-optic communications for both military and telecommunications applications. For many telecommuni...1 IntroductionLiNbO3 optical modulators have become essential transmission devices for current and future wideband fibre-optic communications for both military and telecommunications applications. For many telecommunications applications, only a narrow bandwidth is required and thus resonantly enhancedMach-Zehndermodulators(RE-MZMs)have been developed to improve modulation efficiency at the expense of bandwidth.展开更多
This paper report an 1645 nm Er：YAG laser resonantly pumped by an Er-fiber laser operating at 1532 rim. 1.78 W continous wave （CW） output power with a slope efficiency of 52% was obtained using a long ring cavity a...This paper report an 1645 nm Er：YAG laser resonantly pumped by an Er-fiber laser operating at 1532 rim. 1.78 W continous wave （CW） output power with a slope efficiency of 52% was obtained using a long ring cavity and an 1 at.% doped Er：YAG crystal. In Q-switched mode, the obtained pulse energy was 1.6 mJ at a repetition rate of 500 Hz; for 1 kHz repetition rate, 1.2 mJ output energy was obtained.展开更多
Research on the interstellar medium and its interaction with the solar system constitutes a significant topic in planetary physics.As the Sun traverses the local interstellar cloud,interstellar neutrals penetrate the ...Research on the interstellar medium and its interaction with the solar system constitutes a significant topic in planetary physics.As the Sun traverses the local interstellar cloud,interstellar neutrals penetrate the heliosphere,forming the interstellar wind,and scattering solar extreme ultraviolet(EUV)emission lines.The intensity of the scattered radiation provides an indicator of the characteristic parameters of the interstellar wind,crucial for characterizing the heliosphere,the interstellar medium,and the evolution of the solar system.Meanwhile,a powerful method for studying stellar evolution is investigating the EUV emissions of stars.The only ongoing mission conducting an EUV full-sky survey is the relay satellite Queqiao-2.Due to the strong absorption of the interstellar medium at EUV wavelengths,modelling is essential to any study of these influences.In this study,we reviewed classical modelling methods for the density distribution of the interstellar helium atoms in the heliosphere,and the corresponding 58.4 nm radiation intensity.We established distinct density and intensity models for different orbital positions of Earth’s revolution.We found that when the Earth enters the helium focusing cone in the downwind region,both the helium density and the 58.4 nm radiation intensity increase rapidly,with the temperature effect being particularly important.The radiation intensity in the downwind direction can be 170 times that of the upwind direction.Some negligible factors were omitted for simplicity,such as the effects of the solar line width and Doppler shift.Our research can serve as an aid to the interpretation of the EUV observations in the full-sky survey conducted by Queqiao-2.展开更多
Terahertz(THz)frequency is an important spectrum for highspeed communications,body security,nondestructive matter sensing,bioimaging,biomedicines and other applications.For example,it overlaps with the characteristic ...Terahertz(THz)frequency is an important spectrum for highspeed communications,body security,nondestructive matter sensing,bioimaging,biomedicines and other applications.For example,it overlaps with the characteristic fingerprints of molecular vibrations and rotations(such as protein and DNA)and thus could resonantly interact with various biosamples.展开更多
Ⅰ. INTRODUCTIONLaser-excited atomic fluorescence spectrometry in hollow cathode discharge(HCD) has been widely used in the research field of laser spectroscopy in recent years. Similar to traditional method, informat...Ⅰ. INTRODUCTIONLaser-excited atomic fluorescence spectrometry in hollow cathode discharge(HCD) has been widely used in the research field of laser spectroscopy in recent years. Similar to traditional method, information obtained in the researches was direct line nonresonance fluorescence arising from the resonantly transitional upper level. Attention has not been sufficiently paid to the phenomenon of population change on the resonantly transitional lower level due to laser irradiation of plasma in HCD, so展开更多
文摘1 IntroductionLiNbO3 optical modulators have become essential transmission devices for current and future wideband fibre-optic communications for both military and telecommunications applications. For many telecommunications applications, only a narrow bandwidth is required and thus resonantly enhancedMach-Zehndermodulators(RE-MZMs)have been developed to improve modulation efficiency at the expense of bandwidth.
文摘This paper report an 1645 nm Er：YAG laser resonantly pumped by an Er-fiber laser operating at 1532 rim. 1.78 W continous wave （CW） output power with a slope efficiency of 52% was obtained using a long ring cavity and an 1 at.% doped Er：YAG crystal. In Q-switched mode, the obtained pulse energy was 1.6 mJ at a repetition rate of 500 Hz; for 1 kHz repetition rate, 1.2 mJ output energy was obtained.
基金supported by the National Key R&D Program of China(2021YFA0718600)the National Natural Science Foundation of China(42441809).
文摘Research on the interstellar medium and its interaction with the solar system constitutes a significant topic in planetary physics.As the Sun traverses the local interstellar cloud,interstellar neutrals penetrate the heliosphere,forming the interstellar wind,and scattering solar extreme ultraviolet(EUV)emission lines.The intensity of the scattered radiation provides an indicator of the characteristic parameters of the interstellar wind,crucial for characterizing the heliosphere,the interstellar medium,and the evolution of the solar system.Meanwhile,a powerful method for studying stellar evolution is investigating the EUV emissions of stars.The only ongoing mission conducting an EUV full-sky survey is the relay satellite Queqiao-2.Due to the strong absorption of the interstellar medium at EUV wavelengths,modelling is essential to any study of these influences.In this study,we reviewed classical modelling methods for the density distribution of the interstellar helium atoms in the heliosphere,and the corresponding 58.4 nm radiation intensity.We established distinct density and intensity models for different orbital positions of Earth’s revolution.We found that when the Earth enters the helium focusing cone in the downwind region,both the helium density and the 58.4 nm radiation intensity increase rapidly,with the temperature effect being particularly important.The radiation intensity in the downwind direction can be 170 times that of the upwind direction.Some negligible factors were omitted for simplicity,such as the effects of the solar line width and Doppler shift.Our research can serve as an aid to the interpretation of the EUV observations in the full-sky survey conducted by Queqiao-2.
文摘Terahertz(THz)frequency is an important spectrum for highspeed communications,body security,nondestructive matter sensing,bioimaging,biomedicines and other applications.For example,it overlaps with the characteristic fingerprints of molecular vibrations and rotations(such as protein and DNA)and thus could resonantly interact with various biosamples.
文摘Ⅰ. INTRODUCTIONLaser-excited atomic fluorescence spectrometry in hollow cathode discharge(HCD) has been widely used in the research field of laser spectroscopy in recent years. Similar to traditional method, information obtained in the researches was direct line nonresonance fluorescence arising from the resonantly transitional upper level. Attention has not been sufficiently paid to the phenomenon of population change on the resonantly transitional lower level due to laser irradiation of plasma in HCD, so
