A passively Q-switched Yb: YAG microchip laser has been constructed by using a doped GaAs as the saturable absorber as well as the output coupler. At 13.5 W of pump power the device produces high-quality 3.4μJ 52ns p...A passively Q-switched Yb: YAG microchip laser has been constructed by using a doped GaAs as the saturable absorber as well as the output coupler. At 13.5 W of pump power the device produces high-quality 3.4μJ 52ns pulses at 1030nm with a pulse repetition rate of 7.8 kHz in a TEM00-mode.展开更多
Picosecond optical parametric generation and amplification in the near-infrared region within 1.361-1.656 μm and the mid-infrared region within 2.976-4.875 μm is constructed on the basis of bulk MgO:LiNbO 3 crystals...Picosecond optical parametric generation and amplification in the near-infrared region within 1.361-1.656 μm and the mid-infrared region within 2.976-4.875 μm is constructed on the basis of bulk MgO:LiNbO 3 crystals pumped at 1.064 μm.The maximum pulse energy reaches 1.3 mJ at 1.464 μm and 0.47 mJ at 3.894 μm,corresponding to a pumpto-idler photon conversion efficiency of 25%.By seeding the hard-to-measure mid-infrared radiation as the idler in the optical parametric amplification and measuring the amplified and frequency up-converted signal in the near-infrared or even visible region,one can measure very week mid-infrared radiation with ordinary detectors,which are insensitive to mid-infrared radiation,with a very high gain.A maximum gain factor of about 7 × 10 7 is achieved at the mid-infrared wavelength of 3.374 μm and the corresponding energy detection limit is as low as about 390 aJ per pulse.展开更多
奥登的诗说理性强,真实意图常隐藏在字面之后。本文以其较有代表性的《赋5》《告诉我爱的真谛》入手探究他的思想。九叶诗人穆旦深受奥登影响,他的爱情诗与中国传统诗歌不同,消解了浪漫的想象,而代之以看似冷酷的理性分析。《诗八首》...奥登的诗说理性强,真实意图常隐藏在字面之后。本文以其较有代表性的《赋5》《告诉我爱的真谛》入手探究他的思想。九叶诗人穆旦深受奥登影响,他的爱情诗与中国传统诗歌不同,消解了浪漫的想象,而代之以看似冷酷的理性分析。《诗八首》虽非直接受《O Tell Me the Truth About Love》的影响,但总体风格有传承关系,一定程度上算是穆旦对奥登的遥远呼应,且都比较代表两人的爱情观,因此便以这两首诗为例分析奥登在思想上对穆旦的内在影响。展开更多
Tunable coherent emission is generated in a single-pass,cascaded wavelength conversion process from mode-locked laser-pumped monolithic periodically poled lithium niobate(PPLN).Three ranges of wavelength,including vis...Tunable coherent emission is generated in a single-pass,cascaded wavelength conversion process from mode-locked laser-pumped monolithic periodically poled lithium niobate(PPLN).Three ranges of wavelength,including visible output from 628 nm to 639 nm,near-infrared output from 797 nm to 816 nm,and mid-infrared output from 3167 nm to 3459 nm,were obtained from the monolithic PPLN,which consists of a 10-mm section for 532-nm-pumped optical parametric generation(OPG)and a 7-mm section for 1064-nm-pumped sum frequency generation(SFG).A pump-to-signal conversion efficiency of 23.4%for OPG at 50°C and a quantum efficiency of 26.2%for SFG at 200°C were obtained.展开更多
文摘A passively Q-switched Yb: YAG microchip laser has been constructed by using a doped GaAs as the saturable absorber as well as the output coupler. At 13.5 W of pump power the device produces high-quality 3.4μJ 52ns pulses at 1030nm with a pulse repetition rate of 7.8 kHz in a TEM00-mode.
基金Project supported by the National Natural Science Foundation of China (Grant No. 61078005)the National Basic ResearchProgram of China (Grant No. 2007CB613205)the China Postdoctoral Science Foundation
文摘Picosecond optical parametric generation and amplification in the near-infrared region within 1.361-1.656 μm and the mid-infrared region within 2.976-4.875 μm is constructed on the basis of bulk MgO:LiNbO 3 crystals pumped at 1.064 μm.The maximum pulse energy reaches 1.3 mJ at 1.464 μm and 0.47 mJ at 3.894 μm,corresponding to a pumpto-idler photon conversion efficiency of 25%.By seeding the hard-to-measure mid-infrared radiation as the idler in the optical parametric amplification and measuring the amplified and frequency up-converted signal in the near-infrared or even visible region,one can measure very week mid-infrared radiation with ordinary detectors,which are insensitive to mid-infrared radiation,with a very high gain.A maximum gain factor of about 7 × 10 7 is achieved at the mid-infrared wavelength of 3.374 μm and the corresponding energy detection limit is as low as about 390 aJ per pulse.
文摘奥登的诗说理性强,真实意图常隐藏在字面之后。本文以其较有代表性的《赋5》《告诉我爱的真谛》入手探究他的思想。九叶诗人穆旦深受奥登影响,他的爱情诗与中国传统诗歌不同,消解了浪漫的想象,而代之以看似冷酷的理性分析。《诗八首》虽非直接受《O Tell Me the Truth About Love》的影响,但总体风格有传承关系,一定程度上算是穆旦对奥登的遥远呼应,且都比较代表两人的爱情观,因此便以这两首诗为例分析奥登在思想上对穆旦的内在影响。
基金Project supported by the National Basic Research Program of China(Grant No.2013CB632704)
文摘Tunable coherent emission is generated in a single-pass,cascaded wavelength conversion process from mode-locked laser-pumped monolithic periodically poled lithium niobate(PPLN).Three ranges of wavelength,including visible output from 628 nm to 639 nm,near-infrared output from 797 nm to 816 nm,and mid-infrared output from 3167 nm to 3459 nm,were obtained from the monolithic PPLN,which consists of a 10-mm section for 532-nm-pumped optical parametric generation(OPG)and a 7-mm section for 1064-nm-pumped sum frequency generation(SFG).A pump-to-signal conversion efficiency of 23.4%for OPG at 50°C and a quantum efficiency of 26.2%for SFG at 200°C were obtained.
