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161.
实验研究了正色散固体介质中的激光脉冲自压缩现象,证明了无需任何外加色散补偿情况下,固体透明介质中的自聚焦传输过程可使高功率飞秒激光脉冲实现时域脉冲压缩,并详细研究了输出脉冲的时域和频域特性随入射脉冲强度的演化规律.实验结果表明脉冲自压缩量随入射脉冲强度的增加呈递增趋势,然而当入射光强增大到足以引起超连续谱及锥形辐射产生时,脉冲时域形状会发生分裂.此外还发现发散光束入射情况下同样可以观察到脉冲自压缩现象.
关键词:
超短激光脉冲
脉冲压缩
非线性传输 相似文献
162.
A compact two-stage optical parametric chirped pulse amplifier based on photonic crystal fibre is demonstrated.A 1064-nm soliton pulse is obtained in a home-made photonic crystal fibre (PCF) with femtosecond pulse pumping and then amplified to 2 mJ in an Nd:YAG regenerative amplifier.After the amplified pulses pass through the LBO crystal,the 532-nm double-frequency light with an energy of 0.8 mJ and a duration of over 100 ps at 10-Hz repetition rate is generated as a pump source in the following two-stage optical parametric amplification (OPA).The 850-nm chirped signal light gain from the stretcher is 1.5×10 4 in the first-stage OPA while it is 120 in the second-stage OPA.The total signal gain of optical parametric chirped pulse amplification (OPCPA) can reach 1.8×10 6. 相似文献
163.
164.
Detection of amyloid-β deposition in the brain region is of significant importance for early diagnosis of Alzheimer's disease (AD). In the last few decades, the fluorescent imaging technique has been considered an effective tool for detecting amyloid-β plaques due to its safety, sensitivity, and operability. Thus, numerous fluorescent probes for amyloid-β have been developed. The design of a probe with high selectivity and improved sensing performance requires knowledge about the potential binding sites for the probe in amyloid-β and local microstructure of the probe in different sites. In this study, amyloid-β-specific photophysical properties of a novel fluorescent probe (cis-PAD-1) are theoretically investigated by using multiscale simulations, including molecular docking and quantum mechanics/molecular mechanics calculations. Binding profile of cis-PAD-1 in amyloid-β has been simulated, and binding affinity of the probe in various sites is calculated. An excited-state property study on cis-PAD-1 illustrates that the probe shows remarkable fluorescence enhancement in amyloid-β due to the influence of the microenvironment, which is consistent with the experimental observation. Most importantly, two-photon absorption cross section of the probe is greatly increased in the near-infrared region when targeting with amyloid-β owing to the enhanced transition dipole moment. Therefore, one can propose the usage of cis-PAD-1 as an excellent candidate in two-photon fluorescent imaging for amyloid-β. The detailed investigations provide information on the development and design strategy of a new fluorescent probe for amyloid-β imaging in AD. 相似文献
165.
Some Inequalities Involving Two Simplexes 总被引:5,自引:0,他引:5
Leng Gangsong 《Geometriae Dedicata》1997,66(1):89-98
We establish some inequalities on the inradius and circumradius of two simplexes, and prove a number of applications thereof. 相似文献
166.
167.
A temperature distribution sensing system based on the reflection spectrum of a 70 mm apodized chirped fiber Bragg grating has been demonstrated. Reflection variations created by the Fabry-Perot effect due to the intra-grating wavelength shift are presented. By fitting a parametric transfer matrix model of the grating response to measured spectra, the temperature change, position and width of a localized temperature change are obtained. This system is particularly attractive of its simplicity, high spatial resolution and ability in measuring a non-monotonic distribution. Experiments to measure two localized heating regions along the grating indicate that the technique is promising for measuring more complex temperature profiles. 相似文献
168.
杂多阴离子的NMR和ESR研究:Ⅱ磷钼钒杂多酸及其镧盐的NMR 总被引:1,自引:0,他引:1
具有Keggin结构的磷钼钒杂多酸及其盐是有效的氧化剂.本文通过磷钼钒杂多酸及其镧盐的~(31)p,~(51)V,~(139)La,~(17)O及~1H的NMR测定,并结合红外和差热分析,说明镧的引入对Keggin结构没有影响,但镧对水分子有强的作用力,使阴离子之间存在更多的水分子,从而对催化氧化活性产生了影响. 相似文献
169.
Baozhen Zhao Yuxin Leng Cheng Wang Yongliang Jiang Juan Du Zhizhan Xu 《Optics Communications》2006,259(1):137-141
Optical parametric chirped pulse amplification with different pump wavelengths was investigated using LBO crystal, at signal central wavelength of 800 nm. According to our theoretical simulation, when pump wavelength is 492.5 nm, there is a maximal gain bandwidth of 190 nm centered at 805 nm in optimal noncollinear angle using LBO. Presently, pump wavelength of 492.5 nm can be obtained from second harmonic generation of a Yb:Sr5(PO4)3F laser. The broad gain bandwidth can completely support ∼6 fs with a spectral centre of seed pulse at 800 nm. The deviation from optimal noncollinear angle can be compensated by accurately tuning crystal angle for phase matching. The gain spectrum with pump wavelength of 492.5 nm is much better than those with pump wavelengths of 400, 526.5 and 532 nm, at signal centre of 800 nm. 相似文献
170.
对掺Cr~(3 )乙酰丙酮铝单晶的(001),(100)和(110)晶面进行晶面旋转EPR扫描,得到共振磁场随旋转角度变化的实验图形,根据本征插方法编写的程序,对实验谱图进行投合,得到下述顺磁参数,D=0.5870±O.005cm~(-1),E=-0.00490±0.0001cm~(-1),g~2=g_y=1.965土0.001,g_r=1.984±0.001. 相似文献