A femtosecond LBO optical parametric oscillator(OPO)with widely adjustable repetition rate by fractionally decrement of the cavity length is demonstrated.The repetition rate of 755 MHz to 1.43 GHz at an interval of 75...A femtosecond LBO optical parametric oscillator(OPO)with widely adjustable repetition rate by fractionally decrement of the cavity length is demonstrated.The repetition rate of 755 MHz to 1.43 GHz at an interval of 75.5 MHz is realized,which is 10 to 19 times that of the pump laser.The properties of output signal at 750 nm at different repetition rates are studied.The power of signal decreases with increasing the repetition rate.The maximum power of 194 mW at the repetition rate of 755 MHz and the minimum power of 22 mW at repetition rate of 1.43 GHz for the signal at 750 nm are obtained for the pump power of 3 W.展开更多
We demonstrated a nonlinear temporal filter based on the self-diffraction(SD)process.Temporal contrast enhancement,angular dispersion and spectrum broadening properties of the SD process are investigated in experiment...We demonstrated a nonlinear temporal filter based on the self-diffraction(SD)process.Temporal contrast enhancement,angular dispersion and spectrum broadening properties of the SD process are investigated in experiment and simulation.Driven by spectral phase well compensated laser pulses with bandwidth of 28 nm,the filter produced clean pulses with a temporal contrast higher than 10^(10) and excellent spatial profile,the spectrum of which was smoothed and broadened to 64 nm.After implementing this filter into a home-made 30 TW Ti:sapphire amplifier,temporal contrast of the amplified pulses was enhanced to 10^(10) within the time scale of−400 ps.展开更多
Aphysical model facility was designed, built, and setup for conducting model tests on a composite foundation in a soil ground. The model tests were carried out on a composite foundation with different combinations of ...Aphysical model facility was designed, built, and setup for conducting model tests on a composite foundation in a soil ground. The model tests were carried out on a composite foundation with different combinations of vertical reinforcement elements in the same soil ground. Via the analysis of the collected data the characteristics of the composite foundation with different reinforcing elements were obtained, including the characteristics of load-settlement curves, column stresses, stresses of the intercolumn soil, pile-soil stress ratio, and load-sharing ratios of columns and soil. Results from the model tests reveal the mechanism of a composite foundation with different reinforcing elements quantitatively. It is concluded that both a composite foundation with a combination of steel pipe pile and sand column and that with a combination of concrete pile and lime column have a higher bearing capacity than the composite foundation with only sand columns with the same conditions of soil ground and loading. A composite foundation with lime column and sand column embodies no much better performance than that with sand colunms only.展开更多
基金Supported by the National Key R&D Program of China under Grant Nos 2017YFC0110301 and 2017YFB0405202the National Natural Science Foundation of China under Grant Nos 91850209,11774410 and 61575217+2 种基金the Youth Innovation Promotion Association,Chinese Academy of Sciences(No 2018007)the Strategic Priority Research Program of CAS(XDB16030200)the Key Research Program of Frontier Sciences of CAS(KJZD-EW-L11-03)
文摘A femtosecond LBO optical parametric oscillator(OPO)with widely adjustable repetition rate by fractionally decrement of the cavity length is demonstrated.The repetition rate of 755 MHz to 1.43 GHz at an interval of 75.5 MHz is realized,which is 10 to 19 times that of the pump laser.The properties of output signal at 750 nm at different repetition rates are studied.The power of signal decreases with increasing the repetition rate.The maximum power of 194 mW at the repetition rate of 755 MHz and the minimum power of 22 mW at repetition rate of 1.43 GHz for the signal at 750 nm are obtained for the pump power of 3 W.
基金Supported by the National Natural Science Foundation of China(Grant Nos.11774410 and 91850209)the Strategic Priority Research Program of CAS(Grant No.XDB16030200).
文摘We demonstrated a nonlinear temporal filter based on the self-diffraction(SD)process.Temporal contrast enhancement,angular dispersion and spectrum broadening properties of the SD process are investigated in experiment and simulation.Driven by spectral phase well compensated laser pulses with bandwidth of 28 nm,the filter produced clean pulses with a temporal contrast higher than 10^(10) and excellent spatial profile,the spectrum of which was smoothed and broadened to 64 nm.After implementing this filter into a home-made 30 TW Ti:sapphire amplifier,temporal contrast of the amplified pulses was enhanced to 10^(10) within the time scale of−400 ps.
基金Project (No.50478090) supported by the National Natural Science Foundation of China
文摘Aphysical model facility was designed, built, and setup for conducting model tests on a composite foundation in a soil ground. The model tests were carried out on a composite foundation with different combinations of vertical reinforcement elements in the same soil ground. Via the analysis of the collected data the characteristics of the composite foundation with different reinforcing elements were obtained, including the characteristics of load-settlement curves, column stresses, stresses of the intercolumn soil, pile-soil stress ratio, and load-sharing ratios of columns and soil. Results from the model tests reveal the mechanism of a composite foundation with different reinforcing elements quantitatively. It is concluded that both a composite foundation with a combination of steel pipe pile and sand column and that with a combination of concrete pile and lime column have a higher bearing capacity than the composite foundation with only sand columns with the same conditions of soil ground and loading. A composite foundation with lime column and sand column embodies no much better performance than that with sand colunms only.
