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191.
A passive mode-locked diode-pumped self-frequency-doubling Yb:YAB laser with a low modulation depth semiconductor saturable absorber mirror operating at 374 MHz is demonstrated. The measured pulse duration is 1.98 ps at the wavelength of 1044 nm. The maximum average power reaches 45 mW. 相似文献
192.
This paper proposed a ray-tracing model for the Martinez stretcher, derived the calculation formulae for the stretcher of a grating-spherical mirror system and discussed the error for the total dispersion resulted from the spatial dispersion. The calculated results show that the error could be ignored for the beam returned to the stretcher for the second pass in the wavelength range of 750 nm and 850 nm. 相似文献
193.
194.
A compact Er:fiber ring laser operated at a fundamental repetition rate of 325 MHz is reported.Two gain fibers with opposite dispersion are employed to shorten the fiber laser cavity for high repetition rate and soliton-like pulse generation without losing gain and compactness.The spectral bandwidth of the output pulse is 24 nm and the direct pulse duration is 123 fs without extra-cavity compression,which are values near the transform-limited range. 相似文献
195.
改性Ag/α-Al_2O_3催化丙烯气相环氧化反应 总被引:1,自引:0,他引:1
制备了以分子氧为氧化剂,对丙烯气相环氧化具有较好催化性能的改性负载银催化剂,并利用氧气程序升温脱附(O2-TPD)技术研究了氧在其表面上的脱附行为.实验结果表明:Ag/α-Al2O3催化剂只能使丙烯完全氧化成二氧化碳和水;当该催化剂用K2O改性后,可获得少量的环氧丙烷;Y2O3改性的Ag/α-Al2O3催化剂,可获得极少量的丙醛和丙酮;将0.1%(w)Y2O3添加到Ag-K2O/α-Al2O3后,可以显著提高催化剂的丙烯环氧化性能.在0.1MPa、245℃、20%C3H6/8%O2/72%N2和气体空速2000h-1的反应条件下,通过20%(w)Ag-0.1%Y2O3-0.1%K2O/α-Al2O3催化剂时,丙烯转化率为4.0%,环氧丙烷的选择性为46.8%.O2-TPD研究表明,少量的Y2O3、K2O或Y2O3-K2O作为助剂添加到20%Ag/α-Al2O3催化剂中时,减少了高温区与丙烯完全氧化有关的吸附氧物种的量,低温区余下的吸附氧物种量不变,有利于丙烯环氧化反应,提高了环氧丙烷的选择性. 相似文献
196.
通过酰胺键将酞菁(电子给体单元)和苝二酰亚胺(电子受体单元)偶联,合成了新型的酞菁-苝分子异质结,其在二氯甲烷、氯仿、四氢呋喃等常用溶剂中有较好的溶解度.紫外光谱分析表明其吸收光谱是酞菁和苝二酰亚胺信号的叠加,出现在300~780 nm之间.该分子摩尔消光系数高达105L mol-1 cm-1数量级,说明具有较宽的太阳光谱覆盖范围和很高的吸光系数.基于这些良好的光谱响应特性,制备了以该分子与[6,6]-苯基-C61-丁酸酸甲酯(PC61BM)为光活性层的有机太阳能电池(OSCs),该电池器件结构为ITO/聚(3,4-乙撑二氧噻吩):聚苯乙烯磺酸(PEDOT:PSS)/酞菁-苝给受体分子:PC61BM/Ca/Al,光电转换效率(PCE)为0.009%,对应的开路电压(Voc)为0.472 V,短路电流(Jsc)为0.104 mA/cm2,填充因子(FF)为0.18. 相似文献
197.
Ruthenium (Ru) nanocrystals (NCs) embedded in SiO2 gate stacks are formed by rapid thermal annealing for the whole gate stacks and embedded in the memory structure, which is compatible with conventional CMOS technology. The devices exhibit a substantial and clockwise hysteresis in capacitance-voltage measurement. The Ru NCs exhibit high density (2 × 10^12cm^-2), small size (2-4 nm) and good uniformity both in spatial distribution and morphology. The charging and long-term retention performances are explained by the Coulomb Blockade phenomena and the asymmetric electron tunnel barrier between the Ru NCs and the Si substrate, respectively. 相似文献
198.
199.
Numerical simulation for characterizing femtosecond optical pulses with the SPIDER algorithm 下载免费PDF全文
In this article based on the spectral phase interferometry for direct electric-field reconstruction (SPIDER), the femtosecond pulses with various phase characters are numerically simulated. The spectral phases and amplitudes of the transform-limited pulse, the linear chirped pulse, the cubic dispersion pulse, the quartic dispersion pulse, the self-phase modulation pulse and the pulses with the combination of different chirped characters are retrieved. These characterized pulses are applicable to the real-time measurement as samples for diagnosing the chirped characters of pulses quickly. 相似文献
200.
We present an Er-doped fiber(Er:fiber)-based femtosecond laser at 780 nm with 256 MHz repetition rate, 191 fs pulse duration, and over 1 W average power. Apart from the careful third-order dispersion management, we introduce moderate self-phase modulation to broaden the output spectrum of the Er:fiber amplifier and achieve 193 fs pulse duration and 2.43 W average power. Over 40% frequency doubling efficiency is obtained by a periodically poled lithium niobate crystal. Delivering through a hollow-core photonic bandgap fiber, this robust laser becomes an ideal and convenient light source for two-photon autofluorescence imaging. 相似文献