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941.
苯丙炔酸低聚物的合成及性能 总被引:1,自引:0,他引:1
极性-共轭双取代乙炔-苯丙炔酸在Pd(PPh3)2Cl2催化下直接通过易位催化机理聚合为低聚物.单体苯丙炔酸由两步制得,先通过液溴和肉桂酸的加成反应得到二溴代苯丙酸,然后消去两分子溴化氢得到单体.通过红外光谱(IR)、核磁共振(NMR)对单体及低聚物的结构进行了表征.凝胶渗透色谱(GPC)结果显示,聚合反应以甲苯作溶剂,75℃下效果最好,产率中等.这种共轭低聚物可以溶于四氢呋喃(THF)等极性溶剂,TGA结果表明低聚物热稳定性高.紫外可见吸收光谱(UV-Vis)显示,由于聚合后共轭主链大大增长,苯丙炔酸低聚物骨架上电子的跃迁使得低聚物的四氢呋喃溶液在波长高于310 nm光谱的区域中有吸收.荧光光谱(FS)显示,低聚物的四氢呋喃溶液在342 nm激发光下发蓝光,420 nm处有特征荧光发射峰. 相似文献
942.
943.
944.
945.
946.
Narrow linewidth continuous-wave Tm:YLF laser at room temperature with a Volume Bragg grating and double Fabry-Perot etalons
by using the end-pumping configuration was presented. The Tm:YLF laser operates at 1907.3 nm with FWHM of approximately 60
pm. We achieved the maximum output power of 1.92 W when the incident pump power of 13.9 W, corresponding to the optical-to-optical
conversion efficiency of 13.8% and slope efficiency of 16.4%. 相似文献
947.
Diode pumped operation of 1 mm Tm,Ho:YAP microchip laser 总被引:1,自引:0,他引:1
A single-longitudinal-mode (SLM) operation of a c-cut 1 mm Tm(5%), Ho(0.3%):YAP micro-chip laser pumped by a fiber-coupled
diode-laser was reported. Under cryogenic temperature, the output power of 216 mW was obtained under the incident power of
2230 mW, corresponding to the slope efficiency was 13.6%. As much as 133 mW output and slope efficiency of 4.9% was obtained
under the pump power of 3000 mW at 291 K. In addition, a maximum SLM output power of 30 mW at wavelength of 2130.56 nm is
demonstrated under 77 K. 相似文献
948.
We report an experimental demonstration of muliwavelength erbium-doped fiber laser with adjustable wavelength number based
on a power-symmetric nonlinear optical loop mirror (NOLM) in a linear cavity. The intensity-dependent loss (IDL) induced by
the NOLM is used to suppress the mode competition and realize the stable multiwavelength oscillation. The controlling of the
wavelength number is achieved by adjusting the strength of IDL, which is dependent on the pump power. As the pump power increases
from 40 to 408 mW, 1–7 lasing line(s) at fixed wavelength around 1601 nm are obtained. The output power stability is also
investigated. The most power fluctuation of single wavelength is less than 0.9 dB, when the wavelength number is increased
from 1–7. 相似文献
949.
In this paper, we report two crystals Tm:YLF laser pumped by a fiber coupled diode laser with total power of 180 W at 792
nm. When the incident power reached up to 117.0 and 37.3 W of the emission wave-length at 1.91 μm was achieved. Through linear
fit, the corresponding slope efficiency of 38.5%, optical-to-optical conversion efficiency of 31.9% and the beam quality factor
of M
2 ∼ 1.1 were obtained, indicating nearly diffraction limited beam propagation. To our best knowledge, this is the best beam
quality among the reported paper results under the similar experiments. 相似文献
950.
A diode end-pumped single-frequency Tm,Ho:YAP laser at room temperature was reported. We obtain a single frequency Tm,Ho:YAP
laser of up to 31 mW with Fabry-Perot etalons in the cavity at 2130.8 nm. The optical conversion efficiency is 1.0% and the
slope efficiency is 6.3%. The measured full width at half maximum (FWHM) is approximately 65 pm. The single-longitudinal-mode
(SLM) laser can be used as a seed laser for coherent wind measurements and differential absorption LIDAR systems. 相似文献