摘要：“戊戌变法与中国现代化道路”学术研讨会近在山东大学举行。来自中国社会科学院,中国艺术研究院,南京大学、中国人民大学、国家行政学院、武汉大学、首都师范大学、山东经济学院、山东社会科学院、山东大学和美国未来趋势国际集团等30多个单位的专家、学者就戊戌变法、中国现代化、知识分子的作用等问题进行了热烈而广泛的探讨。必须从思想文化史、历史学和政治学多个角度研究戊戌变法关于戊戌变法的起因和性质有的学者认为,戊戌变法是中国的知识分子和中国统治阶级中的开明分子。

摘要：分布反馈(DFB)激光器被广泛用于气体、水质的开放光程监测,其驱动的稳定性和波长扫描的精确性是影响监测系统性能的主要因素。为提高监测系统性能,通过分析分布反馈激光器的工作原理,研究高稳定驱动和高精度波长扫描方法,设计了驱动和波长扫描电路。以5 Hz的锯齿波作为扫描信号,以5 kHz的正弦波作为调制信号,用叠加的信号作为驱动芯片MAX3669的输入信号,获得了良好的实验效果。实验的成功,为提高整个开放光程气体监测系统的精度奠定了基础。

摘要：结合改进的化学汽相沉积(MCVD)法的特点,设计纯硅芯石英光纤最佳折射率剖面结构,并对采用改进的石墨炉加热的MCVD法制备纯硅芯石英光纤预制棒和拉丝工艺进行讨论.分析了制作工艺中内包层掺氟量的提高、内包层厚度增加和纤芯折射率保持等难点的原理,并给出了解决方案.同时给出了制备的纯硅芯石英光纤预制棒的折射率剖面图和拉制成型的纯石英光纤折射率剖面图.

摘要：To improve the performance of double clad high power fibre lasers, inner cladding design plays a significant role. A triangular inner cladding and silica structure second cladding with large air holes go acquire high inner cladding numerical aperture are designed. Single mode and high power output of the fibre lasers need the double clad Yb doped fibre with large core. A fibre with annular refractive index distribution core and low numerical aperture to acquire a large mode area fibre core is designed and fabricated. Furthermore co-doping with aluminium （A1） has been used to improve the solubility of ytterbium （Yb） into silicate network, and the core absorption coefficients of two Yb doped fibres are compared with different A1 concentration experimentally.

摘要：To obtain the stable operation of erbium-doped fibre laser, the simple and ideal technology is adopted by use of the erbium doped polarization maintaining fibre （EDPMF）. The design criteria of the Panda-type EDPMF are presented, which take into account the cutoff wavelength, mode field diameter, modal birefringence and background loss. Four groups of optimum structural paramcter combinations are determined in terms of the design criteria. Two kinds of the Panda-type EDPMFs are selected to be fabricated. The fabrication process and the parameter control of the Panda-type EDPMFs are presented in detail. Their refractive index profiles, birefringence and absorption spectra are experimentally investigated. The absorption coefficient of the EDPMF, whose core is co-doped with Bi, Ga, A1 and Ge, is about 57.9dB/m at 1.53μm. Co-doping Bi, Ga and A1 can greatly increase the erbium concentration in the silica-based fibre. The high birefringence is obtained for the Panda-type EDPMF. The group birefringence of the EDPMF, whose outer cladding diameter is 125 μm, is about 4.8 × 10%^-4.