A chirped fiber grating with cladding made of uniaxial crystal material whose optical axis is parallel to the axis of grating, i.e., z-axis is proposed. Electro-optic effect and elasto-optic effect in this kind of fiber gratings are theoretically analyzed for the first time. The influences of the electric field and the strain applied to the fiber grating cladding along z-axis on Bragg wavelength kB and the reflectivity spectra of this kind of chirped grating are theoretically examined using coupled-mode theory and transfer matrix method. The curves of Bragg wavelength kB as a function of an external electric field or the strain are theoretically obtained respectively for three kinds of uniaxial crystal materials as the grating claddings. The calculated results indicate that when the axial electric field applied to the grating cladding varies from 1

建立了一光纤传感器系统，并对NO气体的特性进行了研究，得到了NO气体对光的吸收谱和光波长分别为350，400 及500nm 时，吸收特性随气体浓度变化特性。实验结果表明在一定条件下NO气体浓度与吸收百分比成线性关系。该系统的响应时间仅为5s，恢复时间在10s之内。

In this paper, the chromatic dispersion and chromatic dispersion slope of two kinds of triple-clad single-mode fibers with a depressed index inner cladding named WI-and WII-type were examined. A feasible approach to calculate chromatic dispersion and higher-order dispersion was established successfully, and the influences made by the optical parameters and geometric parameters on the chromatic dispersion coefficient and its slope were analyzed in detail. The calculated results show that the optical parameter R2; which symbolizes the third cladding effect, has a strong impact on the chromatic dispersion coefficient and the chromatic dispersion slope, and the degrees of such impact are closely related to the other parameters.

The chirped Gaussian pulse broadening induced by chromatic dispersion in two kinds of tripleclad single-mode fibers with a depressed index inner cladding was examined in this paper. In view of the impossibility to deduce the expression of chromatic dispersion directly due to the complexity of the characteristic equations, a feasible approach to calculate chromatic dispersion was established, and the influences made by the optical parameters and geometric parameters on the chromatic dispersion and chirped Gaussian pulse broadening were analyzed. The calculated results indicated that the optical parameter, that symbolizes the third clad effect, has a strong impact on chromatic dispersion and pulse broadening, and the degrees of such impact were closely related to the other parameters and operating wavelength. The evolvement processes of a traveling chirped Gaussian pulse in the kinds of triple-clad single-mode fibers with different parameters were also analyzed

研究了三包层WⅠ和WⅡ型单模光纤的波导色散特性。结果发现在相同条件下，三包层WⅠ和WⅡ型单模光纤零色散点的调节范围比传统的双包层W型单模光纤明显增大。详细分析了几何参量P、Q和光学参量R1、R2对单模传输时的波导色散特性和低次模截止频率的影响。所得的研究结果为获得更为理想的色散补偿、色散平坦光纤及设计新型无源光器件提供了重要的依据。计算波导色散的方法可推广到多包层光纤。