高频CO2激光脉冲写入的相移长周期光纤光栅

运用矩阵传输法，并结合长周期光纤光栅的模式耦合理论，阐述了相移长周期光纤光栅传输光谱的形成原理.利用高频CO2激光脉冲制作出相移长周期光纤光栅.该方法仅需用计算机绘制光栅结构图形，再由计算机依照此图形控制CO2激光器对普通光纤曝光，就可自动完成光纤光栅的制作.实际制造出一条相移长周期光纤光栅，在1520~1570 nm和1610~1670 nm波长范围内分别呈现出相移图样，相移波段的通带中心波长分别为1546 nm和1640 nm.对光栅进行温度测试，观测1610~1670 nm范围内相移光谱的变化，发现相移光栅的通带及阻带中心波长具有相同的温度变化系数，其数值为0.064 nm/℃，另外又测试了光栅的应变特性，灵敏度约为－0.51 nm/mε.因此在利用光栅温度特性或应变特性做传感的过程中，可以仅测试通带中心波长的变化，实现低成本多样化的测量手段.

Phase-shifted Long-period Fiber Grating Written by High-frequency CO2 Laser Pulses

The spectrum of phase-shifted long-period fiber grating is analyzed by the coupled-mode theory and transfer-matrix method. Then under the guidance of this analysis, it is for the first time that the phase-shifted long-period fiber grating is fabricated successfully by using high-frequency CO 2 laser pulses. During the process of fabrication, computer is used to draw the structural graph of the gratings and to control the power and time of laser pulses exposed on the optical fiber. In such a way, the gratings are made automatically. The grating made actually shows the phase-shifted spectrum during the scale of 1520～1570 nm and 1610～1670 nm. The temperature response of the latter is tested, and the result shows that the center wavelengths of the one pass band and the two loss bands have the same index: 0.064 nm/℃.What′s more, the strain response of the PSLPG is measured, and the result shows that the index is -0.51 nm/mε. So in the sensing field, it is viable to test the centre wavelength of the pass band to m