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随着光信息技术的发展,长周期光纤光栅(LPFG)凭借其插入损耗小、传感灵敏度高,体积小等优点,广泛应用于光纤传感和光纤通信等领域,成为最具有发展前途的光子无源器件。作为加工光纤传感器等重要功能器件的飞秒激光,其在透明介质内部的三维结构加工上具有高峰值功率、热效应小等得天独厚的优势。介绍了采用飞秒激光刻写不同扭转周数的扭转型长周期光纤光栅,并分析了其扭转特性。通过对比扭转2、4、6和8周的长周期光纤光栅的扭转调控实验结果,发现8周的扭转型长周期光纤光栅在单方向上主谐振峰波长对扭转率的响应灵敏度达到了117.4pm/(rad/m),线性度达到了0.999 5,波长调控范围约12.33nm,非常适合波长和带宽调控。实验研究了8周扭转型长周期光纤光栅的曲率特性,发现这种方式下刻写的扭转型LPFG在大曲率(13)各个方向下,光谱0°和180°相似,90°和270°相似,但是这两对光谱差异很大,即该光栅依然有各向异性。
With the development of optical information technology, long-period fiber grating (LPFG) has become the most promising photon due to its advantages of small insertion loss, high sensing sensitivity and small volume, which are widely used in optical fiber sensing and optical fiber communication Passive components. As an important functional device for processing optical fiber sensors and other femtosecond laser, the three-dimensional structure of the transparent medium inside the processing of high peak power, small thermal effects, and so unique. The torsional long - period fiber grating with different number of twists is introduced by using femtosecond laser and its torsional characteristics are analyzed. By comparing the results of torsion control of long period fiber gratings with 2, 4, 6 and 8 weeks of torsion, we found that the sensitivity of torsion type long period fiber gratings to twist rate of 117.4pm / (rad / m) with a linearity of 0.999 5 and a wavelength control range of about 12.33 nm, making it ideal for wavelength and bandwidth control. The experimental results show that the twisted LPFG written in this way is similar to 0 ° and 180 ° in all directions with large curvature (13), similar to 90 ° and 270 °. However, the two pairs of spectra vary greatly, that is, the grating is still anisotropic.