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理论和实验上研究了利用飞秒激光微纳加工技术制备的广义高斯切趾光纤布拉格光栅(FBG)的带宽特性。模拟结果表明,FBG带宽随着折射率调制度的增大而增大,随着光栅长度的增大先减小后趋于饱和。利用飞秒激光相位掩模法制备FBG的实验结果表明,当飞秒激光功率较小时,随着激光功率的增加,FBG带宽基本不变;激光功率超过一定阈值,FBG带宽随着激光功率的增大而逐渐增大。曝光时间较短时,FBG带宽随曝光时间的增加而急剧增大;随着曝光时间的继续增加,FBG带宽逐渐趋近于饱和。FBG带宽随着飞秒激光功率和曝光时间的变化可以归因于飞秒激光诱导FBG折射率调制度和光栅长度的变化。这些规律为调控利用飞秒激光微纳加工技术制备FBG带宽提供了参考。
The bandwidth characteristics of a generalized Gaussian apodized fiber Bragg grating (FBG) fabricated by the femtosecond laser micro-nano processing technology are theoretically and experimentally studied. The simulation results show that the bandwidth of FBG increases with the increase of the refractive index modulation, decreases first and then becomes saturated with the increase of the grating length. The experimental results of FBG fabrication using femtosecond laser phase mask show that the FBG bandwidth is basically unchanged with the increase of laser power when the power of femtosecond laser is small. When the laser power exceeds a certain threshold, the bandwidth of FBG increases with the increase of laser power Large and gradually increase. When the exposure time is short, the bandwidth of FBG increases sharply with the increase of exposure time. As the exposure time continues to increase, the FBG bandwidth gradually approaches saturation. The variation of FBG bandwidth with femtosecond laser power and exposure time can be attributed to the femtosecond laser-induced changes in FBG index modulation and grating length. These rules provide a reference for controlling the preparation of FBG bandwidth by using femtosecond laser micro-nano processing technology.