基于弯曲压杆的光纤光栅可调谐线性啁啾化

摘要

A tunable linear chirp method without central wavelength shift was achieved theoretically by introducing nitinol alloys lever bending strain into fiber Bragg grating(FBG),and it was verified through the experiments.Nitinol alloys lever structure was designed,and its strain distribution was calculated and analyzed by finite element software. FBG was pasted on the nitinol alloy lever,thus bending lever introduced linear stretch and compressing strain into the grating,and reflective spectrum of fiber grating was recorded by spectrograph.Experiment results show that reflective spectrum bandwidth increases up to 1.57nm and central wavelength shift is 0.11nm when lever bending displacement is 12.5mm.According to FBG chirp theory,the chirped FBG spectrum is reconstructed based on transmission matrix method and Runge-Kutta method.Experiment results agree with simulation results.The chirped FBG with this meth-od can realize tunable bandwidth and have no central wavelength shift,and this method has a great application pros-pect in fiber optic transmission and sensor field.%提出利用镍钛合金压杆弯曲应变引入到光纤布拉格光栅(fiber Bragg grating,FBG)实现无中心波长漂移可调谐线性啁啾化方法并进行了实验验证.设计一种镍钛合金压杆结构,理论计算并有限元分析验证了应变分布情况.将光纤光栅粘贴在镍钛合金压杆上,弯曲压杆将线性拉伸与压缩应变引入到栅区,利用光谱仪记录反射谱.实验结果表明,当压杆移动距离达到12.5 mm时,反射谱带宽增大到1.57 nm,中心波长漂移量仅为0.11 nm.利用光纤光栅啁啾化理论,结合传输矩阵法和龙格库塔法实现啁啾光纤光栅光谱重构.实验结果与仿真结果吻合.该方法制作的啁啾光栅可以实现带宽可调谐且基本无中心波长漂移,在光纤传输和传感领域均具有一定的应用前景.