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将光纤光栅的傅里叶模式耦合理论应用于光纤布拉格光栅型全光纤声光调制器的理论分析中.与现有的分析方法相比,该模型算法简单、求解容易,能够快速有效地获得调制器的传输特性.基于该模型,理论分析了超声波频率及声致应变幅度对调制器特性的影响.仿真结果表明,该调制器反射谱的主反射峰与次反射峰的波长间隔与超声波频率成正比,反射峰的反射率随着声致应变幅度的改变而发生周期性的变化.另外,在同一声致应变幅度下,低频超声波调制的光栅反射中存在更多的次反射,光栅反射能量的周期性变化更加明显.实验中,使用频率为885.5kHz的超声波对光纤布拉格光栅进行调制.实验结果与仿真结果相一致.
The Fourier-mode coupling theory of fiber grating is applied to the theoretical analysis of fiber Bragg grating all-fiber acousto-optic modulator.Compared with the existing analysis methods, the model algorithm is simple and easy to be solved, and the modulation can be obtained quickly and effectively Based on the model, the influence of ultrasonic frequency and acoustic strain amplitude on the modulator’s characteristics is analyzed theoretically.The simulation results show that the wavelength interval between the primary reflection peak and the secondary reflection peak of the modulator’s reflection spectrum is proportional to the ultrasonic frequency The reflectance of the reflection peak changes periodically with the amplitude of the acoustically induced strain.Furthermore, there are more sub-reflections in the grating reflections modulated by the low frequency ultrasonic at the same acoustical strain amplitude, The periodic change is more obvious.In the experiment, the fiber Bragg grating is modulated by the ultrasonic wave with the frequency of 885.5kHz.The experimental results are consistent with the simulation results.