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用傅里叶衍射光学分析了准分子激光束发散度对于光纤光栅制备的影响 ,发现光束发散角使光纤光栅的布拉格波长发生改变 ,相位版后干涉场沿光纤轴向和径向不均匀 ,对制备 30dB高反射率光纤光栅造成困难。实验结果与理论分析基本一致 ,相对于理想平行光束情况 ,会聚光束使得光纤光栅布拉格波长出现在短波一边 ,发散光束使得光纤光栅布拉格波长出现在长波一边
The effect of excimer laser beam divergence on the fabrication of fiber gratings was analyzed by Fourier-diffraction optics. It was found that the beam divergence angle changed the Bragg wavelength of the fiber grating. The interference field of the phase plate was uneven along the axial and radial directions of the fiber. Difficulties arise in the preparation of 30 dB high-reflectivity fiber gratings. The experimental results are basically the same as the theoretical analysis. Compared with the ideal parallel beam, the convergent beam causes the Bragg wavelength of the FBG to appear on the short wavelength side. The divergent beam causes the Bragg wavelength of the FBG to appear on the long wavelength side