光束发散度对紫外写入光纤光栅的影响

Influence Effect of Beam Divergence on Fiber Bragg Grating Fabricated by UV Imprinting

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 。

The effects of divergency of excimer beam on the fabrication of fiber Bragg grating using phase-mask has been theoretically analyzed according to Fourier Optics. It is found that the divergency of incident beam leads to the changes of resonant Bragg wavelength and the axial and radial non-uniform in the visibility of interference field just behind the phase-mask and makes the fabrication of 30 dB fiber Bragg grating more difficult. The experimental results basically agree with the deduced conclusion. Compared to the parallel incident light, Bragg wavelength will be shorter in the convergent incident light, while longer in the divergent incident light.