顺电相KTN晶体中相位栅的衍射效率分析

为了在应用中提高读出光的衍射效率,必须合理选择参量。采用将KOGELNIK的耦合波理论与Kukhtarev方程相结合,可以得出顺电相KTN晶体中透射型相位栅衍射效率的解析式。对影响光栅衍射效率的各因素进行计算分析,发现衍射效率对入射角、晶体厚度以及外加电场的变化敏感,而45°入射角附近出现较宽的高衍射区。另外,晶体的吸收对衍射效率的影响可以忽略。结果表明,该计算分析有助于在实践中调整参量以获得较高的读出光衍射效率。

Diffraction efficiency analysis of the phase grating in paraelectric KTN crystal

In order to improve the diffraction efficiency of read out light,reasonable parameters must be selected.Combining Kogelnik coupling wave theory with the Kukhtarev equations,the expression of the diffraction efficiency of the transmission grating in paraelectric KTN crystal was obtained.After analyzing the factors affecting the diffraction efficiency of a grating,it was found that the reading diffraction efficiency was sensitive to incident angle,crystal thickness and applied field.A high diffraction efficiency district existed in close vicinity of 45°incident angle.The influence of absorption of crystal on reading diffraction efficiency was negligible.The results provide useful guides to choose the optimal parameters for high reading diffraction efficiency in application.