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讨论了在光折变LiNbO3晶体中建立电场控制的 2× 2直通交换开关的原理设计方案。通过控制读出光栅时外加电场的大小使读出光满足或偏离布拉格条件 ,从而控制衍射效率为 1或 0 ,实现开关的交换和直通操作。全面考虑了电场作用下晶体的压电和电光效应 ,基于衍射效率公式和光栅的布拉格条件 ,给出了为获得最佳衍射效率比时外加电场及写入光束比与记录角度间的关系曲线
The principle design of 2 × 2 direct-current switch for establishing electric field control in photorefractive LiNbO3 crystal is discussed. By controlling the size of the applied electric field when the readout grating is applied, the readout light meets or deviates from the Bragg condition, thereby controlling the diffraction efficiency to be 1 or 0, so as to realize the exchange and the through operation of the switch. The piezoelectric and electro-optic effects of the crystal under the electric field are fully considered. Based on the diffraction efficiency formula and the Bragg condition of the grating, the curves of applied electric field, written beam ratio and recording angle for the best diffraction efficiency ratio are given