利用二维耦合波理论，研究了用短波长记录全息光栅而用通讯波段内的长波长读出时，用于90°结构垂直读出平板型的光折变局域体全息光栅的衍射性质．讨论了局域体全息光栅的几何尺寸对其衍射效率及光栅布喇格选择性的影响．结果表明，随着光栅的纵向和横向尺寸的增加，光栅的衍射效率也逐渐增加．当光栅的纵向和横向尺寸发生改变但光栅的总面积不变时，光栅衍射效率保持不变．此外，随着光栅尺寸的增加光栅的布喇格选择性越好．在利用短波长记录全息光栅而用长波长读出的光学器件设计过程中，为了获得最佳的衍射效率及其布喇格选择特性，应当根据要求合理地设计光栅的几何尺寸．

Using the two-dimensional coupled-wave theory,the diffraction properties of the 90-degree readout geometry of the finite size planar holographic grating which recorded by short-wavelength,but reconstructed by telecommunication long-wavelength were investigated. The effects of the grating geometrical size to the diffraction efficiency and to the Bragg selectivity of the grating were studied. It was shown that,as the horizontal direction and vertical direction sizes of the grating increase,the diffraction efficiency of holographic grating increased. When the horizontal and vertical direction sizes were changed while their products contain constant,the diffraction efficiency contain constant. The Bragg selectivity increased with the geometrical size of the grating increasing.