在量子阱红外探测器(QWIP)上制备光栅的目的是对垂直入射的红外辐射进行有效的耦合。为了研究光栅的光耦合性能，基于模式扩展理论，详细计算长波(14．7 μm)QWIP二维周期矩形光栅的耦合效率。计算结果表明，光栅周期D=4．7μm，栅孔深度h=1．45 μm，d(栅孔)／D=0．707时，光栅的耦合效率达到最大。并且从几何光学的考虑出发，对计算结果进行了验证和分析。还讨论了二维周期光栅衍射光场的分布情况。

Based on the conventional MEM theory,it has been exactly calculated that coupling efficiency of the 2-d grating for long-wavelength(14.7μtm)QWIPs. The result shows that the coupling efficiency is highest when grating period D=4.7μm,grating depth h=1.45μm and d/D=0.707,and it also has been proved by geometrical optical method. Moreover,the distribution of optical field has been calculated in the diffractive grating.