采用平面波展开的散射矩阵方法研究n型甚长波量子阱红外探测器的二维衍射光栅,并同时从实验方面研究了其红外透射光谱.研究表明,n型量子阱器件的光栅耦合是传输场和倏逝场共同作用的结果.对于n型量子阱红外探测器的光栅耦合,光栅周期、光栅深度和占空比三者之间相互影响;要达到好的光学耦合效果,需要根据量子阱器件的峰值探测波长选择合适的光栅参数.
Because of the isotropic energy band structure of the Г electrons in the GaAs/AlGaAs quantum well infrared photodetector ( QWIP), normal incident radiation absorption is forbidden, so that the optimization of optical grating becomes a key technology. In this work we present a scattering-matrix method based on plane-wave expansion for the two-dimensional QWIP grating. The transmission spectrum of the QWIP grating has been studied theoretically and experimentally. It has been shown that in general, both the propagating wave and the evanescent wave contribute to the optical coupling in n-type QWIP. The grating parameters, like period, depth and filling factor, will strongly affect the optical coupling.