利用对入射光源偏振性不敏感的二维金光栅结构来增强AlGaN/GaN量子阱中红外光电 探测器的垂直光耦合。采用有限元法(FEM)计算了探测器结构中的电场分布和能量流 动,发现采用二维金光栅时量子阱区有效电场强度比采用Si3N4光栅时高出2个数 量级,这主要源于金光栅与AlGaN界面处激发形成的表面等离激元(SPP),对光能流动 方向、光场振动方向产生了强烈的改变。无论光源的偏振性如何,当垂直入射电磁波波 长为4.7 μm,电场强度E为1 V/m时,量子阱区的有效|Ez|2达到了0.7 (V/m)2, 为实现AlGaN/GaN量子阱中红外光电探测器焦平面阵列提出了一种解决方案。

The vertical optical coupling of AlGaN/GaN quantum well mid-infrared photodetector is enhanced by using two-dimensional gold grating structure, which is not sensitive to the polarization of incident light source. The electric field distribution and energy flow in the detector structure are calculated by the finite element method (FEM). It is found that the effective electric field intensity of quantum well with two-dimensional gold grating is two orders of magnitude higher than that of Si3N4 grating. It is mainly due to the surface plasmon polariton (SPP) excited at the interface of gold grating and AlGaN, which strongly changes the direction of light energy flow and electric field vibration. No matter how the light source polarization is, when the vertical incident electromagnetic wavelength is 4.7 μm, electric field intensity E is 1 V/m, the effective |Ez|2 in quantum well region reaches 0.7 (V/m)2, which provides a solution to realize the focal plane array of AlGaN/GaN quantum well mid-infrared photodetector.