Metasurface integrated high energy efficient and high linearly polarized InGaN/GaN light emitting diode
Metasurface integrated high energy efficient and high linearly polarized InGaN/GaN light emitting diode
复制标题
超表面集成高能效高线偏振InGaN/GaN发光二极管
作者：
Wang Miao;Xu Fuyang;Lin Yu;Cao Bing;Chen Linghua;Wang Chinhua;Wang Jianfeng;Xu Ke
我们提出并展示了一种集成的高能效和高线性偏振的InGaN/GaN绿色LED，该LED生长在（0001）取向蓝宝石上，结合了超表面偏振转换器和偏振器系统。它与传统的等离子体金属光栅产生的偏振光发射不同，其中至少50%的高能量损失是由于电场的横向电（TE）分量的高反射而固有的。在LED的底部集成了一个具有半波片功能的二维椭圆金属圆柱阵列（EMCA）的反射超表面，使得LED的顶部发射表面上的介电/金属双层线栅（DMBiWG）偏振器丢失的背反射TE组件可以在从超表面反射后转换为所需的横向磁（TM）极化发射。这大大提高了偏振光发射效率。实验结果表明，在±60°广角范围内，与裸底相比，偏振发射的提取效率平均提高了40%，与反射Al膜相比，平均提高了20%。在±60°角度内，InGaN/GaN LED可同时获得平均20 dB的消光比（ER）。我们的研究结果表明，在集成器件级同时实现高偏振度和高偏振提取效率的可能性。这推动了GaN LED领域朝着节能、照明、显示、医学和光操纵等多功能应用的方向发展。
We proposed and demonstrated an integrated high energy efficient and high linearly polarized InGaN/GaN green LED grown on (0001) oriented sapphire with combined metasurface polarizing converter and polarizer system. It is different from those conventional polarized light emissions generated with plasmonic metallic grating in which at least 50% high energy loss occurs inherently due to high reflection of the transverse electric (TE) component of an electric field. A reflecting metasurface, with a two dimensional elliptic metal cylinder array (EMCA) that functions as a half-wave plate, was integrated at the bottom of a LED such that the back-reflected TE component, that is otherwise lost by a dielectric/metal bi-layered wire grids (DMBiWG) polarizer on the top emitting surface of the LED, can be converted to desired transverse magnetic (TM) polarized emission after reflecting from the metasurface. This significantly enhances the polarized light emission efficiency. Experimental results show that extraction efficiency of the polarized emission can be increased by 40% on average in a wide angle of ±60° compared to that with the naked bottom of sapphire substrate, or 20% compared to reflecting Al film on the bottom of a sapphire substrate. An extinction ratio (ER) of average value 20 dB within an angle of ±60° can be simultaneously obtained directly from an InGaN/GaN LED. Our results show the possibility of simultaneously achieving a high degree of polarization and high polarization extraction efficiency at the integrated device level. This advances the field of GaN LED toward energy efficiency, multi-functional applications in illumination, display, medicine, and light manipulation.