太赫兹波在亚波长随机金属Al颗粒中的相干传播

Coherent transmission of terahertz wave through randomly packed subwavelength-sized aluminium particles

本文报道亚波长特征尺寸的随机金属颗粒体系由于表面等离子体效应,在太赫兹(THz)电磁波段出现的异常透射现象.通过THz时域光谱实验测量,发现THz波的透射强度不仅随着金属颗粒体系的厚度减小,而且当颗粒体系的横向尺寸大于THz光斑时,透射强度会随着体系横向尺寸的增大而减小,并伴随着透射时间的延迟.同时发现,入射THz电磁场在导电粒子体系中激发的表面等离子波主要沿着体系的边界传播.

We experimentally discovered that the efficient coupling of surface plasmon wave to free-space radiation beyond the interaction zone via random metallic particles. In the experiments of terahertz wave transmission through an ensemble of randomly packed aluminium particles with sub-wavelength sizes,we observed a strong dependence of the transmission on the lateral boundary conditions. Our results showed that the processes of terahertz wave propagating in the disk-shaped samples and reemitting to the free space were resulted from surface modes excitation,which is critically affected by lateral sizes of the particle ensembles.