Electrical-gain-assisted circularly polarized photodetection based on chiral plasmonic metamaterials
Chenghao Chen, Zhenhai Yang, Tianyi Hang, Yining Hao, Yijing Chen, Chengzhuang Zhang, Jiong Yang, Xiaoyi Liu, Xiaofeng Li, Guoyang Cao
Abstract
Abstract Circularly polarized light (CPL) detectors based on chiral organic materials or inorganic structures hold great potential for highly integrated on-chip applications; however, these devices usually have to seek an optimal balance among the asymmetry factor ( g ), responsivity ( R ), and stability. Here, we aim to break such a limitation by combining chiral inorganic plasmonic metamaterials with electrical gain, by which one can enhance both g and R while simultaneously securing the stability. We demonstrate a CPL detector based on “S”-shaped chiral Ag nanowires/InAs/Si heterostructures, where the meticulous construction of the “S”-shaped chiral Ag nanowires with the overlaying InAs channel enables a substantial absorption asymmetry in InAs due to differentiated localized surface plasmon resonances excited by left- and right-circularly polarized (LCP and RCP) light. The InAs serves as a conductive channel, achieving significant electrical gain through photoconductive effects assisted by photogating, gate modulation, and trap effects. The proposed inorganic stable device exhibits a high electrical g of ~1.56, an ultra-high R of ~33,900 A W −1 , a large specific detectivity of ~1.8 × 10 11 Jones, and an ultra-short response time of ~23 ns, with the high performance achieved in a broad spectral range from 2 μm to 2.8 μm. Ultimately, by encoding ASCII code 1 and 0 onto LCP and RCP light, respectively, and leveraging the device’s heightened discrimination and response performance to these polarizations, we demonstrate a simple yet key-free optical encryption communication scheme at the device level, highlighting its extensive potential for system-level applications.