基于手性超表面的宽波段圆偏振光电探测器的仿真设计

Simulation Design of Wide Band Circularly Polarized Photodetector Based on Chiral Metasurface

针对用于检测圆偏振光的超紧凑光电探测器的工作波段大多分布在近红外及中红外且工作波段较窄的问题,设计了一种具有较宽工作带宽的圆偏振光集成光电探测器。该探测器由石墨烯与手性超表面集成,当不同圆偏振光作用在手性超表面上时,会产生不同程度的近场光学增强,利用手性超表面在较宽波段下的强偏振依赖性来增强探测器的偏振选择性。通过时域有限差分(FDTD)仿真及优化超表面结构,手性超表面在波长为577~797nm波段内的圆二色性≥0.18。设计的圆偏振光电探测器主要工作在可见光波段,工作带宽可以达到约220nm。该探测器的设计为单一片上偏振计检测更宽波段的圆偏振光提供了新的设想。

For the ultra-compact photodetectors used to detect circularly polarized light,the working band mostly distributes in near-infrared and mid-infrared bands and is relatively narrow.A circularly polarized light integrated photodetector with a wide operating bandwidth was proposed.The detector consists of graphene integrated with the chiral metasurface.When different circularly polarized lights act on the chiral metasurface,it can produce different degrees of near-field optical enhancement.The strong polarization dependence of the chiral metasurface in a wide band was used to enhance the polarization selectivity of the detector.Through finitedifferent time-domain(FDTD)simulation and optimization of the metasurface structure,the circular dichroism of the chiral metasurface is≥0.18 in the wavelength of 577-797 nm.The designed circularly polarized photodetector mainly works in the visible light band,and the working bandwidth can reach about 220 nm.The design of the detector can provide a new idea for detecting circularly polarized light in a wider band with a single on-chip polarimeter.