石墨烯（甚）长波红外探测器应用与性能增强技术

To figure out key issues including the diffraction limit and low responsibility for graphene (extra) long-wave infrared detector, we propose a utilization of enhanced absorption structure based on the metal surface plasmons (SP) technology to realize graphene photodetector with the performances improved significantly. The investigation mainly includes: i) Resonance structure of polarization-transformed metamaterial and near-field enhancement based on localized SP (LSP); ii) Metal F-P micro resonator structure and characteristic of grating-coupling metamaterial based on LSP & surface-plasmonic polaritons (SPP); and iii) their applications for polarization-sensitive or insensitive graphene photodetector, device physics, and performance and its controlling. This arrangement has merits of: a) as the incident irradiation is highly concentrated within the metal gap of metamaterial by LSP or SPP technology, the photo-sensitive pixel can be designed in a smaller size beyond the diffraction limited, and shorter space from two electrodes will lead to an increased photo-electron gain; b) polarization-insensitive photodetector can be realized by transformation between TE and TM polarizations; c) as transmitting photo-energy of TM-polarized radiation flow in longitudinal direction is turned to that of LSP & SPP in transverse direction and along the graphene surface, an introduced confinement to the optical field and standing-wave effect in the micro resonator increases the infrared absorption (~50%); d) the metamaterial also worked as the electrodes. This arrangement is easy for electrical signal readout, and increases integration and reliability for the devices.

为解决石墨烯（甚）长波红外探测器应用中衍射受限、低光谱响应率等关键问题，项目提出利用超材料金属表面等离子体（SP）共振局域场的增强收集能力实现性能增强的（甚）长波红外探测。主要研究内容：i）偏振转换局域SP（LSP）谐振结构、近场增强特性；ii）光栅耦合LSP、SP波（SPP）微F-P腔结构与性能；iii）SP增强吸收结构应用于石墨烯（甚）长波红外探测器、器件物理、性能及调控。其意义：a）LSP、SPP技术把红外辐射汇聚到电极间距远小于辐射波长的探测器光敏元上，突破了衍射极限、提高了器件的光电增益；b）TE与TM间的偏振转换可以实现偏振无关探测；c）光栅衍射或谐振耦合把沿纵向传输的TM辐射转换为沿石墨烯表面的LSP、SPP，产生的光场限制效应、微F-P腔中驻波效应增大了石墨烯的红外吸收率（~50%）；d）超材料结构同时作为器件的电极，易于光电信号采集、更提高了器件的集成度和可靠性。

为解决石墨烯（甚）长波红外探测应用中衍射受限、低光谱响应率等关键问题，项目提出利用超材料（或超表面）金属表面等离子体激元（SP）或双曲半导体材料的表面声子激元（SPh）共振局域场的增强收集能力实现性能增强的（甚）长波红外探测器。主要研究内容：i）偏振转换局域SP、SPh超表面结构、近场增强特性；ii）光栅耦合SP、SPh波与微F-P腔结构与性能；iii）石墨烯长波红外探测器制备、器件性能及调控；iv）石墨烯集成长波红外吸收器结构及频率调控；v）红外传感应用的集成光子器件。意义：a）借助于SP、SPh技术把红外辐射汇聚到电极间距远小于红外辐射波长的探测器光敏元上，突破了衍射极限、提高了器件的光电增益；b）TE与TM间的偏振转换可以实现偏振无关探测；c）光栅衍射或谐振耦合把沿纵向传输的TM辐射转换为沿石墨烯表面的SP、SPh，产生的光场限制效应、微F-P腔中的驻波效应把石墨烯的红外吸收率分别提高到~67%和32%；d）超材料结构同时作为器件的电极，易于光电信号采集、更提高了器件的集成度和可靠性；e）不同的吸收器结构分别可实现宽带或双带可调谐长波红外完美吸收；f）高Q值环形微腔与超表面吸收器单片集成的光子集成器件，实现了亚微妙响应时间以及响应率~341pm/mW的热光红外传感。