集成微纳光学结构的非制冷中远红外石墨烯探测器研究

With the development of space science and technology, uncooled infrared detectors with high responsivity and high speed are demanded. Uncooled high-speed mid-far-IR detection is facilitated by graphene due to its ultrafast photothermoelectric response. However, the atomic layer structure of graphene leads to low responsivity. In order to enhance photothermoelectric response, not only the light absorption needs to be increased, but also a proper control of the temperature field is required. In this project, we propose to integrate micro- and nano-photonic structures with graphene based mid-far-IR detectors to improve photothermoelectric response. By using electromagnetic simulation, physical modeling, light-thermal coupled field simulation, micro and nano fabrication techniques, optical spectrum and opto-electronic characterization, we are going to investigate three scientific problems: 1) the mechanism of enhancing and tuning the coupling between graphene and mid-far-IR radiation by micro- and nano-photonic structures, 2) the thermal behavior of graphene under mid-far-IR radiation for photothermalelectric response, 3) micro- and nano-photonic structure based tuning of graphene light absorption and temperature distribution as two coupled fields. Base on the study, we propose to clarify the physics of tuning the local field and graphene-light coupling by micro- and nano-photonic structures, build up a model of the thermal behavior of graphene under mid-far-IR radiation, reveal the mechanism of micro- and nano-photonic structure based tuning of coupled light and thermal field in graphene, achieve the prototype devices and realize over one order of enhancement in photo response due to the micro- and nano-photonic structure. This project will facilitate the development of graphene based uncooled high-response mid-far-IR detectors.

航天科技的发展给未来航天红外探测器提出了非制冷、高灵敏、快响应的要求。石墨烯凭借超快的光热电响应使非制冷高速中远红外探测成为可能，但其单原子层结构导致了低响应。提高光热电响应不仅需要增强光吸收，还需合理调控热场。为此，本项目提出集成微纳光学结构的非制冷中远红外石墨烯探测器研究，利用电磁仿真、物理建模、光-热双物理场耦合仿真、微纳加工、光谱和光电测量等手段研究1）微纳光学结构增强并调控石墨烯与中远红外光耦合的物理机制、2）中远红外光激发下石墨烯的热学行为以及形成光热电响应的原理、3）微纳光学结构对于石墨烯光吸收以及热分布的耦合调控机理等三个科学问题，阐明中远红外波段微纳光学结构对于局域光场和石墨烯光耦合的调控机制，建立中远红外光激发下石墨烯热学行为的物理模型，揭示微纳光学结构对于石墨烯的光-热耦合调控机理，实现原型器件以及光响应一个量级以上的提高，推动高响应非制冷中远红外石墨烯探测器的发展。

非制冷、高灵敏、快响应是红外探测航天应用的发展方向，目前的红外探测器很难同时满足这三项要求。石墨烯凭借超快的光热电响应成为极具潜力的非制冷高速红外探测器的候选材料，但响应率低是其发展瓶颈，而其中蕴含的如何通过调控石墨烯的光耦合和热分布显著提升其光热电响应是需要解决的科学难题。本项目提出集成微纳光学结构调控石墨烯光热电响应的研究。构建了石墨烯复数表面电导率的物理模型，实现了等离激元谐振腔-石墨烯复合结构的电磁仿真。揭示了通过共振耦合把入射光转化为能够与石墨烯充分相互作用的局域光子模式，从而提高石墨烯光吸收和光响应的物理原理。建立了光-热双物理场耦合模型与仿真方法，获得了复合结构中石墨烯电子温度场的分布。发展了器件制备工艺，成功实现了原型器件。通过等离激元谐振腔的非对称集成，获得了泛光照射下显著的净的自驱动光响应，且比普通耦合光栅非对称集成的情况高出1个量级以上，响应时间小于几个微秒。利用各向异性的等离激元谐振腔，使石墨烯红外光响应的偏振消光比达到30:1，高出所有报道的单种二维材料（包括微纳结构集成的二维材料）偏振探测消光比3-10倍。进而把光耦合调控原理推广到其它器件。利用磁共振模式显著增强了低折射率纳米颗粒的共振散射，实现了基于光学方法的8纳米精细尺寸分辨。利用bowtie天线增强了远红外光在单壁碳纳米管薄膜结区的深亚波长超聚焦和偏振选择，实现了响应率1-2个量级的提升以及偏振消光比320倍的提升。基于光吸收竞争调控与临界耦合调控相结合的方法，提高等离激元谐振腔集成的量子阱长波红外吸收至82%，抑制金属吸收损耗至18%；提出了圆偏振消光比达到14的手性超材料集成的量子阱红外圆偏振探测新器件。本项目厘清了集成微纳结构调控石墨烯光-热耦合特性的机理，并发展了有效的调控方法。发表SCI论文10篇，包括1篇Phys. Rev. Lett.、1篇Carbon、2篇Adv. Opt. Mater.、1篇Nanoscale（内封底）；申请发明专利4项。相关成果获美国科学院院士等专家的肯定，获国际和国内科技媒体的报道。