可片上集成的突破衍射极限光场的产生与传输

The generation and transmission of the field of light beyond the diffraction limit is the cornerstone for light manipulation at the nanometer scale. It will make great contribution to the miniaturization and integration of photoelectric devices. Surface plasmons (SPs), capable of light concentration and propagation in subwavelength region, represent one of the main route for breaking through the diffraction limit. Unfortunately, the coupling efficiency of SPs by light in free space is low because of the momentum mismatch between the SPs and the light. Such low excitation efficiency and the high propagation loss associated with SPs, greatly limit the development of plasmonic devices. In this project, we will address the high excitation efficiency and high performance remote propagation of the localized light field beyond the diffraction limit, on four aspects in the following. (i) Ultrafast electric generation of SPs and their integration with subwavelength waveguides; (ii) The generation and propagation of highly localized electromagnetic field and its interaction with phonons or excitons; (iii) Entangled photon pairs generation based on SPs; and (iv) The use of SP focusing on metallic nanowire for scanning probe and its application in the interaction of SPs with phonons and excitons. We are aiming to the high quantum yield generation of deep subwavelength SPs, and high performance transmission, integration and its application in high signal-to-noise ratio spectroscopy. These would serve as important reference for light manipulation at the nanometer scale and the miniaturization and integration of photoelectric devices.

突破衍射极限光场的产生和传输是实现纳米尺度光操控的基本前提，对片上集成光电器件的发展有极大的推动作用。表面等离激元由于具有高空间局域、亚波长传输等特性，是实现突破衍射极限光场的主要手段。而由于表面等离激元与自由光场动量不匹配导致其激发效率低，加上其自身传输损耗较大，极大地限制了表面等离激元纳米光子器件的发展。在本项目中我们将从四个方面开展可片上集成的突破衍射极限光场的高效产生与远程传输的研究，包括：超快电激发表面等离激元光源及与波导的集成、高局域表面等离激元光场的产生与传输及其与声子/激子的相互作用、基于表面等离激元共振的纠缠光子对的产生与传输、表面等离激元在金属针尖的聚焦效应及其与声子/激子的相互作用。本项目旨在研究深亚波长尺度表面等离激元的高量子效率激发，进而实现高效率传输、可集成性以及在高信噪比光谱学中的应用，期望为纳米尺度光操控、光电器件的小型化与集成化提供重要参考。

纳米光子学以纳米尺度光与物质相互作用为核心，是半导体激光器、LED、电光调制器与传感器等光电器件的基础，对发展大规模集成光电芯片、服务未来信息技术、智能社会有重要作用。突破衍射极限光场的产生和传输是纳米光子学核心研究课题，是设计纳米光源、实现光芯片集成的必要环节之一。表面等离激元具有高空间局域、亚波长传输等特性，是实现突破衍射极限光场的主要手段之一。但由于表面等离激元与自由光场动量不匹配导致其激发效率低、电激发产生等离激元技术难度高，加上金属内部耗散较大，极大地限制了表面等离激元光子器件的发展。本项目针对突破衍射极限光场的产生与传输的难题，主要开展四个方面的研究内容，包括：电激发表面等离激元及其与波导的集成、光激发产生高局域表面等离激元光场及其在传感检测方面的应用，衍射极限下二阶非线性光学（倍频、和频、下转换）、高局域表面等离激元与声子/激子的相互作用。项目提升了基于电子非弹性隧穿激发的纳腔等离激元发光的稳定性，实现了忆阻纳米发光天线，为超快速率光源的设计提供重要参考；利用阻抗匹配的“纳米天线对”实现光激发高局域光场的传输；实现任意方向的合并连续谱束缚态，大幅提升光场的束缚特性，可用于光束控制以及定向激光器的设计；实现了高局域光场与半导体激子/声子的相互作用，利用光子自旋-轨道耦合效应实现声子散射信号的定向发射；观测到巨大光热电效应以及完成对二维异质结中层间激子的辨认。项目的实施为认识亚波长尺度光与物质相互作用规律，纳米尺度光操控、光电器件的小型化与集成化提供重要参考。