超小片上激光的设计与操控

The on-chip lasers with miniaturization, multi-functionalization, and controllability are of importance for the low-consumption and high-density photonics integrated circuits. The gain materials and cavity structures in most on-chip lasers were chemically synthesized or physically grown. Based on these method, the shapes and sizes of the gain materials were uncontrollable. This uncontrollability makes the on-chip lasers exhibiting the simple functionality and uncontrollable lasing emission. To address these problems, the ultra-small, multifunctional, and controllable on-chip lasers together with the deep-subwavelength coherent output sources are proposed by designing cavity structures and using positioning technology based on the previous works of the applicant. The content of the project includes four parts. The first one is the design of the cavity and coupled-cavity system as well as nano-structures. By this way, the modes, wavelengths, directions, and polarizations of the lasing emission are manipulated. The second one is the development of the micro-nano fabrication methods, and the cavities and nano-structures are controllably fabricated in the experiment. Moreover, the damage to the gain materials in the micro-nano fabrication processes are reduced. The third one is the realization of the ultra-small (~μm3), multifunctional, and controllable on-chip lasers by further optimizing the micro-fluorescence microscopy system. The linewidth of the single-mode lasing is about 0.1 nm, and the side-mode suppression ratio of the single-mode lasing is greater than 20 dB. The last one is the integration of the ultra-small, multifunctional, and controllable on-chip lasers with the plasmonic waveguide based on the dark-field optical image positioning technique, and thus the deep-subwavelength coherent output sources are achieved in the experiment.

片上激光器的微型化、功能化和可控性对于实现低能耗、高集成度光子回路具有重要意义。目前大部分片上激光器采用的增益材料和腔结构是通过化学合成和物理生长得到的。这些增益材料的形状和尺寸很难控制，导致片上激光器光场难以操控、功能简单。本项目拟针对上述难题，基于前期研究基础，提出通过设计激光腔结构并发展微纳加工和定位技术，在实验上实现超小、功能化、可控的片上激光器，经表面等离激元波导精确耦合输出，获得深亚波长相干光源。主要研究内容包括：设计谐振腔和耦合腔及纳米结构，用来操控激光的模式、波长、方向、偏振等；发展微纳加工工艺，在实验上可控制备微纳腔结构并减少对增益材料的损伤；优化微区荧光显微系统，实验上获得超小(~μm3)、功能化的可控片上激光器，线宽~0.1 nm，边模抑制比>20 dB；利用暗场光学显微成像等定位技术，把片上激光精确耦合到表面等离激元波导上，获得深亚波长(<λ2/200)相干光源。

片上激光器的微型化、功能化和可控性对于实现低能耗、高集成度光子回路具有重要意义。目前大部分片上激光器采用的增益材料和腔结构是通过化学合成和物理生长得到的。这些增益材料的形状和尺寸很难控制，导致片上激光器光场难以操控、功能简单。本项目针对上述难题，基于前期研究基础，提出通过设计激光腔结构并发展微纳加工和定位技术，在实验上实现超小、功能化、可控的片上激光器，经波导精确耦合输出，获得深亚波长相干光源。项目按计划进行，完成了预期目标，共发表论文15篇（通讯作者），其中Physical Review Letters一篇、Advanced Functional Materials一篇、Laser & Photonics Reviews一篇、Nanophotonics两篇。综述文章三篇（Materials Chemistry Frontiers，Journal of Semiconductors，中国激光），国内期刊三篇（Chinese Phys B，Journal of Semiconductors，中国激光）。申请专利3项，培养博士生5名，项目负责人陈建军教授2019年获得国家自然科学基金优秀青年科学基金项目。取得的主要成果有：1.通过在非对称微腔内引入特定的局域结构，从理论和实验上实现了对相空间中动力学轨道的精确“裁剪”，从而为操纵光子输运提供了新的可能。2.采用转移打印方法，用片上局域的波导模式代替自由空间光泵浦微纳激光器，泵浦功率阈值降低一个量级，同时激光线宽变窄30%。这种片上波导泵浦的方式在低能耗和高集集成密度的微纳激光器以及集成光子回路中具有重要的应用。本项目挖掘的新原理（如相位剪裁）在超小片上激光器中实现了对光场的有效操控，对于理解光与物质相互作用具有重要的理论指导意义。片上激光器的微型化、功能化以及深亚波长相干光源的实现对于实现低能耗、高速、高集成度光子回路具有重要意义。另外，本项目发展的无损微纳加工工艺和精确集成技术对未来微纳制备技术和纳光电子学及集成的发展具有重要意义。