Nanophotonic optical link

实现高能效的光纤链路将对降低数据中心的能源消耗产生明显影响，数据中心已被公认为全球能源增长最快的消费者。解决这一问题的一种有希望的方法是利用光信号而不是电信号来发送和接收数据，这在理论上可以导致更高的速度和更低的功耗。然而，将高性能光学元件集成到硅电子设备上的困难一直阻碍着光链路在芯片级数据通信中的实际应用。在这里，我们提出了一种创新而又可行的光链路体系结构，由硅平台上的纳米级发射机和接收机组成。将光电子的魅力与其对数据中心碳足迹的影响联系起来，将是一个新的教育和社区参与平台的基础。PI已经参与了几项活动，以扩大实验室研究对社会的影响，包括与高中的直接关系，校园教师培训，并帮助组织加州大学洛杉矶分校的学生参与社区活动。在这种情况下，PI将(A)将拟议的研究成果纳入加州大学洛杉矶分校的课程(B)通过暑期实习和学生交换计划培训和指导高中生，(C)通过高中技术路演和校园访问形成旨在增加社区知识和参与的有针对性的努力，以创造对高速、节能光学链路创新的兴奋。这项提议的研究目标是开发基于紧凑、节能和直接集成的激光和光探测器的纳米光子光学链路，作为绝缘体上通过选择区域外延III-V纳米管作为发射器和接收器。由于发射器和接收器都是单片对准的，并且同时集成在传统的硅波导上，因此所提出的设计从根本上不同于其他具有外部键合激光器的互连。拟议的光学链路包括电驱动纳米柱阵列激光器和单纳米柱光电探测器，其设计目的是实现10fJ/比特的能量数据比。对于激光器来说，由纳米柱阵列组成的一维光子晶体腔可以获得19000个高的腔品质因数和60%的波导耦合效率，而占地面积仅为7.7×0.2µm2。利用超小的高Q腔增强了珀塞尔效应，并引入了InGaAs/InP纳米异质结的三维扩散势垒，得到了93%的内量子效率。对于探测器，纳米级光电二极管与金属纳米槽耦合器实现的等离子体增强相结合，实现了远远超过衍射极限的效率，在10V处产生了1pA的暗电流，带宽为3.4 GHz，噪声等效功率为1.5×10-13W/Hz1/2。假设这些收发机通过3厘米长的波导连接，总功耗预计为6.3FJ/bit，与最先进的光互连相比，功耗降低了一个数量级以上。所提出的硅上电注入纳米谐振器和等离子体光操纵体系结构不仅实现了超紧凑和高能效的光学链路，而且为量子计算、全光开关和存储器、单光子源以及生物和化学传感器铺平了道路。

The realization of an energy-efficient optical link would have an obvious impact in reducing the energy consumption of data centers, which have been recognized as the most rapidly growing consumers of global energy. One promising approach to solve this issue is to utilize optical rather than electrical signals to send and receive data, which can theoretically lead to much higher speed and lower power consumption. However, difficulties in integrating high-performance optical components onto silicon electronics have been hindering practical application of optical links to chip-scale data communications. Here, we propose an innovative yet feasible optical link architecture consisting of nanoscale transmitters and receivers on a silicon platform. Relating the fascination of optoelectronics to its impact on carbon footprint of data centers will be the foundation of a new education and community involvement platform. Already, the PI participates in several activities to broaden the impact of laboratory research to society including direct relationships with high-schools, on-campus teacher training and helping to organize UCLA students for community involvement. In this case, the PI will (a) incorporate the findings of the proposed research into the UCLA curriculum (b) train and mentor high-school students through summer internships and student exchange programs, (c) form a targeted effort aimed at increasing community knowledge and participation through a high-school technology roadshow and campus visitations to create excitement for innovations in high-speed, energy-efficient optical links.The research objective of this proposal is to develop nanophotonic optical links based on compact, energy-efficient, and directly integrated lasers and photodetectors as transmitters and receivers on silicon-on-insulator via selective-area epitaxy of III-V nanopillars. The proposed design is fundamentally different from other interconnects with externally bonded lasers, as both transmitters and receivers are monolithically aligned and simultaneously integrated on conventional silicon waveguides. The proposed optical links include electrically-driven nanopillar array lasers and single nanopillar photodetectors, which are engineered to achieve an energy-to-data ratio of 10 fJ/bit. For lasers, a one-dimensional photonic crystal cavity consisting of an array of nanopillars can achieve a high cavity quality factor of 19,000 and waveguide coupling efficiency of 60 % with a footprint of only 7.7 × 0.2 µm2. Purcell enhancement from an ultra-small and high-Q cavity as well as an introduction of three-dimensional diffusion barriers from InGaAs/InP nanopillar heterostructures results in an internal quantum efficiency of 93 %. For detectors, nanopillar photodiodes combined with plasmonic field enhancement achieved by metal nanoslot couplers realize the efficiency far beyond the diffraction limit, resulting in a dark current of 1 pA at 10 V, a bandwidth of 3.4 GHz, and a noise-equivalent power of 1.5 × 10-13 W/Hz1/2. The total power consumption is expected to be 6.3 fJ/bit assuming that these transceivers are linked by 3 cm-long waveguide, which is more than an order of magnitude reduced power consumption compared with the state-of-the-art optical interconnects. The proposed electrically injected nanoresonators and plasmonic light manipulation architectures on silicon not only enable ultra-compact and energy-efficient optical links, but also pave the way toward quantum computing, all-optical switching and memories, single-photon sources, and bio- and chemical sensors.