Resonant acousto-optic devices in silicon for ultra-low power optical modulation and non-reciprocity

用于超低功率光调制和非互易性的硅谐振声光器件这个项目的目标是结合芯片规模纳米技术的两个主要研究方向来解决硅光学电路中长期存在的实际问题。通过将为控制芯片上的光流动而开发的电路技术的进步与能够产生和检测高频机械振动的纳米器件的发明相结合，该计划旨在开发一类非凡的新型光学设备。互联网的主干完全基于使用光和光纤在遥远的距离上高效、快速地发送大量数据的系统。在过去十年中，云计算、数据中心和无处不在的高带宽无线的兴起促使我们努力提高执行更集成、更复杂的光数据路由和调制的能力。这导致了在硅和其他半导体材料上成功地展示了复杂的光子电路。尽管这些系统在提高计算网络的吞吐量和效率方面取得了重大成功，但在更广泛的经济中对数据需求的增长以及相应的信息技术能源消耗的增长已经完全超过了平行技术的进步。因此，成功的应对这些挑战的新办法预计将对经济和环境产生重大影响。目前，大多数高速光开关和调制器以及所有主要的工业研究工作都是基于利用电子或电场来局部改变材料的光学性质，从而导致对光场的电气控制。相比之下，这个研究项目探索了一种新的方法，使用高频机械振动或声音来代替电子来控制光的传播。值得注意的是，最近的计算和实验结果表明，制造出比最先进的实验室演示效率高近1000倍、比通常部署的技术高10万倍以上的光学高速调制器是可能的。该计划将开发实验演示利用声音处理光的潜力的设备。最后，在其后期阶段，该计划将带头开发光学电路设计者所缺乏的基本器件-S工具箱：光学环行器。通过利用声音动态地改变光学结构的特性，可以在光只能沿一个方向传播并且被阻止向后流动的模式下操作。该方案的核心概念围绕以下最新技术发展：1)光和运动的同时局部化导致微米级封装中的光的极其高效的调制；2)通过纳米掺杂换能器对高频机械波的微波电容式传输允许将频率传输到GHz及以上；3)在高频下调制的滤光器可以基于驱动器的幅度和相位具有高度非平凡和可定制的响应，并可用于滤光器整形和非互易光子传播工程。该项目将演示超低功耗(attojoule/bit)声光调制器和开关，以及在数据中心和无线后端光网络中的应用。待开发的核心技术是一种高效地对频率高达10 GHz的光子晶体腔进行机电调制的方法。最后，在其后期阶段，该计划将开发新的器件，利用机械调制腔来打破光子电路中的时间反转对称，从而实现新型的芯片级光子环行器以及其他有趣的非互易元件。

Resonant acousto-optic devices in silicon for ultra-low power optical modulation and non-reciprocity The objective of this program is to combine two major strands of research in chip-scale nanotechnology to address long-standing practical problems in silicon optical circuits. By merging the advances in circuit technologies developed for controlling the flow of light on a chip, with the invention of nanodevices capable of generating and detecting high frequency mechanical vibrations, this program aims to develop a remarkable class of new optical devices. The backbone of the Internet is entirely based on systems that use light and fiber optics to efficiently send large amounts of data quickly over vast distances. In the last decade, the rise of cloud computing, data centers, and ubiquitous high bandwidth wireless has led to an effort to increase our ability to perform more integrated and complex routing and modulation of optical data. This has led to several successful demonstrations of complex photonic circuits on Silicon and in other semiconductor materials. Despite the significant successes of these systems in increasing throughput and efficiency of computing networks, the growth of demand for data in the wider economy and the corresponding growth in information technology energy consumption has completely out-paced parallel technological advances. Therefore, successful new approaches to address these challenges are expected to have a significant economic as well as environmental impact. Currently, most high-speed optical switches and modulators, as well as all major industrial research efforts, are based on using electrons or electric fields to locally change the optical properties in material, leading to electrical control of optical fields. In contrast, this research program explores a novel approach using high frequency mechanical vibrations, or sound, in lieu of electrons to control the propagation of light. Remarkably, recent calculations and experimental results suggest the possibility of making optical high-speed modulators that operate nearly a thousand times more efficiently than state-of-the-art laboratory demonstrations, and more than one hundred thousand times more efficiently than commonly deployed technologies. This program will develop devices that experimentally demonstrate the potential of using sound to process light. Finally, in its later stage, this program will spearhead the development of a fundamental device that has been lacking from the optical circuit designer?s toolbox: the optical circulator. By dynamically modifying the properties of an optical structure with sound, it is possible to operate in a mode where light can propagate in only one direction and is inhibited from flowing backwards. This significantly simplifies the design of robust multi-element systems and can lead to new types of optical circuitry that are far less difficult to scale up.The core concepts of this proposal are centered around the following recent technological developments: 1) simultaneous localization of light and motion leads to extremely efficient modulation of light in a micron-scale package, 2) microwave capacitive transduction of high frequency mechanical waves via nanopatterened transducers allows transduction frequencies into the GHz and above, 3) optical filters modulated at high frequencies can have highly non-trivial and tailorable responses based on the amplitude and phase of the drives and can be utilized for filter-shaping and non-reciprocal photon propagation engineering. This program will demonstrate ultra-low power (attojoule/bit) acousto-optic modulators and switches with application in data center and wireless back-end optical networks. The core technology to be developed is a way to efficiently electromechanically modulate photonic crystal cavities at frequencies up to 10 GHz. Finally, in its later phase, this program will develop novel devices utilizing mechanically modulated cavities to break time-reversal symmetry in photonic circuits enabling a new type of chip-scale photonic circulator as well as other interesting non-reciprocal elements.