New directions in piezoelectric phononic integrated circuits: exploiting field confinement (SOUNDMASTER)

在芯片级平台中操纵光和千兆赫（GHz）频率声波之间的类比已经被广泛探索，来自硅光子学的想法，主要是强几何约束和路由，被应用于声波以开发声子集成电路（PnIC）。重要的是要注意，虽然光-声类比通常应用于应变场，但压电材料中的声波也具有共同传播的电磁（EM）场。这种电磁场以GHz频率振荡，但限于声波波长（小10^5），支持压电谐振器和滤波器在射频（RF）设备中的主导地位。尽管PnIC在过去十年中取得了进展，但大多数压电器件，无论是体波还是表面波，仍然依赖于弱横向限制和准平面声波的操纵。本项目旨在回答以下问题：如果可以在具有强横向限制的波导几何结构中主动地控制和操纵这些共同传播的EM场，什么样的质量新的传感和信息处理范例可以启用？我们表明，通过利用PnIC平台中的强场增强，可以设计用于电子自旋共振实验的共振磁近场发生器，其可以将自旋检测灵敏度提高~10^7，直到热噪声极限。此外，通过设计波导几何形状中的声电相互作用，可以实现声学移相器和模式选择性非互易放大器，其对声波传播施加主动控制，并将有源无源器件集成推向极限，从而实现用于RF信号处理的新型器件。为了确保这些设备的性能符合预期，我们还解决了一个重要的问题：我们能否以接近1的效率将GHz频率的声波送入和送出微米级的设备？

The analogy between manipulating light and gigahertz (GHz) frequency acoustic waves in chip-scale platforms has been extensively explored, with ideas from silicon photonics, mainly strong geometric confinement and routing, being applied to acoustic waves to develop phononic integrated circuits (PnICs). It is important to note that while the light-sound analogy is generally applied to the strain field, acoustic waves in piezoelectric materials have a co-propagating electromagnetic (EM) field as well. This EM field, which oscillates at GHz frequencies, but is confined to acoustic wavelengths (~10^5 smaller), underpins the dominance of piezoelectric resonators and filters in radio frequency (RF) devices. Despite the advances made in PnICs in the past decade, the majority of piezoelectric devices, both bulk and surface wave based, still rely on weak transverse confinement and manipulation of quasi plane acoustic waves.This project seeks to answer the question: if one could actively control and manipulate these co-propagating EM fields in waveguide geometries with strong transverse confinement, what qualitatively new sensing and information processing paradigms can one enable?We show that by exploiting strong field enhancement in a PnIC platform, one can design resonant magnetic near field generators for electron spin resonance experiments that can improve the spin detection sensitivity by ~10^7, down to the thermal noise limit. In addition, by engineering acousto-electric interactions in waveguide geometries, acoustic phase shifters and mode-selective, non-reciprocal amplifiers can be realized that exert active control on acoustic wave propagation, and push active passive device integration to its limit, enabling a new class of devices for RF signal processing. To ensure these devices perform as expected, we also address the important question: can we get GHz frequency acoustic waves into and out of micrometre-scale devices with near-unity efficiency?