ECCS-EPSRC Micromechanical Elements for Photonic Reconfigurable Zero-Static-Power Modules

集成光子学在过去十年中取得了突飞猛进的发展，其广泛的应用远远超出了最初设想的电信领域。例如，光子学初创公司Lightmatter和PsiQuantum最近的几轮融资表明，集成光子学有望在人工智能和量子计算硬件的发展中发挥关键作用。尽管取得了所有这些进展和希望，但仍有一个关键问题尚未得到解决。为了实现光子学在规模和能源效率方面的前景，它需要使用高质量的因数谐振器，这种设备可以使光以低损耗长时间循环。虽然在减少光子器件的传播损耗方面已经取得了很大的进展，但即使在最先进的铸造工艺中，也存在固有的制造变化，这使得不可能设计出名义上相同的器件来实现任何给定的功能。这意味着必须采用一些加工后补偿和调谐的方法。虽然目前存在几种这样的调谐方法，但它们要么需要大的稳态能耗（热调谐），要么需要大的片上占用空间（MEMS调谐）。理想情况下需要的是一种机制，允许谐振器的频率在制造后进行调谐，其中调谐机制既占用空间小又高效（零静态能量耗散）。该项目旨在通过利用机械双稳态结构来实现这一目标，该结构可以在两种稳定状态之间翻转以诱导调谐。我们将开发可切换的，数字的（一步一步），非易失性（无静态功耗）微机械调谐元件，用于在制造后调整集成光子谐振器的谐振波长。这些调谐元件将有选择地和永久地切换到数字调谐谐振器，使其彼此对齐，从而消除了应用持久的谐振器特定调谐来补偿制造变化的需要。我们将展示这些机械双稳态元件可以在最先进的铸造工艺中设计和制造，并且还展示了从室温到4K的操作稳定性。我们的主要目标是表明，通过使用这种调谐方法，我们可以将“有效”制造变化减少约10倍，并使围绕高q谐振器设计的新一代集成光子器件成为可能。

Integrated photonics has developed by leaps and bounds over the past decade and has seen widespread application far beyond the originally envisioned domain of telecommunications. For instance, the recent funding rounds raised by photonics startups Lightmatter and PsiQuantum, point to the fact that integrated photonics is expected to play a key role in the development of hardware for both artificial intelligence and quantum computing.In spite of all this progress and promise, there is one key problem that has remained unaddressed. For photonics to realise its promise, both in terms of scale and energy efficiency, it requires the use of high quality factor resonators, devices in which light can circulate for long periods with low-loss. While there has been great progress in reducing the propagation loss in photonic devices, the inherent fabrication variation present even in state of the art foundry processes, makes it impossible to design nominally identical devices for implementing any given function. This means that some method for post fabrication compensation and tuning must be utilised. While several such approaches for tuning currently exist, all of them either require large steady state energy consumption (thermal tuning) or large on-chip footprint (MEMS tuning). What is ideally needed is a mechanism that allows a resonator's frequency to be tuned post-fabrication where the tuning mechanism is both small footprint and efficient (zero static energy dissipation). This project is designed to address this goal by exploiting mechanically bistable structures that can be flipped between two stable states to induce the tuning. We will develop switchable, digital (step-by-step), nonvolatile (no static power dissipation) micromechanical tuning elements for adjusting the resonant wavelength of integrated photonic resonators after fabrication. These tuning elements will be selectively and permanently switched to digitally tune resonators into alignment with each other, eliminating the need to apply a persistent, resonator-specific tuning to compensate for fabrication variations. We will demonstrate that these mechanically bistable elements can be designed and fabricated in a state of the art foundry process, and also show the stability of operation from room temperature down to 4K. Our main goal is to show that by using this tuning method, we can reduce the 'effective' fabrication variation by ~10x, and enable a new generation of integrated photonic devices, designed around high-Q resonators.