Photonic integration has seen tremendous progress over the previous decade, and several integration platforms have reached industrial maturity. This evolution has prepared the ground for miniaturized photonic sensors that lend themselves to efficient analysis of gaseous and liquid media, exploiting large interactions lengths of guided light with surrounding analytes, possibly mediated by chemically functionalized waveguide surfaces. Among the various sensor concepts, phase-sensitive approaches are particularly attractive: offering a flexible choice of the operation wavelength, these schemes are amenable to large-scale integration on mature technology platforms such as silicon photonics or silicon nitride (${{\rm{Si}}_3}{{\rm{N}}_4}$) that have been developed in the context of tele- and data-communication applications. This paves the path toward miniaturized and robust sensor systems that offer outstanding scalability and that are perfectly suited for high-volume applications in life sciences, industrial process analytics, or consumer products. However, as the maturity of the underlying photonic integrated circuits (PICs) increases, system-level aspects of mass-deployable sensors gain importance. These aspects include, e.g., robust system concepts that can be operated outside controlled laboratory environments as well as readout schemes that can be implemented based on low-cost light sources, without the need for benchtop-type tunable lasers as typically used in scientific demonstrations. It is, thus, the goal of this tutorial to provide a holistic system model that allows us to better understand and to quantitatively benchmark the viability and performance of different phase-sensitive photonic sensor concepts under the stringent limitations of mass-deployable miniaturized systems. Specifically, we explain and formulate a generally applicable theoretical framework that allows for a quantitatively reliable end-to-end analysis of the overall signal chain. Building upon this framework, we identify and explain the most important technical parameters of the system, comprising the photonic sensor circuit, the light source, and the detector, as well as the readout and control scheme. We quantify and compare the achievable performance and the limitations that are associated with specific sensor structures based on Mach–Zehnder interferometers (MZIs) or high-Q optical ring resonators (RRs), and we condense our findings by formulating design guidelines both for sensor concepts. As a particularly attractive example, we discuss an MZI-based sensor implementation, relying on a vertical-cavity surface-emitting laser (VCSEL) as a power-efficient low-cost light source in combination with a simple and robust readout and control scheme. In contrast to RR-based sensor implementations, MZIs can be resilient to laser frequency noise, at the cost of a slightly lower sensitivity and a moderately increased footprint. To facilitate the application of our model, we provide a MATLAB-based application that visualizes the underlying physical principles and that can be readily used to estimate the achievable performance of a specific sensor system. The system-level design considerations are complemented by an overview of additional aspects that are important for successful sensor system implementation such as the design of the underlying waveguides, photonic system assembly concepts, and schemes for analyte handling.

中文翻译：

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集成相敏光子传感器：系统设计教程

光子集成在过去十年中取得了巨大进步，多个集成平台已达到工业成熟度。这种演变为小型化光子传感器奠定了基础，这些传感器利用导光与周围分析物的大相互作用长度，可能由化学功能化的波导表面介导，从而有效地分析气态和液态介质。在各种传感器概念中，相敏方法特别有吸引力：提供工作波长的灵活选择，这些方案适合在硅光子学或氮化硅等成熟技术平台上进行大规模集成（${{\rm{ Si}}_3}{{\rm{N}}_4}$) 是在电信和数据通信应用的背景下开发的。这为小型化和强大的传感器系统铺平了道路，这些传感器系统具有出色的可扩展性，非常适合生命科学、工业过程分析或消费产品中的大批量应用。然而，随着底层光子集成电路 (PIC) 的成熟度提高，可大规模部署传感器的系统级方面变得越来越重要。这些方面包括，例如，可以在受控实验室环境外运行的稳健系统概念，以及可以基于低成本光源实施的读出方案，而不需要通常用于科学演示的台式可调谐激光器。因此，它是 本教程的目标是提供一个整体系统模型，使我们能够在可大规模部署的小型化系统的严格限制下，更好地理解和量化不同相敏光子传感器概念的可行性和性能。具体来说，我们解释并制定了一个普遍适用的理论框架，允许对整个信号链进行定量可靠的端到端分析。在此框架的基础上，我们确定并解释了系统最重要的技术参数，包括光子传感器电路、光源和检测器，以及读出和控制方案。我们量化并比较了可实现的性能以及与基于马赫-曾德干涉仪 (MZI) 或高 Q 光学环形谐振器 (RR) 的特定传感器结构相关的限制，并通过为传感器概念制定设计指南来浓缩我们的发现. 作为一个特别有吸引力的例子，我们讨论了基于 MZI 的传感器实现，它依赖于垂直腔面发射激光器 (VCSEL) 作为高能效低成本光源，并结合了简单而强大的读出和控制方案。与基于 RR 的传感器实施相比，MZI 可以对激光频率噪声具有弹性，但代价是灵敏度略低，占地面积适度增加。为了方便我们的模型的应用，我们提供了一个基于 MATLAB 的应用程序，它可视化了基本的物理原理，并且可以很容易地用于估计特定传感器系统的可实现性能。系统级设计注意事项辅以对成功实施传感器系统很重要的其他方面的概述，例如底层波导的设计、光子系统组装概念和分析物处理方案。