CAREER: On-Chip Terahertz Electronic Frequency Combs

保持电子信号生成、传感和处理的指数增长对于应对即将到来的时代的新挑战至关重要，该时代的特点是无处不在的传感器用于医疗保健、环境监测、自动驾驶车辆/机器等。特别是，如果低成本电子设备的工作频率可以扩展到太赫兹（THz）范围，则前所未有的宽带宽将使众多新应用成为可能，例如非电离成像、分子识别、高分辨率雷达和超高速数据链。尽管在过去的十年中，硅中的THz集成电路在输出功率和效率方面有了显着的提高，但它们对高品质因数谐振的依赖使得当前的THz传感器窄带化，并且未能充分利用宽范围气体传感和高精度雷达测距的可用宽频谱。为了突破这一限制，本项目研究了一种基于电子太赫兹频率梳的新技术。通过在集成电路芯片上进行并行信号处理，使用该技术的气体传感器和成像雷达将实现更好的频谱覆盖和能源效率。这项研究工作也将与首席研究员的教育事业目标相结合，即通过创建新课程和通过麻省理工学院的推广计划吸引代表性不足的学生和K-12学生来促进高度跨学科的研究。这项建议的目的是利用硅半导体制造工艺的集成能力，并使用太赫兹频率梳技术来分配信号-传感负载的窄带，精确控制的太赫兹电路单元的阵列。它保持高能效，同时以可扩展的方式覆盖宽带宽。基于两种类型的太赫兹频率梳的传感器将在该计划下进行研究。首先，将使用均匀分布的频率梳演示旋转模式分子传感器。频率梳将无缝覆盖超过100 GHz的带宽，并将芯片级THz光谱仪的光谱扫描速度提高200倍。通过片上频率校准技术，频谱仪将以十亿分之一的频率精度扫描频谱。第二，将使用非均匀梳状和压缩感知演示成像雷达。该雷达采用一组非线性分布的波长对目标距离进行量化，并采用误差校正算法，从而实现低信噪比和低功耗工作。太赫兹梳状雷达还将与低成本的传感器阵列集成在准光学配置中，以便实现具有电子扫描和高分辨率的实时3D成像。通过这些全面的研究，该计划将建立芯片级宽带信号传感和处理的并行优势。

Maintaining the exponential growth of electronic signal generation, sensing, and processing is essential to meet the new challenges of the upcoming era featuring ubiquitous sensors for healthcare, environment monitoring, autonomous vehicles/machines, etc. In particular, if the operating frequency of low-cost electronics can be extended into the terahertz (THz) regime, the unprecedented wide bandwidth will enable numerous new applications, such as non-ionizing imaging, molecular identification, high-resolution radar, and ultra-high-speed data link. Although in the past decade THz integrated circuits in silicon have improved remarkably in output power and efficiency, their reliance on high-quality-factor resonance makes the current THz sensors narrowband and fails to fully capitalize on the available broad spectrum for wide-range gas sensing and high-precision radar ranging. To break such a limit, this project investigates a new technique based on electronic THz frequency comb. Through parallel signal processing on the integrated circuit chip, gas sensor and imaging radar using the proposed technique will achieve significantly better spectral coverage and energy efficiency. This research effort will also be integrated with the principal investigator's educational career goal of promoting highly-interdisciplinary studies through the creation of new courses and engaging underrepresented and K-12 students through MIT's outreach programs.The objective of this proposal is to leverage the integration capability of the silicon semiconductor fabrication process and use THz frequency comb technique to distribute the signal-sensing load to an array of narrowband, precisely-controlled THz circuit units. It maintains high energy efficiency while covering a wide bandwidth in a scalable fashion. Sensors based on two types of THz frequency comb will be investigated under this program. First, a rotational-mode molecular sensor will be demonstrated using an evenly distributed frequency comb. The frequency comb will seamlessly cover more than 100 GHz of bandwidth and increase the spectral scanning speed of chip-scale THz spectrometer by a factor of 200. Through an on-chip frequency calibration technique, the spectrometer will scan the frequency spectrum with one-part-per-billion level frequency precision. Second, an imaging radar will be demonstrated using a non-uniform comb and compressive sensing. By quantizing the target distance with a set of nonlinearly distributed wavelengths and by using an error-correction algorithm, the radar can operate with low signal-to-noise ratio and low power consumption. The THz comb radar will also be integrated with a low-cost sensor array in a quasi-optical configuration, so that real-time 3D imaging with electronic scanning and fine resolution can be realized. Through these comprehensive studies, the program will establish the advantages of parallelism in chip-scale wide-band signal sensing and processing.