Non-destructive testing of materials by time-domain terahertz (THz) imaging

太赫兹(THz)波覆盖了从100 GHz到15 THz的电磁波区域，从而弥合了微波和红外光之间的差距。很长一段时间以来，由于缺乏太赫兹源，也就是所谓的“太赫兹频隙”，这个频率范围一直未被开发。今天太赫兹光的亮度为从光谱成像到超高速短距离电信设备的新型应用打开了大门。然而，要直接影响该行业，简单的生成和检测方案仍有待发现，这些方案将使交钥匙应用成为可能(例如，在太赫兹频率下进行高效、无损的评估)。预期的方法是结合不同的技术，如电子学和等离子激元，以实现新的太赫兹系统，以比实际系统更低的成本提供数量级的性能改进。这将使太赫兹辐射能够被用来获得使用X射线或红外辐射无法获取的重要物理数据。拟议的研究是研究利用太赫兹频率的电磁波探测光与物质的超快相互作用的时间分辨成像技术。为了完成这项任务，我们将开发新的成像工具，使用光纤激光技术、精确同步系统和上转换探测方法来处理太赫兹波。这里描述的项目的主要目标是建立使用太赫兹波的非破坏性技术，以便表征各种材料的组成和结构，以便(及时)控制它们的制造过程和质量。其中，这些太赫兹脉冲将用于探测新材料，如用于质量控制的可打印电子设备的交流导电性，从而成为工业太赫兹应用的基准过程。由太赫兹脉冲开发的技术和方法将可转移到塑料生产制造、生物传感和食品工业等不同领域。这些研究让人们得以一窥这一令人兴奋的领域的潜力，并为渴望走在太赫兹技术前沿的下一代工程师带来了希望。

Terahertz (THz) waves cover the electromagnetic region from 100 GHz to 15 THz, thus bridging the gap between microwaves and infrared (IR) light. For long time, this frequency range has been unexplored due to a lack of THz source, the so-called `THz frequency gap'. Today's brightness of THz light opens up the door for novel applications ranging from spectroscopic imaging to ultra-high speed short-range telecommunication devices. To directly impact the industry, however, simple generation and detection schemes are still awaiting to be discovering that will enable turnkey applications (e.g. for efficient, non-destructive evaluations at THz frequency). The anticipate approach is to combine different technologies, such as electronics and plasmonics, for realizing novel THz systems that offer orders of magnitude improvements in performance at lower cost than actual systems. This will enable THz radiation to be used to obtain important physical data that are not accessible using X-ray or infrared radiation.The proposed research is to investigate time-resolved imaging techniques for probing the ultrafast interactions of light-matter using electromagnetic waves of THz frequency. To accomplish this task, we will develop new imaging tools to manipulate THz waves using fiber-laser technologies, precise synchronization systems and up-conversion detection methods. The main objective of the project described here is to build non-destructive techniques using THz waves in order to characterize the composition and the structure of various materials in order to control (in time) their fabrication process and quality. Among other things, these THz pulses will be used to probe novel materials such as the AC conductivity of printable electronics (PE) devices for quality control toward a benchmarking process for industrial THz applications.The technology and methodology developed by the PI will be transferable to various fields, such as plastic production manufacturing, biosensing and food industry. These investigations provide a glimpse into the potential of this exciting field, and hold promise for the next generation of engineers who desire to be at the front edge of THz technologies.