MRI: Development of a single-mode terahertz free electron lasers for research in materials, physics, chemistry and biology

太赫兹频率范围位于电磁频谱的中心，介于电子学和光学领域之间。 频率为1太赫兹的电磁波每秒振荡1万亿次？大约比手机使用的电磁波快1000倍，比构成可见光的电磁波慢500倍。 到目前为止，太赫兹电磁波在社会中的应用相对较少，因为它们很难产生。 然而，在光学和电子革命的推动下，这种情况正在迅速改变。 加州大学圣巴巴拉分校的自由电子激光器是世界上最亮的可调谐太赫兹辐射源。该项目将使UCSB自由电子激光设备用户可用的亮度增加100至1000倍。 升级后的设施将使电磁辐射与电子材料，分子和生物物质相互作用的基础研究成为可能。从这一基础研究中获得的见解将对信息技术、国防和生物技术产生重要影响。 太赫兹技术正在迅速发展，现在可用的桌面源可以产生超过1 MV/cm的峰值电场（峰值功率106 W），脉冲带宽约为1 THz，并且更紧凑的电子源可以产生亚kHz线宽的mW功率。 越来越多的有趣的科学问题和重要的技术发展需要获得具有非常高的光谱亮度的可调谐太赫兹电磁场，其结合了极高的功率和极窄的线宽的电场的联合收割机。 这里要开发的主要研究仪器将大大提高在这个高功率/窄线宽利基的艺术状态。 加州大学圣巴巴拉自由电子激光器，这是可调谐的0.24至4.5太赫兹与1千瓦的功率在几微秒的脉冲，将通过减少发射辐射的线宽为1兆赫在其整个调谐范围，同时精确控制和测量发射辐射的频率，使？切片？将自由电子激光器（FEL）输出的脉冲宽度转换为一系列脉冲，脉冲宽度从~1 ns到几微秒。自由电子激光增强将使凝聚态物理学，化学和生物学的重要新研究成为可能，通过（1）提高加州大学圣巴巴拉自由电子激光设施已经开发的几种实验方法的精度和控制，以及（2）使一些以前无法想象的实验成为可能。 这一发展在很大程度上利用了加州大学圣巴巴拉35年以上的基础设施、投资、机构承诺和专业知识。

The terahertz frequency range lies at the heart of the electromagnetic spectrum, between the domains of electronics and optics. An electromagnetic wave with a frequency of one terahertz oscillates one trillion cycles per second?about 1000 times faster than the electromagnetic waves used by cell phones, and 500 times slower than the electromagnetic waves that constitute visible light. Terahertz electromagnetic waves have been, so far, relatively little used by society because they are hard to generate. However, that is changing rapidly, propelled by revolutions in optics and electronics. The UC Santa Barbara Free-Electron lasers are the brightest sources of tunable terahertz radiation in the world. This project will increase the brightness available to users of the UCSB Free-Electron Laser facility by a factor between 100 and 1000. The upgraded facility will enable fundamental research on the interaction of electromagnetic radiation with electronic materials, molecules, and biological matter. The insights gained from this fundamental research will have important implications for information technology, defense, and biotechnology. Terahertz technology is rapidly advancing, with tabletop sources now available that generate peak electric fields in excess of 1 MV/cm (peak power 106 W) in pulses with bandwidths of ~1 THz, and much more compact electronic sources that generate mW powers with sub-kHz linewidths. An increasing number of fascinating scientific questions and important technological developments require access to tunable terahertz electromagnetic fields with very high spectral brightness, which combine extremely high power and electric field with extremely narrow linewidth. The major research instrumentation to be developed here will greatly enhance the state of the art in this high-power/narrow-linewidth niche. The UC Santa Barbara Free-Electron Lasers, which are tunable from 0.24 to 4.5 THz with 1 kW power in few-microsecond pulses, will be enhanced by reducing the linewidth of the emitted radiation to 1 MHz over their entire tuning range while precisely controlling and measuring the frequency of the emitted radiation and enabling ?slicing? of the Free-Electron Laser (FEL) output into a series of pulses with durations variable from ~1 ns to the full few-microsecond pulse duration. The free-electron laser enhancements will enable important new research in condensed matter physics, chemistry and biology by (1) improving the precision and control of several experimental methodologies that have already been developed at the UC Santa Barbara FEL facility, and (2) enabling some experiments that could not previously be envisioned. This development heavily leverages more than 35 years of infrastructure, investment, institutional commitment, and expertise at UC Santa Barbara.