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

University Of California-Santa Barbara, Santa Barbara CA

Investigators

Abstract

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.