Compact and powerful strong-field terahertz light source for exploring water in new regimes

Descripción del proyecto

Fuentes de terahercios de campo fuerte de sobremesa en química física

Las fuentes ultrarrápidas impulsadas por láser de radiación de terahercios (THz) de pocos ciclos se han convertido en herramientas de laboratorio muy extendidas para la espectroscopia. Los últimos avances en la generación de dichos pulsos con fuertes intensidades de campo eléctrico han permitido que la espectroscopia no lineal de THz abra nuevos campos de investigación. Sin embargo, persiste la falta de fuentes de THz de sobremesa que combinen una alta intensidad de campo y una elevada tasa de repetición. El objetivo del proyecto TerAqua, financiado con fondos europeos, es conseguir fuentes de THz de campo fuerte de sobremesa con una potencia media de un vatio mediante novedosas técnicas intracavitarias. El equipo de TerAqua aplicará este método en la química física para dilucidar el papel del agua como «disolvente de la vida».

Objetivo

Ultrafast laser driven sources of few-cycle THz pulses have progressed from being specialized systems to widespread laboratory tools. This has enabled THz time-domain spectroscopy to emerge as a powerful technique for time-resolved studies of the dynamics of many fundamental constituents of matter. Recent progress in the generation of few-cycle THz pulses with electric field strengths exceeding several MV/cm, has allowed nonlinear THz spectroscopy to open new exciting fields of research.
However, many fields suffer from a persistent lack of table-top THz sources combining high field strength and high repetition rate (i.e. high average power). So far, these parameters can only be achieved by costly and restrictive accelerator facilities. In most cases, scientists will either abandon research lines where high pulse energy is required or operate at low repetition rate (typically <1 kHz). This imposes severe limits on the explored parameter space in many measurements, for which minuscule average powers result in very long integration time and low signal-to-noise ratio.
My objective is to fill this gap by achieving table-top strong-field THz sources with watt-level average power. The key feature is to leverage existing THz generation techniques to higher efficiency by driving them inside the resonator of a high-power ultrafast thin-disk oscillator, operated in the mid-infrared (2 µm) spectral region.
This source will have impact in various fields of physics, physical chemistry, engineering, biology and medicine. I envision to apply this source in physical chemistry, to gain understanding of the role of water as “the solvent of life”. THz spectroscopy is perfectly suited to study aqueous samples, however, so far, most THz studies in liquid phase have been performed in the linear domain, and in a restricted parameter space due to the inadequacy of the sources. Our source will enable us to expand these studies into the nonlinear domain, which was previously impossible.