Ultra-broadband and nonlinear THz spectroscopy

光谱的太赫兹区域位于微波(频率为100 GHz)和光学(频率为15太赫兹)之间，是为造福社会而开发的电磁频谱的最后一部分。今天，由于对太赫兹频率光与新材料相互作用的更好理解，在控制这一地区的光方面取得了巨大的进展。潜在的好处包括从新的成像系统到超高速无线通信。 这项拟议的研究是为了研究固态材料与极短的太赫兹频率光脉冲(称为太赫兹脉冲)之间的超快相互作用。使用最近开发的方法，可以产生带宽覆盖整个太赫兹区域并到达中红外的脉冲，带宽是传统系统的10倍以上。该系统将是加拿大首个此类系统。这些“超宽带”太赫兹脉冲将被用来探测半导体塑料和量子点阵列等新材料中电荷的运动，时间尺度短于100飞秒。这对于确定降低下一代太阳能电池和其他基于溶液可加工聚合物和纳米材料的光电子器件效率的关键损耗机制非常重要。通过了解这些超快过程，可以合成新材料，将这些廉价制造的太阳能电池的效率提高到可以成为重要的可再生能源的程度。 此外，还将研究太赫兹频率下的新型非线性相互作用，这是首次通过台式激光系统发出的高强度太赫兹脉冲实现的。这些实验提供了一个了解量子受限系统中电荷的相干动力学的机会，并为未来的太赫兹技术和设备提供了有趣的可能性。

The terahertz region of the light spectrum lies between microwave (frequencies < 100 GHz) and the optical (frequencies > 15 THz), and is the last part of the electromagnetic spectrum to be exploited for the benefit of society. Today, massive progress is being made to control light in this region, driven by a better understanding of the interactions of THz frequency light with novel materials. The potential benefits range from new imaging systems to ultra-high speed wireless communication. The proposed research is to investigate the ultrafast interactions of solid-state materials with extremely short pulses of THz frequency light, called THz pulses. Using recently developed methods, pulses with bandwidth covering the entire THz region and reaching into the mid-infrared can be generated, with over 10 times the bandwidth of conventional systems. This system will be the first of its kind in Canada. These 'ultrabroadband' THz pulses will be used to probe the motion of charges in novel materials such as semiconducting plastics and quantum dot arrays, on time scales shorter than 100 femtoseconds. This is important for determining crucial loss mechanisms that deteriorate the efficiency of next generation solar cells and other optoelectronic devices based on solution processable polymers and nanomaterials. By understanding these ultrafast processes, new materials can be synthesized to push the efficiency of these cheaply made solar cells to the point where they can be a significant source of renewable energy. In addition, new types of nonlinear interactions at THz frequencies will be investigated, now made possible for the first time by high intensity THz pulses from a table-top laser system. These experiments provide a glimpse into the coherent dynamics of charges in quantum-confined systems, and hold intriguing possibilities for future THz technologies and devices.