IMR: Acquisition of an Amplified Ultrafast Laser System for Terahertz Spectroscopic Research and Student Training

来自材料研究计划仪器（IMR）的奖项将用于获得放大的飞秒激光系统。这种脉冲可见光辐射的可用性将为利用强脉冲电磁辐射（光学和远红外）提供极好的机会。后一个光谱区域具有重要的科学和技术意义，但用于光谱测量的高强度相干辐射通常只能从同步加速器或自由电子激光器等来源获得。远红外至中红外的高强度辐射的产生将通过可见激光脉冲的光学整流来实现。这种方法将产生单周期电磁脉冲，其光谱内容超过30 THz。 除了允许对这些非线性光学频率转换过程的物理和基本限制进行研究外，所要求的设备将允许开发重要的新光谱技术。计划用于这些增强能力的主要应用领域是研究各种材料中的动态和非线性过程，包括电子和生物。除了激光系统将对PI的研究工作产生影响外，高强度宽带太赫兹光谱系统的独特功能将增强和扩大与物理，化学，材料科学与工程，生物学以及电气和计算机工程部门成员的合作机会。这些互动的更广泛的影响主要与来自许多不同学科的学生的研究培训有关。该奖项来自材料研究计划（IMR）的仪器，支持获得放大飞秒激光系统。这种脉冲可见光辐射的可用性将为利用强脉冲电磁辐射（光学和远红外）提供极好的机会。后一个光谱区域具有重要的科学和技术意义，但用于光谱测量的高强度相干辐射通常只能从同步加速器或自由电子激光器等来源获得。远红外至中红外的高强度辐射的产生将通过可见激光脉冲的光学整流来实现。这种方法将产生单周期电磁脉冲，其光谱内容超过30 THz（即， 1000 cm-1）。 研究工作的主要目标将是开发新的和独特的光谱应用，允许测量以前难以或不可能的材料特性。线性时域太赫兹光谱是一种在过去十年中发展良好的技术，用于测量介质的线性静态介电特性。然而，涉及时间分辨太赫兹光谱测量或非线性太赫兹光谱的应用的数据相对较少。在前一种技术中，人们可以探测各种材料中的电荷传输，例如液体，绝缘体和量子点。该技术是全光学的，不需要电接触，并且该方法可以应用于表现出低本征电导率或短复合寿命的材料。这些能力预计将产生有价值的信息，包括在远红外的非线性极化率的属性。当应用于液体，该方法将产生有价值的信息的时间尺度取向松弛。除了激光系统将对PI的研究工作产生影响外，高强度宽带太赫兹光谱系统的独特功能将增强和扩大与物理，化学，材料科学与工程，生物学以及电气和计算机工程部门成员的合作机会。这些互动的更广泛的影响主要与来自许多不同学科的学生的研究培训有关。

The award from the Instrumentation for Materials Research program (IMR) will be used to acquire an amplified femtosecond laser system. The availability of such pulsed visible radiation will open up exceptional opportunities for the utilization of intense pulsed electromagnetic radiation, both optical and far-infrared. This latter spectral region is of great scientific and technological significance, but high-intensity coherent radiation for spectroscopic measurements has typically only been available from sources such as synchrotrons or free-electron lasers. The production of high-intensity radiation in the far- to mid-infrared will be accomplished via optical rectification of the visible laser pulses. This method will produce single-cycle electromagnetic pulses with spectral content extending beyond 30 THz. In addition to allowing research on the physics and fundamental limitations of these nonlinear optical frequency conversion processes, the requested equipment will permit important new spectroscopic techniques to be developed. The primary areas of application planned for these enhanced capabilities are to the study of both dynamic and nonlinear processes in a variety of materials, including both electronic and biological. In addition to the impact that the laser system will have on the PI's research effort, the unique capabilities of a high-intensity broadband terahertz spectroscopic system will enhance and expand collaborative opportunities with members of the Physics, Chemistry, Materials Science and Engineering, Biology, and Electrical and Computer Engineering Departments. The broader impact of these interactions is related primarily to the research training of students from many different disciplines. The award from the Instrumentation for Materials Research program (IMR) supports the acquisistion of an amplified femtosecond laser system. The availability of such pulsed visible radiation will open up exceptional opportunities for the utilization of intense pulsed electromagnetic radiation, both optical and far-infrared. This latter spectral region is of great scientific and technological significance, but high-intensity coherent radiation for spectroscopic measurements has typically only been available from sources such as synchrotrons or free-electron lasers. The production of high-intensity radiation in the far- to mid-infrared will be accomplished via optical rectification of the visible laser pulses. This method will produce single-cycle electromagnetic pulses with spectral content extending beyond 30 THz (i.e., 1000 cm-1). The primary goal of the research effort will be in developing new and unique spectroscopic applications that allow for the measurement of materials properties that were previously difficult or impossible. Linear time-domain terahertz spectroscopy is a technique that has been well developed over the last decade to measure the linear, static dielectric properties of a medium. However, there is a relative paucity of data involving the application of time-resolved terahertz spectroscopic measurements or nonlinear THz spectroscopy. In the former technique, one can probe electronic charge transport in a wide variety of materials, such as liquids, insulators, and quantum dots. The technique is all-optical, no electrical contacts are required, and the approach can be applied to materials exhibiting low intrinsic conductivity or short recombination lifetimes. These capabilities are expected to yield valuable information that includes the properties of the nonlinear susceptibility in the far-infrared. When applied to liquids, the approach will yield valuable information about the timescale for orientation relaxation. In addition to the impact that the laser system will have on the PI's research effort, the unique capabilities of a high-intensity broadband terahertz spectroscopic system will enhance and expand collaborative opportunities with members of the Physics, Chemistry, Materials Science and Engineering, Biology, and Electrical and Computer Engineering Departments. The broader impact of these interactions is related primarily to the research training of students from many different disciplines.