Ultrafast Optoelectronics for Broad Bandwidth Microwave Measurements of Materials

该提案支持使用中田纳西州立大学的超快光电激光实验室（UOLL）对材料进行宽带微波/毫米波测量的研究。UOLL的中心是一个基于光导天线的太赫兹测量系统，该系统由锁模钛蓝宝石激光器驱动。本研究的天线结构设计为在10 GHz至200 GHz的频率范围内发射极化定向辐射；一个技术兴趣日益增长的频率范围，在这个频率范围内几乎没有其他宽频带存在。有两个研究重点领域。(1)测量光子带隙材料的微波特性，特别是确定介电阵列和金属介电阵列中体模和表面模的色散关系。(2)演示宽带微波椭偏仪作为一种非接触方法，用于测定半导体衬底上薄膜的微波介电常数和损耗。该提案是在美国国家科学基金会本科院校研究（RUI）项目下提交的。许多因素促成了这个研究项目对本科生的价值。由于这种光电技术并没有得到广泛的应用，因此很容易构建一些研究项目，这些研究项目可以分成几个部分，这些部分可以在本科生可用的时间框架内完成。科学是可访问的，并结合并加强了现代本科物理课程（特别是电动力学，固态物理，傅立叶方法和光学）所涵盖的主题。最后，培养学生在光学和激光、电子学、半导体和薄膜方面的技术相关实验技能。

The proposal supports research in broad bandwidth microwave/millimeter-wave measurements of materials using the Ultrafast Optoelectronics Laser Laboratory (UOLL) at Middle Tennessee State University. The UOLL centers around a Terahertz measurement system based on photoconductive antennas which are driven by a mode-locked Ti:sapphire laser. The antenna structures for the proposed research aredesigned to emit polarized, directional radiation over the frequency range 10 GHz to 200 GHz; a frequency range of growing technological interest and one in which few other broad bandwidth sources exist.There are two research focus areas. (1) Measure the microwave properties of photonic band gap materials, in particular determine the dispersion relations of bulk and surface electromagnetic modes in dielectric and metallo-dielectric arrays. (2) Demonstrate the use of broad bandwidth microwave ellipsometry as a non-contact method for determining the microwave dielectric constant and loss of thin films on semiconducting substrates. This proposal is submitted under the NSF's Research in Undergraduate Institutions (RUI) program. A number of factors contribute to the value of this research program for undergraduates. Because this optoelectronic technique is not widely practiced it is easy to frame a number of research projects that can be partitioned into segments which can be accomplished in the time frame available to undergraduate students. The science is accessible and incorporates and reinforces topics covered in the modern undergraduate physics curriculum (particularly electrodynamics, solid state physics, Fourier methods, and optics).Finally, the students develop technologically relevant experimental skills in optics and lasers, electronics, semiconductors, and thin films.