High power GaInAs photoconductive terahertz radiation source

目的：我们的目标是开发一个紧凑的亚皮秒太赫兹辐射源的时域（TD）太赫兹光谱和太赫兹成像的平均功率为1 mW的工作在MHz的重复率。智力的优点：该方法利用电压偏置太赫兹发射器由三元和四元合金半导体驱动的多瓦锁模镱（Yb）激光器。采用垂直布里奇曼法和垂直梯度凝固法生长晶体，并采用坩埚加速旋转技术，可获得高电阻率（104-107？100cm）、高迁移率（3000-5000 cm 2/Vs）和飞秒载流子寿命以及0.4eV至1.5eV之间的可变带隙。与从气相或固相生长的薄膜相比，从熔体生长的材料由于接近平衡的生长过程而将提供上级的电学和光学性质。三元和四元合金半导体的能带隙可以与Yb激光器在1000- 1100 nm波段的发射波长完美匹配。更广泛的影响：拟议的研究通过课程改进以及本科生和研究生的研究参与来整合研究和教育。从非博士授予机构的本科生的外联将通过夏季REU计划进行实践。另一个重点将是与科学和工程领域代表性不足的少数民族联系，并为我们的研究招募这些学生。拟议的研究将通过更明亮的发射器和紧凑的THz系统，在广泛的学科研究和工业中推进时域THz光谱和成像的应用。时域太赫兹技术将是未来多瓦级锁模镱激光器的重要应用之一。

Objective: Our objective is the development of a compact sub-picosecond THz-radiation source for time-domain (TD) THz spectroscopy and THz-imaging with an average power of 1mW operating at MHz repetition rates.Intellectual merit: The approach utilizes voltage-biased THz-emitters made from ternary and quaternary alloyed semiconductors driven by multi watt mode-locked Ytterbium (Yb) lasers. Unique crystal growth by Vertical Bridgman and Vertical Gradient Freezing Methods with accelerated crucible rotation technique will be used to produce crystals with high-resistivity (104-107?Çcm), high-mobility (3000-5000 cm2/Vs) and femtosecond carrier lifetimes as well as variable band gaps between 0.4eV to 1.5eV. Materials grown from melt will provide superior electrical and optical properties due to the near-equilibrium growth process compared to thin films grown from vapor or solid phases. The energy band gap of ternary and quaternary alloyed semiconductors can be perfectly matched to the emission wavelengths of Yb-lasers in the 1000-1100nm band.Broader impact: The proposed research integrates research and education through curriculum enhancement as well as undergraduate and graduate students¡¦ research participation. Outreach to undergraduate students from non-PhD-granting institutions will be practiced through a summer REU program. Another strong focus will be outreach to minorities underrepresented in science and engineering and recruiting of these students for our research. The proposed research will advance applications of time-domain THz- spectroscopy and imaging in research and industries across a broad range of disciplines through brighter emitters and compact THz-systems. Time-domain THz technology will be one key application of multi watt mode-locked Ytterbium lasers in the future.