Optical Generation of Coherent Hypersonics in the 100GHz to THz Range

100GHz 至 THz 范围内的光学相干高超音速技术

• 批准号: 8913056
• 负责人: R. J. Dwayne Miller
• 金额: $ 14万
• 依托单位: University of Rochester
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1989
• 资助国家: 美国
• 起止时间: 1989-12-15 至 1993-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=8913056&HistoricalAwards=false
• 关键词: Optical; Generation; Coherent; Hypersonics; 100GHz

The proposed research will extend the optical technique of generating and detecting coherent ultrahigh frequency ultrasonics from the 100 GHz range to the THz range. The generation of THz waves will be accomplished by using specifically engineered quantum-well structures of alternating AlGaAs and GaAs layers. This quantum-well structure will be designed to be a static image of a sound field. Subpicosecond optical excitation of hot electron and hole carriers and subsequent non-radiative relaxation of the carriers in the pattern prescribed by the quantum well structure will lead to selective excitation of coherent acoustic waves with the same wavelength as the well period. The structures will be designed to provide acoustic wavelengths corresponding to THz frequencies. The detection of the acoustic wave amplitude will be accomplished by using a specifically designed single quantum well layer (optical detector layer) to follow the acoustic strain amplitude through the modulation of the exciton resonance. Theoretical modelling of the optically driven strain fields, through both non-radiative relaxation and photostriction effects, will be carried out in parallel with the experimental studies. The propagation and transmission of these high frequency acoustics at interfaces and within the periodic well structure will also be treated. This work will provide an all optical acoustic transducer, compatible with diode pumped micro laser sources, as a future generation of acoustic devices for imaging.

拟议的研究将把产生和检测相干超高频超声波的光学技术从 100 GHz 范围扩展到太赫兹范围。 太赫兹波的产生将通过使用专门设计的交替 AlGaAs 和 GaAs 层的量子阱结构来实现。 这种量子阱结构将被设计为声场的静态图像。 热电子和空穴载流子的亚皮秒光学激发以及随后在量子阱结构规定的模式中载流子的非辐射弛豫将导致具有与阱周期相同波长的相干声波的选择性激发。 这些结构将被设计为提供与太赫兹频率相对应的声波波长。 声波振幅的检测将通过使用专门设计的单量子阱层（光学探测器层）通过激子共振的调制来跟踪声应变振幅来完成。 通过非辐射弛豫和光致伸缩效应的光学驱动应变场的理论建模将与实验研究同时进行。 还将处理这些高频声学在界面处和周期性井结构内的传播和传输。 这项工作将提供一种与二极管泵浦微型激光源兼容的全光学声换能器，作为下一代成像声学设备。