MRI: Development of Integrated Tunable Picosecond Optical Microscopy System with Multichannel Heterodyning Detector Array

施密特显微镜和超快光学的不断进步使研究人员能够在更小的长度和更短的时间尺度上研究现象，导致了许多新的应用。在这里，PI建议建立一个结合了超高空间和时间分辨率的测量系统。该系统将使人们能够进入一个全新的实验类别，这两个特征都是必需的，并将显著增强加州大学圣克鲁斯分校的研究设施。他们建议开发一种系统，将可调谐超快钛宝石激光器的时间分辨率与具有NSOM功能的原子力显微镜的空间分辨率和高分辨率光电探测器阵列相结合。从钛宝石激光器发出的超短光脉冲被送入近场显微镜的光纤中，或利用远场光学直接聚焦在样品上。NSOM输出端的亚波长孔径用于发射或收集光脉冲，并创建了一种独特的光学探头，用于研究各种样品和衬底。钛宝石的可调性允许在近红外范围内获得较大的光谱，同时为未来的升级留出选择。整个系统将同时具有约200毫微秒的时间分辨率和100纳米的空间分辨率。如果获得资金，将开展纳米电子学方面的研究项目和学生培训：随后的研究活动的一个例子是研究用于高密度磁存储的单畴金属纳米磁体的磁化转换动力学。只有将高空间和时间分辨率结合起来，才能研究单个磁铁的动力学。磁化反转时间的知识对于评估使用这种纳米磁体的写入操作的内在限制至关重要。磁光克尔光谱学能够捕捉反转动力学，但到目前为止还不具备单磁区磁体所需的能力。第二个项目是空间分辨率皮秒超声波。这里的目标是分析金属覆盖的半导体表面下的界面，这是集成电路的典型情况。通过用短光脉冲加热金属，产生的声波在半导体内部传播，并在界面处部分反射。根据反射信号的返回时间可以确定界面的深度。结合近场扫描显微镜的高空间分辨率和使用光电探测器阵列的独特的多通道外差检测方法，可以获得晶片的非破坏性高分辨率成像。这些例子清楚地表明了将可以进行的广泛的实验。其主要部件(钛蓝宝石激光器、AFM/NSOM)都是广泛使用的最先进的仪器，它们的组合需要在脉冲展宽补偿、偏振控制方面有重大发展，而且多通道探测器阵列将在更多的纳米技术领域创造独特的能力，如半导体量子点的时间分辨光谱。预计将在校园各部门以及与其他大学展开令人兴奋的合作。该系统将对纳米科学的研究和教育产生广泛的影响。它将为学生提供当前感兴趣的几个关键领域的优秀培训，如纳米显微镜、激光光学和时间分辨光谱学。此外，它还将被集成到一个纳米光学课程的实验室实验中，该课程是作为NSF职业计划的一部分，由加州大学洛杉矶分校开发的。

0216155SchmidtContinuous progress in microscopy and ultrafast optics has allowed researchers to investigatephenomena on ever smaller length and shorter time scales, leading to a multitude of novel applications. Here, the PIs propose to build a measurement system that combines both ultrahigh spatial and temporal resolution. This system will enable access to a whole new class of experiments for which both characteristics are required and will significantly enhance the research facilities at UC Santa Cruz. They propose to develop a system that integrates the temporal resolution of a tunable ultrafast Ti:Sapphire laser with the spatial resolution of an atomic force microscope with NSOM capabilities and a high-resolution photodetector array. The ultrashort optical pulses emanating from the Ti:Sapphire laser are fed into the fiber of the near-field microscope or focused directly on a sample using far-field optics. A subwavelength aperture at the output of the NSOM is used to emit or collect the light pulses, and creates a unique optical probe for investigating a wide variety of samples and substrates. The tunability of the Ti:Sapphire allows for a large accessible spectrum in the near-infrared while leaving options for future upgrades. The complete system will simultaneously have a time resolution of about 200fs and a spatial resolution of 100 nm.If funded, research projects and student training in nanoscale electronics will be carried out: One example for the ensuing research activities is the study of the dynamics of magnetization switching in single-domain metallic nanomagnets for high-density magnetic storage. Only the combination of both high spatial and temporal resolution will allow studying the dynamics of individual magnets. Knowledge of the magnetization reversal time is critical for assessing the intrinsic limitations for write-operations using such nanomagnets. Magneto-optic Kerr spectroscopy is capable of capturing reversal dynamics, but so far not with the required capabilities for single-domain magnets. The second project is spatially resolvedpicosecond ultrasonics. Here, the goal is to analyze interfaces below a metal-covered semiconductor surface, a situation typical for integrated circuits. By heating the metal with a short optical pulse, an acoustic wave is created that propagates inside the semiconductor and is partially reflected at interfaces. The depth of the interface can be determined from the return time of the reflection signal. In combination with the high spatial resolution of a near-field scanning microscope and a unique multichannel heterodyning detection method using a photodetector array, non-destructive high-resolution imaging of the wafer can be obtained.These examples clearly demonstrate the wide range of experiments that will become accessible. The main components (Ti-sapphire laser, AFM/NSOM) are each widely used state-of-the-art instruments and their combination which require significant development for pulse broadening compensation, polarization control and also multi-channel detector array will create unique capability for many more fields in nanotechnology, such as time-resolved spectroscopy of semiconductor quantum dots. Exciting collaborations across campus departments and with other universities are anticipated. The system will have broad impact on research and education in nanoscience. It will provide excellent training for students in several key areas of current interest such as nanoscopy, laser optics, and time-resolved spectroscopy. In addition, it will be integrated in a laboratory experiment for a nano-optics class that the P.I. is developing at UCSC as part of an NSF CAREER program.