Fiber Laser Excitation CARS Microscopy with Auto-Synchronized Chirped Femtosecond

描述（由申请人提供）：本项目的目标是建立一个新的，强大的，紧凑的源相干反斯托克斯拉曼光谱（汽车）显微镜的基础上光纤激光器。汽车是一种潜在的强大的显微镜技术，因为细胞成分（如脂质，蛋白质或DNA）的分子身份可以成像，而不需要荧光标记。光学切片是汽车过程中固有的，因为脉冲强度的非线性依赖。此外，近红外波长可用于增加组织穿透。因此，汽车显微镜具有成为重要的生物医学和临床工具的潜力。然而，所需的激光源通常体积庞大，昂贵且难以处理，因此汽车显微镜迄今为止的应用有限。我们提出开发一种基于光纤激光器的技术：光纤激光器激励汽车（“汽车”），其使用单个光纤激光器作为泵浦和“斯托克斯”脉冲的源。非线性光纤（光子晶体光纤）将被用来移动斯托克斯脉冲的波长。因此，泵、探头和斯托克斯在时间上自动同步。我们将开发基于1030 nm光纤激光器的FLEX-汽车。FLEX-CARS的频率分辨率将显着提高一种新的脉冲“啁啾”的方法，利用泵和斯托克斯脉冲的全脉冲功率。斯托克斯光束的波长可以在微秒时间尺度上快速调谐或切换，从而允许新方法探测多个振动频率。通过极化和时间延迟方法选择振动共振信号，通过抑制非共振背景分量，将提高信号质量。所提出的系统中快速波长切换的独特能力也使得调频（FM）汽车简单明了，这有助于进一步抑制非谐振背景。FLEX-CARS将首先应用于标准样品，然后应用于脑组织，以证明该方法作为汽车microsocpy的稳健系统的潜力。

DESCRIPTION (provided by applicant): The goal of this project is to build a new, robust, and compact source for Coherent anti-Stokes Raman Spectroscopy (CARS) microscopy based on fiber lasers. CARS is a potentially powerful technique for microscopy because the molecular identity of cellular components (e.g. lipids, proteins, or DNA) can be imaged without the need for fluorescence labeling. Optical sectioning is intrinsic to the CARS process because of the nonlinear dependence on pulse intensity. In addition, near-infrared wavelengths can be used for increased tissue penetration. Therefore, CARS microscopy has the potential to be an important biomedical and clinical tool. However, the laser sources required are typically bulkly, expensive and hard to handle, and as a result CARS microscopy has so far found limited application. We propose to develop a technique based on fiber lasers: Fiber Laser EXcitation CARS ("FLEX- CARS"), which uses a single fiber laser as the source of pump and "Stokes" pulses. A nonlinear optical fiber (photonic crystal fiber) will be used to shift the wavelength of the Stokes pulses. As a result, pump, probe, and Stokes are automatically synchronized in time. We will develop FLEX- CARS based on a fiber laser at 1030 nm. The frequency resolution of FLEX-CARS will be significantly improved by a novel pulse "chirping" method that utilizes the full pulse power of pump and Stokes pulses. The wavelength of the Stokes beam can be tuned or switched rapidly on the microsecond time scale, allowing new methods to probe multiple vibrational frequencies. Signal quality will be enhanced by rejection of nonresonant background components through the implementation of polarization and time-delay methods to select the vibrationally resonant signal. The unique capability for fast wavelength switching in the proposed system also makes frequency modulated (FM) CARS straightforward, which helps further rejection of non-resonant background. FLEX-CARS will be applied first to standard samples and then to brain tissue to demonstrate the potential of the method as a robust system for CARS microsocpy.