Entangled-Photon Fluorescence Microscopy

纠缠光子荧光显微镜

• 批准号: 9800300
• 负责人: Malvin Teich
• 金额: $ 15.68万
• 依托单位: Trustees of Boston University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-07-01 至 2000-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9800300&HistoricalAwards=false
• 关键词: Entangled; Photon; Fluorescence; Microscopy

9800300 Teich The proposed research pertains to the development of a new form of microscopy: entangled-photon fluorescence microscopy. The recent surge in the development of fluorescence microscopy based on two-photon excitation using classical (or laser) light has been driven by the principal advantages of this technique over single-photon excitation: a pair of low-energy photons can deposit as much energy as a single ultraviolet photon thereby exciting a fluorescent molecule within a sample with greater penetration depth, better resolution, and less risk of damage upon absorption along the optical path. However, in order to obtain two-photon absorption with a classical light source such as a laser, a very large photon-flux density is necessary to place two photons within a small enough volume and within a small enough time window to effect the absorption. In this case, a femtosecond-pulsed high-power laser is used directly &- the source of light, which can produce undesired phototoxicity and photobleaching. On the other hand, entangled light generated by the process of spontaneous parametric downconversion in a nonlinear crystal comprises intrinsically paired photons within a very short time window and small volume. Far smaller photon-flux densities can be used and the absorption of entangled-photon pairs is directly proportional to the photon-flux density, whereas for ordinary two-photon absorption it is quadratic in the photon-flux density. The sum of the photon energies in each pair is a constant and equal to the energy of the downconverted pump photon, whereas the sum energy is far broader for photons from a femtosecond laser. These features lead to unique advantages with the use of nonclassical entangled light when compared to classical light sources like a laser. Simply put, at low photon-flux densities entangled light is a more efficient source of two-photon excitation than a conventional classical laser source. The use of a weak entangled-light source is therefore expec ted to cause less damage than that caused by a direct laser source while providing the same amount of fluorescent light for detection. An experimental investigation of the feasibility of entangled-photon fluorescence microscopy is proposed. Entangled light for fluorophore excitation will be generated using nonlinear parametric downconversion. A basic study of the two-photon absorption rate will be carried out using measurements of the induced fluorescence.

[9800300 . Teich]提出的研究涉及一种新型显微镜的发展：纠缠光子荧光显微镜。基于经典（或激光）光的双光子激发的荧光显微镜的最新发展是由这种技术比单光子激发的主要优势所驱动的：一对低能光子可以沉积与单个紫外光子一样多的能量，从而在样品中激发荧光分子，具有更大的穿透深度，更好的分辨率，并且沿着光路吸收时损坏的风险更小。然而，为了用激光等经典光源获得双光子吸收，需要非常大的光子通量密度才能将两个光子放置在足够小的体积和足够小的时间窗口内以影响吸收。在这种情况下，直接使用飞秒脉冲高功率激光——光源，它会产生不希望的光毒性和光漂白。另一方面，非线性晶体中自发参量下转换过程产生的纠缠光在很短的时间窗和很小的体积内包含本征对光子。可以使用更小的光子通量密度，并且纠缠光子对的吸收与光子通量密度成正比，而对于普通的双光子吸收，它是光子通量密度的二次元。每对光子能量的总和是一个常数，等于下转换泵浦光子的能量，而飞秒激光器的光子能量总和要宽得多。与激光等经典光源相比，这些特性使得使用非经典纠缠光具有独特的优势。简单地说，在低光子通量密度下，纠缠光比传统的经典激光源更有效地激发双光子。因此，使用弱纠缠光源预计比直接激光光源造成的损害更小，同时提供相同数量的荧光进行检测。对纠缠光子荧光显微镜的可行性进行了实验研究。利用非线性参数下转换产生用于荧光团激发的纠缠光。双光子吸收率的基本研究将通过测量诱导荧光来进行。