RUI: Unilateral Lasing in Underwater Animals

非技术描述：自然界中一些最鲜艳的颜色不是由吸收光的染料或颜料引起的，而是由物体的非常微观的结构引起的。许多热带鱼通过被称为彩虹团的特殊细胞内的小平面结构反射的光波的干涉显示出美丽的彩虹色。这些反射结构与现代显微激光技术有相似之处。虹膜细胞可以注入荧光分子并发光，而不是反射光。虹膜团内部的结构使光在很长一段时间内反弹，这就产生了在微观尺度上发射激光所必需的反馈。该项目的目标是更好地了解激光散射和荧光生物结构的发射，并利用这些信息作为工具，获得围绕某些特殊细胞中发现的微观结构的新见解。为此，将使用基于光的实验方法以及原子级的尖端悬臂和电子束来探测从两种不同鱼类中发现的虹膜团发出的激光的潜在物理特性。将发展模型，以便对观测到的现象有更深入的了解。了解生物介质的激光发射可以潜在地影响生物学、激光物理学、材料科学和医学领域。通过这项提案，将专门为本科生和高中生创造对培养未来科学家和工程师至关重要的研究机会。技术描述：淡水鱼（Paracheirodon innesi）和入侵夏威夷珊瑚礁的海鱼（Cephalopholis argus）都有一种叫做虹膜细胞的特殊色素体细胞，这种细胞由于反射光的干扰而呈现出彩虹色。经科学验证的鸟嘌呤/细胞质多层结构可以作为多层分布反馈激光结构。增益将通过高量子产率的荧光发色团通过各种方法通过脂质双分子层膜的扩散引入细胞质层。研究了两种荧光团的激光阈值行为和斜率效率，以及光子晶体结构物理变化引起的激光发射可调性。鸟嘌呤血小板的尺寸将决定单个鸟嘌呤晶体血小板的结构，透射电子显微镜技术将成像光子晶体结构的横截面。基于物理的现象学模型将从物理、电子束、线性光学和激光测量发展。激光发射结果将通过利用原子力显微镜和透射电子显微镜研究获得的空腔信息进行时域有限差分模拟测试。这两种鱼类的发射特性将与无机、有机和生物激光的既定结果进行比较。从基本的角度来看，可调谐激光器的新激光结构可以从复杂生物结构的激光研究中得到。从系统的角度来看，这项研究将进一步加深我们对动物体内相干光的产生和操纵的理解。从工程的角度来看，新的生物相容性和/或生物源设计的微观激光器将实现。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Nontechnical Description:Some of the most brilliant colors in nature are not caused by light-absorbing dyes or pigments, but rather from the very microscopic structure of objects. Many tropical fish display beautiful iridescent colors through the interference of reflected light waves from small planar structures inside specialized cells called iridophores. These reflective structures have similarities to modern microscopic laser technologies. Instead of reflecting light, iridophore cells can be infused with fluorescent molecules and emit light. The structures inside the iridophores cause light to bounce around for long periods of time which causes the feedback necessary for laser emission at the microscopic scale. The project’s goals are to better understand laser light scattering and emission from iridescent biological structures and use this information as a tool to gain new insights surrounding the microscopic structures found in some specialized cells. To this end, the underlying physics of laser light emitted from the iridophores found in two different fish species will be probed using light-based experimental methods as well as atom-scale tipped cantilevers and beams of electrons. Models will be developed to gain a deeper understanding of the observed phenomena. Understanding laser emission from biological media can potentially impact the fields of biology, laser physics, materials science, and medicine. Research opportunities, critical to training future scientists and engineers, will be created specifically for undergraduate and high school students through this proposal. Technical Description:The freshwater fish, Paracheirodon innesi, and the marine fish invasive to Hawaiian reefs, Cephalopholis argus, have specialized chromatophore cells called iridophores that exhibit iridescent colors caused by the interference of reflected light. The scientifically verified multilayer guanine/cytoplasm structures in Paracheirodon innesi that cause the colorful appearance can act as a multilayer distributed feedback laser architecture. Gain will be introduced into the cytoplasm layers through diffusion of fluorescent chromophores with high quantum yields that are passed across the lipid bilayer membrane through various methods. The laser threshold behavior and slope efficiencies will be studied in the iridophores of both species as well as the laser emission’s tunability from induced physical changes in the photonic crystal structures. The guanine platelet dimensions will determine the structure of individual guanine crystal platelets, and transmission electron microscopy techniques will image cross sections of the photonic crystal structures. Physics-based phenomenological models will be developed from physical, electron beam, linear optical, and laser measurements. The laser emission results will be tested against finite-difference time-domain simulations using cavity information gained from atomic force microscopy and transmission electron microscopy studies. The emission characteristics in both fish species will be compared with established results for inorganic, organic, and biological lasers. From a fundamental perspective, new laser architectures for tunable lasers could result from this study of lasing in complex biological architectures. From a systems perspective, the investigation will further our understanding of the production and manipulation of coherent light in animals. From an engineering perspective, new biocompatible and/or biogenic designs for microscopic lasers will be realized.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.