RUI: Unilateral Lasing in Underwater Animals

自然界中一些最鲜艳的颜色不是由吸光染料或颜料引起的，而是由物体的微观结构引起的。许多热带鱼通过来自称为虹彩细胞的专门细胞内的小平面结构的反射光波的干涉而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。虹膜细胞内部的结构使光长时间地反弹，这导致了微观尺度上激光发射所必需的反馈。该项目的目标是更好地了解激光散射和虹彩生物结构的发射，并使用这些信息作为工具，以获得围绕在一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尖端杠杆和电子束来探测从两种不同鱼类中发现的虹膜细胞发射的激光的基本物理学。将开发模型，以更深入地了解观察到的现象。了解生物介质的激光发射可能会对生物学、激光物理学、材料科学和医学等领域产生潜在影响。研究机会，培养未来的科学家和工程师至关重要，将通过这一建议专门为本科生和高中生创造。技术描述：淡水鱼Paracheirodon innesi和入侵夏威夷珊瑚礁的海洋鱼类Cephalopholis argus具有称为虹膜细胞的特殊色素细胞，这些细胞通过反射光的干涉而呈现彩虹色。科学验证的多层鸟嘌呤/细胞质结构，在Paracheirodon innesi，导致彩色的外观可以作为一个多层分布反馈激光架构。增益将通过具有高量子产率的荧光发色团的扩散引入细胞质层，所述荧光发色团通过各种方法穿过脂质双层膜。激光阈值行为和斜率效率将在这两个物种的iridophores以及激光发射的可调谐性从诱导的物理变化的光子晶体结构进行研究。鸟嘌呤小片尺寸将决定单个鸟嘌呤晶体小片的结构，并且透射电子显微镜技术将对光子晶体结构的横截面成像。基于物理的唯象模型将从物理，电子束，线性光学和激光测量中发展出来。激光发射的结果将进行测试，对有限差分时域模拟使用腔的信息从原子力显微镜和透射电子显微镜的研究。这两种鱼类的发射特性将与无机，有机和生物激光器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器架构可以从复杂生物架构中的激光研究中产生。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/或生物的设计显微激光器将实现。这个奖项反映了NSF的法定使命，并已被认为是值得通过评估使用基金会的智力价值和更广泛的影响审查标准的支持。

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.