Assemblies of Metal Nanoparticles and Single Quantum Dots with Low-Power, Ultrafast Nonlinear Optical Response

继续建造更快、更强大的计算机的能力正在达到运行这些计算机所需的能量所设定的极限。只有制造出超快、超小和超低功率的光子器件，才有可能克服这一能量障碍，方法是用光子组件取代使用电流处理信息的电子元件。该项目开发了一类这样的设备，可以用来控制未来全光计算机中的光流动。这是通过使用化学手段来生产纳米尺度的金属和半导体颗粒，并通过将它们组装成受控的混合排列来在颗粒之间诱导强烈的光学相互作用来实现的。这些科学目标与拓宽科学队伍多样性的努力相结合，通过让高中生、本科生和研究生参与尖端研究，特别是来自代表不足的群体的学生、女学生和退伍军人。该项目的目标是生产具有超低入射功率的非线性光学响应的金属纳米颗粒(MNPs)和单量子点(Qds)的组件。这种非线性是由于纳米粒子之间的近场光学相互作用而产生的，并且与各组分的响应性质不同。通过量子点和各向异性金纳米粒子(纳米棒或双金字塔)的化学合成，单个量子点与MNPs末端的选择性共价结合形成MNP-QD-MNP三聚体，并将这些三聚体从更小和更大的组装中分离出来，制备了具有较强粒子间相互作用的胶体量子点和MNPs组装。光学功能通过相关的线性和非线性光学光谱学以及单个组件的电子显微镜成像来验证。实验结果与数值模拟结果进行了比较，从而能够详细了解结构-特性关系并优化非线性响应。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

The ability to continue to build faster, more powerful computers is reaching a limit set by the amount of energy needed to run the computers. It may be possible to overcome this energy barrier by replacing electronic components, which use electrical current to process information, with photonic components, which use light to process information, but only if ultrafast, ultrasmall, and ultra-low-power photonic devices can be built. This project develops one class of these devices, which can serve to control the flow of light in future all-optical computers. This is accomplished by using chemical means to produce nanometer-scale metal and semiconductor particles and to induce strong optical interactions among the particles by assembling them into controlled hybrid arrangements. These scientific goals are integrated with efforts to broaden the diversity of the scientific workforce, through the involvement of high-school, undergraduate, and graduate students in cutting-edge research, particularly students from underrepresented groups, female students, and veterans.The objective of this project is to produce assemblies of metal nanoparticles (MNPs) and single quantum dots (QDs) with nonlinear optical response at ultralow incident powers. The nonlinearity arises due to near-field optical interactions among the nanoparticles and is qualitatively different from the response of the components separately. Assemblies of colloidal QDs and MNPs with strong interparticle interactions are fabricated through the chemical synthesis of QDs and anisotropic gold nanoparticles (nanorods or bipyramids), the selective covalent binding of single QDs to the ends of the MNPs to form MNP-QD-MNP trimers, and the separation of these trimers from smaller and larger assemblies. Optical functionality is verified by correlated linear and nonlinear optical spectroscopy and electron-microscope imaging of individual assemblies. Experimental results are compared to numerical simulations, enabling detailed understanding of structure-property relationships and optimization of the nonlinear response.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.