Taming the randomness of random lasers with reconfigurable active particle assemblies

本研究计划旨在利用可重构粒子组件，开发一种具有增强激光性能的新型随机激光系统。随机激光器依靠放大光学介质中的光散射来产生激光发射。与传统激光器相比，随机激光器具有器件制造成本低、无散斑成像空间相干性低等特点。然而，目前随机激光器在激光特性上的“驯服随机性”（如不受控制的发射方向、偏振、模态分布等）仍然受到限制，限制了其对光子应用的影响。该研究的目标是通过开发具有动态可调增益和散射景观的可重构随机激光平台来克服这些限制，以控制激光特性，如阈值，输出功率，发射方向性和偏振。所提出的方法利用可重构的、电场定向的粒子装配来控制粒子的位置和方向。电场的时空规划（例如，调整场梯度，形状和频率）加上粒子功能的多功能选择（例如，增益，散射，各向异性），提供了前所未有的能力来控制粒子群的集体激光响应。提出了三个研究目标：(1)了解和控制染料溶液中悬浮散射粒子的随机激光，包括发射方向和偏振的控制；(2)理解并控制增益和散射都由粒子提供的组件中的随机激光，包括一种同时发挥两种作用的粒子（例如ZnO）或不同的粒子组合作为增益/散射和仅散射的组件（例如ZnO+TiO2）；(3)演示反馈控制的智能随机激光，该激光可以通过学习获得所需的激光特性。该研究项目将为学生研究人员提供跨学科的、以团队为基础的培训，帮助他们成为未来的领导者。它将与以可持续发展为重点的绿色实验室工作和旨在培养未来科学家和工程师的教育活动相结合。该教育计划将支持增加多样性，并为代表性不足的群体以及K-12学生提供机会。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。

This proposed research program aims to develop a novel random laser system with enhanced lasing performance using reconfigurable particle assemblies. A random laser relies on light scattering in an amplifying optical medium to generate lasing emission. Compared to traditional lasers, the random laser has unique features such as low cost in device fabrication and low spatial coherence for speckle-free imaging. However, currently the random laser is still hindered by limited means to “tame the randomness” in its lasing properties (e.g., uncontrolled emission direction, polarization, modal profile etc.), limiting its impact on photonic applications. The goal of the proposed research is to overcome these limitations by developing a reconfigurable random lasing platform with dynamically tunable gain and scattering landscapes for controlling the lasing characteristics, such as threshold, output power, emission directionality and polarization. The proposed method leverages reconfigurable, electric field directed particle assembly to control particle locations and orientations. Spatiotemporal programming of the electric field (e.g., tuning the field gradient, shape, and frequency) coupled with the versatile choice of particle functionalities (e.g., gain, scattering, anisotropy), provides unprecedented capability to control the collective lasing response of particle populations. Three Research Objectives are proposed: (1) Understand and control random lasing in assemblies of scattering particles suspended in dye solution, including control of emission directionality and polarization; (2) Understand and control random lasing in assemblies where both gain and scattering are provided by particles, including one type of particles serving both roles (e.g., ZnO) or different particles combined to serve as gain/scattering and scattering-only components (e.g., ZnO+TiO2); (3) Demonstrate feedback controlled, smart random lasing that can learn to achieve desired lasing properties. The research program will provide cross-disciplinary, team-based training for student researchers to help prepare them as future leaders. It will be integrated with a sustainability-focused Green Lab effort and education activities aimed at training future scientists and engineers. The education plan will support increased diversities and provide opportunities for underrepresented groups as well as K-12 students.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.