RII Track-4: NSF: Development of Semiconductor Lasers and Passive Devices on a Single Sapphire Platform for Integrated Microwave Photonics

该项目的目标是为集成微波光子学（IMWP）技术开发一种新的蓝宝石平台，将无线信号处理和传输的挑战从电子领域转移到光子领域，可以为实现更高的数据通信速率提供丰富的新机会。Sapphire平台特点：（1）由于紧密匹配的热膨胀系数，更有利于优良激光材料的集成，以及（2）使用氮化硅技术可获得的超低损耗波导。该NSF EPSCoR RII Track-4项目为阿肯色州大学的一名副教授和一名研究生提供奖学金，以访问位于阿灵顿的德克萨斯大学，旨在建立强大的研究合作，以支持推进蓝宝石IMWP技术的长期研究目标。这项工作奠定了基础，调查的可行性，获得一套完整的高性能光学元件异质集成在一个单一的蓝宝石平台。如果成功，新的蓝宝石平台将在国防系统（如雷达信号处理）和众多民用应用（如5G系统、蜂窝和医疗成像系统）中有巨大的应用。除了研究生和本科生的参与，首席研究员从当地HBCU招募学生。该项目的愿景是利用一种新的材料系统，在单个芯片上实现微波光子学的有源和无源光电子元件的异构集成。其动机在于蓝宝石的可行性，为一个完全集成的解决方案，包括一套完整的组件与光源，调制器，光检测，波导，耦合器，谐振器，CMOS控制电路，蓝宝石上的硅（SOS）电路一体化蓝宝石平台，以实现高性能低成本的混合信号光链路。蓝宝石平台采用成熟的SOS CMOS和RF高频电路技术，具有低功耗的特点。蓝宝石平台具有（1）不能传导电流，从而减少寄生效应;（2）足够的光学折射率对比度，导致低光功率损耗;以及（3）非常独特地，与许多III-V族材料匹配的优异的热膨胀系数，用于高操作可靠性。研究目标集中于蓝宝石激光器和无源器件构建模块的开发，包括波导（直波导和弯曲波导）、分光器、耦合器和环形谐振器。研究目标是：（1）透过发展晶圆间共价键合技术，在蓝宝石基板上获得高性能的III-V族激光器;（2）利用新设计的蓝宝石氮化硅技术，开发低损耗波导;及（3）开发谐振器、耦合器等，以获得一套无源器件。所提出的基于租用的技术提供了在铸造厂制造时以非常低的成本降低尺寸重量和功率（SWaP）的承诺。该奖项反映了NSF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。

The goal of this project is to develop a new sapphire platform for integrated microwave photonics (IMWP) technology, which transfers wireless signal processing and transmission challenges from the electronic to the photonic domain, could provide a wealth of new opportunities to achieve higher data communication rate. Sapphire platform features: (1) more favorable for the integration of excellent laser materials due to a closely matched coefficient of thermal expansion, and (2) attainable ultra-low-loss waveguides using silicon nitride technology. This NSF EPSCoR RII Track-4 project provides a fellowship to an Associate Professor and a graduate student at the University of Arkansas to visit the University of Texas at Arlington, aiming to establish a strong research collaboration that would support the long-term research goal to advance sapphire based IMWP technology. This work lays the foundation to investigate the feasibility of obtaining a complete set of high-performance optical components heterogeneously integrated on a single sapphire platform. If successful, the new sapphire platform would have tremendous applications in defense systems, such as Radar signal processing, and numerous civilian applications, such as 5G system, cellular, and medical imaging systems. In addition to the involvement of graduate and undergraduate students, the principal investigator recruits students from a local HBCU. The vision of this project is to leverage a new material system to enable heterogeneous integration of active and passive optoelectronics components, for microwave photonics, on a single chip. The motivation lies in the feasibility of sapphire for a fully integrated solution to include a complete set of components with light source, modulator, light detection, waveguides, couplers, resonators, CMOS control circuit, Silicon on Sapphire (SOS) circuit all-in-one sapphire platform to achieve high-performance low-cost mixed-signal optical links. The proposed sapphire platform utilizes the mature SOS CMOS and RF high frequency circuit technology featuring low power consumption. The sapphire platform has the (1) inability to conduct current thereby reducing parasitics; (2) sufficient optical index contrast resulting in low optical power loss; and (3) very uniquely, an excellent thermal expansion coefficient match to many III-V materials for high operating reliability. The research goal focuses on the development of sapphire based lasers and passive device building blocks including waveguides (straight and bend), splitters, couplers, and ring resonators. The research objectives are: (1) obtain the high performance III-V lasers on sapphire substrate via the development of wafer-to-wafer covalent bonding technology; (2) develop the low loss waveguide using the newly designed silicon nitride on sapphire technology; and (3) develop the resonators, couplers, etc. to obtain a set of passive devices. The proposed sapphire-based technology offers the promise of reduced size weight and power (SWaP) at a very low cost when manufactured in a foundry. This has the potential to benefit many applications in Radar signal processing, 5G system, satellite communications, and medical imaging systems.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.