Creating dynamic poling of ferroelectric thin films for chip-scale reconfigurable optical systems

集成光子学的概念是将薄膜技术应用于光学电路和器件，以实现高效、高性能和经济的光学系统。人们可以将该领域视为集成电路的微电子学的光学等价物。人们对集成光子学的兴趣源于对小型化、便携和高效的光通信、计算和传感平台的需求，这些平台不受大规模整体光学、分立元件和长距离光纤的限制。应用包括用于精确测量的不同颜色的光的产生、用于高速信号处理的短光脉冲的控制以及用于低噪声保密通信的光颜色的修改。为了在薄膜中制造功能光学器件，需要在千伏范围内进行一种称为极化的过程。因此，一旦由外部高压电源制造，器件就是静态的。该研究计划旨在将所需电压降低到仅几伏特。由于低电压要求，静态设备可以变为动态设备。光学系统曾经被认为是固定的和僵化的，现在变得可重构和可编程。动态功能使系统能够利用光的特性来克服电子施加的物理限制，影响信息技术、电信、医疗保健、生命科学和国防。综合教育计划通过开发古典和现代光学研讨会系列，为产生综合研究思维的综合光学课程创建新的课堂模块，并让研究生和本科生、代表性不足的群体和少数族裔参与研究计划，回应了将科学和工程与公共利益问题联系起来的挑战。首次提出了一项涉及理论、设计、建模、制造和测试的综合研究计划，以创造用于芯片上可重构光学系统的铁电薄膜的动态极化。其目标是在晶片尺度的掺镁铌酸锂薄膜中制造微尺度的平面光波导，具有光学透明的极化电极和低的矫顽场，允许片上极化和自发极化波形的编程。该设计和建模方法是基于麦克斯韦方程的非线性耦合振幅方程的数值解。该芯片将在俄亥俄州立大学使用纳米级制造技术制造。我们将演示一系列中心频率和带宽可调的非线性光学现象。展望了新的宽带和紧凑型光学系统体系结构，涉及集成电路中的光子学和电子学的融合。这项研究解决了硅中缺乏二阶磁化率的问题，这是实现芯片级非线性光学的主要障碍。该计划利用掺镁铌酸锂亚微米薄膜的低矫顽场、具有微米级模场直径的条形加载光波导、透明光学电极和片上加热器，将极化所需的电压降低到5伏以下。当直接在芯片上开发铁电域的动态极化能力时，新的视野立即变得明显。极化周期变得可调，极化电极现在可以被认为是可编程的，而不是静态的。调谐极化周期会导致相位匹配频率的动态变化。将极化编程为线性啁啾会产生对相位匹配带宽的动态控制。这些概念提供了一种在芯片上实现动态可调非线性光学系统的新方法。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 integrated photonics concept is the application of thin-film technology to optical circuits and devices for the purpose of achieving efficient, high-performance, and economical optical systems. One can view the field as the optical equivalent of microelectronics for integrated circuits. The interest in integrated photonics is driven by the need for miniature, portable, and efficient optical communications, computing, and sensing platforms that are not limited by large scale bulk optics, discrete components, and long distance optical fiber. Applications include the generation of light of different colors for precision measurements, the control of short optical pulses for high speed signal processing, and the modification of light color for low noise secure communications. To create functional optical devices in thin films, voltages in the kilovolt range are required for a process referred to as poling. Consequently, devices are static once fabricated by an external high voltage power supply. The research program aims to reduce the required voltage to only a few volts. Due to the low voltage requirements, static devices can become dynamic. Optical systems once thought of as fixed and inflexible become reconfigurable and programmable. Dynamic functionalities enable the realization of systems that utilize the properties of light to overcome the physical limitations imposed by electrons, impacting information technology, telecommunications, health care, the life sciences, and national defense. The integrated educational plan responds to the challenge of linking science and engineering to problems of public interest by developing a classical and modern optics seminar series, creating new classroom modules for integrated optics curriculum that engenders integrative research thinking, and involving graduate and undergraduate students, underrepresented groups, and minorities in the research program.A comprehensive research program is proposed involving theory, design, modeling, fabrication, and test to create dynamic poling of ferroelectric thin films for reconfigurable optical systems on a chip for the first time. The objectives are to create microscale planar optical waveguides in wafer scale thin films of magnesium oxide doped lithium niobate with optically transparent poling electrodes and low coercive field, allowing for on-chip poling and programming of the spontaneous polarization waveform. The design and modeling approach is based on numerical solutions to nonlinear coupled amplitude equations based on Maxwell's equations. The chip will be fabricated at Ohio State University using nanoscale fabrication techniques. A host of nonlinear optical phenomena with tunable center frequency and tunable bandwidth will be demonstrated. New broadband and compact optical system architectures involving the convergence of photonics with electronics in integrated circuits are envisioned. The research addresses the lack of second order susceptibility in silicon which is a major obstacle to achieving chip-scale nonlinear optics. The program exploits the low coercive field of sub-micrometer thin films of magnesium oxide doped lithium niobate, strip loaded optical waveguides with micrometer scale mode field diameter, transparent optical electrodes, and on-chip heaters to reduce the voltage required for poling to less than five volts. New horizons immediately become apparent when exploiting the capability of dynamic poling of the ferroelectric domains directly on-chip. Instead of being static, the poling period becomes tunable and poling electrodes can now be considered as programmable. Tuning the poling period results in the dynamic variation of the phase matching frequency. Programming the poling into a linear chirp produces dynamic control of the phase matching bandwidth. These concepts provide a new method of attack to achieve dynamically tunable nonlinear optical systems on a chip.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.