发表机构
Cornell University; NTT Research, Inc.; Yale University; Stanford University（康奈尔大学; NTT研究所; 耶鲁大学; 斯坦福大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本文提出在纳米光子波导内实现可编程χ(2)全息图，通过光电导电极投影实现可重构准相位匹配，支持快速更新、闭环优化及原位诊断，规避制造缺陷并保留波导优势。
AI 中文摘要
非线性纳米光子学利用纳米尺度结构中精心设计几何形状的光与物质相互作用来实现光学功能的工程化。非线性光学中的相位匹配通常对于实现所需过程的高效率和复杂功能的工程化至关重要，但在纳米光子波导中可靠地实现相位匹配可能具有挑战性。传统上，纳米光子学中的相位匹配通过纳米制造实现，例如利用具有固定几何形状的电极对器件的非线性材料进行极化。这种方法有两个缺点：器件能执行的光学功能在制造时就被固定，且器件的性能可能因制造缺陷而退化。在此，我们通过在纳米光子波导内部工程化可编程的$\chi^{(2)}$全息图来规避这些限制，实现了可在器件制造后约一秒钟内更新的可重构准相位匹配。通过将结构化的光学照明投射到光电导电极上，我们生成了电场诱导的$\chi^{(2)}$空间图案，以对三波混频过程施加光谱、模态和偏振控制。这种可编程性还使我们能够采用闭环原位优化来补偿复杂波导结构中的相位失配，例如宽度调制的波导和长度超过10厘米的螺旋波导。此外，我们展示了可编程非线性能够实现强大的原位诊断，包括各种横模的直接色散测量和片上波前相位层析成像。我们的工作为构建级联非线性纳米光子学系统开辟了可能性，在这些系统中，由于制造变化引起的良率问题可以被规避，同时保留刻蚀波导的优势，如限制和色散工程。
英文摘要
Nonlinear nanophotonics enables the engineering of optical functions using light-matter interactions in nanoscale structures with carefully designed geometries. Phase matching in nonlinear optics is typically essential for realizing high efficiency for desired processes and engineering of sophisticated functions, but it can be challenging to reliably achieve in nanophotonic waveguides. Conventionally, phase matching in nanophotonics is achieved through nanofabrication, e.g., by poling a device's nonlinear material using electrodes with fixed geometry. This approach has two drawbacks: the optical functions a device can perform are fixed at the time of fabrication, and the device's performance can be degraded by fabrication imperfections. Here, we circumvent these limitations by engineering programmable $χ^{(2)}$ holograms inside nanophotonic waveguides, enabling reconfigurable quasi-phase matching that can be updated after device fabrication in approximately one second. By projecting structured optical illumination onto photoconductive electrodes, we generated spatial patterns of electric-field-induced $χ^{(2)}$ to exert spectral, modal, and polarization control over three-wave mixing processes. This programmability also allowed us to employ closed-loop in situ optimization to compensate for phase mismatch in complex waveguide structures, such as width-modulated waveguides and spiral waveguides exceeding 10 cm in length. Furthermore, we show that programmable nonlinearity enables powerful in situ diagnostics, including direct dispersion measurements of various transverse modes and on-chip wavefront phase tomography. Our work opens up the possibility of building cascaded nonlinear nanophotonic systems where yield issues due to fabrication variations can be sidestepped while retaining the benefits of etched waveguides such as confinement and dispersion engineering.
CommentsFirst three authors contributed equally to this work; 69 pages, 5 main text figures, 1 main text table, 49 appendix figures, 3 appendix tables
