AI 中文总结
本文提出双折射有效折射率法，结合伴随拓扑优化与工艺约束，设计出性能良好的薄膜铌酸锂波长解复用器，可优化多功能光子器件以用于非线性光学和量子应用。
AI 中文摘要
薄膜铌酸锂（TFLN）光子器件的逆设计计算需求极高，因为光学双折射和工艺诱导的倾斜侧壁通常需要三维电磁模型。本文提出一种双折射有效折射率（BEI）方法，将该问题简化为二维问题，同时保留与偏振相关的平板限制及刻蚀几何的代表性横截面。该方法结合伴随拓扑优化与工艺约束，设计了一款尺寸为30×10μm的解复用器，可将1550nm和775nm光路由至不同输出端口。与三维有限差分时域模拟的定量比较证实了该简化模型的准确性及刻蚀深度依赖性。制备的器件在1540-1560nm波段的平均串扰抑制比为13.9dB，在770-780nm波段为13.3dB；两级级联配置使电信波段的输出消光比提升至26.8dB，近可见光波段提升至20.3dB。这种感知工艺的降维方法可实现TFLN平台上用于非线性光学和量子应用的多功能光子器件优化。
英文摘要
Inverse design of thin-film lithium niobate (TFLN) photonic devices is computationally demanding because optical birefringence and fabrication-induced slanted sidewalls generally require three-dimensional electromagnetic models. We introduce a birefringent effective-index (BEI) method to reduce this problem to two dimensions while retaining polarization-dependent slab confinement and a representative cross section of the etched geometry. The method is integrated with adjoint topology optimization and fabrication constraints to design a 30 x 10 um demultiplexer that routes 1550 and 775 nm light to separate output ports. Quantitative comparisons with three-dimensional finite-difference time-domain simulations establish the accuracy and etch-depth dependence of the reduced model. The fabricated device provides mean signal-to-crosstalk ratios of 13.9 dB across 1540-1560 nm and 13.3 dB across 770-780 nm. A two-stage cascaded configuration increases the output extinction ratio to 26.8 dB in the telecom band and 20.3 dB in the near-visible band. This fabrication-aware reduced-dimensional approach enables optimizations of the multifunctional photonic devices for nonlinear optical and quantum applications on the TFLN platform.
Comments32 pages, 7 figures, Supporting Information (23 figures)
