High-efficiency scattering field modeling in metallic components: a machine-learning-inspired approach.

We present a highly efficient method for characterizing the scattering field distribution of surface plasmon polaritons in metallic components by combining the eXtended Pseudospectral Frequency-Domain (X-PSFD) method with an iterative, machine-learning-inspired procedure. Shifting away from traditional matrix operations, we utilize the "Adam" optimizer-an effective and swift machine learning algorithm-to solve the scattering field distribution. Our method encompasses the derivation of the associated cost function and gradient differentiation of the field, leveraging spectral accuracy at Legendre collocation points in the Helmholtz equation. We refine the total-field/scattered-field (TF/SF) formulation within the X-PSFD framework for optimized incident field management and employ Chebyshev-Lagrange interpolation polynomials for rapid, accurate computation of broad-band results. To ensure global accuracy, we introduce unique physical boundary conditions at subdomain interfaces. Demonstrating our method's robustness and computational efficiency, we model perfect electric conductors (PECs) and silver nanocylinders, and we apply our approach to analyze the excited electric field on subtly distorted metallic surfaces, particularly plasmonic structures, thereby validating its wide-ranging effectiveness.

Excitation of surface plasmon mode in bulk semiconductor lasers.

We propose a realistic process for the excitation of surface plasmon polariton (SPP) modes in a silicon photonic waveguide (WG). The process involves the placement of buried oxide (BOX) composed of silica between a WG and silicon substrate. When the BOX thickness is manipulated, different amounts of modal power leak toward the BOX into the substrate and simultaneously acquire compensation from a semiconductor located on the WG. The compensation related to the leakage can be used to infer transparency gain. Similar to the case for a semiconductor laser cavity, the lowest transparency gain among WG modes can be favored; thus, only one mode can survive in the WG, and it is in the region with the specified BOX thickness. Finally, we propose a credible mechanism suitable for demonstrating the region requirements of the existence of SPP modes.