Non-Uniform Programmable Photonic Waveguide Meshes

[EN] Multipurpose photonic processors have emerged as a powerful platform for implementing diverse optical functions on a chip via software-driven reconfiguration. At the core of these processors, photonic waveguide meshes enable flexible light routing and manipulation. However, recirculating meshes are limited by the fixed dimensions of their cells, constraining their spectral and temporal resolution. Here, we introduce the concept of non-uniform programmable waveguide meshes by incorporating defect cells into a uniform hexagonal architecture. These defect cells preserve an external hexagonal perimeter while embedding smaller internal sub-cells that modify the spectral response via the Vernier effect. By coupling cells with different optical path lengths, we achieve a tenfold increase in free spectral range (FSR) up to 133 GHz and reduce sampling times from 75 to 7.5 ps, surpassing the capabilities of conventional programmable meshes. Beyond broadband signal processing, it paves the way for advanced applications in topological photonics, quantum information processing, and high-speed optical computing.