Silicon Programmable Photonic Circuits Based on Periodic Bimodal Waveguides

Abstract

Programmable photonic circuits are dense assemblies of waveguide meshes in which the flow of light can be reconfigured by software to implement a wide variety of functions, ranging from radiofrequency filtering to optical computing. However, most programmable architectures to date rely on rather bulky Mach-Zehnder interferometers (MZIs), which are not suitable for large-scale and high-density integration. Here, an alternative approach to MZI-based programmable photonic circuits by using slow-light-enhanced periodic bimodal waveguides (PBWs) as programmable units is presented. This study experimentally demonstrates low-loss short tuning elements of 30× 1.7 µm2 in area, achieving a two-orders of magnitude integration density improvement compared to conventional MZIs. A rectangular arrangement of these tunable units is proposed for 3× 3 and 4× 4 matrix multiplication operations to design a feedforward circuit with a footprint of only 100× 250 µm2. Finally, the performance trade-off and benchmark with alternative programmable unit cells are analyzed in order to address the ever-growing demand for large computing requirements in next-generation applications such as artificial intelligence and quantum information processing.