Space Division Multiplexed Optical Coherence Tomography on a Silicon Chip―An Experimental and Numerical Analysis of Potential Artifacts

This work presents a detailed experimental and numerical study of a multi-arm on-chip optical coherence tomography (OCT) system employing a space division multiplexing (SDM) approach. While SDM-OCT systems promise enhanced imaging speeds, they also introduce complexities in signal processing due to challenges like crosstalk between ports, cross-referencing, multiple reflections among the sample, chip, and input fiber facet, as well as mixed polarization states of light. To address these challenges, we developed and characterized single-arm and four-arm on-chip SDM-OCT systems using a low-loss silicon nitride platform. Through rigorous experiments, we identified the key sources of artifacts and numerically validated their effects. Furthermore, we proposed practical strategies to mitigate these issues. We believe our experimental findings, numerical analysis, and proposed solutions provide a robust foundation for advancing SDM-OCT system designs in future research.