Efficient photonic circuits analysis method based on subnetwork growth approach

Efficient photonic circuit simulation tools are essential for the design and optimization of photonic integrated circuits (PICs). However, the computational speed of current commercial simulators remains insufficient to support large-scale circuit optimization and statistical verification. In this paper, a multimode scattering matrix computation method based on a multimode subnetwork growth approach (referred to as MSG) for efficiently calculating the frequency-domain response of photonic circuits is proposed. The presented method starts with accurate photonic devices modeling leveraging the multimode scattering matrix. It then utilizes the established multimodal models to precisely characterize component parameters and topology information of the arbitrarily interconnected multiport photonic circuit. By employing an iterative strategy that connects only two subnetworks at each step, the global response is progressively computed, which significantly reduces the complexity of matrix inversion. The sequence of network connections is optimized using a suboptimal ordering algorithm, further minimizing the total computational cost. Benchmark results demonstrate that our approach enables fast multimode simulation, delivering over twice the speed of commercial simulators and strong engineering applicability.