Design and numerical simulation of a multi-port 3-dB power splitter based on a hybrid MMI–MZI structure with low-loss waveguide bends and crossings on SOI platform

Abstract

Multi-directional optical power splitters with compact size and high performance are essential components in modern silicon photonic integrated circuits. However, achieving uniform power distribution across multiple directions while maintaining low loss and minimal crosstalk remains a significant challenge. In this work, a novel multi-directional 3-dB power splitter based on a hybrid multimode interference–Mach-Zehnder interferometer (MMI–MZI) configuration is proposed on a silicon-on-insulator (SOI) platform. The design employs a symmetric four-port architecture that integrates MMI regions with optimised waveguide bends and crossings, enabling simultaneous power splitting and cross routing within a single structure. By exploiting the self-imaging effect in MMI sections, both equal power division and directional signal transfer are realised in a compact footprint. Numerical results indicate that the proposed device achieves low excess loss at a wavelength of around 1.55 µm, with near-equal power distribution between the output ports and suppressed back-reflection. In addition, the structure demonstrates consistent behaviour under different propagation directions, highlighting its inherent symmetry and direction-independent operation. These features make the proposed design suitable for applications in optical interconnects, signal routing, and complex photonic integrated networks.