First Unified Optical-Microwave Switching Architecture with Frequency-Level Granularity for Hybrid Satellite Networks

Satellite systems serve as the core infrastructure for global connectivity. Modern communication systems mainly rely on stable microwave links and high-speed optical transmission, which have traditionally operated independently and lack a unified signal interaction mechanism. In this work, we build upon conventional all-optical switching architectures and propose the first hybrid switching system that integrates all-optical switching with microwave photonic switching. This design enables flexible optical-microwave interaction with granularity refined from the wavelength level to the frequency level. The system ensures that signals undergo at most one electro-optical-electrical (E/O/E) conversion during cross-domain switching, thereby preserving signal integrity. It features low loss, structural simplicity, and operates without requiring computing chips. We conduct both rigorous theoretical analysis and experimental validation. Specifically, we demonstrate cross-domain switching between a dual-wavelength optical signal modulated with 2×10 GBaud 8PSK subcarriers and two 2×10 GBaud QPSK microwave signals. The system achieves a switching granularity of 10 GBaud, with post-switching demodulation yielding error vector magnitudes (EVMs) no greater than 14.5%. The proposed hybrid architecture holds strong potential for future integrated space-ground communication networks.