Multi-Beam Microwave Photonic Beamforming Based on Self-Coherent Detection of a WDM Signal

The increasing ubiquity of mobile services is driving wireless communications to fully exploit spatial-division multiplexing (SDM). However, SDM’s key enabling technology – the beamformer – is hindered by scalability hurdles that electronic technologies have failed to overcome. This manuscript tackles this challenge by introducing a novel photonic beamforming architecture, which leverages and combines key techniques of both past photonic beamformers and cutting-edge optical communications. The proposed architecture makes use of wavelength-division multiplexing, coherent detection, and programmable photonic processing to realize a truly scalable photonic beamformer. The proposed architecture is analytically and numerically validated, as well as experimentally demonstrated. The experimental validation includes a practical demonstration of two RF beams at $12 \,\mathrm{G}\mathrm{Hz}$ , each carrying a 1 GBd QPSK signal, being independently beamformed, and down-converted to $5 \,\mathrm{G}\mathrm{Hz}$ .