A 5-bit, 1.6ps resolution true time delay optical beamforming network for 4-element antenna arrays

Next-generation mobile networks will use mmWave frequencies as part of their strategy to meet the ever increasing wireless data rate demands. To mitigate the challenging propagation characteristics at these high frequencies, beamforming will be key. In this paper, we discuss a true time delay optical beamforming network (OBFN) based on switchable optical delay lines for $\mathrm{a}4 \times 1$ antenna array. This OBFN is implemented on a Si-Photonics platform and the delay lines are capable of discretely tuning the delay difference between elements with a resolution of 1.6 ps up to a maximum delay of 49.6 ps.