Design and characterization of a photonic integrated circuit for beam forming in 5G wireless networks

We present the design and experimental characterization of a silicon-on-insulator photonic integrated circuit to be used as building block in photonics-based beamforming networks for 5G wireless systems. The integrated module controls the phase of the millimeter-wave signals transmitted and received by an antenna element in a phased-array antenna. It comprises an optical de-interleaver for carrier-sideband separation, a microring resonator (MRR) -based phase-shifter (PS) and a carrier depletion-based MRR electro-optic modulator. The photonic de-interleaver enables flexible operation with different RF frequencies. The PS exploits two thermally-tunable cascaded MRRs that allow continuous shifting of the carrier phase over more than 400 degrees. The device is proved allowing a precise beamforming control with a power consumption of few tens of mWs per antenna element.