Enabling photonic integration technology for microwave photonics in 5G systems

Within the European project HAMLET, we develop a large scale photonic integrated circuit as a flexible interface between the optical front-haul part and the wireless access part at the remote antenna units (RAU) of future 5G networks. The circuit will be based on the hybrid integration of a polymer platform (PolyBoard) with a low-loss silicon-nitride platform (TriPleX), and will accommodate a number of processing functionalities in the digital and analog domains including optical beamforming. The analog optical link on-chip will be based on the use of graphene-based electro-absorption modulators in the polymer part of the circuit and will be able to transfer through the optical beamforming network radio signals at 28 GHz with 1 Gbaud symbol rate and modulation format up to 64-QAM. In this paper, we present early experimental results with bulk components that emulate the operation and evaluate the expected performance of our optical system on-chip.