Development of a Broadband Integrated Microwave Photonic Beamformer for 5G applications

Microwave photonics (MWP) is an emerging field in which radio frequency (RF) signals are generated, distributed, processed, and analyzed using the advantages of photonic techniques such as large RF frequency bandwidth capability and absence of cross-talk between integrated waveguides. Using this technology numerous functionalities become feasible in the microwave domain. In particular the use of photonic integrated circuit (PIC) technology in MWP to enhanced functionalities and increase the robustness as well as the reduction of size, weight, cost as well as power consumption [1]. For this reason, over the last few years, a tremendous amount of research and development was focused to our hybrid PIC platform to combine Si3N4-based TriPleX with InP [2, 3]. The need of hybrid integration is evident as the advantages of both platforms can be combined. Figure 1 and 2 show a schematic and photograph of a state-of-art microwave photonic beamformer, respectively. The laser light is generated in the hybrid InP-TriPleX laser then modulated by incoming RF signals in the InP chip with an array of 30 GHz modulators. The modulated signals are then processed in the beamforming network on TriPleX and finally converted back to the RF domain in an InP chip with an array of 40 GHz detectors. An additional fiber array is connected to the TriPleX chip for the sole purpose of testing and calibration or possible remoting of the signals. The processing (splitting, combining, filtering, beamforming, phase, and delay tuning) is performed on the ultra-low loss (