Silicon integrated microwave photonic beamformer

Optical beam-forming networks (OBFNs) based on optical true-time delay lines (OTTDLs) are well known as the promising candidate for solving the bandwidth limitation of traditional electronic phased array antennas (PAAs) due to beam squinting. Here we report, to the best of our knowledge, the first monolithic 1 x 8 microwave photonic beamformer, based on switchable OTTDLs on the silicon-on-insulator platform. The chip consists of a modulator, an eight-channel OBFN, and eight photodetectors, thus including hundreds of active and passive components in total. It has a wide operating bandwidth from 8 to 18 GHz, which is almost two orders larger than that of electronic PAAs. The beam can be steered to 31 distinguishable angles in the range from -75.51 degrees to 75.64 degrees, based on the beam pattern calculation with the measured radiofrequency response. The response time for beam steering is 56 mu s. These results represent a significant step toward the realization of integrated microwave photonic beamformers that can satisfy compact-size and low-power consumption requirements for the future radar and wireless communication systems. (C) 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement