Innovative optical beam steering network for sub-meter satellite SAR

This paper reports on designing an innovative spaceborne SAR with a sub-meter spatial resolution (< 90 cm) in Stripmap mode. The study particularly focuses on the photonic beam steering network operating in the Ka-band (35.75 GHz), which exhibits a 45 dB directivity while ensuring a squint-free bandwidth of 0.5 GHz and a steering angle of +/- 15 degrees The designed network includes wide-tunable external-cavity laser diodes, tuned to steer the beam in the desired direction, electro-optic modulators, innovative asymmetric power splitters, fixed delay lines, and photodiodes. The whole network can be integrated into a single silicon photonics chip, resulting in a highly compact and integrated solution. Furthermore, the proposed architecture overcomes the need for tunable delay lines, thus drastically reducing design and fabrication costs and overall system power consumption (1 kW).