Reconfigurable photonic integrated circuits for space applications

Integrated photonics is rapidly emerging as a transformative technology for space engineering, expected to disrupt satellite systems in much the same way fiber optics reshaped terrestrial networks. Photonic integrated circuits (PICs), conceived as scalable systems-on-chip, provide decisive advantages in terms of size, weight, power efficiency, bandwidth, and reconfigurability, all of which are critical within the NewSpace paradigm of reduced cost, rapid development cycles, and proliferating small-satellite constellations. With a market projected to grow from hundreds of millions to several billions of dollars within a decade, PICs combine compactness with embedded computing capabilities and high functional integration, positioning them as indispensable building blocks for future payloads. This thesis investigates the use of integrated photonic devices and photonic integrated circuits to enable advanced functionalities in satellite payloads, with particular focus on reconfigurable filtering, beamforming, and on-board data processing for Synthetic Aperture Radar (SAR) systems. The work first analyzes the requirements and architectures of reconfigurable photonic filters, introducing novel schemes based on cascaded ring resonators and coupled-resonator optical waveguides (CROWs) to achieve wide tunability and low insertion loss. Subsequently, photonic beamforming networks for next-generation phased array antennas are addressed, with emphasis on architectures exploiting delay lines, asymmetric power splitters, or metasurfaces for wideband beam steering and optical intersatellite links. Finally, a fully reconfigurable integrated photonic FFT processor for on-board SAR data processing is proposed. This architecture overcomes the main limitations of conventional electronic processors and previously reported optical approaches, enabling real-time data compression directly in orbit. The integration of these building blocks culminates in the design of a complete photonic SAR payload system, comprising a linearly chirped waveform generator, a beamforming network, and an FFT processor. The proposed solutions are benchmarked against state-of-the-art technologies and validated against the requirements of representative Earth observation missions, such as COSMO-SkyMed and Sentinel-1, or Agencies and Space companies constraints. Results demonstrate that photonic integration not only ensures compliance with stringent spaceborne specifications but also enables miniaturization, reduced power consumption, and enhanced functionality, thereby addressing the emerging needs of distributed SAR constellations and small-satellite platforms. The contributions of this thesis provide a comprehensive analysis of the role of photonic technologies in future satellite payloads, paving the way toward fully photonic SAR instruments. These advances highlight the potential of photonics to transform next-generation space missions, where reconfigurability, scalability, and real-time processing will be essential to meet the challenges of Earth observation, global monitoring, and secure space communications.