Photonic-enabled Microwave/millimeter-wave Phased Array Antennas： A Review of Three Typical Architectures （Invited）

Phased array antennas， renowned for their capability to flexibly control spatially radiated electromagnetic waves， are widely used in fields such as communications， detection， and electronic warfare. As system demands for higher gain and broader operating bandwidth continue to increase， phased array antennas are evolving toward larger scales and higher operating frequencies.Photonics technology exhibits notable advantages including strong resistance to electromagnetic interference， low transmission loss， and large operating bandwidth， offering new possibilities for further enhancing the performance of phased array antennas. By integrating optical and electromagnetic waves and leveraging the flexible control of optical parameters such as delay and intensity， it has become an important direction for the development of microwave and millimeter-wave phased array antennas. Within the framework of optoelectronic integration， relevant technical approaches can be categorized into three typical implementations： optical true-time-delay phased arrays， laser-space-fed phased arrays， and optically controlled metasurface antennas. The first two focus on providing high-precision time delay in the optical domain or through optical links， while the latter employs optical means to dynamically control the electromagnetic response of metasurface units.Specifically， optical true-time-delay phased arrays utilize the large tuning range and low-loss characteristics of optical delay lines to achieve real-time delay control in the optical domain， effectively mitigating beam squint issues during wideband， large-angle scanning， thereby supporting beamforming and steering of wideband signals. Laser-space-fed phased arrays leverage the low-crosstalk nature of laser carriers to transmit optically carried microwave and millimeter-wave signals to radiating elements via free-space optical links， offering the potential to simplify complex electrical interconnections in large-scale arrays and providing a new technical pathway for implementing high-frequency， large-scale phased arrays. Optically controlled metasurface antennas retain the advantages of electronic metasurfaces， such as low cost and easy integration， while introducing light as an additional control dimension to enhance flexible beam manipulation. Moreover， thanks to the good penetration of light in underwater environments， this technology shows potential for future integrated space-air-ground-sea systems. It is worth noting that the rapid development of optoelectronic integration technology is driving continuous improvements in the performance， integration level， and cost-effectiveness of photonic devices. This lays a solid foundation for the miniaturization， integration， and weight reduction of optoelectronically integrated phased array systems， and also points to important technical directions for addressing the limitations in array scale.This paper focuses on optoelectronically integrated microwave and millimeter-wave phased array antenna technology， with emphasis on the three typical architectures mentioned above： optical true-time-delay phased arrays， laser-space-fed phased arrays， and optically controlled metasurface antennas. It outlines their key technologies and development trajectories， reviews representative research progress， and， on this basis， analyzes and prospects the future application potential of optoelectronic integration technology in the field of optoelectronically converged phased arrays.