Frequency-comb-steered ultrawideband quasi-true-time-delay beamformer for integrated sensing and communication

Ultrawideband beamforming is essential for next-generation radar and communication systems, however, the instantaneous bandwidth of phase-shifter-based phased array antennas (PAAs) is limited by beam squint. Photonic true-time-delay (TTD) beamformers offer a potential solution, yet their practical deployment is hindered by complex delay-line architectures. Here, we report a frequency-comb-steered photonic quasi-TTD beamforming approach that eliminates delay lines by leveraging frequency-diverse arrays and photonic microwave mixing arrays. This enables squint-free beamforming and continuous beam steering for widely used linear frequency modulation (LFM) waveforms, effectively delivering infinite spatial resolution. We present 16-element linear and 4×4 planar PAA prototypes, achieving 6 GHz instantaneous bandwidth across the entire Ku-band. Furthermore, we demonstrate integrated sensing and communication capabilities, including inverse synthetic aperture radar imaging with 2.6 × 3.0 cm resolution and 4.8 Gbps wireless transmission. This work establishes a compact, robust, and scalable architecture for ultrawideband, large-scale photonic PAAs, paving the way for future integrated radar and communication systems.