On-Chip Microcomb-Powered Reconfigurable Ultra-Wideband Radar Waveform Synthesis

Driven by the rapid evolution of radar systems toward higher resolution and multi-functionality, the synthesis of reconfigurable ultra-wideband waveforms has become a cornerstone of next-generation high-performance radar architectures. In this work, we propose an approach for ultra-wideband and reconfigurable radar waveform generation by leveraging an integrated microcomb chip. In the proposed system, wideband radar waveforms are generated via heterodyne detection between the output of an optical recirculating frequency-shifting loop (RFSL) and an injection-locked comb line from an on-chip electro-optic frequency comb (EOFC). Specifically, the RFSL facilitates the generation of ultra-wideband frequency-modulated optical signals, with an instantaneous bandwidth that is flexibly reconfigurable via intra-loop filter control. By employing a thin-film lithium niobate microring resonator (TFLN MRR), an EOFC with a 20 nm spectral span is synthesized. Leveraging the injection-locking of discrete comb lines, the center frequency of the generated microwave signals can be precisely tuned across a wide range. An experimental demonstration validates the system's capability to synthesize wideband linearly frequency-modulated (LFM) radar waveforms, achieving a maximum bandwidth of 39 GHz (8-47 GHz) and a center frequency tuning range exceeding 30 GHz, alongside a flexibly adjustable chirp rate. Beyond LFM microwave waveforms, the platform's versatility is underscored by the generation of reconfigurable stepped frequency-modulated (SFM) waveforms with a maximum bandwidth of 28 GHz. Combining ultra-wide bandwidth with exceptional agility, the proposed photonics-assisted radar waveform generation system provides a robust framework for next-generation high-resolution and adaptive radar applications in complex electromagnetic environments.