Integrated photonic receiver with synergistic modulation and demultiplexing functions for dual-band radar

Microwave photonics (MWP) has emerged as a key technology for next-generation radar, thanks to its exceptional broadband signal processing capability. In particular, dual-band or multi-band radar architectures with coherent fusion are essential for breaking the resolution limit of a single-band signal. However, the receiver of such dual-band radars faces severe constraints in size, weight, and power (SWaP), since a few different functional devices or components are required. Here, we propose a novel integrated photonic receiver on the thin-film lithium niobate (TFLN) platform, which simultaneously enables electro-optic modulation and microwave demultiplexing. As for the fabricated integrated receiver, the electro-optic modulation is realized via cascaded phase modulations, while the microwave demultiplexing is achieved through interference filtering arising from the inter-stage delay between the optical and microwave paths. This architecture features a dynamically tunable filtering period while maintaining a maximum extinction ratio exceeding 33.2 dB. Using the integrated receiver, a dual-band radar is experimentally demonstrated by adopting two linear frequency-modulated (LFM) signals centered at 3.55 GHz and 14.25 GHz respectively, each occupying a 1.3 GHz bandwidth. An equivalent bandwidth of 12 GHz was synthesized through coherent fusion of dual-band echoes, resulting in a ranging resolution of 1.27 cm. The proposed architecture greatly simplifies the front-ends by synergistic integration of electro-optic modulation and microwave demultiplexing, providing a promising chip-scale approach towards a compact solution for dual-band radars.