Thin-film lithium niobate integrated photonic receiver enables high-resolution dual-band radar

Southwest Jiaotong University

Researchers at Southwest Jiaotong University have developed a thin-film lithium niobate (TFLN) integrated photonic receiver for dual-band radar, designed to simplify the receiver front-end by integrating electro-optic modulation and microwave demultiplexing on a single chip. The work, published in PhotoniX Synergy, combines the integrated photonic receiver with coherent fusion processing to synthesize an equivalent bandwidth of 12 GHz and achieve a ranging resolution of 1.27 cm, providing a highly integrated approach for high-resolution dual-band radar.

As next-generation radar systems demand higher ranging resolution and greater flexibility in spectral resources, dual-band radar with coherent fusion provides an approach to synthesize a wider equivalent bandwidth from separated sub-bands. However, conventional dual-band radar receivers typically require multiple discrete components for modulation and demultiplexing, increasing system size, weight, power consumption, and inter-component loss. Integrating these functions into a compact photonic platform therefore remains challenging.

To address these challenges, the researchers developed a dual-channel TFLN integrated photonic receiver based on cascaded phase modulators. By introducing a fixed optical delay between the modulation stages and controlling the corresponding microwave delay, the device generates complementary electro-optic responses in the two channels, enabling frequency-selective modulation and microwave demultiplexing. The modulation period can be dynamically reconfigured by adjusting the inter-stage microwave delay, while the device maintains a maximum single-tone extinction ratio exceeding 33.2 dB.

“Our approach integrates electro-optic modulation and microwave demultiplexing within a single thin-film lithium niobate receiver, reducing the number of discrete components required in the radar front-end,” said Xihua Zou, corresponding author of the paper and professor at Southwest Jiaotong University. “The frequency-selective response can be configured through the inter-stage delay, allowing the same integrated receiver architecture to process separated radar sub-bands.”

The researchers experimentally demonstrated a dual-band microwave photonic radar system based on the integrated photonic receiver, using linear frequency-modulated signals centered at 3.55 GHz and 14.25 GHz, with a bandwidth of 1.3 GHz for each band. The received radar sub-bands were subsequently processed through coherent fusion to synthesize an equivalent bandwidth of 12 GHz. In a ranging experiment, two targets separated by 1.3 cm were clearly resolved, corresponding to a ranging resolution of 1.27 cm.

“By combining integrated microwave photonic chip with coherent fusion processing, this work provides a compact approach for dual-band radar system,” said Yongtao Du, first author of the paper. “The thin-film lithium niobate platform also provides consistent channel behavior, which is beneficial for the phase stability required in subsequent coherent fusion.”