Recently, the research team led by Professor Xingjun Wang and Researcher Haowen Shu at the Center has achieved a significant breakthrough in the field of integrated optical computing and sensing. Their work, entitled “Ultralow-latency spectral-resolving for coherent ranging via an optical frequency-shifting loop computing system,” has been published in the journal APL Photonics.

In this study, the team for the first time deeply integrates an optical Fourier transform (OFT) system driven by a frequency-shifting loop (FSL) with frequency-modulated continuous-wave (FMCW) LiDAR. This integration enables real-time spectral analysis in the optical domain with nanosecond-level latency, providing a new generation of optoelectronic computing solutions for high–real-time-demand applications such as autonomous driving and space exploration.

Research Background:
FMCW LiDAR determines target distance and velocity by analyzing the beat frequency between the received echo and the local laser. However, conventional spectral analysis relies on electronic Fourier transforms, which suffer from microsecond-level latency and susceptibility to electromagnetic interference. While traditional OFT schemes can exploit the ultrafast speed and strong anti-interference capability of optics, they typically require large dispersion, leading to increased processing delay and a trade-off between time window and spectral resolution.

Technical Breakthrough:
In this work, the researchers construct an OFT system based on an optical frequency-shifting loop. By leveraging the frequency-shifting and time-delay characteristics of the FSL, the spectral information of the FMCW LiDAR beat signal is directly mapped into a time-domain pulse sequence, enabling real-time retrieval of target distance and velocity. Through optimized parameter matching among subsystems, the optical processing is synchronized with the LiDAR frequency sweep, significantly reducing computational latency and enhancing robustness against interference. The system achieves a frequency resolution of 15 kHz over a 40 GHz bandwidth (corresponding to a ranging precision of 7 mm), with a processing latency reduced to below 20 ns—representing a 20-fold improvement over conventional electronic FFT methods. Experimental demonstrations validate static and dynamic ranging as well as three-dimensional imaging using purely optical spectral computing.

Application Prospects:
This technology offers a low-latency and highly reliable optical signal processing solution for scenarios with stringent real-time requirements, such as real-time obstacle avoidance in autonomous driving and on-orbit space services, as well as environments subject to strong electromagnetic or radiation interference. It effectively advances LiDAR data processing toward lower latency and higher immunity to interference.

Original Article Link:
https://doi.org/10.1063/5.0287712