Recirculating frequency-shifting loop for flexible optical chirp generation and FMCW LiDAR

TL;DR

This paper introduces a recirculating frequency-shifting loop that generates highly tunable, coherent optical chirps for FMCW LiDAR, achieving fast, flexible, and high-bandwidth laser pulses suitable for compact ranging systems.

Contribution

The work presents a novel FSL-based source capable of producing fast, tunable optical chirps with high bandwidth and demonstrates its application in FMCW LiDAR measurements.

Findings

Achieved 10 GHz chirp bandwidths with nanosecond durations.

Demonstrated FMCW LiDAR measurements up to 3 meters.

Enabled deterministic waveform synthesis using low-frequency electronic signals.

Abstract

A recirculating frequency-shifting loop (FSL) provides a highly flexible platform for generating coherent optically chirped light with tunable bandwidth, duration, chirp rate and repetition rate. The properties of the chirped light are controlled using low-frequency sinusoidal electronic drive signals, enabling deterministic waveform synthesis without complex high-speed electronics. We achieve chirp bandwidths of 10 GHz with a duration in the nanosecond regime, representing one of the fastest tunable laser sources to date. Using such chirped laser pulses, we demonstrate coherent FMCW LiDAR measurements over distances up to 3 m, highlighting the potential of FSL-based sources for compact, scalable and high-performance ranging systems.