Chaotic frequency combs for massively parallel laser ranging

Nonlinear systems often exhibit a fascinating phenomenon called chaos, which is widely prevalent in various fields. Recently, chaotic modulation instability in continuous-wave-driven photonic-chip-based Kerr microresonators has been studied extensively. However, such chaotic states were deemed impractical for applications compared to coherent-light states like solitons, which have been widely used in optical communication and photonic computing demonstrations.

But now, researchers from EPFL, led by Tobias Kippenberg, have made a groundbreaking discovery. They found a novel way to harness the unique features of chaotic frequency combs for unambiguous and interference-immune massively parallel laser ranging. This method capitalizes on the intrinsic random amplitude and phase modulation of the chaotic comb lines, introducing a new paradigm for laser ranging in optical microresonators.

The concept behind this technique is based on random modulation continuous-wave (RMCW), where random amplitude and phase modulation are utilized to interrogate a target using amplitude and frequency cross-correlation at the detector. The EPFL team’s approach utilizes the inherent random amplitude and phase modulation of chaotic comb lines in the optical microresonator, supporting hundreds of multicolor independent optical carriers for massive parallel laser ranging and velocimetry.

As this technology gains traction, numerous LiDAR companies have already incorporated RMCW in their commercial products. This approach’s advantage lies in its immunity to mutual interference with other LiDARs and ambient light sources, making it highly desirable for the anticipated era of unmanned vehicles.

Moreover, this novel technique does not require stringent conditions on frequency noise, tuning agility, or linearity of the lasers, eliminating the need for waveform initiation routines.

The operation in the chaotic modulation instability regime surprisingly results in a wideband signal modulation of the comb lines, leading to centimeter-scale range resolution. Additionally, chaotic microcombs are power-efficient, thermally stable, simple to operate, and provide a flat-top optical spectrum.

The EPFL team’s breakthrough opens up exciting possibilities for optical ranging, spread spectrum communication, optical cryptography, and random number generation. This research not only advances our understanding of chaotic dynamics in optical systems but also provides practical solutions for high-precision laser ranging in various domains.

The findings of this research have been published in the prestigious journal Nature Photonics.

Source: Ecole Polytechnique Federale de Lausanne

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