Leonard Vossgrag | Searcharxiv

arXiv2026

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

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.

physics.optics↗

arXiv2025

Dynamically reconfigurable multi-wavelength interferometry

Single-wavelength interferometry achieves high resolution for smooth surfaces but struggles with rough, industrially relevant ones due to limited unambiguous measuring range and speckle effects. Multi-wavelength interferometry addresses these challenges by using synthetic waveleths, enabling a balance between extended measurement range and resolution by combining several synthetic wavelengths. This approach holds immense potential for diverse industrial applications, yet it remains largely untapped due to the lack of suitable light sources. Existing solutions are constrained by limited flexibility in synthetic-wavelength generation and slow switching speeds. We demonstrate a light source for multi-wavelength interferometry based on electro-optic single-sideband modulation. It reliably generates synthetic wavelengths with arbitrary values from centimeters to meters and switching times below 30 ms. This breakthrough paves the way for dynamic, reconfigurable multi-wavelength interferometry capable of adapting to complex surfaces and operating efficiently even outside laboratory settings. These capabilities unlock the full potential of multi-wavelength interferometry, offering unprecedented flexibility and speed for industrial and technological applications.

physics.optics↗