Spectral Vector Beams for High-Speed Spectroscopic Measurements

TL;DR

This paper introduces spectral vector beams generated by ultrafast lasers, enabling high-speed spectroscopic measurements through polarization state detection, with potential for GHz read-out rates and broad spectral range applications.

Contribution

The work presents a novel method to generate and tune spectral vector beams and demonstrates their use for rapid spectroscopic measurements using polarization detection.

Findings

Achieved 6 MHz read-out rate for spectroscopic measurements.

Demonstrated potential for GHz read-out rates with improved modulation.

Extended spectral range to over 1000 nm using supercontinuum sources.

Abstract

Structured light harnessing multiple degrees of freedom has become a powerful approach to use complex states of light in fundamental studies and applications. Here, we investigate the light field of an ultrafast laser beam with a wavelength-depended polarization state, a beam we term spectral vector beam. We demonstrate a simple technique to generate and tune such structured beams and demonstrate their spectroscopic capabilities. By only measuring the polarization state using fast photodetectors, it is possible to track pulse-to-pulse changes in the frequency spectrum caused by, e.g. narrowband transmission or absorption. In our experiments, we reach read-out rates of around 6 MHz, which is limited by our technical ability to modulate the spectrum and can in principle reach GHz read-out rates. In simulations we extend the spectral range to more than 1000 nm by using a supercontinuum light source, thereby paving the way to various applications requiring high-speed spectroscopic measurements.