Correlating space, wavelength, and polarization of light: Spatio-Spectral Vector Beams

TL;DR

This paper introduces a novel class of light fields that simultaneously correlate space, wavelength, and polarization, enabling advanced studies of non-separable classical light and potential applications in imaging and spectroscopy.

Contribution

It extends the concept of vector beams by combining spatial, spectral, and polarization degrees of freedom into a non-separable light state.

Findings

Degree of polarization depends on narrow spatial and spectral definitions.

Analogies to quantum coherence loss are demonstrated.

Potential for new imaging and spectroscopic techniques.

Abstract

Increasing the complexity of a light field through the advanced manipulation of its degrees of freedom (DoF) provides new opportunities for fundamental studies and technologies. Correlating polarization with the light's spatial or spectral shape results in so-called spatial or spectral vector beams that are fully polarized and have a spatially or spectrally varying polarization structure. Here, we extend the general idea of vector beams by combining both approaches and structuring a novel state of light in three non-separable DoF's, i.e. space, wavelength, and polarization. We study in detail their complex polarization structure, show that the degree of polarization of the field is only unveiled when the field is narrowly defined in space and wavelength, and demonstrate the analogy to the loss of coherence in non-separable quantum systems. Such light fields allow fundamental studies on the non-separable nature of a classical light field and new technological opportunities, e.g. through applications in imaging or spectroscopy.