Ultrashort coherence times in partially polarized stationary optical beams measured by two-photon absorption

Prism-based approach to create intensity-interferometric non-diffractive cw light sheets

Light sheets are optical beam-like fields with one-dimensional intensity localization. Ideally, the field intensity should be independent of the longitudinal and one of the transverse coordinates, which is difficult to achieve even for truncated light sheets. In this work, we present a general theoretical framework for intensity-interferometric continuous wave (cw) light sheets formed by overlapping the interference fringe patterns of mutually uncorrelated frequency components of the field. We show that the key parameters of the light sheets can be calculated using simple analytical expressions. We propose a practical way to generate such light sheets with the help of prisms and demonstrate numerically the abilities of the method. Both bright and dark light sheets with an exceptionally small thickness and long divergence-free propagation distance are possible to generate. We also show that the transverse profile of the generated light sheets can be shaped by modifying the spectrum of the light. We believe our findings advance the beam-engineering technology and its applications.

Ultra-fast Stokes parameter correlations of true unpolarized thermal light: type-I unpolarized light

We measure Stokes parameter correlations in analogy to the intensity correlation measurements in the original Hanbury-Brown & Twiss configuration by realizing an experimental setup by combining a Schaefer-Collett or Berry-Gabrielse-Livingston polarimeter with a Hanbury-Brown & Twiss intensity interferometer. We investigate true unpolarized light emitted from a broadband thermal light source, which we realize by an erbium-doped fiber amplifier, thus being an ideal source of true unpolarized light. We find that all Stokes parameter correlations ⟨S_nS_n⟩, n∈{1,2,3} are equal to 0.5⟨I⟩². The proven invariance of the Stokes parameter correlations against retardation by wave-plates clearly shows for the first time, to the best of our knowledge, that our true unpolarized thermal light represents type I unpolarized light in accordance with a theoretical prediction for a classification of unpolarized light postulated more than 20 years ago.

Electromagnetic theory of optical coherence [Invited]

The coherence theory of random, vector-valued optical fields has been of great research interest in recent years. In this work we formulate the foundations of electromagnetic coherence theory both in the space-time and space-frequency domains, with particular emphasis on various types of optical interferometry. Analyzing statistically stationary, two-component (paraxial) electric fields in the classical and quantum-optical contexts we show fundamental connections between the conventional (polarization) Stokes parameters and the associated two-point (coherence) Stokes parameters. Measurement of the coherence and polarization properties of random vector beams by nanoparticle scattering and two-photon absorption is also addressed.