Characterization of spatial polarization fluctuations in scattered field

Abstract

We extend the concept of Poincare vector correlations for the characterization of spatial polarization fluctuations of scattered fields. Spatial (rather than temporal) dynamics of polarization in the scattered field is investigated experimentally by detecting instantaneous polarization with a specially designed polarization interferometer. Use of the Poincare-vector correlation in characterization is demonstrated by determining polarization dynamics of three different cases of scattered fields. This confirms usefulness of the proposed technique in diagnosis of scatterers. Under the condition of spatial ergodicity and Gaussian statistics of the scattered field, we replace the ensemble average of the instantaneous field with the space average, and estimate generalized Stokes parameters (GSPs) of the polarization speckles. Results of GSPs are used to obtain spatial correlation of the Poincare vectors.

Poincare vector correlations to estimate polarization dynamics in the laser speckle

“…We use the two-point correlation of SPs for the estimation of the correlation of the Poincare vector to access the spatial polarization dynamics. For this purpose, the normalized polarization correlation function is expressed [41] as Upper limit of g p correspond to the same SOPs at points r r and , 1 2 whereas lower limit of g p correspond to mutually orthogonal SOPs at points r r and .…”

“…A study on polarization dynamics to measure the characteristic time, called polarization time, has been experimentally implemented [40]. However, such a study has not attracted much attention to the spatially fluctuating light except for a recent study using a polarization interferometer [41].…”

“…A concept of spatial polarization length specifies this length scale during which the SOP of the fluctuating field stays unaltered. Mathematically, the spatial polarization length is defined as the length at which g D ( ) r p decreases to half of its greatest worth as prescribed in [41].…”

Autocorrelation functions and power spectral densities of the Stokes parameters in a polarization speckle pattern

“…Just as the intensity autocorrelation has been widely adopted to measure the coarseness of a scalar speckle pattern [8][9][10], so, too, will the autocorrelation functions of the Stokes parameters provide means for measuring the polarization-related spatial structure for polarization speckle. As for the correlations between the Stokes parameters, there is a great deal of previous work in the literature that is pertinent to this subject, including the covariance matrix of instantaneous Stokes parameters [11], the polarization time and length [12,13], and experimental investigation of the Stokes autocorrelations and their applications [6,[14][15][16][17]. More relevant recent work is that of Kuebel and Visser [18], where the autocorrelations and crosscorrelations between all the Stokes parameters have been given in terms of the cross-spectral density matrix for the study of polarization-resolved Hanbury Brown-Twiss effect.…”

Structuring Stokes correlation functions using vector-vortex beam

“…In the speckle field, the first order field correlations or second order field (intensity) correlations are extensively studied. In this article, we focus on structuring less known second order correlation functions, such as spatial Stokes correlation functions [27,28].…”