Paraxial propagation of a class of Bessel-correlated fields.

Atri Halder,Jari Turunen,Henri Partanen,Matias Koivurova

doi:10.1364/oe.26.011055

Abstract

The propagation of a novel class of paraxial spatially partially coherent beams exhibiting Bessel-type correlations is studied in free space and in paraxial optical systems. We show that, under certain conditions, such beams can have functionally identical forms of the absolute value of the complex degree of spatial coherence not only at the source plane and in the far zone, but also at all finite propagation distances. Under these conditions the degree of spatial coherence properties of the field is a shape-invariant quantity, but the spatial intensity distribution is only approximately shape-invariant. The main properties of this class of model beams are demonstrated experimentally by passing a coherent Gaussian beam through a rotating wedge and measuring the coherence of the ensuing beams with a Young-type interferometer realized with a digital micromirror device.

Highlights

Spatially coherent model sources and light beams generated by them have attracted a great deal of interest over the past few decades
Apart from classical Gaussian Schell-model (GSM) sources and beams [1], a large number of fields with more unconventional correlation properties have been introduced and demonstrated, which exhibit a wide variety of interesting propagation properties and applications [2,3,4]
We have recently introduced a class of Bessel-correlated fields, which can be generated by simple experimental techniques: passing a coherent light beam through a rotating tilted glass plate or wedge [22]

Summary

Introduction

Spatially coherent model sources and light beams generated by them have attracted a great deal of interest over the past few decades. These include standard GSM fields, which can be thought of as superpositions of either laser modes [13,14,15] or ‘elementary’ spatially or angularly displaced Gaussian beams [16,17,18] Such superpositions can lead to spatially partially coherent fields with anisotropic shape-invariant intensity distributions extending from the source plane to the far zone, which is not possible with fully coherent fields [19]. Under certain conditions the cross-spectral density function at the source plane and the angular correlation function were found to have the same functional form In this sense the fields introduced in [22, 23], behave like self-Fourier-transforming fields.

Source model

Propagation in free space

Propagation of self-Fourier-transforming fields

Propagation in paraxial systems

Experimental verification

Conclusions