Partially coherent sources with radial coherence are proposed. They present a circularly symmetric intensity profile and a degree of coherence whose absolute value only depends on the angular difference between the two considered points. In particular, the source is completely coherent at pairs of points belonging to the same radius. The modal structure of such sources is determined in the general case, and conditions are derived under which the field propagated in paraxial approximation remains radially coherent at any transverse plane. In such cases, the angular dependence of the correlation function is preserved upon propagation, although the intensity profile generally changes. An example of this kind of source has been experimentally synthesized by means of a simple setup, and its coherence characteristics have been tested by means of a Young interferometer.
Piquero, G., Santarsiero, M., Martínez-Herrero, R., De Sande, J.C.G., Alonzo, M., Gori, F. (2018). Partially coherent sources with radial coherence. OPTICS LETTERS, 43(10), 2376-2379 [10.1364/OL.43.002376].