Propagation characteristics of partially coherent decentred annular beams propagating through oceanic turbulence

Abstract

The analytical expressions for the average intensity and the centroid position of partially coherent decentred annular beams propagating through oceanic turbulence are derived, and the propagation equation of the position of the maximum intensity is also given. Changes of the average intensity, the centroid position and the position of the maximum intensity of partially coherent decentred annular beams during propagation are studied in detail. It is shown that both in free space and in oceanic turbulence, the position of the maximum intensity moves to the propagation z-axis with increasing the propagation distance, and is kept unchanged when the propagation distance is large enough. Furthermore, in free space the position of the maximum intensity is closer to the propagation z-axis than to the centroid position when the propagation distance is large enough. The position of the maximum intensity is closer to the propagation z-axis with increasing the correlation parameter, and far from the propagation z-axis with increasing the decentered parameter and the obscure ratio. However, in oceanic turbulence the position of the maximum intensity is close to the centroid position when the propagation distance is large enough, and the evolution is speeded with increasing the strength of oceanic turbulence. The influence of the beam coherence on propagation characteristics decreases due to oceanic turbulence. On the other hand, the centroid position is independent of the beam coherence, the propagation distance and the oceanic turbulence. The centroid position is far from the propagation z-axis with increasing the decentered parameter and the obscure ratio. In addition, the hollow core of partially coherent decentred annular beams is filled up as the propagation distance increases, and the evolution is speeded with increasing the strength of oceanic turbulence. The results obtained in this paper are very useful for applications of partially coherent decentred annular beams in oceanic turbulence.