Theoretical And Experimental Study On The Generation And Propagation Of Partially Coherent Anomalous Hollow Beams

Partially coherent beams have been attracted more and more attention in theoretical and experimental study due to the wide applications in optical imaging, laser scanning, free space optical communications, nonlinear optics, materials processing and other fields. As one of the dark hollow beams, anomalous hollow beam has been widely studied in particle trapping, laser communication and other fields due to its special property. So based on the important value of partially coherent beams and anomalous hollow beams, in this paper we generated partially coherent anomalous hollow beams and studied the propagation properties in free space in experiment and theory. At the same time, due to the importance and wide application of the uniaxial crystal, we also studied the propagation properties of partially coherent anomalous hollow beam in uniaxial crystal in theory. The main work of this paper is divided into two parts:First, the fully coherent anomalous hollow beam is extended to the partially coherent case. Analytical propagation formulae for a partially coherent anomalous hollow beam passing through a paraxial ABCD optical system are derived. The partially coherent anomalous hollow beams were generated in experiment. The propagation properties of the partially coherent anomalous hollow beams passing through a focusing system were studied in theory and experiment. We studied the influence of the initial coherent width on the propagation properties of the partially coherent anomalous hollow beam. Therefore, we can modulate the intensity distribution of the laser beam by changing the initial coherent width of the beam.Second, based on the widely applications of uniaxial crystals in optical fiber polarizer, optical compensator, optical switch and other kinds of photoelectric devices, we studied the propagation properties of partially coherent anomalous hollow beam in uniaxial crystals. We obtained the analytical formulae for partially coherent anomalous hollow beams in uniaxial crystals. Then, paraxial propagation properties of partially coherent anomalous hollow beams in uniaxial crystals orthogonal to the optical axis were investigated. We mainly focused on the influence of the initial coherent width and crystal parameters on the propagation properties. The propagation properties of partially coherent anomalous hollow beams in uniaxial crystals and in free space are studied numerically. It is found that the propagation properties of partially coherent anomalous hollow beams in uniaxial crystals are very different from those in free space and are closely determined by the parameters of the uniaxial crystals and the initial coherence width. This provides an important guidance for future research of laser beam propagation in uniaxial crystals.