Generalized high-order twisted partially coherent beams and their propagation characteristics

Twist phase is a nontrivial statistical phase that only exists in partially coherent fields, which makes the beam carry orbital angular momentum (OAM). In this paper, we introduce a new kind of partially coherent beams carrying high-order twist phase, named generalized high-order twisted partially coherent beams (GHTPCBs). The propagation dynamics such as the spectral density and OAM flux density propagating in free space are investigated numerically with the help of mode superposition and fast Fourier transform (FFT) algorithm. Our results show that the GHTPCBs are capable of self-focusing, and the beam spot during propagation exhibits teardrop-like or the diamond-like shape in some certain cases. Moreover, the influences of the twist order and the twist factor on the OAM flux density during propagation are also illustrated in detail. Finally, we experimentally synthesize the GHTPCBs with controllable twist phase by means of pseudo-mode superposition and measure their spectral density during propagation. The experimental results agree well with the theoretical predictions. Our studies may find applications in nonlinear optics and particle trapping.