Measuring the photonic topological charge of power-exponent-phase vortex beam via cross phase

Abstract

We propose a method for measuring the photonic topological charge of the power-exponent-phase vortex (PEPV) beam with the cross phase. Based on the superimposition of the power-exponent phase and the cross phase, we analyzed the axial diffraction properties of the modulated PEPV beam with different parameters by using the scalar diffraction theory. The simulations demonstrated that dark regions are embedded in the intensity profile of the modulated PEPV beam, and the number of the dark regions is just equal to the photonic topological charge carried by the PEPV beam. Moreover, the sign of the photonic topological charge can be distinguished by the alignment direction of the modulated PEPV light field. The experimental results are consistent with the theoretical ones. The method is promising in the fields of beam shaping and optical trapping.