Measuring the fractional topological charge of LG beams by using interference intensity analysis

We demonstrate a method to measure the fractional topological charge (TC) of Laguerre-Gaussian (LG) beams by analyzing the interference intensity patterns between the vortex beam and its conjugate beam. By this method, the magnitude of integer and fractional TCs is quantitatively measured by using a simple unified formula. The proposed method can measure TCs up to 60.