Probing higher OAM of LG beams via diffraction through translated single slit

Abstract: Laguerre-Gaussian (LG) beams carry orbital angular momentum (OAM) as a consequence of a singularity in their phase profile. In this work, we probe the OAM of LG beams using a movable single slit. We invoke the method of stationary phase to determine the resulting diffraction pattern for different topological charges, observe how these patterns changes when the slit is moved transversely and show that by looking at the resulting diffraction pattern for different slit positions, we can determine the orbital angular momentum of the incoming beam. Using a digital micromirror device (DMD) as a dynamic slit, we were able to access higher $\ell$ that were not possible in previous works involving slit diffraction. Our results are valuable in the study of OAM specially for beams where the current technology for detection is not yet mature, for example, beams whose wavelengths are in the terahertz regime or beams of higher energy such as, electron vortex beams.