Determining orbital angular momentum of light by analyzing interferogram with conjoined fork-like structures

摘要

Light beam with helical wavefront carries well-defined orbital angular momentum (OAM) specified by its topological charge (TC). The off-axis self-interference of laterally displaced vortex beams results into interferogram consisting of pair of fork-like structures. In this study, it has been demonstrated that the interferogram consisting of conjoined fork-like structures allow simpler and unambiguous way of determining the sign and magnitude of TC carried by incoming vortex beam using interferogram analysis method. The method uses a Mach-Zehnder interferometer to introduce lateral displacement and tilt angles between the interfering beams.