title: Off-axis points encoding/decoding with orbital angular momentum spectrum.
abstract: Encoding/decoding off-axis points with discrete orbital angular momentum (OAM) modes is investigated. On-axis Laguerre-Gaussian (LG) beams are expanded into off-axis OAM spectra, with which off-axis points are encoded. The influence of the mode and the displacement of the LG beam on the spread of the OAM spectrum is analysed. The results show that not only the conventional on-axis point, but also off-axis points, can be encoded and decoded with OAM of light. This is confirmed experimentally. The analytical result here provides a solid foundation to use OAM modes to encode two-dimensional high density information for multiplexing and to analyse the effect of mis-alignment in practical OAM applications.
authors.affiliation: Centre for Photonic Devices and Sensors, University of Cambridge, 9 JJ Thomson Avenue, Cambridge CB3 0FA, UK.
authors.forename: Jiaqi
authors.initials: J
authors.lastname: Chu
authors.affiliation: Centre for Photonic Devices and Sensors, University of Cambridge, 9 JJ Thomson Avenue, Cambridge CB3 0FA, UK.
authors.forename: Daping
authors.initials: D
authors.lastname: Chu
authors.affiliation: Disney Research, Glendale, California 91201-5020, USA.
authors.forename: Quinn
authors.initials: Q
authors.lastname: Smithwitck