Title: Lidar Orbital Angular Momentum Sensor
Presenting Author: Carl Weimer
Organization: Ball Aerospace & Technologies Corporation
Co-Author(s): Yongxiang Hu, Jeff Applegate, Mike Lieber, Wenbo Sun

Abstract:
A revolution in our understanding of light is occurring across optical sensing areas including optical communication, optical tweezers, adaptive optics, spectroscopy, and turbulence sensing. The revolution has been powered by 1) the recognition that all electromagnetic waves carry angular momentum not only in the form of polarization (or "spin" angular momentum SAM), but also in the form of "orbital" angular momentum (OAM), and by 2) technologies developed to manipulate this "new" degree of freedom. This field is undergoing dramatic growth as the theory, its implementation, and associated technology is developed. The overarching goal of the LOAMS effort is to apply these OAM manipulation techniques to lidars through the design of unique beam parameters and receiver angular momentum discriminators (mode sorters). One objective is to explore the possibility of controlling the beam/atmosphere interactions. A second is to provide a new method for additional rejection of sunlight. The LOAMS project will tackle these challenges by combining laboratory demonstrations, instrument modeling, and scattered-field finite-difference time-domain (FDTD) electromagnetic field numerical modeling of the interactions of beams with OAM and atmospheric constituents. The work is progressing with the first paper accepted to JQRST with the results of FDTD modeling that shows the suppression of forward scattering from Mie particles when the OAM value is non-zero, which in turn will reduce multiple scattering biases. Results on laboratory demonstration of the effect will be reported on, and the plans for the next stages.