Measurement of light's orbital angular momentum

Lavery, Martin P.J. (2013) Measurement of light's orbital angular momentum. PhD thesis, University of Glasgow.

Abstract

The desire to increase the amount of information that can be encoded onto a single photon has driven research in many areas of optics. One such area is the study of the orbital angular momentum (OAM) carried by a light beam. These beams have helical phase-fronts and carry an orbital angular momentum of l_hbar per photon, where the integer l is unbounded, giving a large state space in which to encode information. In the work that follows I discuss the development of new methods to measure the OAM carried by a light beam. An adaptation of a previously outlined interferometric technique is presented, resulting in a compact, robust measurement tool while dramatically reducing the number of degrees of freedom required for alignment. A new approach to sorting OAM is discussed, inspired by the simple example of the discrimination of plane waves focussed by a lens within direction space. This new approach is a telescopic system comprising two bespoke optical elements that transform OAM states into transverse momentum states; the various stages of development are outlined. Further to the development of this technique, investigations into the effects of misalignment and atmospheric turbulence on a communication link are presented. Outwith the area of optical communications, it is shown that by analysing the orbital angular momentum of light scattered from a spinning object we can observe a frequency shift many times greater than the rotation rate.

• Item Type: Thesis (PhD)
• Qualification Level: Doctoral
• Keywords: Orbital Angular Momentum, Optics, Optical Communications, Remote Sensing
• Subjects: Q Science > QC Physics
• Colleges/Schools: College of Science and Engineering > School of Physics and Astronomy
• Supervisor's Name: Padgett, Prof. Miles J.
• Date of Award: 2013
• Depositing User: Dr Martin Lavery
• Unique ID: glathesis:2013-4716
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 23 Dec 2013 15:44
• Last Modified: 17 Apr 2023 07:58
• Thesis DOI: 10.5525/gla.thesis.4716
• URI: https://theses.gla.ac.uk/id/eprint/4716