A Device to Measure the Orbital Angular Momentum of a Beam of Light
Yaagnik Kosuri, Herricks High School, New Hyde Park, NY; Harold Metcalf and John Noe, Laser Teaching Center, Department of Physics and Astronomy, Stony Brook UniversityTransverse laser modes with helical wave fronts carry with them the interesting property of orbital angular momentum. It is known that transverse laser modes carry with them angular momentum that can be expressed as the sum of two discreet vectors, spin angular momentum and orbital angular momentum. Unlike spin angular momentum, there is no limit to the number of orbital angular momentum states that can be occupied. Therefore, the orbital angular momentum state of a single photon is a piece of information. This device sorts a beam of light with a definite orbital angular momentum by interfering a beam with its rotated image. In essence, it extracts the single piece of information that can be encoded on one photon.