A stressed fiber-optic waveguide is used to impart orbital angular momentum to a Hermite–Gaussian (HG<sub>10</sub>) laser mode. The transmitted beam has an annular intensity profile and a well-defined azimuthal phase dependence. We confirm the phase structure of the beam by observing the interference pattern produced between it and a plane wave. The transfer of the angular momentum to the light occurs because of a difference in phase velocity within the fiber for two orthogonal modes that comprise the input beam. This represents a mechanism for the transfer of orbital angular momentum to a light beam that has not hitherto been identified.
© 1998 Optical Society of America
David McGloin, Neil B. Simpson, and Miles J. Padgett, "Transfer of Orbital Angular Momentum from a Stressed Fiber-Optic Waveguide to a Light Beam," Appl. Opt. 37, 469-472 (1998)