Generation of continuously tuneable fractional optical orbital angular momentum using internal conical diffraction
DONEGAN, JOHN FRANCIS
LUNNEY, JAMES GERARD
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Citation:D. O'Dwyer, C. Phelan, Y. Rakovich, P. R. Eastham, J. G. Lunney and J. F. Donegan, Generation of continuously tuneable fractional optical orbital angular momentum using internal conical diffraction, Optics Express, 18, 16, 2010, 16480 16485
Abstract: When a left-circularly polarised Gaussian light beam, which has spin angular momentum (SAM) Jsp = ?? = 1? per photon, is incident along one of the optic axes of a slab of biaxial crystal it undergoes internal conical diffraction and propagates as a hollow cone of light in the crystal. The emergent beam is a superposition of equal amplitude zero and first order Bessel like beams. The zero order beam is left-circularly polarised with zero orbital angular momentum (OAM) Jorb = ?? = 0, while the first order beam is right-circularly polarized but carries OAM of Jorb = 1? per photon. Thus, taken together the two beams have zero SAM and Jorb = ?? per photon. In this paper we examine internal conical diffraction of an elliptically polarised beam, which has fractional SAM, and demonstrate an all-optical process for the generation light beams with fractional OAM up to ? 1?
Science Foundation Ireland
Series/Report no:Optics Express