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Orbital angular momentum exchange in cylindrical-lens mode converters

2002; IOP Publishing; Volume: 4; Issue: 2 Linguagem: Inglês

10.1088/1464-4266/4/2/362

1741-3575

Miles J. Padgett, L.J. Allen,

Cold Atom Physics and Bose-Einstein Condensates

Cylindrical-lens mode converters (Beijersbergen M W, Allen L, van der Veen H E L O and Woerdman J P 1993 Opt. Commun. 96 123-32) are used to transform between Hermite-Gaussian and Laguerre-Gaussian modes with a resulting transfer of angular momentum to the light beam and a corresponding torque on the lenses. By numerically analysing both the total and local angular momentum of the light beam, we explain the origin of this torque and confirm that is not evenly distributed between the lenses. We also confirm that any vortex contained within the beam may change sign even when the orbital angular momentum of the beam remains constant.