Orbital angular momentum sidebands of vortex beams transmitted through a thin metamaterial slab

A pure vortex beam carrying m-order orbital angular momentum (OAM) will be deformed when transmitting through a thin slab, and neighboring sideband {m + 1} and {m-1} modes will emerge. The emergence of the OAM sideband is accompanied with OAM-dependent Goos-Hanchen (GH) shift. When the energies carried by the {m} mode of the transmitted beam and by the sideband modes are identical, the OAM-dependent shifts reach their upper limits, vertical bar m vertical bar w(0)/2(vertical bar m vertical bar + 1)1/2, where w(0) is the incident beam waist. The epsilon-nearzero metamaterial is found to be suitable to achieve the upper-limited OAM-dependent GH shifts. These findings provide a deeper insight into the beam shifts of vortex beams and have potential applications in the optical sensing, detection of OAM, and other OAM-based applications. (C) 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement