title: Tunable orbital angular momentum generation in optical fibers.
abstract: We present a method in this Letter to generate optical vortices with tunable orbital angular momentum (OAM) in optical fibers. The tunable OAM optical vortex is produced by combining different vector modes HE2,meven (HE2,modd) and TE0,m(TM0,m) when l=1 or combining HEl+1,meven (HEl+1,modd) and EHl-1,modd (EHl-1,meven) when l>1 with a π/2 phase shift. The vortex can be regarded as a result of overlapping two orthogonal optical vortex beams of equal helicity but opposite chirality with a π/2 phase shift. We have experimentally demonstrated the smooth variation of OAM from l=-1 to l=+1 by adjusting a polarizer at the output end of the fiber.
authors.forename: Youchao
authors.initials: Y
authors.lastname: Jiang
authors.forename: Guobin
authors.initials: G
authors.lastname: Ren
authors.forename: Yudong
authors.initials: Y
authors.lastname: Lian
authors.forename: Bofeng
authors.initials: B
authors.lastname: Zhu
authors.forename: Wenxing
authors.initials: W
authors.lastname: Jin
authors.forename: Shuisheng
authors.initials: S
authors.lastname: Jian