title: Arbitrarily tunable orbital angular momentum of photons.
abstract: Orbital angular momentum (OAM) of photons, as a new fundamental degree of freedom, has excited a great diversity of interest, because of a variety of emerging applications. Arbitrarily tunable OAM has gained much attention, but its creation remains still a tremendous challenge. We demonstrate the realization of well-controlled arbitrarily tunable OAM in both theory and experiment. We present the concept of general OAM, which extends the OAM carried by the scalar vortex field to the OAM carried by the azimuthally varying polarized vector field. The arbitrarily tunable OAM we presented has the same characteristics as the well-defined integer OAM: intrinsic OAM, uniform local OAM and intensity ring, and propagation stability. The arbitrarily tunable OAM has unique natures: it is allowed to be flexibly tailored and the radius of the focusing ring can have various choices for a desired OAM, which are of great significance to the benefit of surprising applications of the arbitrary OAM.
authors.affiliation: MOE Key Laboratory of Weak Light Nonlinear Photonics and School of Physics, Nankai University, Tianjin 300071, China.
authors.forename: Yue
authors.initials: Y
authors.lastname: Pan
authors.affiliation: MOE Key Laboratory of Weak Light Nonlinear Photonics and School of Physics, Nankai University, Tianjin 300071, China.
authors.forename: Xu-Zhen
authors.initials: XZ
authors.lastname: Gao
authors.affiliation: MOE Key Laboratory of Weak Light Nonlinear Photonics and School of Physics, Nankai University, Tianjin 300071, China.
authors.forename: Zhi-Cheng
authors.initials: ZC
authors.lastname: Ren
authors.affiliation: MOE Key Laboratory of Weak Light Nonlinear Photonics and School of Physics, Nankai University, Tianjin 300071, China.
authors.forename: Xi-Lin
authors.initials: XL
authors.lastname: Wang
authors.affiliation: MOE Key Laboratory of Weak Light Nonlinear Photonics and School of Physics, Nankai University, Tianjin 300071, China.
authors.forename: Chenghou
authors.initials: C
authors.lastname: Tu
authors.affiliation: MOE Key Laboratory of Weak Light Nonlinear Photonics and School of Physics, Nankai University, Tianjin 300071, China.
authors.forename: Yongnan
authors.initials: Y
authors.lastname: Li
authors.affiliation: MOE Key Laboratory of Weak Light Nonlinear Photonics and School of Physics, Nankai University, Tianjin 300071, China.|National Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093, China.|Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China.
authors.forename: Hui-Tian
authors.initials: HT
authors.lastname: Wang