title: Fiber coupler for generating orbital angular momentum modes.
abstract: We propose a fiber coupler consisting of a central ring and four external cores to generate up to ten orbital angular momentum (OAM) modes. Four coherent input lights are launched into the external cores and then coupled into the central ring waveguide to generate OAM modes. By changing the size of the external cores, one can selectively excite a high-order OAM mode. The quality of the generated OAM modes can be enhanced by adjusting the polarization state and the phase of input lights. We show the generation of OAM modes with odd charge numbers of -9 to +9 (i.e., 10 modes totally) with mode purity of >99% using <2 mm long fiber. This fiber coupler design can be extended to enable all-fiber spatial-mode (de)multiplexing.
authors: Department of Electrical Engineering, University of Southern California, Los Angeles, California 90089, USA. yanyan@usc.edu
authors: Yan
authors: Y
authors: Yan
authors: Jian
authors: J
authors: Wang
authors: Lin
authors: L
authors: Zhang
authors: Jeng-Yuan
authors: JY
authors: Yang
authors: Irfan M
authors: IM
authors: Fazal
authors: Nisar
authors: N
authors: Ahmed
authors: Bishara
authors: B
authors: Shamee
authors: Alan E
authors: AE
authors: Willner
authors: Kevin
authors: K
authors: Birnbaum
authors: Sam
authors: S
authors: Dolinar