title: Self-imaging of orbital angular momentum (OAM) modes in rectangular multimode interference waveguides.
abstract: We study the propagation of orbital angular momentum (OAM) modes in rectangular multimode waveguides. Due to the multimode interference effect, an OAM mode input forms self-images at certain propagation distances. As OAM modes can be decomposed as the superposition of a pair of quarter-wave phase-shifted even and odd modes, their symmetry properties lead to two different self-imaging categories - forming the OAM-maintaining and the field-splitting self-images. We analyze these phenomena using multimode interference theory, and establish the rules governing the OAM-maintaining self-imaging, which allows the multi-mode interference waveguides to be used as OAM mode splitters and couplers.
authors.forename: Zelin
authors.initials: Z
authors.lastname: Ma
authors.forename: Hui
authors.initials: H
authors.lastname: Chen
authors.forename: Kaiyi
authors.initials: K
authors.lastname: Wu
authors.forename: Yanfeng
authors.initials: Y
authors.lastname: Zhang
authors.forename: Yujie
authors.initials: Y
authors.lastname: Chen
authors.forename: Siyuan
authors.initials: S
authors.lastname: Yu