Open AccessOrbital-angular-momentum-preserving helical Bloch modes in twisted photonic crystal fiber
Author(s) -
X. M. Xi,
G. K. L. Wong,
Michael H. Frosz,
Fehim Babic,
Goran Ahmed,
Xin Jiang,
T. G. Euser,
P. St. J. Russell
Publication year - 2014
Publication title -
optica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.074
H-Index - 107
ISSN - 2334-2536
DOI - 10.1364/optica.1.000165
Subject(s) - angular momentum , photonic crystal fiber , photonic crystal , physics , fiber , optics , orbital angular momentum multiplexing , orbital angular momentum of light , optical fiber , materials science , classical mechanics , total angular momentum quantum number , composite material
In optical fiber telecommunications, there is much current work on the use of orbital angular momentum (OAM) modes for increasing channel capacity. Here we study the properties of a helically twisted photonic crystal fiber (PCF) that preserves the chirality of OAM modes of the same order, i.e., it inhibits scattering between an order +1 mode to an order -1 mode. This is achieved by thermally inducing a helical twist in a PCF with a novel three-bladed Y-shaped core. The effect is seen for twist periods of a few millimeters or less. We develop a novel scalar theory to analyze the properties of the twisted fiber, based on a helicoidal extension to Bloch wave theory. It yields results that are in excellent agreement with full finite element simulations. Since twisted PCFs with complex core structures can be produced in long lengths from a fiber drawing tower, they are of potential interest for increasing channel capacity in optical telecommunications, but the result is also of interest to the photonic crystal community, where a new kind of guided helical Bloch mode is sure to excite interest, and among the spin-orbit coupling community. (C) 2014 Optical Society of Americ