Abstract
In this paper, we propose and design a Ge-doped air-core ring fiber, which can support a large amount of OAM modes for mode-division multiplexing (MDM) in optical fiber communications. By varying the mole fraction of GeO2 and adjusting the structure parameter, including the air-core radius and the GeO2-doped ring width, we investigate the influence of different fiber parameters on the total supported OAM mode number. The hollow silica fiber with a 50- $\mu \text{m}$ air core and a 1.5- $\mu \text{m}$ thickness of Ge-doped ring is designed in simulation to support fiber eigenmodes up to HE112,1 and EH107,1. This provides 436 OAM modes at 1550 nm while maintaining radially single mode condition. Moreover, it can support more than 400 radially fundamental OAM modes for the wavelength from 1460 nm to 1625 nm, covering entire S, C and L bands. The optical parameters of the guided OAM modes in the fiber are also numerically analyzed, including effect of material loss, optical field distribution, effective refractive index profile and chromatic dispersion, etc. The simulation results show that the higher-order OAM modes have longer $2\pi $ and 10-ps walk-off length in the air-core ring fiber with ellipticity or bending compared with low-order modes.
Highlights
Orbital angular momentum (OAM) beams associated with azimuthal phase dependence of the complex electric field have gained tremendous interest in recent years
The results show that this design could ensure the large effective index difference between the adjacent modes, improving the stability of the OAM modes transmission
We found that numerous OAM modes would be provided across S, C, and L-band for the designed fiber with r1 = 50 μm and 100 mol.% fractions of GeO2 in the single-mode condition of radial direction, which linearly decrease with wavelength and reach the minimum to about 400 at 1625 nm
Summary
Orbital angular momentum (OAM) beams associated with azimuthal phase dependence of the complex electric field have gained tremendous interest in recent years. It can potentially facilitate a variety of applications, such as micromanipulation [1], [2], imaging [3], [4], laser material processing [5], [6] and sensing [7], [8]. The amount of 2lπ phase shift that occurs in the azimuthal direction represents different states or modes, which are orthogonal to each other while propagating coaxially They are completely independent to other multiplexing dimensions, The associate editor coordinating the review of this manuscript and approving it for publication was Maged Abdullah Esmail. OAM modes couple less than LP modes do, lessening the need for MIMO processing [18]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
