Air-Core Ring Fiber Guiding >400 Radially Fundamental OAM Modes Across S + C + L Bands

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-m air core and a 1.5-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 2π and 10-ps walk-off length in the air-core ring fiber with ellipticity or bending compared with low-order modes.INDEX TERMS Orbital angular momentum, fiber optics, ring fiber, multiplexing.

Twisted Silica Few-Mode Hollow GeO2-Doped Ring-Core Microstructured Optical Fiber

“…. 1700 nm wavelength band (HRC MOF with a total outer diameter of 116 µm, an air core diameter of 51 µm, a ring wall thickness of 1.5 µm with ∆n = 0.12 (analogue to the Schott FBG1 glass-56.7% SiO 2 , 0.35% Al 2 O 3 , 30% PbO, 4.15% Na 2 O, and 8.65% K 2 O)) [41], 22 OAM modes at λ = 1550 nm (HRC PCF with a total outer diameter of 28 µm, an air core of 11 µm, bounded by an lanthanum optical glass ring (HIKARI LaSF09) with a wall thickness of 0.1 µm and ∆n = 0.37) [42], 436 at λ = 1550 nm with 400 modes over S + C + L bands (203 µm HRC optical fiber with 100 µm hollow highly-GeO 2 -doped-ring-core under a ring wall thickness of 1.5 µm and ∆n = 0.15) [43], 874 OAM modes at λ = 1550 nm with 514 modes over almost the entire telecommunication band (62.5 µm HRC PCF with an air core of 20 µm in diameter, bounded by the As 2 S 3 -ring with a wall thickness of 0.5 µm and an extremely high ∆n = 1.00) [44], and up to 1004 OAM modes extended over the wavelength range, covering almost all ratified telecommunication bands (O, E, S, C, L), under a record-high number of 1346 OAM modes at λ = 1550 nm (62.5 µm HRC optical fiber with 20 µm air core, bounded by As 2 S 3 -ring with a wall thickness of 0.9 µm and an extremely high ∆n = 1.00) [45].…”

“…It is obvious that previously published papers, containing not only simulations, but also the main results of tests performed to successfully fabricate the designed optical fibers, are of special interest. However, in spite of the great potential for guiding and transmitting OAM modes that HRC MOFs are declared to have [1][2][3][40][41][42][43][44][45], there are not many reports presenting properties, the results of tests, and the measured data of manufactured HRC fibers. Finally, there is a set of works, prepared by the same group of authors, that demonstrates the experimentally verified stable transmission of 12 OAM modes over a C-band along a designed and fabricated HRC optical fiber with an air core diameter of 6 µm, bounded by a ring with a wall thickness of 5.25 µm, and where ∆n = 0.03 [3,[46][47][48][49], with the following enhancing the AOM mode quantity up to 28 by enlarging the air core diameter up to 19 µm under the same ring parameters [50].…”

Orbital Angular Momentum Data Transmission Using a Silicon Photonic Mode Multiplexer

“…Over the past decade, OAM fibers have been designed and fabricated where multiple orders of OAM modes have been transmitted [6][7][8][9][10][11][12]. Recently, some fiber designs have been reported supporting over 400 modes [13,14]. Although they are still on the stage of numerical analysis and the mode purity remains to be improved, they indicate the great potential of using OAM fiber for high capacity transmission.…”

Smile face array: Generating oblique incident and front output vortex beam for both TE and TM waves

“…In comparison to SAM, which usually provides limited channel [5], OAM carries more orthogonal modes and therefore bears greater channel capacity [6,7]. In recognition of this potential, OAM beams have been applied in many occasions, like radio propagation [8][9][10][11][12], fibre transmission [13][14][15], and quantum communication [16,17].…”