Air-Core Ring Fiber With >1000 Radially Fundamental OAM Modes Across O, E, S, C, and L Bands

Abstract

In this work, an air-core ring fiber is designed with a record high 1322 orbital angular momentum (OAM) modes at 1550 nm while maintaining radially single-mode condition. Moreover, it can support over 1004 OAM modes across all O, E, S, C, and L bands, exploiting to our knowledge the highest number of OAM modes ever supported in the optical fiber within a wide wavelength range. Simulations show that, across the C and L bands, the fiber with 55-µm air-core radius and 0.45-µm ring width can preserve 3.3 × 10 −3 effective refraction index difference between the two highest-order OAM modes HE 340,1 and EH 271,1. This enables efficient mode separation, and thus achieving stable OAM modes transmission. The effective refractive index differences between the even and odd fiber eigenmodes are also analyzed in the elliptical and bent fibers. We note that higher-order OAM modes are more tolerant to the fiber ellipticity and bending. This ring fiber design has the potential to increase the spectral efficiency and the overall capacity in fiber-based communications system. INDEX TERMS Orbital angular momentum, fiber optics, ring fiber, multiplexing.

Hollow Ring-Core Photonic Crystal Fiber With >500 OAM Modes Over 360-nm Communications Bandwidth

“…First of all, the symmetric structure and large material refractive index, can lead to the large difference of neff between the even and odd mode of HEl+1,1 or EHl-1,1 mode of the same |l| family, which can hinder decomposition of OAM modes. Moreover, the thin-ring make it suitable for preserving OAM modes due to the similarly annular intensity profile of OAM beams [38].…”

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

“…The reach and stability of OAM mode propagation in the ring fiber can potentially provide an effective avenue for a host of different applications. In our previous research, an air-core As2S3 ring fiber is introduced for supporting numerous OAM modes [29] and OAM supercontinuum generation [30], [31], which is promising but challenging because the complex fabrication procedure. Compared to using As2S3 as high-index ring region, Ge-doped glass is more frequently used core material of telecommunication optical fiber, as its many excellent physical properties are close to silica glass.…”

Air-Core Non-Zero Dispersion-Shifted Fiber With High-Index Ring for OAM Mode

“…Over the past few years, researchers have been applying OAM MDM technology into fiber-based optical communication systems, in which ring fiber was introduced for supporting numerous OAM modes be significantly reduced modal crosstalk [10,11]. In order to further improve the transmission speed of information in the fiber-based communication system, the combination of OAM MDM and wavelength division multiplexing (WDM) technologies would be necessary [12][13][14].…”

“…Therefore, it can be a complete set of orthogonal basis functions [5]. OAM has become a popular choice among the multifarious fiber spatial modes to further achieve higher spectral efficiency and faster data capacity in the fiber-based mode-division-multiplexing (MDM) communication systems [5][6][7][8][9].Over the past few years, researchers have been applying OAM MDM technology into fiber-based optical communication systems, in which ring fiber was introduced for supporting numerous OAM modes be significantly reduced modal crosstalk [10,11]. In order to further improve the transmission speed of information in the fiber-based communication system, the combination of OAM MDM and wavelength division multiplexing (WDM) technologies would be necessary [12][13][14].…”