Design of a family of ring-core fibers for OAM transmission studies

Abstract

We propose a family of ring-core fibers, designed for the transmission of OAM modes, that can be fabricated by drawing five different fibers from a single preform. This novel technique allows us to experimentally sweep design parameters and speed up the fiber design optimization process. Such a family of fibers could be used to examine system performance, but also facilitate understanding of parameter impact in the transition from design to fabrication. We present design parameters characterizing our fiber, and enumerate criteria to be satisfied. We determine targeted fiber dimensions and explain our strategy for examining a design family rather than a single fiber design. We simulate modal properties of the designed fibers, and compare the results with measurements performed on fabricated fibers.

Orbital-Angular-Momentum Polarization Mode Dispersion in Optical Fibers

“…For the other modes, there is a scaling factor |l|±1. According to (10), this scaling factor would also be transferred to g θ (z). As a result, the modal birefringence correlation length is dependent on the topological charge l: (12) where L C 0 is the birefringence correlation length of the fundamental HE 11 mode.…”

“…The other OAM fiber to be measured has a ring-shaped step-index profile, referred to as "RCF" [27]. It has an inner-ring radius of 0.97 µm and an outer-ring radius of 2.44 µm.…”

“…A variety of OAM fibers have been proposed with either solid [8]- [10] or hollow cores [11], [12]. Most of them feature a ring-shaped refractive index profile and a large index contrast between the core and cladding.…”

Amplification of 12 OAM Modes in an air-core erbium doped fiber

“…~0.25 dB) is OAM (8,1) . In comparison, the calculated DMG is about 3.1 dB when pumped by OAM (0,1) , because the OAM (0,1) pump has a much better overlap with the OAM (5,1) signal mode over the OAM (7,1) signal mode. Finally, we present the modal gain spectrum using WDM signals pumped by the OAM (8,1) mode as shown in Fig.…”

“…In the first class based on solid-core fiber designs (e.g. the vortex fiber [1] and the ring-core fiber [7]), MIMO-free transmission of low-order OAM modes over 1 km length of vortex fiber has been achieved [1]. However, solid-core fibers are typically incapable of transmitting higher-order OAM modes, because either the fiber's effective V-number is not sufficient, or the vector splitting of the higher-order OAM modes becomes small.…”