Seven air-core fibers with germanium-doped high-index rings supporting hundreds of OAM modes

Abstract

In this paper, we propose and design a multi-orbital-angular-momentum multi-ring air-core fiber, which has seven high-index rings with each ring supporting 62 radially fundamental OAM modes across C and L bands (from 1530 nm to 1625 nm), i.e. 434 OAM modes in total. The designed fiber features >4×10−4 intra-ring modal indices difference for OAM modes with the same topological charge l in a ring across the C and L bands. Moreover, it can keep <−52 dB crosstalk between the OAM modes in the adjacent rings at 1550 nm, and <−24 dB crosstalk across C and L bands after 100-km fiber propagation. This kind of seven-air-core-ring fiber would be a robust candidate for transmitting efficient OAM modes and boosting the capacity of optical fiber communications systems.

Silica microstructured optical fiber with centralized inclusion of seven GeO2-doped capillaries and induced twisting. Part I: fabrication of pilot samples

“…SDM x MDM) technique. There is a set of known earlier on published works [7][8][9][10][11] , concerned with simulation and mode analysis of described complicated fiber optic structures with seven 7,8 , nineteen 9,10 and even thirty seven 11 HRCs. A logical continuation of those theoretical approach, proposed in work 12 by the same group of authors [6][7][8][9][10] , was to combine multi-HRC basis with MOF.…”

“…There is a set of known earlier on published works [7][8][9][10][11] , concerned with simulation and mode analysis of described complicated fiber optic structures with seven 7,8 , nineteen 9,10 and even thirty seven 11 HRCs. A logical continuation of those theoretical approach, proposed in work 12 by the same group of authors [6][7][8][9][10] , was to combine multi-HRC basis with MOF. Here 19-HRC MOF (where each HRC is designed as complicated silica MOF with non-equal holes to achieve desired mentioned above great difference between refractive indexes) was proposed and analyzed: here according to simulation results, it supports 684 channels in total.…”

Terahertz fiber with multi-concentric ring cores for OAM modes propagation

“…MDM employs different spatial modes to transmit independent information streams synchronously [2,4]. In general, the subsets of MDM including linearly polarized (LP) modes and orbital angular momentum (OAM) modes can be adopted for MDM [5,6]. LP modes are relatively easy to generate, but are composed of eigenmodes having distinct propagation constant, which lead to mode walk-off during transmission, resulting in large intra-modal dispersion and highly distorted mode profile.…”

“…However, the previous reports of OAM mode multiplexing in multi-core fiber are in optical or radio frequency rather than THz band, which does not maximize the capacity owing to the lacking of the spectra expanding [5,6,[10][11][12][13][14][15]. Moreover, the fibers for THz OAM transmission have rarely been reported and are all featured single-core with few numbers of channels and relatively narrow operating bandwidth, hence limited capacity enlargement [16][17][18][19][20][21][22].…”