Elliptical-Core Highly Nonlinear Few-Mode Fiber Based OXC for WDM-MDM Networks

• Published in: IEEE journal of selected topics in quantum electronics Vol. 27; no. 2; p. 1
• Main Authors: Jitao, Gao, Nazemosadat, Elham, Yang, Yi, Fu, Songnian, Tang, Ming, Schroeder, Jochen, Karlsson, Magnus, Andrekson, Peter
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.03.2021; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: C band; Conversion; Few-mode fiber; Four-wave mixing; Frequency conversion; Germanium; Intermodal; Linear polarization; Networks; nonlinear fiber optics; Nonlinear optics; Optical communication; optical cross-connect; Optical fiber networks; Optical fibers; Optical pumping; optical signal processing; Optical wavelength conversion; Quadrature amplitude modulation; Refractivity; Signal processing; Switching theory; Wave division multiplexing; Wavelength division multiplexing
• ISSN: 1077-260X; 1558-4542; 1558-4542
• DOI: 10.1109/JSTQE.2020.3012405

In order to realize an optical cross-connect (OXC) converting wavelengths and spatial modes into one-dimensional switching ports, we propose an active mode selective conversion without parasitic wavelength conversion, based on the intermodal four-wave mixing (FWM) arising in a few-mode fiber (FMF). First, we design a dispersion-engineered elliptical-core highly nonlinear FMF (e-HNL-FMF) with a graded refractive index (RI) profile, which can independently guide 3 linearly polarized (LP) spatial modes. Meanwhile, a high doping concentration of germanium in the core leads to relatively high intermodal nonlinear coefficients of 3.23 (Wkm)-1 between LP01 and LP11a modes and 3.14 (Wkm)-1 between LP01 and LP11b modes. Next, we propose an e-HNL-FMF based OXC scheme for wavelength division multiplexing-mode division multiplexing (WDM-MDM) networks. After optimizing both the e-HNL-FMF length and pump power, we can realize either active mode selective conversion over the designated wavelength-band or three-wavelength to three-mode superchannel conversion for 100 Gbaud 16-quadratic-amplitude modulation (16-QAM) signals over the C-band. Due to excellent characteristics of the e-HNL-FMF, both cost and configuration complexity of the OXC can be reduced, showing great potentials for all-optical signal processing in the future WDM-MDM networks.