Fabrication and Characterization of a Mode-selective 45-Mode Spatial Multiplexer based on Multi-Plane Light Conversion

Abstract

Space Division Multiplexing (SMD) is a very attractive technique for addressing the ever-growing demands in transmission capacity by enabling the use of a new parameter -space -to increase the number of channels in multi-mode fibers. One key component to build a spatially multiplexed-based optical network is a spatial multiplexer and demultiplexer combining signals from multiple single-mode fibers into as many channels in a multi-mode fiber. In this article, we report the fabrication and characterization of a pair of 45-mode spatial multiplexer and demultiplexer saturating all the modes of a standard 50 µm core graded-index (OM2) multi-mode fiber. The multiplexers are based on Multi-Plane Light Conversion (MPLC), a technique that enables the control of the transverse shape of the light by multiple reflections on specifically designed phase plates. We show that by using a separable variable basis of modes, such as Hermite-Gaussian (HG) modes, we are able to drastically reduce the number of reflections hence reducing the insertion losses and modal crosstalks. The multiplexers typically show an average 4 dB insertion loss and -28 dB cross-talk across the C band. Finally, we emphasize the use of this higher-order modes multiplexer to explore the propagation properties inside multi-mode fibers and more specifically the mode group crosstalks as well as the impact of fiber bending.

Coherent combining of 7 fiber lasers using a multi-plane light converter device

“…An MPLC used in the reverse direction implements the demultiplexing operation. In previous work, the fabrication and characterization of multiplexers with up to 45 modes has been demonstrated 8 . Moreover, this technology is particularly suitable for combining incoherent beams to combine a large number of beams while keeping M2 low 9 .…”

On the Performance of Digital Back Propagation in Spatial Multiplexing Systems

“…Currently, performance is mainly limited by prototype components MDL [31] and by fiber IM-NL interactions [32,33]. But given the continuous improvement of mode/core multiplexers [34][35][36][37][38] the impact of IM-NL will become dominant. Here we demonstrate the applicability of digital back propagation (DBP) to address the IM-NL penalties in SDM systems.…”

Simulation of nonlinear signal propagation in multimode fibers on multi-GPU systems

“…[1] Recently, the utilization of 45 spatial modes in a multimode fiber as individual transmission channels was demonstrated for the first time [2]. With the availability of mode multiplexers for 45 Hermite-Gaussian modes [3,4], and to potentially excite even more modes [5], the investigation of MDM systems supporting a large mode count is getting more and more rele-vant. During the design process of fiber optic transmission systems, numerical simulations are the common choice to study different system aspects.…”