Mode Vector Modulation: Extending Stokes Vector Modulation to Higher Dimensions
Jarosław Kwapisz, I. Roudas, Eric Fink
Abstract
We examine the scalability of Stokes vector modulation (SVM) to higher-dimensional Stokes spaces in order to decrease the energy consumption of optical links. We propose and study mode vector modulation (MVM), a new multidimensional SVM scheme for transmission over multimode/multicore optical fibers or free-space modes. MVM can be demodulated using a digital polarimetric direct-detection (DD) receiver that is an extension of the original single-mode Stokes vector receiver to multimode links. This paper focuses on the MVM transceiver architecture, the back-to-back performance of optically-preamplified DD MVM receivers, the optimized geometric shaping of the MVM constellation, and the related bit-to-symbol mapping. We show that MVM DD outperforms conventional single-mode, direct-detection-compliant, digital modulation formats by several dB in terms of receiver sensitivity and the SNR gain increases with the number of spatial degrees of freedom (SDOFs) <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$N$</tex-math></inline-formula> . At the conclusion of the study, we consider the potential application of MVM as a substitute for <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$M$</tex-math></inline-formula> -ary pulse amplitude modulation ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$M$</tex-math></inline-formula> -PAM) or <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$M$</tex-math></inline-formula> -SVM in short-haul optical links and evaluate its benefits and drawbacks.