Multidimensional hybrid modulations for ultra-high-speed optical transport

摘要

Systems and methods are disclosed with a spatial-domain-based multi-dimensional coded-modulation scheme that improves dramatically OSNR sensitivity and tolerance to fiber nonlinearities by using D-dimensional signal constellations, where D=2(2+M)N. The factor 2 originates from two polarizations, 2+M electrical basis functions are selected (2 in-phase/quadrature channels and M pulse-position like basis functions), and N represents the number of orbital angular momentum (OAM) states used in FMFs/MMFs. For single mode fiber applications N is 1.

主权项

1. A method for optical communications, the method comprising
a. using a 2(M+2)-dimensional signal-space for single-mode fiber applications, with two phase coordinates (I and Q) and M pulse-position like coordinates per single polarization; and b. alternatively using a D=2(2+M)N-dimensional space for few-mode fiber (FMF)/multimode fiber (MMF) applications, where the factor 2 originates from two polarizations, and N represents the number of orbital angular momentum (OAM)states used in FMF/MMF applications, wherein spectral efficiency improvement to pulse position modulation (PPM) can be expressed asSE,D-dim.SE,PPM=log2⁢LD/(M/Ts)log2⁢MPPM/(MPPM⁢/Ts)=D⁢⁢log2⁢L/Mlog2⁢MPPM⁢/MPPM, Where SE,D-dim is spectral efficiency for the D-dimensional space,
SE,PPM is spectral efficiency for the PPM,L is the number of amplitude levels per dimension,MPPM is the number of pulse-position like coordinates per polarization, andTs is a symbol duration, and wherein M and N are integers, M≧1, and N≧1.