Abstract
We perform an experimental investigation of a maximum likelihood-based (ML-based) algorithm for bulk chromatic dispersion estimation for digital coherent receivers operating in uncompensated optical networks. We demonstrate the robustness of the method at low optical signal-to-noise ratio (OSNR) and against differential group delay (DGD) in an experiment involving 112Gbit/s polarization-division multiplexed (PDM) 16-ary quadrature amplitude modulation (16QAM) and quaternary phase-shift keying (QPSK).
Highlights
Linear impairments, in particular chromatic dispersion (CD) and polarization-mode dispersion (PMD) resulting from fiber transmission are routinely mitigated by digital signal processing (DSP) in coherent receivers
In this paper we present an experimental investigation of a method for CD estimation based on the maximum likelihood (ML) criterion [14]
The CD estimates provided by the ML-based estimator are compared against estimates obtained with the reference method implemented with default parameters (n 1⁄4 1:25; Ra 1⁄4 0:6; Rb 1⁄4 1:5; Rc 1⁄4 2) [4]
Summary
In particular chromatic dispersion (CD) and polarization-mode dispersion (PMD) resulting from fiber transmission are routinely mitigated by digital signal processing (DSP) in coherent receivers. This advancement allows for fiber-optic networks that no longer require dispersion compensating modules (DCMs) and two-stage amplification to perform reliable transmission. A conventional approach, where a coherent receiver uses a static CD filter, does no longer apply. This makes an accurate adaptive CD estimation for dispersion unmanaged coherent photonic backbones indispensable
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