Open AccessSensitivity penalty induced by non-ideal dual polarization downconverter in digital coherent receivers
Author(s) -
P. J. Reyes-Iglesias,
Í. Molina-Fernández,
Alejandro OrtegaMoñux
Publication year - 2015
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.23.012784
Subject(s) - computer science , dual polarization interferometry , performance metric , extinction ratio , phase shift keying , polarization (electrochemistry) , electronic engineering , optics , sensitivity (control systems) , physics , bit error rate , telecommunications , decoding methods , engineering , wavelength , chemistry , management , antenna (radio) , economics
The implementation agreement of the Optical Internet Forum for a dual polarization (DP) I/Q downconverter defines strict requirements for the phase diversity network, resulting in a negligible penalty, but does not specify the extinction ratio (ER) of the polarization beam splitters (PBS) on which the polarization diversity network is based. We propose a novel metric, based on the Frobenius norm of the Jones receiver matrix, to accurately estimate the sensitivity penalty from receiver non-idealities, stablishing a precise interface for hardware specification. Results will be numerically verified for the reception of 112 Gbps DP-QPSK signals in a realistic receiver scenario with subsequent state-of-art DSP algorithms. The proposed metric highlights the benefits of the polarization diversity scheme based on two PBS, compared to the common alternative based on a PBS and a BS, as it achieves an improvement in the receiver sensitivity of at least 3 dB for the same ER. Furthermore, this paper shows than the sensitivity penalty is negligible for an ER higher than 16 dB and that it less than 2 dB for an ER of 8 dB. These results can have an important impact in monolithically integrated DP downconverters in which practical integration of PBS with high ER is still challenging.