<div style="text-align:justify;"> Error vector magnitude (EVM) as a performance metric for <em>M</em>-ary quadrature amplitude modulation (QAM) formats in optical coherent systems is presen...<div style="text-align:justify;"> Error vector magnitude (EVM) as a performance metric for <em>M</em>-ary quadrature amplitude modulation (QAM) formats in optical coherent systems is presented. It is shown that the calibrated BER, which would otherwise be under-estimated without the correction factor, can reliably monitor the performance of optical coherent systems near the target BER of 10<sup>-3</sup> for quadrature phase shift keying (QPSK), 16-QAM, and 64-QAM employing carrier phase recovery with differential decoding to compensate for laser phase noise. The impact on the number of symbols used to estimate the BER from EVM analysis is also presented and compared to the BER obtained by error counting. </div>展开更多
文摘<div style="text-align:justify;"> Error vector magnitude (EVM) as a performance metric for <em>M</em>-ary quadrature amplitude modulation (QAM) formats in optical coherent systems is presented. It is shown that the calibrated BER, which would otherwise be under-estimated without the correction factor, can reliably monitor the performance of optical coherent systems near the target BER of 10<sup>-3</sup> for quadrature phase shift keying (QPSK), 16-QAM, and 64-QAM employing carrier phase recovery with differential decoding to compensate for laser phase noise. The impact on the number of symbols used to estimate the BER from EVM analysis is also presented and compared to the BER obtained by error counting. </div>
