Equalization-enhanced phase noise for 100Gb/s transmission and beyond with coherent detection

Abstract

The probability density function and impact of equalizationenhanced phase noise (EEPN) is analytically investigated and simulated for 100 Gb/s coherent systems using electronic dispersion compensation. EEPN impairment induces both phase noise and amplitude noise with the former twice as much as the latter. The effects of transmitter phase noise on EEPN are negligible for links with residual dispersion in excess of 700 ps/nm. Optimal linear equalizer in the presence of EEPN is derived but show only marginal performance improvement, indicating that EEPN is difficult to mitigate using simple DSP techniques. In addition, the effects of EEPN on carrier recovery techniques and corresponding cycle slip probabilities are studied.

Analytical BER performance in differential n-PSK coherent transmission system influenced by equalization enhanced phase noise

“…The CD coefficient of 16 ps/nm/km is applied in all the evaluations. arises from the LO laser phase noise rather than the Tx phase noise, which is consistent with the reported analysis [18][19][20][21][22]. We can also find that the limits of the BER achieve a very good agreement with the BER floors (the dash curve) presented in our previous work [25,29].…”

“…Among these methods, the digital coherence enhancement shows the best performance [26,36], while it requires a complicated hardware implementation to measure the LO laser phase fluctuation. By contrast, EEPN does not exist in the coherent transmission systems using optical dispersion compensation, such as dispersion compensating fibers (DCFs) and dispersion compensating modules (DCMs) [18,19,22,25,37,38]. However, the management and the compensation of the fiber nonlinearities in such systems should be seriously considered.…”

“…8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 It has been demonstrated that the EEPN scales linearly with the accumulated CD, the linewidth of LO laser, and the symbol rate [18][19][20], and the variance of the additional noise due to the EEPN can be expressed as…”

“…This is because that the influence of EEPN is actually a complicated combination of enhanced phase noise, enhanced amplitude noise and time jitter, etc. [18][19][20]24,28,29], and the leading order Taylor expansion (e x ≈1+x), which ensures a conversion between the phase noise impact and the amplitude noise impact in n-PSK systems, is not accurate for a large EEPN and higher modulation formats. A higher order Taylor expansion in Eq.…”

“…However, the analysis of the phase noise in the transmitter (Tx) and the local oscillator (LO) lasers is often lumped together, and the interplay between the CD and the PN is not considered in the traditional evaluation of carrier phase estimation (including differential phase estimation). W. Shieh et al have provided the theoretical assessment to evaluate the equalization enhanced phase noise (EEPN) from the interaction between the LO phase fluctuation and the fiber dispersion [18][19][20][21]. C. Xie has investigated the impacts of CD on both the LO phase noise to amplitude noise conversion and the fiber nonlinear effects [22,23].…”