Phase noise influence in coherent optical DnPSK systems with DSP based dispersion compensation
2014 (English)In: Journal of optical communications, ISSN 0173-4911, Vol. 35, no 1, 57-61 p.Article in journal (Refereed) Published
We present a comparative study of the influence of dispersion induced phase noise for n-level PSK systems. From the analysis, we conclude that the phase noise influence for classical homodyne/heterodyne PSK systems is entirely determined by the modulation complexity (expressed in terms of constellation diagram) and the analogue demodulation format. On the other hand, the use of digital signal processing (DSP) in homodyne/intradyne systems renders a fiber length dependence originating from the generation of equalization enhanced phase noise. For future high capacity systems, high constellations must be used in order to lower the symbol rate to practically manageable speeds, and this fact puts severe requirements to the signal and local oscillator (LO) linewidths. Our results for the bit-error-rate (BER) floor caused by the phase noise influence in the case of QPSK, 16PSK and 64PSK systems outline tolerance limitations for the LO performance: 5 MHz linewidth (at 3-dB level) for 100 Gbit/s QPSK; 1 MHz for 400 Gbit/s QPSK; 0.1 MHz for 400 Gbit/s 16PSK and 1 Tbit/s 64PSK systems. This defines design constrains for the phase noise impact in distributed-feed-back (DFB) or distributed-Bragg-reflector (DBR) semiconductor lasers, that would allow moving the system capacity from 100 Gbit/s system capacity to 400 Gbit/s in 3 years (1 Tbit/s in 5 years). It is imperative at the same time to increase the analogue to digital conversion (ADC) speed such that the single quadrature symbol rate goes from today's 25 GS/s to 100 GS/s (using two samples per symbol).
Place, publisher, year, edition, pages
2014. Vol. 35, no 1, 57-61 p.
coherent systems, n-level PSK systems, phase noise
Other Physics Topics
IdentifiersURN: urn:nbn:se:kth:diva-161503DOI: 10.1515/joc-2013-0065ScopusID: 2-s2.0-84896757915OAI: oai:DiVA.org:kth-161503DiVA: diva2:794856
QC 201503132015-03-132015-03-122015-03-13Bibliographically approved