Abstract
Long-haul optical fiber communication employing digital signal processing (DSP)-based dispersion compensation can be distorted by the phenomenon of equalization-enhanced phase noise (EEPN), due to the reciprocities between the dispersion compensation unit and the local oscillator (LO) laser phase noise (LPN). The impact of EEPN scales increases with the increase of the fiber dispersion, laser linewidths, symbol rates, signal bandwidths, and the order of modulation formats. In this work, the phase noise cancellation (PNC) employing a radio frequency (RF) pilot tone in coherent optical transmission systems has been investigated. A 28-Gsym/s QPSK optical transmission system with a significant EEPN has been implemented, where the carrier phase recovery (CPR) was realized using the one-tap normalized least-mean-square (NLMS) estimation and the differential phase detection (DPD), respectively. It is shown that the RF pilot tone can entirely eliminate the LPN and efficiently suppress the EEPN when it is applied prior to the CPR.
Highlights
Long-haul optical communication is seriously deteriorated by transmission impairments, e.g., chromatic dispersion (CD), polarization mode dispersion (PMD), laser phase noise (LPN), and Kerr fiber nonlinearities [1,2]
The results show canfully be fully removed and the can bealso effectively suppressed, when the radio frequency (RF) the pilot scheme is applied prior toprior the carrier phase recovery (CPR)
Interactions will degrade interplayswith withthethe dispersion compensation component in and EDCtheand the interactions will the performance of the optical communication system
Summary
Long-haul optical communication is seriously deteriorated by transmission impairments, e.g., chromatic dispersion (CD), polarization mode dispersion (PMD), laser phase noise (LPN), and Kerr fiber nonlinearities [1,2]. Is induced and from the local oscillator (LO), a phenomenon of equalization enhanced phase noise (EEPN) is induced plays a significant role in the carrier phase recovery (CPR). The performance of an orthogonally polarized RF pilot tone scheme is investigated for eliminating both the LPN and the EEPN in long-haul. The LPN from the transmitter (Tx) laser passes through the optical fiber andand the the dispersion compensation the CD net CD experienced by Tx theLPN. LPN interplays dispersion compensation component in EDC interactions will degrade interplayswith withthethe dispersion compensation component in and EDCtheand the interactions will the performance of the optical communication system This effect is called [10,11,12,13]. [22,23]
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