interchannel nonlinearities in polarization-multiplexed transmission marcus winter klaus petermann...
TRANSCRIPT
Interchannel Nonlinearities in Polarization-Multiplexed Transmission
Marcus WinterKlaus Petermann
Hochfrequenztechnik-Photonik
TECHNISCHEUNIVERSITÄTBERLIN
Dario Setti
http://www.marcuswinter.de/publications/ecoc2009
TECHNISCHEUNIVERSITÄTBERLIN
ECOC 2009 – Tu.10.3.4
cross-phase modulation (XPM)and
cross-polarization modulation (XPolM)
TECHNISCHEUNIVERSITÄTBERLIN
ECOC 2009 – Tu.10.3.4
XPolM is similar to XPM
nonlinear variation of the
birefringence refractive index
proportional to sum of interfering channel
Stokes vectors powers
results in the modulation of signal
polarization phase
TECHNISCHEUNIVERSITÄTBERLIN
ECOC 2009 – Tu.10.3.4
XPolM – where and what?
TECHNISCHEUNIVERSITÄTBERLIN
ECOC 2009 – Tu.10.3.4
systems with large XPM impairment are affected(e.g. selective 10G 40G/100G upgrades)
fully polarized signal becomes depolarized
TECHNISCHEUNIVERSITÄTBERLIN
ECOC 2009 – Tu.10.3.4
depolarization can be visualized on the Poincaré sphere
quantified by nonlinear DOP reduction
XPolM model exists to predict this magnitude*
* Winter et al., JLT 17 (27), p. 3739, 2009.
TECHNISCHEUNIVERSITÄTBERLIN
ECOC 2009 – Tu.10.3.4
impairments in PolDM systems
TECHNISCHEUNIVERSITÄTBERLIN
ECOC 2009 – Tu.10.3.4
single-polarization Tx is replaced by PolDM Tx
Rx signal processing can follow PMD changes, but not XPolM
TECHNISCHEUNIVERSITÄTBERLIN
ECOC 2009 – Tu.10.3.4
Rx polarization misalignment generates crosstalk between PolDM subchannels
statistically, crosstalk depends only on the degree of polarization and the source amplitude
TECHNISCHEUNIVERSITÄTBERLIN
ECOC 2009 – Tu.10.3.4
interleaving RZ-shaped symbols minimizes crosstalk amplitude at target sampling instant
even with interleaving, the crosstalk is never zero, but significantly smaller
due to signal distortions, noise, etc.
TECHNISCHEUNIVERSITÄTBERLIN
ECOC 2009 – Tu.10.3.4
system simulations
TECHNISCHEUNIVERSITÄTBERLIN
ECOC 2009 – Tu.10.3.4
nonlinear threshold of the NRZ interferers is reduced by 2dB due to XPolM
(1dB when interleaving is used)
10 × 10G NRZ interferers w/ 25Gbaud PolDM-RZ-QPSK probe
TECHNISCHEUNIVERSITÄTBERLIN
ECOC 2009 – Tu.10.3.4
mean values ► individual distribution
TECHNISCHEUNIVERSITÄTBERLIN
ECOC 2009 – Tu.10.3.4
ROSNR penalties at 4 dBm NRZ power (mean DOP = 0.961)
TECHNISCHEUNIVERSITÄTBERLIN
ECOC 2009 – Tu.10.3.4
ROSNR penalties at 3 dBm NRZ power (mean DOP = 0.975)
TECHNISCHEUNIVERSITÄTBERLIN
ECOC 2009 – Tu.10.3.4
ROSNR penalties at 2 dBm NRZ power (mean DOP = 0.984)
at 2 dBm, fluctuations become comparable toXPM-related spread at 4 dBm
(3 dBm when interleaving is used)
TECHNISCHEUNIVERSITÄTBERLIN
ECOC 2009 – Tu.10.3.4
summary
TECHNISCHEUNIVERSITÄTBERLIN
ECOC 2009 – Tu.10.3.4
XPolM-induced depolarization leads to crosstalk between PolDM subchannels
interleaving the subchannels can significantly reduce the crosstalk penalty (but not eliminate it)
the mean nonlinear DOP reduction for 25 Gbaud PolDM-RZ-QPSK should not exceed 0.98
the resulting 10G NRZ interferer NLT penalty is up to2 dB over XPM alone