nonlinear impact of diverse optical routing in uncompensated 120 gb/s pm-qpsk links

Steven Searcy and Sorin Tibuleac ADVA Optical Networking, Norcross, GA, USA 14 October 2014

Nonlinear Impact of Diverse Optical Routing in Uncompensated 120 Gb/s PM-QPSK Links

IEEE Photonics Conference 2014, paper TuF1.4 2 2

• Assessing transmission performance for DWDM systems

• Common assumption in analyzing system performance (esp. nonlinear effects) is that all channels co-propagate over entire link

• Many deployed point-to-point systems match this configuration

Introduction & Motivation

Purely Point-to-Point

System (No Add/Drop)


• Assessing transmission performance for DWDM systems

• Common assumption in analyzing system performance (esp. nonlinear effects) is that all channels co-propagate over entire link

• Many deployed point-to-point systems match this configuration

• However, many deployed systems have a substantial degree of add/drop traffic and may behave differently investigate this scenario

Introduction & Motivation

Network with Add/Drop traffic at

ROADM nodes along path


• Changes in add/drop conditions have been shown to have substantial impact on nonlinear tolerance in CD-compensated 10G systems; effect is strongly dependent on residual CD

Dispersion compensated systems

Figure from [3] T. Zami, et al., Proc. ECOC 2009, paper 1.5.2


• Nonlinear performance in uncompensated system often analyzed based on assumption of Gaussian nonlinear noise [1]

• These underlying conditions are not always met with frequent add/drop

• Add channels may have zero initial CD if originating at Add node, or some positive CD accumulated on a different path in mesh network

Dispersion uncompensated systems

Figure from [5] F. Vacondio, et al., Opt. Express 20(2), 2012.


Experimental configuration

• Commercial 120 Gb/s PM-QPSK transceiver with real-time DSP

• Recirculating Loop with all-EDFA amplification, four spans TrueWave-RS fiber, WSS every two spans for optional add/drop


Test conditions

• 19x100G channels on 50 GHz grid (test channel + 18 neighbors)

• 50GHz channel slots adjacent to test channel are left empty, to eliminate filtering on test channel in all cases optical filtering may produce

complex interactions with nonlinear effects [4] (left for further study)

• Four different test cases:

• A: No Add/Drop (all channels co-propagate)

• B: Add/Drop all neighbors every 4 spans

• C: Add/Drop all neighbors every 2 spans

• C-PD: same as C, with Add channels pre-dispersed • Initially passed through 1 span of ULAF (~2000 ps/nm pre-dispersion)


Nonlinear OSNR Penalty results

• Baseline case—no add/drop, all channels co-propagate



• ~0.75-1.0 dB nonlinear benefit (@1 dB OSNR penalty) from Add/Drop of all neighbors every 4 spans



• ~1.0-1.25 dB benefit from Add/Drop of all neighbors every 2 spans More frequent add/drop only produces incremental improvement (0.25dB)



• Pre-dispersion on add signals greatly reduces nonlinear benefit Higher input CD degrades NL tolerance, esp. on NZ-DSF [1,5,6]


• Nonlinear benefit from frequent add/drop up to 1.25 dB shown

for add/drop of all neighbors every 2 spans

• Much of the add/drop nonlinear benefit is due to reduced PAPR when add signals have zero initial CD

• Topics for further study

• Behavior with combined nonlinearity and optical filtering

• Filtering penalty will at least partially offset nonlinear benefit?

• Behavior with other fiber types besides NZ-DSF

• Less impact from pre-dispersion over higher-dispersion fiber? (e.g. SSMF)

• Other modulation formats

• Mixed QPSK-OOK networks?

• Next-gen 16QAM/8QAM?

Conclusions

[email protected]

Thank You

Questions?


• [1] P. Poggiolini, G. Bosco, A. Carena, V. Curri, Y. Jiang, and F. Forghieri, “The GN-Model of Fiber Non-Linear Propagation and its Applications,” J. Lightwave Technol. 32(4), pp. 694–721, February 2014.

• [2] T. Zami, A. Morea, and N. Brogard, “Impact of routing on the transmission performance in a partially transparent optical network,” Proc. OFC/NFOEC, paper JThA50 (2008).

• [3] T. Zami, P. Henri, L. Lorcy, and C. Simonneau, “Impact of the optical routing on the transmission in transparent networks,” Proc. ECOC, paper 1.5.2 (2009).

• [4] Y. Ye, G. Goeger, E. Zhou, S. Zhang, and X. Xu, “Interplay of Filtering and Nonlinear Transmission in Coherent Uncompensated DWDM System,” Proc. OFC/NFOEC, paper OM3B.4 (2013).

• [5] F. Vacondio, O. Rival, C. Simonneau, E. Grellier, A. Bononi, L. Lorcy, J.-C. Antona, and S. Bigo, “On nonlinear distortions of highly dispersive optical coherent sytsems,” Opt. Express 20(2), p. 1022-1032, Jan. 2012.

• [6] X. Liu and S. Chandrasekhar, “Experimental Study of the Impact of Dispersion on PDM-QPSK and PDM-16QAM Performance in Inhomogeneous Fiber Transmission,” Proc. ECOC, paper P.4.17 (2013).

• [7] S. Searcy and S. Tibuleac, “Impact of Channel Add/Drop on Nonlinear Performance in Uncompensated 100G Coherent Systems,” submitted to OFC 2015.

References

nonlinear impact of diverse optical routing in uncompensated 120 gb/s pm-qpsk links

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