Henrik Eliasson

Mitigation of nonlinearities using conjugate data repetition

We investigate a time-domain implementation of generalized phase-conjugated twin waves which we call conjugate data repetition. A theory based on time-domain perturbation analysis explaining the mitigation of nonlinear effects is provided, and the concept is evaluated using numerical simulations. Compared to PM-QPSK at the same channel bit rate, the single-channel transmission reach in a conventional system with standard single-mode fiber of conjugate data repetition-QPSK is increased by approximately a factor of 2.

Mitigation of nonlinear distortion in hybrid Raman/phase-sensitive amplifier links

Hybrid systems combining distributed Raman amplification and phase-sensitive amplifiers (PSAs) are investigated in numerical simulations. We focus on the mitigation of fiber nonlinearities and the impact of the span power map which is also important in systems employing optical phase conjugation or phase-conjugated twin waves. We simulate multi-span PSA links with and without distributed Raman amplification and show that by including distributed Raman amplification, the transmission distance increases more at optimum launch power than in the linear regime. For a 5-channel WDM QPSK PSA-amplified system, we observe a transmission reach increase by a factor of 8.1 by including ideal distributed Raman amplification.

Dispersion management for nonlinearity mitigation in two-span 28 GBaud QPSK phase-sensitive amplifier links

We present an investigation of dispersion map optimization for two-span single-channel 28 GBaud QPSK transmission systems with phase-sensitive amplifiers (PSAs). In experiments, when the PSA link is operated in a highly nonlinear regime, a 1.4 dB error vector magnitude (EVM) improvement is achieved compared to a one-span optimized dispersion map link due to improved nonlinearity mitigation. The two-span optimized dispersion map of a PSA link differs from the optimized dispersion map of a dispersion managed phase-insensitive amplifier (PIA) link. Simulations show that the performance of the two-span dispersion map optimized PSA link does not improve by residual dispersion optimization. Further, by using the two-span optimized dispersion maps repeatedly in a long-haul PSA link instead of one-span optimized maps, the maximum transmission reach can be improved 1.5 times.

Comparison between coherent superposition in DSP and PSA for mitigation of nonlinearities in a single-span link

An experimental comparison is made between nonlinearity mitigation through coherent superposition optically in a phase-sensitive amplifier and electrically in DSP. The improved nonlinear tolerance is quantified in terms of EVM with high received power and sensitivity with high launch power.

Publisher Correction: Long-haul optical transmission link using low-noise phase-sensitive amplifiers

The original version of this Article incorrectly listed an affiliation of Samuel L.I. Olsson as ‘Thomas Johann Seebeck Department of Electronics, Tallinn University of Technology, Tallinn 19086, Estonia’, instead of the correct ‘Present address: Nokia Bell Labs, 791 Holmdel Road, Holmdel, NJ 07733, USA’. Similarly, Egon Astra had an incorrect affiliation of ‘Present address: Nokia Bell Labs, 791 Holmdel Road, Holmdel, NJ 07733, USA’, instead of the correct ‘Thomas Johann Seebeck Department of Electronics, Tallinn University of Technology, Tallinn 19086, Estonia’. This has been corrected in both the PDF and HTML versions of the Article.

Time-domain digital back propagation: Algorithm and finite-precision implementation aspects

We propose a nonlinear mitigation algorithm designed from an ASIC perspective, and analyze implementation aspects. Given 9 signal and 11 coefficient bits, reach is increased by 105% compared to linear compensation in single-channel 16-QAM transmission.