Modulation format dependence on transmission reach in phase-sensitively amplified fiber links.

Kovendhan Vijayan,Zonglong He,Benjamin Foo,Magnus Karlsson,Peter A Andrekson

doi:10.1364/oe.403475

Abstract

We quantify the maximum transmission reach for phase-insensitive amplifier (PIA) and phase-sensitive amplifier (PSA) links with different modulation formats and show that the maximum transmission reach increase (MTRI) when using PSAs compared to PIAs is enhanced for higher-order modulation formats. The higher-order modulation formats are more susceptible to smaller phase rotations from nonlinearities, and PSAs are efficient in mitigating these smaller phase distortions. Numerical simulations were performed for single- and multi-span PIA and PSA links with single and multiple wavelength channels. We obtain a significant enhancement in the MTRI with PSAs compared to PIAs when using higher-order modulation formats for both the single- and multi-channel systems in single- and multi-span links. We verify the enhancement with a single-span, single-channel system experiment. We also demonstrate, for the first time, a 64-QAM modulation format fiber transmission in phase-sensitively amplified link, with a 13.3-dB maximum allowable span loss increase compared to a phase-insensitively amplified link.

Highlights

The transmission reach in optical communication systems is fundamentally limited by the noise added by the optical amplifiers
We show that the maximum transmission reach increase (MTRI) is enhanced when using phase-sensitive amplifier (PSA) instead of phase-insensitive amplifier (PIA) with higher-order modulation formats numerically for single- and three-channel systems in singleand multi-span links
The allowable span loss is plotted versus the PIN for both the PIA and PSA in Fig. 7 for different modulation formats

Summary

Introduction

The transmission reach in optical communication systems is fundamentally limited by the noise added by the optical amplifiers. In fiber-optic communication systems, nonlinear distortions caused by the Kerr effect in the fiber at high powers limit the maximum power that can be launched into the fiber and the reach [1,2]. Phase-conjugated twin waves (PCTWs) [6,7] is one other technique in which the signal and conjugated copy of the signal known as idler are propagated together through the optical fiber experiencing correlated nonlinear distortions. In OPCs, the signal is phase conjugated at the center of the span, known as mid-span spectral inversion, to reverse the effects of even order dispersion and nonlinearities

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