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Optimizing the subcarrier granularity of coherent optical communications systems
1Department of Electrical & Computer Systems Engineering, Monash University, Clayton, VIC 3800, Australia.
Optics Express
|June 7, 2011
Summary
Lower symbol rates optimize performance in long-haul coherent optical communication systems. Numerical simulations reveal that decreasing symbol rates enhances nonlinearity-limited performance, crucial for maximizing spectral efficiency in optical networks.
Area of Science:
- Optical Communications
- Nonlinear Optics
- Signal Processing
Background:
- Coherent optical communication systems face performance limitations due to nonlinearity.
- Spectral efficiency is often maximized using orthogonal subcarriers.
Purpose of the Study:
- To investigate the impact of symbol rate on nonlinearity-limited performance in coherent optical systems.
- To determine optimal symbol rates for varying link lengths.
Main Methods:
- Numerical simulations of coherent optical communication systems.
- Analysis of systems with orthogonal subcarriers at symbol rates from 0.78125 Gbaud to 100 Gbaud.
- Simulation of links up to 3200 km without inline dispersion compensation.
Main Results:
- Optimal symbol rates were found to be 6.25 Gbaud for an 800-km link and 3.125 Gbaud for a 3200-km link.
- Optimal symbol rate decreases with increasing link length.
- The 100-Gbaud system showed the worst performance after 3200 km, with a 2.4-dB lower received Q compared to the 3.125-Gbaud system.
Conclusions:
- Symbol rate significantly affects nonlinearity-limited performance in coherent optical systems.
- Optimal performance in long, nonlinear dispersive optical links is achieved by using multiple subcarriers at lower symbol rates, not high symbol rates.
- Cross-Phase-Modulation (XPM) theory explains the observed performance variations.
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