Interplay between Raman and polarization effects in next-generation passive optical networks

Area of Science:

• Optical Network Engineering
• Telecommunications Systems
• Photonics

Background:

• Next-Generation Passive Optical Networks (NG-PON2) support multiple PON standards, including GPON and TWDM-PON, in a shared infrastructure.
• Raman scattering is a significant nonlinear effect that can cause signal impairments, particularly power depletion, in optical networks.
• Polarization Mode Dispersion (PMD) can exacerbate signal degradation in optical systems.

Purpose of the Study:

• To investigate Raman-induced impairments in NG-PON2 under a full coexistence scenario of GPON and TWDM-PON.
• To determine the optimal polarization launch strategy for TWDM-PON signals to mitigate Raman effects on GPON.
• To analyze the impact of polarization arrangements on system performance considering realistic PMD values.

Main Methods:

• Detailed analysis of Raman scattering effects in a mixed GPON and TWDM-PON environment.
• Modeling and simulation of signal propagation with varying polarization launch conditions at the transmitter.
• Evaluation of system performance based on out-of-service probability across a range of Polarization Mode Dispersion (PMD) values.

Main Results:

• Launching TWDM-PON wavelengths on alternately orthogonal polarizations was identified as the optimal strategy.
• This specific polarization arrangement significantly minimizes Raman depletion experienced by the GPON signal.
• Alternative polarization launch schemes result in a higher probability of service disruption for realistic PMD conditions.

Conclusions:

• The polarization launch configuration of TWDM-PON signals is critical for mitigating Raman impairments in NG-PON2 coexistence scenarios.
• Alternately orthogonal polarization for TWDM-PON offers the most robust solution against Raman depletion and PMD-induced degradation for GPON.
• Implementing this optimal polarization strategy enhances the reliability and performance of NG-PON2 systems.