EAM-based high-speed 100-km OFDM transmission featuring tolerant modulator operation enabled using SSII cancellation

Area of Science:

• Optical Communications
• Nonlinear Optics
• Signal Processing

Background:

• Orthogonal frequency-division multiplexing (OFDM) signals exhibit high peak-to-average power ratios, leading to nonlinear distortion in electroabsorption modulators (EAMs).
• Nonlinear distortion, caused by EAM nonlinearity and fiber dispersion, limits operational tolerance in optical transmission systems.
• Subcarrier-to-subcarrier intermixing interference (SSII) is a key contributor to nonlinear distortion in EAM-based OFDM systems.

Purpose of the Study:

• To develop and demonstrate a technique for compensating nonlinear distortion in EAM-based OFDM transmission systems.
• To mitigate subcarrier-to-subcarrier intermixing interference (SSII) to improve signal quality and system performance.
• To enhance the operational tolerance and optical modulation index (OMI) of OFDM signals.

Main Methods:

• Developed a technique to cancel subcarrier-to-subcarrier intermixing interference (SSII).
• Applied the SSII cancellation method to an electroabsorption modulator (EAM)-based orthogonal frequency-division multiplexing (OFDM) transmission system.
• Evaluated the impact of SSII cancellation on optical modulation index (OMI) and nonlinear distortion.

Main Results:

• Successfully cancelled subcarrier-to-subcarrier intermixing interference (SSII), reducing nonlinear distortion.
• Increased the optical modulation index (OMI) of the OFDM signal with only a minor increase in nonlinear distortion.
• Expanded the operational tolerance region for bias voltage and driving power.
• Demonstrated 50-Gbps OFDM transmission over 100-km dispersion-uncompensated single-mode fiber using a single 10-GHz EAM.

Conclusions:

• The proposed SSII cancellation technique effectively compensates for nonlinear distortion in EAM-based OFDM systems.
• The technique allows for higher optical modulation index (OMI) and improved operational tolerance, enhancing transmission performance.
• Achieved robust 50-Gbps long-haul transmission, showcasing the viability of the developed method.