Fiber nonlinearity compensation for OFDM super-channels using optical phase conjugation

Area of Science:

• Optical Communications
• Nonlinear Optics
• Signal Processing

Background:

• Fiber nonlinearity poses a significant challenge in high-capacity optical communication systems.
• Optical Orthogonal Frequency Division Multiplexing (OFDM) super-channels are susceptible to nonlinear impairments.
• Optical Phase Conjugation (OPC) is a technique explored for mitigating nonlinear effects.

Purpose of the Study:

• To experimentally demonstrate the effectiveness of mid-link OPC in compensating fiber nonlinearity.
• To evaluate the impact of OPC on the nonlinear threshold and overall performance of coherent optical OFDM super-channels.
• To investigate methods for reducing noise associated with OPC modules.

Main Methods:

• Implementation of mid-link OPC using pump × subcarrier degenerate four-wave-mixing (FWM) in a highly nonlinear fiber.
• Testing a 10 × 80-km, 604.7-Gb/s 16-QAM coherent optical OFDM super-channel system.
• Analysis of nonlinear threshold improvement and system performance penalties.

Main Results:

• A 4.8 dB increase in the nonlinear threshold was achieved for the tested super-channel system.
• A minor 0.2 dB performance improvement was observed at the optimum power.
• A 1.6 dB penalty was measured for the back-to-back system due to the OPC module.

Conclusions:

• Mid-link OPC is a viable method for effectively compensating fiber nonlinearity in coherent optical OFDM super-channels.
• Further optimization of OPC modules, such as increasing pump power, can mitigate associated penalties and improve back-to-back performance.
• The study highlights the potential of OPC for enhancing the capacity and reach of future optical networks.