Multichannel nonlinear distortion compensation using optical phase conjugation in a silicon nanowire

Area of Science:

• Photonics
• Optical Communications
• Nonlinear Optics

Background:

• Nonlinear distortion, particularly the Kerr effect, limits performance in high-speed wavelength-division multiplexing (WDM) systems.
• Optical phase conjugation (OPC) is a technique to mitigate nonlinear impairments in optical fiber transmission.
• Silicon photonics offers potential for compact and efficient nonlinear optical devices.

Purpose of the Study:

• To experimentally demonstrate nonlinear compensation in a 32-Gbaud quadrature phase-shift keying (QPSK) WDM system.
• To investigate the use of optical phase conjugation (OPC) generated in a silicon nanowire for nonlinear distortion mitigation.
• To evaluate the performance improvement and analyze the impact of OSNR degradation.

Main Methods:

• Utilizing a 7-mm silicon nanowire to generate OPC via four-wave mixing (FWM).
• Implementing the OPC module in an 800-km WDM transmission system operating at 32-Gbaud QPSK.
• Comparing system performance (Q-factor) with and without the OPC module under high span input power.
• Analyzing the influence of OSNR degradation by testing systems of varying lengths.

Main Results:

• A significant improvement in Q-factor was observed after 800-km transmission when using the silicon nanowire-based OPC module.
• The system demonstrated effective compensation of Kerr effect-induced nonlinear distortion.
• Analysis confirmed the trade-off between nonlinear compensation and OSNR degradation introduced by the silicon nanowire.

Conclusions:

• This study presents the first experimental demonstration of nonlinear compensation using a silicon nanowire.
• Silicon nanowire-based OPC is a viable method for mitigating nonlinear impairments in high-speed WDM systems.
• Further optimization is needed to minimize OSNR degradation while maximizing nonlinear compensation benefits.