All-optical differential detection for suppressing multiple-access interference in coherent time-addressed optical...

Area of Science:

• Optical Communications
• Telecommunications Engineering
• Signal Processing

Background:

• Multiple-Access Interference (MAI) is a significant challenge in optical Code Division Multiple Access (CDMA) systems, degrading signal quality.
• Coherent time-addressed optical CDMA systems require effective strategies to mitigate MAI for improved performance.
• Existing MAI suppression techniques may have limitations in terms of complexity or effectiveness.

Purpose of the Study:

• To propose and demonstrate a novel scheme for suppressing MAI in coherent time-addressed optical CDMA systems.
• To investigate the efficacy of differential detection using a dual-control nonlinear optical loop mirror (NOLM) for MAI suppression.
• To experimentally validate the proposed scheme and quantify its performance improvement.

Main Methods:

• A novel MAI suppression scheme based on differential detection utilizing a dual-control NOLM was developed.
• The fundamental principle of MAI suppression using this dual-control NOLM configuration was theoretically described.
• An experimental setup was constructed with two encoded channels, which were then decoded and processed through the dual-control NOLM.

Main Results:

• Experimental demonstration confirmed the effectiveness of the proposed scheme.
• A high autocorrelation peak with significantly suppressed MAI was observed at the output of the NOLM.
• The signal-to-interference ratio (SIR) was improved by an impressive 7 dB, indicating substantial MAI reduction.

Conclusions:

• The proposed novel scheme effectively suppresses MAI in coherent time-addressed optical CDMA systems.
• Differential detection with a dual-control NOLM offers a practical and efficient solution for enhancing optical CDMA performance.
• The experimental results validate the significant improvement in signal quality achievable with this technique.