Digital pre-distortion for mitigating modulation nonlinearity in dually modulated EML optical SSB transmitters

Area of Science:

• Optical communications
• Photonics
• Signal processing

Background:

• Dual modulation of electro-absorption modulation lasers (D-EMLs) offers a compact optical single sideband (SSB) transmitter.
• Nonlinear distortions from cascade modulation degrade D-EML signal quality.

Purpose of the Study:

• To mitigate modulation nonlinearity in D-EML transmitters.
• To enhance signal quality and fiber chromatic dispersion tolerance for optical SSB signals.

Main Methods:

• Implementation of digital pre-distortion (DPD) technique.
• Experimental demonstration using a 56-Gb/s optical SSB transmission system.

Main Results:

• Significant improvements in signal-to-noise ratio (SNR) and bit error rate (BER).
• Demonstrated enhanced tolerance against fiber chromatic dispersion.
• Achieved power budget enhancements of ~1.1 dB and ~2.3 dB compared to conventional SSB signals.

Conclusions:

• DPD is an effective method to combat nonlinearity in D-EML transmitters.
• The proposed scheme enhances optical SSB signal performance for high-speed transmission.
• DPD improves system robustness and power budget for optical communication systems.