Photonic-Assisted Scheme for Simultaneous Self-Interference Cancellation, Fiber Dispersion Immunity, and...

Area of Science:

• Photonics and Optical Communications
• Integrated Optics
• Signal Processing

Background:

• Self-interference in optical systems degrades signal quality and limits transmission range.
• Traditional methods for self-interference cancellation often suffer from fiber dispersion effects.
• High-frequency local oscillation (LO) sources are typically required for frequency down-conversion, posing practical challenges.

Purpose of the Study:

• To propose and validate a photonic approach for self-interference cancellation with inherent fiber dispersion immunity.
• To introduce a harmonic frequency down-conversion technique that alleviates the need for stringent LO source requirements.
• To demonstrate effective signal recovery and performance under various conditions in optical communication systems.

Main Methods:

• Utilizing an integrated dual-parallel, dual-drive Mach-Zehnder modulator (DP-DMZM) for optical interference cancellation.
• Employing a second dual-drive Mach-Zehnder modulator (DMZM) for carrier-suppressed, LO-modulated, high-order double optical sidebands.
• Regulating the DC bias of the main modulator for down-conversion to the intermediate frequency (IF) band.

Main Results:

• Successful cancellation of 2 GHz self-interference noise and recovery of a 500 MHz signal after 10 km fiber transmission.
• Demonstrated immunity to fiber-dispersion-induced power-fading (DIPF) and improved frequency-conversion efficiency.
• Achieved a 6 dB improvement in frequency conversion gain compared to previous methods.

Conclusions:

• The proposed photonic scheme offers a compact and cost-effective solution for wideband self-interference cancellation.
• The method effectively recovers desired signals and compensates for fiber dispersion effects.
• This approach is highly suitable for long-range optical signal transmission and weak signal recovery.