Optimized channel allocation scheme for jointly reducing four-wave mixing and Raman scattering in the DWDM-QKD system

Area of Science:

• Quantum communication
• Optical networking
• Information security

Background:

• Integrating quantum key distribution (QKD) with classical communication in optical fibers faces challenges from co-propagating signals.
• Weak quantum signals are susceptible to noise, limiting practical QKD applications.
• Four-wave mixing (FWM) and Raman noise are significant impairments in shared fiber systems.

Purpose of the Study:

• To propose and evaluate a novel scheme for simultaneous suppression of FWM and Raman noise in Wavelength Division Multiplexing (WDM) systems carrying both quantum and classical signals.
• To enhance the performance and compatibility of dense WDM-QKD (DWDM-QKD) systems with high-capacity communication networks.

Main Methods:

• Development of the joint optimized channel allocation (JOCA) scheme, which interleaves quantum and classical channels.
• Strategic placement of quantum channels based on Raman scattering spectra to minimize noise.
• Experimental noise photon measurements and simulation of secure key generation rate and transmission distance.

Main Results:

• The JOCA scheme effectively reduces impairments on quantum signals compared to single-target noise suppression methods.
• Experimental validation confirms significant noise reduction.
• Simulations demonstrate increased secure key generation rates and transmission distances.

Conclusions:

• The JOCA scheme offers a robust solution for co-existing quantum and classical signals in optical fibers.
• It improves the tolerance of DWDM-QKD systems to higher power classical signals and increased channel counts.
• This approach enhances the practical feasibility and scalability of QKD in modern communication infrastructure.