Security optimization of synchronization in DFB lasers under constant-amplitude random-phase drive light by reducing...

Area of Science:

• Optics and Photonics
• Quantum Information Science
• Secure Communications

Background:

• Laser synchronization is crucial for high-speed physical key distribution.
• Constant-amplitude and random-phase (CARP) light was proposed to reduce intensity correlation in laser synchronization.
• The phase correlation between CARP light and laser response remains unexamined.

Purpose of the Study:

• To numerically investigate the phase-intensity correlation in CARP light-induced laser synchronization.
• To analyze the impact of various parameters on this correlation.
• To propose methods for enhancing the security of physical key distribution systems.

Main Methods:

• Numerical simulations were employed to analyze laser synchronization dynamics.
• The correlation coefficient between CARP light phase and response laser intensity (CC_R-φD) was calculated.
• System parameters including optical frequency detuning, modulation depth, noise bandwidth, and transparent carrier density were systematically varied.

Main Results:

• A significant phase-intensity correlation (CC_R-φD ≈ 0.6) was numerically revealed.
• Optimization of optical frequency, modulation depth, and noise bandwidth reduced CC_R-φD to 0.32, 0.18, and 0.10, respectively.
• Further reduction in CC_R-φD was achieved through secondary parameter optimization and increasing transparent carrier density.

Conclusions:

• CARP light exhibits non-negligible phase-intensity correlation in laser synchronization.
• Parameter optimization is effective in mitigating this correlation, enhancing system security.
• This study provides critical insights for improving the security of physical key distribution based on laser synchronization.