Long-distance coherent secure communication network based on synchronized chaotic semiconductor lasers.

Area of Science:

• Optoelectronics
• Secure Communications
• Nonlinear Dynamics

Background:

• Chaos synchronization in semiconductor lasers offers potential for secure communication.
• Fiber optic transmission faces challenges from chromatic dispersion and nonlinear effects.
• Existing secure communication methods require robust signal processing for long-haul transmission.

Purpose of the Study:

• To propose and numerically investigate a long-distance coherent secure communication network.
• To enhance chaotic signal properties for improved communication security and performance.
• To demonstrate high-capacity data transmission over extended fiber optic links.

Main Methods:

• Utilizing a synchronized chaotic semiconductor laser with optical feedback, dispersion, and phase modulation.
• Employing coherent detection and the modified constant modulus algorithm (MCMA) for signal compensation.
• Numerical simulation of bidirectional 16-quadrature amplitude modulation (16-QAM) transmission.

Main Results:

• Achieved high-quality chaos synchronization between a central driving laser (CDL) and response lasers (RLs).
• Demonstrated bidirectional 64 Gb/s 16-QAM message transmission over 800 km.
• Maintained a bit-error rate (BER) below the hard-decision forward-error-correction threshold (3.8×10^-3).

Conclusions:

• The proposed scheme effectively enables long-distance secure communication using synchronized chaotic lasers.
• Coherent detection and MCMA successfully mitigate fiber impairments for high-speed transmission.
• The system shows robust performance under various transmission conditions and parameter mismatches.