Two-Channel OTDM System for Data-Center Interconnects: A Review.

Area of Science:

• Optoelectronics
• Optical Communications
• Integrated Photonics

Background:

• High-speed data-center interconnects (>100 Gb/s) are crucial for modern computing infrastructure.
• Conventional four-channel optical time-division multiplexing (OTDM) systems require expensive narrow pulses.
• Advances in photonics-integrated circuits (PICs) enable practical implementation of integrated transmitters.

Purpose of the Study:

• To review the current research status of two-channel OTDM systems for data-center interconnects.
• To discuss future research directions for cost-effective high-speed optical communication.
• To demonstrate the feasibility of achieving 200 Gb/s transmission with wide pulses and multilevel modulation.

Main Methods:

• Implementation of a two-channel OTDM system utilizing multilevel pulse-amplitude modulation (PAM).
• Generation of wide pulses using a single modulator for cost-effectiveness.
• Utilizing phase-alternating pulses to enhance robustness against chromatic dispersion.

Main Results:

• Demonstrated generation of 200 Gb/s signals using modulators with a modest 17.2 GHz bandwidth.
• Achieved transmission of 200 Gb/s 4-level PAM signals over 1.9 km of standard single-mode fiber.
• The two-channel system offers a cost-effective alternative to conventional four-channel OTDM systems.

Conclusions:

• The two-channel OTDM system with multilevel PAM is a promising solution for future >100 Gb/s data-center interconnects.
• The use of wide pulses and phase-alternating techniques significantly reduces system costs and improves dispersion tolerance.
• Further research in PICs and modulation schemes can pave the way for practical, high-capacity optical communication systems.