O-band quantum-dot mode-locked laser frequency comb for terabit optical transport

Area of Science:

• Photonics and Optical Communications
• Semiconductor Lasers
• High-Speed Data Transmission

Background:

• The exponential growth in data traffic necessitates higher bandwidth solutions for data centers.
• Existing IEEE standards (800 GbE, 1.6 TbE) leverage multi-lane aggregation of 100 Gbps lanes.
• Semiconductor mode-locked lasers (MLLs) offer a promising path for energy-efficient, multi-lane optical sources.

Purpose of the Study:

• To demonstrate the capability of an O-band InAs/InGaAs quantum dot mode-locked laser (QD-MLL) for high-capacity data transmission.
• To evaluate the performance of the QD-MLL in transmitting advanced modulation formats like PAM4 and PAM8.
• To assess the feasibility of using QD-MLLs for terabit-scale wavelength division multiplexing (WDM) systems.

Main Methods:

• Utilized an O-band InAs/InGaAs QD-MLL as the optical source.
• Transmitted 14×100 Gbps Pulse Amplitude Modulation 4-level (PAM4) and 10×100 Gbps probabilistically shaped PAM8 signals over 10 km of single-mode fiber (SMF).
• Demonstrated 128 Gbps On-Off Keying (OOK) signal transmission using four QD-MLL lines spaced at 160 GHz with multichannel amplification.

Main Results:

• Achieved successful transmission of 14×100 Gbps PAM4 and 10×100 Gbps PAM8 signals with low energy consumption (∼284 fJ/bit).
• Demonstrated 128 Gbps/λ OOK transmission with a single booster amplifier for multichannel amplification.
• Confirmed that ≥1 Tbps and 512 Gbps WDM signals meet standard Forward Error Correction (FEC) limits using pre- and booster semiconductor optical amplifiers.

Conclusions:

• The QD-MLL is a viable and energy-efficient optical source for enabling next-generation high-capacity data transmission systems.
• The demonstrated performance supports the development of future 800 GbE and 1.6 TbE standards.
• Quantum dot lasers offer a scalable solution for cost-effective, high-density optical interconnects.