28 GBd PAM-8 transmission over a 100 nm range using an InP-Si₃N₄ based integrated dual tunable laser module.

Area of Science:

• Photonics and Optical Communications
• Semiconductor Lasers
• Data Center Technologies

Background:

• Short-reach data center interconnects require high-performance light sources.
• Advanced modulation formats like 8-level pulse amplitude modulation (PAM-8) demand lasers with low noise and wide tunability.
• Existing laser technologies may face limitations in meeting these stringent requirements.

Purpose of the Study:

• To characterize a novel hybrid-coupled InP-Si3N4 dual laser module.
• To evaluate its performance in a short-reach data center transmission system using PAM-8 modulation.
• To compare its performance against commercial external cavity lasers (ECLs).

Main Methods:

• Detailed characterization of the InP-Si3N4 dual laser module, focusing on relative intensity noise (RIN) and wavelength tunability.
• Deployment of the laser in an unamplified 28 GBd PAM-8 transmission system.
• Experimental evaluation of system performance using bit error ratio (BER) measurements.

Main Results:

• The novel laser module exhibits a low RIN of -165 dB/Hz and 100 nm wavelength tunability.
• The laser successfully supports PAM-8 transmission across the 100 nm tuning range with minimal receiver sensitivity variation (<1 dB).
• The proposed laser outperforms a commercial ECL in an intensity modulation/direct detection (IM/DD) link.

Conclusions:

• The InP-Si3N4 dual laser module is a promising light source for advanced modulation short-reach data center systems.
• Low RIN and wide tunability are critical for the successful implementation of PAM-8 in data centers.
• This hybrid laser technology offers a competitive alternative to existing solutions for high-speed optical interconnects.