8-λ LAN-WDM TOSA for 800-Gb/s links with simplified, non-hermetic packaging.

Area of Science:

• Optoelectronics
• Optical Communications
• Photonics Packaging

Background:

• High-speed optical communication systems require advanced transmitter optical subassemblies (TOSAs).
• Traditional TOSAs often use hermetic packaging, increasing costs and complexity.
• There is a need for cost-effective and manufacturable TOSAs for 800 Gb/s data rates.

Purpose of the Study:

• To develop and demonstrate an 8-wavelength local-area-network wavelength-division-multiplexing (LAN-WDM) TOSA for 800 Gb/s operation.
• To improve cost-effectiveness and manufacturability through a non-hermetic package design.
• To validate the performance of the TOSA for medium-reach intensity-modulated/direct-detect (IM/DD) applications.

Main Methods:

• Utilized an epoxy-sealed, non-hermetic package to reduce manufacturing costs.
• Implemented a ball-lens alignment scheme to simplify the packaging process and reduce alignment complexity.
• Employed a single thermoelectric cooler (TEC) for locking all eight wavelengths to the LAN-WDM grid.
• Integrated series DC-blocking capacitors in the electro-absorption-modulated laser (EML) radio-frequency (RF) path to reduce heat load.

Main Results:

• Achieved 800 Gb/s operation using 53.125-Gbaud PAM4 modulation across 8 wavelengths.
• Demonstrated clear eye diagrams with Transmitter and Dispersion Eye Closure for PAM4 (TDECQ) ≤ 3.0 dB and outer extinction ratio (ER) ≥ 3.7 dB for all lanes.
• Obtained per-lane receiver sensitivities ranging from -11.2 dBm to -7.7 dBm after 20-km transmission at a Bit Error Rate (BER) of 2.4 × 10^-4.
• Reduced TEC input power by 16.1% (from 1.294 W to 1.086 W) due to reduced heat load.

Conclusions:

• The proposed non-hermetic 8-λ TOSA is a viable solution for 800 Gb/s IM/DD deployments.
• The design enables reliable optical communication over distances of 10 km and beyond, demonstrated up to 20 km.
• The cost-effective packaging and improved thermal management contribute to the feasibility of next-generation high-speed networks.