Seren Juno and Ribbon completed a 20Tbps transmission trial across the 10,000 km JUNO trans-Pacific submarine cable, marking a major step for ultra-long-haul optical capacity. JUNO, which connects Japan and the U.S., is designed to deliver more than 350Tbps across 20 fiber pairs, positioning it as the largest trans-Pacific system once fully deployed.
The field trial used Ribbon’s Apollo 9408 transponder with 5nm 140GBaud optics and the Apollo 9608 platform, which integrates submarine-grade optical line-system functions. The system supported modulation rates from 400Gbps to 1.2Tbps per wavelength, enabling capacity tuning to the unique conditions of trans-Pacific spans. The performance demonstrates that 20Tbps per fiber pair is viable over 10,000 km—an unusually long distance for this throughput class.
Ribbon says the results rival recent demonstrations from leading submarine-optical vendors. According to Sam Bucci, Ribbon’s EVP and COO, “Our Apollo platform’s ability to deliver 20Tbps over 10,000 km showcases the scalability and robustness of Ribbon’s technology for next-generation global connectivity.” Seren Juno CEO Yoshio Sato added that the results strengthen the company’s view that this technology could become a strategic option for JUNO’s final configuration.
• 20Tbps transmission achieved over JUNO’s 10,000 km route
• JUNO designed for 350Tbps total capacity across 20 fiber pairs
• Trial featured Ribbon Apollo 9408 (5nm, 140GBaud) and Apollo 9608 submarine line system
• Modulation range: 400Gbps–1.2Tbps per wavelength
• JUNO expected to be the largest trans-Pacific cable between Japan and the U.S.
🌐 Analysis
This milestone reinforces competitive pressure in high-end submarine optics, where vendors are pushing toward higher baud rates, probabilistic constellation shaping, and optimized subsea DSP for 20Tbps-class performance. The trial aligns Ribbon with recent high-capacity demonstrations from Infinera, Ciena, and NEC. For Seren Juno, the results validate design decisions as the system moves toward construction and full commercial deployment, where operators demand both high spectral efficiency and long-haul resilience.
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