EUGENE PARK ULTRA LONG HAUL NETWORKS
FLEXIBILITY AND SCALABILITY These modules are designed with host interfaces and power/thermal characteristics that enable them to be plugged directly into existing 400G QSFP-DD based platforms, allowing operators to leverage their current infrastructure and seamlessly upgrade capacity as needed. The ability to support a wide variety of channel plans also accommodates diverse brownfield architectures. GÉANT, the collaboration of European National Research and Education Networks, stated that this architectural shift reduces energy consumption, simplifies design, and enables faster, more cost- efficient service activation. Their trial demonstrating 400G transmission over a 3,403km terrestrial link was conducted on the GÉANT live production network in June 2025. Using commercially available technology, it represents one of the longest known reaches ever demonstrated on a terrestrial network using a 400G QSFP-DD coherent pluggable transceiver with a 24W power envelope, making it compatible with all existing 400G-capable routers. ENHANCED PERFORMANCE FEATURES • High optical transmit output power: >+1 dBm is crucial for overcoming losses in long-distance point-to-point and ROADM networks. It enables alien- wavelength insertion into brownfield amplified line systems. • Built-in tunable optical filter (TOF): The TOF helps minimize adjacent channel interference and maximise transmitter OSNR, especially critical in wavelength-agile networks with colourless ROADMs, ensuring robust performance over long reaches. • C+ L-Band Support: The inclusion of L-band transmission capability, in addition to the traditional C-band DWDM range, allows for approximately doubling network capacity without deploying additional fibre, offering a cost-effective path for future expansion. The successful Arelion and Internet2 trials underscore the significant performance, efficiency and flexibility gains for long-haul and ultra long-haul networks. VENTURING UNDER THE SEA: SUBSEA APPLICATIONS OF 400G ULH PLUGGABLES Traditionally, subsea optical links have been the exclusive domain of highly specialised, dedicated transponder systems leveraging performance optimised coherent modules due to the extreme distances, challenging
From metro DCI to long-haul terrestrial, and even subsea, these pluggables are empowering networks to go further and faster.
DEPLOYING ROUTER-BASED COHERENT OPTICS ACROSS THE NETWORK It has been exciting to see the momentum behind router-based coherent optics, particularly with the introduction of 400G ULH pluggables. These innovations have fundamentally changed how network operators design and scale their infrastructure, offering significant reductions in TCO, simplified operations, and improved power efficiency. From metro DCI to long-haul terrestrial, and even subsea, these pluggables are empowering networks to go further and faster. While dedicated
environmental conditions, and stringent performance requirements. However, the advancements in 400G ULH coherent pluggables are now extending their reach to certain subsea applications, redefining what is possible. The AARNet trial is a compelling example. They successfully demonstrated 400G ULH coherent pluggable over a 4,600km subsea route on the Indigo cable, connecting Sydney and Perth. This trial proved the ability to transmit high-speed data efficiently over existing submarine cables, highlighting the technology’s capacity to enhance network efficiency by optimising the use of available space and power at the endpoints. The 400G wavelength operated at 75 Gigabaud (GBaud) and maintained reliable, error-free performance, confirming its readiness for immediate deployment and seamless integration with existing services. This represents a transformative step, as it allows for greater capacity per rack unit (up to 6.4Tbps) and reduced power consumption, which are critical factors in subsea landing stations where space and power are at a premium. While 400G ULH pluggables are proving to be a highly efficient and cost-effective solution for a segment of subsea applications. Particularly those where IP-over-DWDM benefits are paramount and the distances fall within the demonstrated capabilities, dedicated transponders still hold an advantage for the most demanding, longest, or highly specialised subsea links. In these scenarios, ultimate optical performance, power, and comprehensive impairment management are the overriding priorities. The choice between the two depends on a careful evaluation of the specific subsea route’s length, complexity, capacity requirements, and the desired balance between total cost of ownership (TCO) optimisation and maximum performance.
transponders with performance optimised coherent solutions will
continue to play a vital role in network architectures, the expanding capabilities of coherent pluggables are charting a path towards a more agile, cost- effective, and efficient future for global connectivity.
Eugene Park, Senior Technical Marketing Manager
Eugene Park is a Senior Technical Marketing Manager with over 20 years of experience in the optical communications industry. He has held previous strategy and product management roles in various levels of the optical food chain from carrier to components. He is currently part of the Acacia marketing team.
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| ISSUE 42 | Q3 2025
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