Next Generation Submarine Network – Wet Plant or Submerged Plant

Submarine networking has recently seen several technological evolutions. Recently, many new subsea announcements with make use of innovative technologies in Dry plant or Subsea terminal and Wet Plant or Submerged plant. Latest advancement in Subsea includes:

SDM cable – More fibers, More capacity

Aluminum conductor

Submarine cable is highway for data transmission. Submarine networks carry more than 99 percent of the world’s intercontinental electronic communications traffic. Submarine cables are critical infrastructure, which carries approximately more than $15 trillion worth transactions, every day.

Repeater pump farming

Smart cables – Early warning of earthquakes and tsunami  

Branching Unit ROADMs with fiber pair switching,

Deep water Interconnect – Interconnecting Submarine cables inside sea

Open cable

Open access cable

Virtualized submarine Network

Artificial intelligence and machine learning in Subsea systems 

Wet plant of submarine cable lies between the beach manholes. Equipment of Submarine cable system installed between Beach manholes. 

Wet plant components: Submarine Cables, Repeaters, Branching Units, Tilt Equalizers, OADMs, Gain Equalizers, Land Cables, Filters, and Beach Manhole

Aluminum Power Conductor Submarine

Copper conductor is one of the most expensive raw materials currently used in repeatered submarine systems to feed power to repeaters & branching units.

As per Alcatel Submarine Networks, few advantages below of using aluminum conductor 

·        A better cost-effectiveness, while maintaining a performance equal to copper;

·        A potential for higher speed of production to speed-up the delivery of new systems;

·        An enabler to achieve solutions for low direct current resistance (DCR) with higher number of fiber pairs

Reliable Submerged Repeater

·        Repeater Pump Farming

·        A series of pump lasers and EDFAs are cross connected via two-stage optical fiber couplers. This is highly complex design.

·        Pool of pumps cross connected to pool of FPs

SMART Submarine Cable

·        Submarine cable equipped with sensors for the purposes of earthquake & tsunami warning systems and climate monitoring.

·        Sensors are integrated into repeaters.

As per sources from NEC & Taiwan CWB , when an earthquake occurs in the eastern sea area of Taiwan this new system can provide an emergency warning more than 10 seconds before the actual tremor is felt on land. Moreover, a warning can be issued 20 to 30 minutes before a tsunami reaches the coastal area. As a result, this system will contribute to the enhancement of disaster prevention and mitigation capabilities. For example, public transportation systems, including MRTs (Mass Rapid Transit) and HSRs (High Speed Rail) can quickly decelerate in the event of an earthquake.

WSS ROADM Branching Units & Fiber Pair Switching Branching Units

A branching unit (BU) is a network element that splits the signal between the main trunk and the branch path and vice versa . If there are two or more cable stations,

WSS ROADM Branching Unit

·        WSS filter technology supports fully flexible, reconfigurable routing of the optical spectrum on each fiber pair.

·        This is mainly used when trunk segment and branch segment uses same fiber pair

·        Flexibility drop 25% of fiber pair capacity to branch segment or dynamically increase / decrease by means of wavelength level switching.

Branching Units with Fiber Pair Switching

Branching units with fiber pair switching allows flexibility to switch fiber pairs from trunk segment to branch segment and vice versa

SDM cable can offer more fiber pairs (16FPPs, 24FPPs, 32FPPs, 48FPPs and more ) to trunk segment and branch segment

As per google blog, Equiano will be the first subsea cable to incorporate optical switching at the fiber-pair level, rather than the traditional approach of wavelength-level switching. This greatly simplifies the allocation of cable capacity, giving us the flexibility to add and reallocate it in different locations as needed.

Space Division Multiplexing (SDM )

More fibers, More capacity. Increasing the capacity of submarine cable by adding more fiber pairs is called SDM. In the past, everyone’s goal was to maximize the amount of bandwidth per fiber pair, more wavelengths, and a higher bit rate per wavelength. Now the trend has been shifted to an emphasis on more fiber pairs in a single cable. These new cables being planned with so-called SDM.

Deep Water Interconnect

In traditional approach, two different submarine cables are interconnected to each other in cable landing station to provide onward connectivity or as a restoration during subsea cuts.

Why not, if two submarine cables can connected to each other in middle of the sea or call it as deep water interconnect. Is there any benefits? This is highly complex approach as deep research / study required in wet plant design parameters. 

This technology can be implemented in the era of open subsea cable system, where SLTE is decoupled from wet plant. Open cable enable the use of preferred SLTE and extend Submarine fiber pairs to Pop locations, located far away cable landing stations. SLTE can be installed in Pop locations.


Submarine networking has recently seen several technological evolutions in wet plant & dry plant. Innovation is necessary for responding to competition & trends, creativity and continuous improvement. 

Leave a Comment

Your email address will not be published.